Name: dual-task stroop paradigm for detecting cognitive deficits in high-functioning stroke patients
Uploaded: 2022-12-16T12:50:00.000+00:00
Duration: 7 min 42 s
Description: Watch this Scientific Journal Video about Dual-Task Stroop Paradigm for Detecting Cognitive Deficits in High-Functioning Stroke Patients at JoVE.com

This study was supported by grants from the National Natural Science Foundation of China (No. 81804004, 81902281), China Postdoctoral Science Foundation (No. 2018M643207), Shenzhen Municipal Health Commission Project (No. SZBC2018005), Shenzhen Science and Technology Project (No. JCYJ20160428174825490), the General Guidance Program of Guangzhou Municipal Health and Family Planning (No. 20211A010079, 20211A011106), Guangzhou and University Foundation (No. 202102010100), Guangzhou Medical University Foundation (No. PX-66221494), Key Laboratory of Guangdong Higher Education Institutes&#160; [Grant Number: 2021KSYS009] and Guangdong Province Department of Education [Grant Number: 2021ZDZX2063].

This project was approved by the Medical Ethics Association of the Fifth Affiliated Hospital of Guangzhou Medical University (No. KY01-2020-08-06) and has been registered at the China Clinical Trial Registration Center (No. ChiCTR2000036514). Informed consent was obtained from patients for using their data in this study.
1. Recruitment
<ol>
	<li>Recruit stroke patients with stable conditions as confirmed by imaging examination-diagnosis conforms to the diagnostic criteria of cerebrovascular disease of the Chinese Medical Association Neurology Branch (2005). Choose patients with stroke at Brunnstrom stage IV21.</li>
	<li>Ensure the patients can complete basic daily activities independently. Ensure the patients are without obvious cognitive impairment and meet the following requirements: MoCA in the normal range; no unilateral neglect (Albert&#39;s Test, number of omissions &#8804;2)22; no other neurological diseases, such as language defects; and can cooperate with relevant instructions to complete this study.</li>
	<li>Ensure the subjects participate in the test voluntarily and sign an informed consent form.</li>
</ol>
2. Clinical evaluation
<ol>
	<li>Record the subject&#39;s information, including name, gender, date of birth, education level, body mass index, medical history, and medication history.</li>
	<li>Perform cognitive function assessment.
	<ol>
		<li>Perform MoCA23 on stroke patients by asking 11 questions addressing subjects&#39; attention and concentration, executive function, memory, language, visual structure skills, abstract thinking, computing, and orientation.</li>
		<li>The total score of the MoCA is 30, which is related to education level. If the subject took less than 12 years of education, add one point to the total score of MoCA. Consider a score of 26 and higher as normal23.</li>
		<li>Perform a CDR24 on the stroke patients. Collect information during structured interviews with stroke patients and their families and assess the subjects&#39; abilities in six aspects: memory, orientation, judgment and problem solving, work and social interaction, family life and personal hobby, and independent living.</li>
		<li>The highest possible score is 3. Assess the scores obtained as follows: total score = 0 indicates no dementia; total score = 0.5 indicates suspected dementia; total score = 1 indicates mild cognitive impairment; total score = 2 indicates moderate cognitive impairment; and total score = 3 indicates severe cognitive impairment24.</li>
		<li>Perform the Albert&#39;s test to detect the presence of unilateral spatial neglect (USN) in patients with stroke. Ask the subject to cross out all the lines that are placed in random orientations on a piece of paper.</li>
		<li>Present the subject with a series of 40 black lines, each about 2 cm long, randomly oriented on a sheet of white 11 in x 8.6 in size paper in six rows. Assess the presence or absence of USN, based on the number of lines left uncrossed on each side of the test sheet. If any lines are left uncrossed and more than 70% of these uncrossed lines are on the same side as the motor deficit, this indicates unilateral spatial neglect.</li>
	</ol>
	</li>
	<li>Perform motor function assessment.
	<ol>
		<li>Perform the Fugl-Meyer Assessment (FMA) on the stroke patients to assess motor function, sensation, balance, joint range of motion, and joint pain in patients with post-stroke hemiplegia. The motor domain includes items assessing movement, coordination, and the reflex actions of the shoulder, elbow, forearm, wrist, hand, hip, knee, and ankle.</li>
		<li>The motor function score ranges from 0 (hemiplegia) to 100 points (normal motor performance), divided into 66 points for the upper extremities and 34 points for the lower extremities. Assess the score as follows: 0-49 points indicate severe motor impairment; 50-84 points indicate marked motor impairment; 85-95 points indicate moderate motor impairment; and 96-99 points indicate slight motor impairment.</li>
	</ol>
	</li>
	<li>Perform balance function assessment.
	<ol>
		<li>Perform the Berg balance scale (BBS)27 on the stroke patient, with a total of 14 items from easy to difficult, including sitting balance, standing balance, body transfer, turning, and single-leg standing.</li>
		<li>Asses the scores as follows: the highest score on the scale is 56; a total score of &#60;40 points suggests a risk of falling; 0-20 points scored indicates poor balance function and that a wheelchair is required; 21-40 points scored suggests that the subject has a certain balance function and needs to walk with assistance; 41-56 points scored suggests good balance function and that the subject can walk independently28.</li>
	</ol>
	</li>
	<li>Perform risk of falling assessment.
	<ol>
		<li>Perform the timed up and go test (TUGT)29 on stroke patients. Ask the subject to stand up from the chair, walk for 3 m, turn their body, then return and sit in the chair at a comfortable speed to ensure safety. Concurrently, ask the evaluator to time the whole process from issuing the departure order to sitting in the chair.</li>
		<li>Assess the result obtained as follows: if the total time for the subject to complete TUGT &#8805;14 s, it indicates that the subject has the risk of falling29.</li>
	</ol>
	</li>
</ol>
3. Stroop task evaluations
<ol>
	<li>Perform the Stroop single task evaluation (Stroop task only; Figure 1).
	<ol>
		<li>Ask the patient to sit in a stable chair.</li>
		<li>Run the commercial stimulus presentation software and select the congruence test trials. Make a new profile for the patient. Select the congruence test trials of the Stroop task and repeat three trials.
		<ol>
			<li>Carry out the following experimental paradigm. Design the experiment with a patient rest time of 10 s and then ask the patient to perform one cognitive test with a frequency of 6 s for a total of three trials, with each trial having a 60 s stimulus + 60 s rest.</li>
			<li>Set the total duration of the experiment to 370 s (the specific process is shown in Figure 1). In the resting stage, ask the patient to relax. When the experiment is in the stimulation stage, ask the patient to perform the attention-related test, complete the task in 6 s, and complete it 10x in 60 s.</li>
		</ol>
		</li>
		<li>Ask the patients to follow the instructions for the two test trials as described below.
		<ol>
			<li>Select the congruence test trials. Click the arrow button to the left (&#8592;)&#160;as soon as possible when <img alt="Equation 1" src="/files/ftp_upload/63991/63991eq01.jpg" style="margin: auto;" /> is shown on the left of the square. Click the arrow button to the right (&#8594;) as soon as possible when <img alt="Equation 2" src="/files/ftp_upload/63991/63991eq02.jpg" style="margin: auto;" /> is shown on the right of the square.</li>
			<li>Select the incongruence test trials, which share the same step as the congruence test trials. Click the arrow button to the left (&#8592;) as soon as possible when <img alt="Equation 2" src="/files/ftp_upload/63991/63991eq02.jpg" style="margin: auto;" /> is shown on the left of the square, ignoring the meaning of the character and focusing on its position.</li>
			<li>Click the arrow button to the right (&#8594;) as soon as possible, when <img alt="Equation 1" src="/files/ftp_upload/63991/63991eq01.jpg" style="margin: auto;" /> is shown on the right of the square, ignoring the meaning of the character and focusing on its position. Finish the task, save the data, and export the data to a self-built database.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Perform the Stroop dual-task evaluation (Stroop task + balance control).
	<ol>
		<li>Ask the patient to sit on a balance ball with the therapist being responsible for the patient&#39;s protection. Let the patient complete the Stroop experimental paradigm with the steps mentioned above (steps 3.1.1.-3.1.5.).
		<ol>
			<li>When the experiment is in a resting stage, ask the patient to keep balance and relax on the balance ball as much as possible. When the experiment is in the state of stimulation, ask the patient to carry out the attention-related test while maintaining balance on the balance ball as much as possible.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
4. fNIRS evaluation
<ol>
	<li>Place 10 light sources and 12 receivers on the fNIRS test cap to correspond to this study&#39;s four regions of interest (ROIs), which include the left prefrontal cortex (LPFC), right prefrontal cortex (RPFC), left promoter cortex (LPMC), and right promoter cortex (RPMC).</li>
	<li>Preparation of the subject
	<ol>
		<li>Inform the subjects of the experimental purpose and observe the patients.</li>
		<li>Ensure the Cz site at the top of the test cap, the fourth point from the forehead to the occipital lobe on the midline of the full cap. Ensure the midpoint of the connection lies between the nasal root to the lower edge of the occipital protuberance, the intersection point of the connection from the nasal root to the occipital protuberance, or the connection between the superior auricular fossa of both ears (cymba conchae).</li>
		<li>Place the cap on the subject&#39;s head and adjust the position of the cap so that the Cz point on the subject&#39;s head coincides with the Cz point on the cap. Tighten the tie on both sides of the cap and allow the subject&#39;s ears to pierce through the gap; the front of the cap is naturally attached to the forehead, and the back is naturally attached to the occiput.</li>
	</ol>
	</li>
	<li>Acquisition and pre-acquisition
	<ol>
		<li>Open the software, select the experimental subject, and input the patients&#39; basic information. Set the sampling frequency to 11 Hz.</li>
		<li>Click the Pre-acquisition button to start pre-acquisition and calibrate the test signal. According to the signal intensity of each point displayed by the functional near-infrared spectroscopy, adjust the weak signal points by moving the cap or further exposing the scalp. When the signal intensity of each point collected by the cap tends to be stable, stop pre-collection, and click the automatic gain button. Click the Start button to collect the signal. 
		NOTE: Ensure the signal quality in acquisition and pre-acquisition as follows. The original light intensity signal curve should be stable, accompanied by a 1-2 Hz heartbeat signal fluctuation, and the value should meet the reasonable threshold set by the equipment. The intensity of the signal can be indicated by color, where a gray display signal intensity is low, yellow is good, green is excellent, and red is too strong.</li>
	</ol>
	</li>
	<li>Perform Stroop single task evaluation synchronized with fNIRS. Then, perform Stroop dual-task evaluation synchronized with fNIRS.</li>
</ol>
5. Data processing and analysis
<ol>
	<li>Process general information and clinical evaluation data of the patients.</li>
	<li>Analyze the near-infrared data using the NirSpark software package in MATLAB.
	<ol>
		<li>Perform data pre-procession.
		<ol>
			<li>Click the Exclude button to eliminate the time interval unrelated to the experiment. Click the Motion button to eliminate motion artifacts caused by physiological activities like breathing, heartbeat, pulse, etc., and involuntary activities like blinking, swallowing, etc., and convert the light intensity signal to an optical density signal.</li>
			<li>Click the Filter button to select the bandpass filter (0.01-0.2 Hz) to remove physiological and instrumental noise. Click the Hemo button to calculate the relative changes of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) according to the modified Beer-Lambert Law and convert the optical density signal into the blood oxygen concentration signal. 
			NOTE: HbO2 is more sensitive to changes between conditions than HbR, so subsequent analysis uses only HbO2 data in this study protocol.</li>
		</ol>
		</li>
		<li>General linear model (GLM) building
		<ol>
			<li>Choose HbO2 in Hemo Type as the analysis data. Click the Specification button to take seconds as the time unit and select the standard HRF type as the basis function. Then, eliminate the rest stage to establish the GLM design matrix and select the stimulus stage in the task according to the experimental design.</li>
			<li>Click the Estimation button to fit the established design matrix with the collected data. Click the View button to check out the calculated &#946; value. 
			NOTE: GLM is a linear combination of observed hemodynamic signals (dependent variable) as interesting regressions (task variable), redundant covariates (such as surface noise measured in short-range channels), and error terms.</li>
		</ol>
		</li>
		<li>Calculate the &#946; value as follows. Calculate experimental data in the ROIs by using the established linear correlation model. Obtain the GLM parameters of the required channel and derive the &#946; value of brain activation under each experimental condition (that is, the weight coefficient in the linear model) for analysis.</li>
	</ol>
	</li>
	<li>Run the commercial stimulus presentation software to export the performance data of cognitive tasks in the Stroop task and obtain the accuracy (ACC) and reaction time (RT) for final data analysis.</li>
</ol>

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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Executive+function+and+physical+function+among+community-dwelling+Egyptian+older+adults.">Executive function and physical function among community-dwelling Egyptian older adults.</a> Journal of Alzheimer's Disease. 80 (4), 1583-1589 (2021).</li><li>Al-Yahya, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prefrontal+cortex+activation+while+walking+under+dual-task+conditions+in+stroke:+A+multimodal+imaging+study.">Prefrontal cortex activation while walking under dual-task conditions in stroke: A multimodal imaging study.</a> Neurorehabilitation and Neural Repair. 30 (6), 591-599 (2016).</li><li>Matjacic, Z., Zadravec, M., Olensek, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feasibility+of+robot-based+perturbed-balance+training+during+treadmill+walking+in+a+high-functioning+chronic+stroke+subject:+A+case-control+study.">Feasibility of robot-based perturbed-balance training during treadmill walking in a high-functioning chronic stroke subject: A case-control study.</a> Journal of Neuroengineering and Rehabilitation. 15 (1), 32 (2018).</li></ol>

The authors have nothing to disclose.

In our study, the results of the routine clinical cognitive assessment scales for the high-functioning stroke patient did not show any significant cognitive deficits. However, these assessment scales might show a ceiling effect and be less sensitive for identifying the mild cognitive deficits of high-functioning stroke patients. Hence, this protocol further selected ACC and RT in dual-task assessment based on the Stroop paradigm as major indicators to identify the cognitive deficits of high-functioning stroke patients. The results showed that, when the high-functioning stroke patient performed the dual-task Stroop paradigm, their RT was significantly longer than that of the healthy young subject, the ACC was also relatively lower, and the difference in the incongruence test trials was greater than that in the congruence test trials. Besides, the study also used fNIRS to detect the subjects&#39; extent of brain activation in cognitive regions during the execution of the single/dual task in real-time so as to verify the feasibility of the scheme. The data show that the &#946; value of ROIs of the high-functioning stroke patient was lower than that of the healthy subject.
This study protocol designed the Stroop paradigm combined with motion control and the motor functional assessment scale modules of the routine clinical scales, including the FMA, BBS, and TUGT. Among them, the FMA was used to assess subjects&#39; lower limb motor function, BBS was used to assess balance function, and TUGT was used to assess the risk of falling. The assessment results were all within the normal range of motor function. The assessment results of the routine clinical scales showed that the stroke patient included in the study was a high-functioning stroke patient. On the other hand, it also ensured that the included subject was capable of completing the motor task in the experiment. In addition, the cognitive functioning assessment scale modules of the routine clinical scales included the MoCA, CDR, and Albert&#39;s Test. Among them, the MoCA and CDR were used to assess the level of cognition, and Albert&#39;s Test was used to assess whether the subject suffered from unilateral spatial neglect. Considering that the clinical cognitive functioning assessment scales are semi-quantitative and have a ceiling effect and that there is a lack of sensitivity in the assessment of patients with mild cognitive dysfunction, which causes certain limitations in the evaluation of clinical scales for high-functioning stroke patients, a superior approach needs to be found to solve this problem. Moreover, the study protocol used the ACC and RT of the Stroop paradigm as objective indicators to improve the sensitivity of the assessment results.
According to the representative results, when the high-functioning stroke patient performed the single-task Stroop paradigm, the RT of the congruence test trials was shorter than that of the incongruence test trials, and the ACC was comparable between the two test trials. During the single-task paradigm, the high-functioning stroke patient was able to complete the Stroop test well, showing no obvious cognitive deficits. However, when the high-functioning stroke patient performed the dual-task Stroop paradigm, the RT was significantly higher than that of the healthy young subject, and the ACC of the high-functioning stroke patient was lower. Moreover, the difference in the incongruence test trial was more significant than in the congruence test trial. During the dual-task paradigm, the high-functioning stroke patient had a weakened ability to perform both tasks simultaneously due to his potential cognitive deficits. The patient often uses compensatory strategies (i.e., to maintain stability by sacrificing cognitive task performance), which exposes the cognitive deficits in terms of relatively poor task performance. In the incongruence test trials, the difficulty of the cognitive tasks increased, which made the difference in performance between the high-functioning stroke patient and the healthy young subject more significant and more easily exposed the cognitive deficits of the high-functioning stroke patient. Therefore, this study proposes a dual-task assessment approach based on the Stroop paradigm to identify cognitive deficits in high-functioning stroke patients.
In addition, the study also used the fNIRS technique to verify the feasibility of this protocol. In a case study, fNIRS was used to monitor the subjects&#39; brain activation in cognitive regions in real-time during single/dual-task periods, and six ROIs from cognitive areas were selected to calculate the &#946; value30. The results of the case study showed that the &#946; value of ROIs in the stroke patient was lower than that in the healthy subject. In the process of performing the dual task, the healthy subject used brain resources to complete the cognitive task and motor task simultaneously through activating more brain regions; when the high-functioning stroke patient performed the dual task, sufficient brain areas were not active because of partial damage to brain function. Therefore, enough brain resources were not generated to meet the requirements of performing the cognitive and motor tasks at the same time, which made the performance lower than that of the healthy subject. According to the results of fNIRS monitoring, the degree of brain activation in the high-functioning stroke patient was indeed less than that in the healthy subject, which confirmed the feasibility of using the dual-task Stroop paradigm to identify cognitive deficits in high-functioning stroke patients.
Although the number of included subjects is limited in this study, an earlier case study by Zlatko Matja&#269;i&#263; et al.31 proved that disturbance balance training using a robot may be a feasible method, and this finding illustrates the effectiveness of the case study shown here. Moreover, this study displays the whole process of the experimental design and demonstrates the feasibility of this protocol with the help of the results of a case study. Before the trial, subjects should understand the rules and perform the processes of the Stroop test sufficiently. Additionally, one to two pretests should be performed by subjects before the formal experiment to make smooth progress and improve the accuracy of the data. Besides, the safety of the high-functioning stroke patient needs to be ensured all the time on the balance ball during the dual-task Stroop paradigm, so one must ensure that there is a professional staff member in charge of the subjects&#39; safety.
This protocol has some limitations. First, this study aims to demonstrate a dual-task assessment method that can identify cognitive deficits in high-functioning stroke patients. The representative results present only one subject&#39;s assessment results. Second, this protocol only takes the balance-cognitive task as the dual-task paradigm and fails to show a variety of dual-task assessment schemes. Future studies will be needed to supplement this.
This study proposes the dual-task Stroop paradigm, which could be used to identify cognitive deficits in high-functioning stroke patients.

Stroke is the leading cause of disability in humans1 and can cause varying degrees of motor, cognitive, emotional, and other functional deficits2. Some stroke patients with better prognosis and only slight functional defects show greater functional autonomy in daily activities, but the functional state of their disability may not be sufficient to support their return to work or previous activities. These patients are referred to as high-functioning stroke patients3,4. Due to their minor functional deficits, it is hard to identify their dysfunctions, especially in terms of cognitive functions, through the general assessment of function scales, such as the Montreal cognitive assessment (MoCA)5 and clinical dementia rating (CDR)6, which have a ceiling effect and poor sensitivity for identifying mild functional defects in high-functioning stroke patients. Therefore, it is necessary to develop objective and simple methods to identify cognitive dysfunction in high-functioning stroke patients.
In recent years, the advantages of the dual-task paradigm in assessment and training have gradually become valued7,8. For example, patients may perform normally on simple cognitive single tasks (e.g., calculation) but show varying degrees of cognitive decline when additional tasks are added9,10 (e.g., walking while counting). Manaf et al. found that stroke patients often use compensatory strategies when performing cognitive-motor dual tasks, such as maintaining stability by sacrificing cognitive task performance11. Therefore, the dual-task assessment may have advantages in identifying cognitive deficits in patients with high-functioning stroke. On the one hand, the content of the dual-task assessment is closer to daily life than a single task, such as walking while observing the surrounding environment or talking and calling. In previous studies, the walking + naming task and walking + crossing obstacles task were designed to simulate walking in real environments12.
On the other hand, the executive ability in dual tasks has a close relationship with divided attention (belonging to the category of advanced cognitive function)13. Divided attention is the ability to handle multiple tasks simultaneously and allocate attention to two or more tasks14. This cognitive skill is of great significance to improve the efficiency of daily activities. Therefore, the results of the dual-task assessment can be used for reflecting the individual&#39;s divided attention. Normally, people can deal with two or more simple tasks simultaneously in their daily lives and are not disturbed. However, when brain function is impaired, there may be more dual-task interference when faced with simple dual tasks; that is, when performing dual tasks, the reduced divided attention may be likely to cause the performance of one or two tasks to be impaired15. It is concluded that dual-task execution is more likely to be able to detect advanced cognitive function impairment in patients with high-functioning stroke.
The Stroop paradigm is a classical experimental paradigm to study the Stroop effect (also known as the conflict effect)16, which has been widely used in attention assessment in cognitive function tests, especially in the field of attention inhibition17. The classical Stroop effect refers to the fact that it is difficult for individuals to respond quickly and accurately to non-dominant stimuli due to the interference of the dominant response. This results in a longer response time and lower response accuracy for non-dominant stimuli. The difference in reaction time or accuracy rate between dominant and non-dominant reactions is the Stroop effect18. Therefore, the Stroop requires high levels of attention19. Smaller Stroop effects represent higher attentional inhibition, while larger Stroop effects represent a decline in attentional inhibition18.
The Stroop paradigm may be more suitable for assessing cognitive dysfunction in patients with high-functioning stroke and has higher sensitivity and specificity for attention assessment than the traditional clinical assessment scale20. Therefore, this study designed a dual-task assessment based on the Stroop paradigm to identify cognitive deficits in high-functioning stroke patients. The protocol also includes clinical assessment of cognitive function, lower limb motor function, and balance function in stroke patients to ensure that patients can complete the dual-task assessment. Functional near-infrared spectroscopy (fNIRS) was used as an objective evaluation tool for brain function to detect the activation of brain function in high-functioning stroke patients under the dual task. The effectiveness and feasibility of the dual-task assessment scheme based on the Stroop paradigm were verified from the perspective of neuroimaging, which provides new aspects for clinical practice.

<table><tbody><tr><td>Balance Ball</td><td>Shanghai Fanglian Industrial Co,&amp;nbsp;China</td><td>PVC-KXZ-EVA01-2015</td><td>NA</td></tr><tr><td>E-Prime 3.0</td><td>Psychology softwares Tools</td><td></td><td>commercial stimulus presentation software</td></tr><tr><td>fNIRS</td><td>Hui Chuang, China</td><td>NirSmart-500</td><td>NA</td></tr></tbody></table>

dual-task stroop paradigm for detecting cognitive deficits in high-functioning stroke patients

General clinical cognitive assessment scales are not sensitive enough to cognitive impairment in high-functioning stroke patients. The dual-task assessment has advantages for identifying cognitive deficits in high-functioning stroke patients and has been gradually applied in clinical assessment and cognitive training. Moreover, the Stroop paradigm has higher sensitivity and specificity for attentional assessment than conventional clinical cognitive assessment scales. Therefore, this study presents the dual-task assessment based on the Stroop paradigm to identify cognitive deficits in high-functioning stroke patients. This study demonstrates a single- and dual-task evaluation based on the Stroop paradigm and confirms its feasibility through case experiments and synchronized functional near-infrared spectroscopy evaluation. The Stroop reaction time and correct rate are used as the main indicators to evaluate the cognitive level of the subjects. This study protocol aims to provide new ideas to figure out the ceiling effect in general clinical assessment failure for high-functioning stroke patients.

This study presents results from a high-functioning stroke patient, who was a 71-year-old male who suffered from ischemic stroke with left hemiplegia 2 years ago. The magnetic resonance imaging (MRI) presented bilateral chronic infarction from the basal ganglia to the radiating crown. He was able to walk and live independently in the community but was not satisfied with his cognitive recovery. However, the functional assessments were all within the normal range: FMA = 100, BBS = 56/56, TUGT = 6, MoCA = 26/30, CDR = 0.5, Albert&#39;s Test = 0. Moreover, we also recruited one young female healthy subject as the control. The subjects&#39; information is shown in Table 1.
The single/dual-task assessment results based on the Stroop paradigm showed that, in high-functioning stroke patient performing the single-task Stroop test, the RT of the congruence test trials was shorter than that of the incongruence test trials, and the ACC was comparable to the incongruence test trials (RTCongruence = 547.62 ms, RTIncongruence = 565.07 ms; ACCCongruence = ACCIncongruence = 100%). When performing dual-task congruence test trials, the RT of high-functioning stroke patients was higher than that of healthy young subjects, and their ACC was also relatively lower (RTstroke = 587.03 ms, RThealth = 363.07 ms; ACCstroke = 93.33%, ACChealth = 100%), and the difference in the incongruence test trials was greater than that in the congruence test trials (RTstroke = 613.03 ms, RThealth= 384.67 ms; ACCstroke = 90%, ACChealth = 100%; Table 2).
The results for brain function showed that the &#946; value of ROIs in the stroke patient was lower than that in the healthy young subject during the process of performing dual tasks (RDLPFC: &#946;stroke = &#8722;0.006, &#946;health = 0.1366; LDPFC: &#946;stroke = &#8722;0.0196, &#946;health = 0.0976). The rest of the brain regions are shown in Figure 2 and Figure 3.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63991/63991fig01.jpg" /> 
Figure 1: The single/dual-task Stroop paradigm and the fNIRS design. (A) Congruence test trials. (B) Incongruence test trials. (C)&#160;The timeline diagram of the single/dual-task Stroop paradigm. Abbreviations:ms = millisecond; s = second; <img alt="Equation 1" src="/files/ftp_upload/63991/63991eq01.jpg" style="margin: auto;" /> = left; <img alt="Equation 2" src="/files/ftp_upload/63991/63991eq02.jpg" style="margin: auto;" /> = right. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63991/63991fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/63991/63991fig02.jpg" /> 
Figure 2: The &#946; values in ROIs of the dual-task Stroop effect. The &#946; values of ROIs in the stroke patient was lower than that of the healthy young subject during the dual-task Stroop. Abbreviations: ROIs = regions of interest; RDLPFC = right dorsolateral prefrontal cortex; LDPFC = left dorsolateral prefrontal cortex; RPMC = right promoter cortex; LPMC = left promotor cortex; RSM1 = right primary sensory-motor cortex 1; RPMC = right primary sensory-motor cortex. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63991/63991fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/63991/63991fig03.jpg" /> 
Figure 3: Blood oxygen concentration in brain regions of the stroke patient and healthy young subject under the dual-task Stroop effect. (A) Blood oxygen concentration in brain regions of the stroke patient under the dual-task Stroop effect. (B) Blood oxygen concentration in brain regions of the healthy young subject under the dual-task Stroop effect. The &#946; values are indicated by color bars. The results of brain function showed that the &#946; value of ROIs in the stroke patient was lower than that in the healthy young subject during dual-task performance. Abbreviations: R-DLPFC = right dorsolateral prefrontal cortex; L-DLPFC = left dorsolateral&#160;prefrontal cortex; R-PMC = right promoter cortex; L-PMC = left promotor cortex; R-SMI = right primary sensory-motor cortex; R-PMC = right primary sensory-motor cortex. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63991/63991fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Characteristics</td>
			<td>Healthy young subject</td>
			<td>Stroke patient</td>
		</tr>
		<tr>
			<td>Age (year)</td>
			<td>21</td>
			<td>71</td>
		</tr>
		<tr>
			<td>Gender</td>
			<td>female</td>
			<td>male</td>
		</tr>
		<tr>
			<td>BMI (kg/m2)</td>
			<td>22.27</td>
			<td>23.81</td>
		</tr>
		<tr>
			<td>Cognitive assessment</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Montreal Cognitive Assessment (MoCA)</td>
			<td>30/30</td>
			<td>26/30</td>
		</tr>
		<tr>
			<td>Clinical Dementia Rating (CDR)</td>
			<td>0</td>
			<td>0.5</td>
		</tr>
		<tr>
			<td>Albert&#8217;s Test</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>Motor and balance assessment</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Brunnstrom stage</td>
			<td>NT</td>
			<td>V stage</td>
		</tr>
		<tr>
			<td>Fugl-Meyer Assessment (FMA)</td>
			<td>100</td>
			<td>100</td>
		</tr>
		<tr>
			<td>Berg Balance Scale (BBS)</td>
			<td>56/56</td>
			<td>52/56</td>
		</tr>
		<tr>
			<td>Timed Up and Go Test (TUGT) (s)</td>
			<td>6</td>
			<td>11</td>
		</tr>
		<tr>
			<td colspan="3">Abbreviations: BMI, Body Mass Index; kg/m2, kilogram per square meter; NT, Not testable; s, second.</td>
		</tr>
	</tbody>
</table>
Table 1: The baseline information and characteristics of the healthy young subject and the stroke patient.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td></td>
			<td colspan="2">Congruence test trials</td>
			<td colspan="2">Incongruence test trials</td>
		</tr>
		<tr>
			<td></td>
			<td>ACC</td>
			<td>RT(ms)</td>
			<td>ACC</td>
			<td>RT(ms)</td>
		</tr>
		<tr>
			<td>the stroke patient</td>
			<td>93.33%</td>
			<td>587.03</td>
			<td>90%</td>
			<td>613.03</td>
		</tr>
		<tr>
			<td>the healthy young subject</td>
			<td>100%</td>
			<td>363.07</td>
			<td>100%</td>
			<td>384.67</td>
		</tr>
		<tr>
			<td colspan="5">Abbreviations: ACC, accuracy; RT, reaction time; ms, millisecond.</td>
		</tr>
	</tbody>
</table>
Table 2: The ACC and RT of the healthy young subject and the stroke patient in the dual task. Abbreviations: ACC = accuracy; RT = reaction time; ms = millisecond.

Watch this Scientific Journal Video about Dual-Task Stroop Paradigm for Detecting Cognitive Deficits in High-Functioning Stroke Patients at JoVE.com

Dual-Task Stroop Paradigm for Detecting Cognitive Deficits in High-Functioning Stroke Patients

Clinical assessment scales are notsensitive enough to cognitive dysfunction in high-functioning stroke patients. The dual-task paradigm presents advantages and potential in the assessment and cognitive training of cognitive dysfunction. The study here proposes a dual-task Stroop paradigm to identify cognitive dysfunction in high-functioning stroke patients.

General clinical cognitive assessment scales are not sensitive enough to cognitive impairment in high-functioning stroke patients. The dual-task ...

dual-task-stroop-paradigm-for-detecting-cognitive-deficits-high

Nanyang Technological University

Research

JoVE Journal

Neuroscience

2.8K Views.  Guangzhou University of Chinese Medicine, Shenzhen Traditional Chinese Medicine Hospital. Ons studieprotocol kan worden gebruikt om cognitieve tekorten te identificeren bij hoogfunctionerende beroertepatiënten die niet gemakkelijk worden gedetecteerd door conventionele beoordelingsvaardigheden. Dit onderzoeksprotocol moet nieuwe ideeën bieden om het effect te achterhalen bij het falen van de algemene klinische beoordeling voor hoogfunctionerende beroertepatiënten. Dit onderzoeksprotocol kan gemakkelijk worden gebruikt in de klinische praktijk.De clinicus kan bijvoorbeeld...

Video: Dual-Task Stroop Paradigm for Detecting Cognitive Deficits in High-Functioning Stroke Patients

Training Synesthetic Letter-color Associations by Reading in Color

Synesthesia is a rare condition in which a stimulus from one modality automatically and consistently triggers unusual sensations in the same and/or other modalities. A relatively common and well-studied type is grapheme-color synesthesia, defined as the consistent experience of color when viewing, hearing and thinking about letters, words and numbers. We describe our method for investigating to what extent synesthetic associations between letters and colors can be learned by reading in color in nonsynesthetes. Reading in color is a special method for training associations in the sense that the associations are learned implicitly while the reader reads text as he or she normally would and it does not require explicit computer-directed training methods. In this protocol, participants are given specially prepared books to read in which four high-frequency letters are paired with four high-frequency colors. Participants receive unique sets of letter-color pairs based on their pre-existing preferences for colored letters. A modified Stroop task is administered before and after reading in order to test for learned letter-color associations and changes in brain activation. In addition to objective testing, a reading experience questionnaire is administered that is designed to probe for differences in subjective experience. A subset of questions may predict how well an individual learned the associations from reading in color. Importantly, we are not claiming that this method will cause each individual to develop grapheme-color synesthesia, only that it is possible for certain individuals to form letter-color associations by reading in color and these associations are similar in some aspects to those seen in developmental grapheme-color synesthetes. The method is quite flexible and can be used to investigate different aspects and outcomes of training synesthetic associations, including learning-induced changes in brain function and structure.

Reading in color is a new method for training letter-color associations that are typically found only in grapheme-color synesthetes. It involves an implicit form of training that has potential for long-term associative training methods&#160;because the training is a byproduct of reading and any text can be colored.

Synesthesia is a rare condition in which a stimulus from one modality automatically and consistently triggers unusual sensations in the same and/or other ...

Behavior

Modulating Cognition Using Transcranial Direct Current Stimulation of the Cerebellum

Numerous studies have emerged recently that demonstrate the possibility of modulating, and in some cases enhancing, cognitive processes by exciting brain regions involved in working memory and attention using transcranial electrical brain stimulation. Some researchers now believe the cerebellum supports cognition, possibly via a remote neuromodulatory effect on the prefrontal cortex. This paper describes a procedure for investigating a role for the cerebellum in cognition using transcranial direct current stimulation (tDCS), and a selection of information-processing tasks of varying task difficulty, which have previously been shown to involve working memory, attention and cerebellar functioning. One task is called the Paced Auditory Serial Addition Task (PASAT) and the other a novel variant of this task called the Paced Auditory Serial Subtraction Task (PASST). A verb generation task and its two controls (noun and verb reading) were also investigated. All five tasks were performed by three separate groups of participants, before and after the modulation of cortico-cerebellar connectivity using anodal, cathodal or sham tDCS over the right cerebellar cortex. The procedure demonstrates how performance (accuracy, verbal response latency and variability) could be selectively improved after cathodal stimulation, but only during tasks that the participants rated as difficult, and not easy. Performance was unchanged by anodal or sham stimulation. These findings demonstrate a role for the cerebellum in cognition, whereby activity in the left prefrontal cortex is likely dis-inhibited by cathodal tDCS over the right cerebellar cortex. Transcranial brain stimulation is growing in popularity in various labs and clinics. However, the after-effects of tDCS are inconsistent between individuals and not always polarity-specific, and may even be task- or load-specific, all of which requires further study. Future efforts might also be guided towards neuro-enhancement in cerebellar patients presenting with cognitive impairment once a better understanding of brain stimulation mechanisms has emerged.

Transcranial direct current stimulation (tDCS) over the cerebellum exerts a remote effect on the prefrontal cortex, which can modulate cognition and performance. This was demonstrated using two information-processing tasks of varying complexity, whereby only cathodal tDCS improved performance when the task was difficult, but not easy.

Numerous studies have emerged recently that demonstrate the possibility of modulating, and in some cases enhancing, cognitive processes by exciting brain ...

A Dual Task Procedure Combined with Rapid Serial Visual Presentation to Test Attentional Blink for Nontargets

When viewers search for targets in a rapid serial visual presentation (RSVP) stream, if two targets are presented within about 500 msec of each other, the first target may be easy to spot but the second is likely to be missed. This phenomenon of attentional blink (AB) has been widely studied to probe the temporal capacity of attention for detecting visual targets. However, with the typical procedure of AB experiments, it is not possible to examine how the processing of non-target items in RSVP may be affected by attention. This paper describes a novel dual task procedure combined with RSVP to test effects of AB for nontargets at varied stimulus onset asynchronies (SOAs). In an exemplar experiment, a target category was first displayed, followed by a sequence of 8 nouns. If one of the nouns belonged to the target category, participants would respond &#8216;yes&#8217; at the end of the sequence, otherwise participants would respond &#8216;no&#8217;. Two 2-alternative forced choice memory tasks followed the response to determine if participants remembered the words immediately before or after the target, as well as a random word from another part of the sequence. In a second exemplar experiment, the same design was used, except that 1) the memory task was counterbalanced into two groups with SOAs of either 120 or 240 msec and 2) three memory tasks followed the sequence and tested remembrance for nontarget nouns in the sequence that could be anywhere from 3 items prior the target noun position to 3 items following the target noun position. Representative results from a previously published study demonstrate that our procedure can be used to examine divergent effects of attention that not only enhance targets but also suppress nontargets. Here we show results from a representative participant that replicated the previous finding.&#160;

This paper describes a novel dual task procedure combined with Rapid Serial Visual Presentation to look at attentional blink at varied stimulus onset asynchronies. This experimental procedure differed from others in that it tested attentional blink for nontargets.

When viewers search for targets in a rapid serial visual presentation (RSVP) stream, if two targets are presented within about 500 msec of each other, the ...

The Emotional Stroop Task: Assessing Cognitive Performance under Exposure to Emotional Content

The emotional Stroop effect (ESE) is the result of longer naming latencies to ink colors of emotion words than to ink colors of neutral words. The difference shows that people are affected by the emotional content conveyed by the carrier words even though they are irrelevant to the color-naming task at hand. The ESE has been widely deployed with patient populations, as well as with non-selected populations, because the emotion words can be selected to match the tested pathology. The ESE is a powerful tool, yet it is vulnerable to various threats to its validity. This report refers to potential sources of confounding and includes a modal experiment that provides the means to control for them. The most prevalent threat to the validity of existing ESE studies is sustained effects and habituation wrought about by repeated exposure to emotion stimuli. Consequently, the order of exposure to emotion and neutral stimuli is of utmost importance. We show that in the standard design, only one specific order produces the ESE.

The emotional Stroop effect (ESE) is the result of longer naming latencies to ink colors of emotion words than those of neutral words. This report refers to potential sources of confounding and includes a modal experiment that provides the means to control for them.

The emotional Stroop effect (ESE) is the result of longer naming latencies to ink colors of emotion words than to ink colors of neutral words. The ...

Examining Bilingual Language Control Using the Stroop Task

The Stroop task in its many variations has been used in fields such as psychology, linguistics, and neuroscience to examine questions regarding the automaticity of reading, language processing, and cognitive control, among others. When looking at bilingual individuals, this task can be used to obtain measures of language interference and control in both a bilingual&#39;s first language (L1) and second language (L2), as well as for testing the bilingual advantage hypothesis. The Stroop task presents participants with color terms written in congruent colors (e.g., the word RED written in red font), incongruent colors (e.g., the word RED written in green font), in addition to noncolor terms for control (e.g., the word TREE presented in any color), and uses the reaction times from the different conditions to assess the degree of interference and facilitation. In the covert version of the Stroop bilingual task (i.e., participants respond by pressing a button rather than naming aloud), stimuli in the L1 and the L2 are typically presented in separate blocks. While this allows for a simple, yet effective assessment of processing and cognitive control in each language, it fails to capture any potential differences in processing and control within bilingual young adult groups. The present task combines single-language blocks with a novel mixed-language block to increase the level of difficulty of the task, thus making it suitable for testing cognitive control in young adults. Representative results showing differences between performance in the single-language vs. mixed-language blocks are presented, and the benefits of a mixed-language block are discussed.

This bilingual Stroop task uses Congruent, Incongruent, and Neutral stimuli presented in blocks in the first language (L1) only, the second language (L2) only, and a combination of L1 and L2. This task allows for an examination of language processing and cognitive control in both L1 and L2.

The Stroop task in its many variations has been used in fields such as psychology, linguistics, and neuroscience to examine questions regarding the ...

Evaluation of the Cognitive Performance of Hypertensive Patients with Silent Cerebrovascular Lesions

Evidence accumulated from the last decade has proven that silent cerebrovascular lesions (SCLs) and their underlying pathogenic processes contribute to cognitive decline in the elderly. However, the distinct effects of each type of the lesions on cognitive performance remain unclear. Moreover, research data from Chinese elderly with SCLs is scarce. In this study, 398 otherwise healthy hypertensive elderly subjects (median age 72 years) were included and assessed. All participates were required to complete a battery of structured neuropsychological assessment, including forward and backward digit span tests, symbol digit modalities test, Stroop test, verbal fluency test and Montreal Cognitive Assessment. These tests were used to assess attention, executive function, information processing speed, language, memory and visuospatial function. A multi-sequence 3T MRI scanning was arranged within one month of the neuropsychological assessment to evaluate the burden of SCLs. SCLs were rated visually. Cerebral microbleeds (CMBs) and silent lacunes (SLs) were identified as strictly lobar CMBs and SLs or deep CMBs and SLs according to their locations, respectively. Similarly, white matter hyperintensities (WMHs) were separated into periventricular WMHs (PVHs) and deep WMHs (DWMHs). A series of linear regression models were used to assess the correlation between each type of SCLs and individual cognitive function domain. The results showed that CMBs tend to impair language-related cognition. Deep SLs affect executive function, but this association disappeared after controlling for other types of SCLs. PVHs, rather than DWMHs, are associated with cognitive decline, especially in executive function and processing speed. It is concluded that different aspects of SCLs have differential impact on cognitive performance in hypertensive elderly Chinese.

Here, we present a protocol to assess whether various types of silent cerebrovascular lesions are differentially associated with deficits in certain cognitive domains in a cohort of 398 hypertensive elderly Chinese, using a combination of neuropsychological tests and multi-sequence 3T MRI scanning.

Evidence accumulated from the last decade has proven that silent cerebrovascular lesions (SCLs) and their underlying pathogenic processes contribute to ...

Revised and Neuroimaging-Compatible Versions of the Dual Task Screen

Dual task paradigms simultaneously assess motor and cognitive abilities, and they can detect subtle, residual impairments in athletes with recent mild traumatic brain injury (mTBI). However, past dual task paradigms have focused solely on lower extremity skills and have relied on cumbersome, expensive laboratory equipment - thus limiting their practicality for everyday mTBI evaluation. Subsequently, we developed the Dual Task Screen (DTS), which takes &#60;10 minutes to administer and score, uses low-cost portable equipment, and includes lower extremity (LE) and upper extremity (UE) subtasks. The purpose of this manuscript was twofold. First, we describe the administration protocol for the revised DTS, which we revised to address the limitations of the original DTS. Specifically, the revisions included additions of smart devices to acquire more detailed gait data and inclusion of single cognitive conditions to test for disrupted cognitive performance under dual task conditions. Importantly, the revised DTS is a measure intended for future clinical use, and we present representative results from three male athletes to illustrate the type of clinical data that can be acquired from the measure. Importantly, we have yet to evaluate the sensitivity and specificity of the revised DTS in athletes with mTBI, which is the next research initiative. The second purpose of this manuscript is to describe a neuroimaging-compatible version of the DTS. We developed this version so we could evaluate the neural underpinnings of single and dual task performance, for a better empirical understanding of the behavioral deficits associated with mTBI. Thus, this manuscript also describes the steps we took to enable simultaneous functional near-infrared spectroscopy (fNIRS) measurement during the DTS, along with how we acquired and completed first-level processing of the fNIRS data.

We developed the original Dual Task Screen (DTS) as a portable, low-cost measure that can evaluate athletes with sports-induced mild traumatic brain injury. We revised the original DTS for future clinical use and developed a neuroimaging-compatible version of the DTS to measure neural underpinnings of single and dual task performance.

Dual task paradigms simultaneously assess motor and cognitive abilities, and they can detect subtle, residual impairments in athletes with recent mild ...

Motor Dual-Tasks for Gait Analysis and Evaluation in Post-Stroke Patients

Eighteen stroke patients were recruited for this study involving the evaluation of cognition and walking ability and multitask gait analysis. Multitask gait analysis consisted of a single walking task (Task 0), a simple motor dual-task (water-holding, Task 1), and a complex motor dual-task (crossing obstacles, Task 2). The task of crossing obstacles was considered to be equivalent to the combination of a simple walking task and a complex motor task as it involved more nervous system, skeletal movement, and cognitive resources. To eliminate heterogeneity in the results of the gait analysis of the stroke patients, the dual-task gait cost values were calculated for various kinematic parameters. The major differences were observed in the proximal joint angles, especially in the angles of the trunk, pelvis, and hip joints, which were significantly larger in the dual motor tasks than in the single walking task. This research protocol aims to provide a basis for the clinical diagnosis of gait function and an in-depth study of motor control in stroke patients with motor control deficits through the analyses of dual-motor walking tasks.

This paper presents a protocol specifically for dual motor task gait analysis in stroke patients with motor control deficits.

Eighteen stroke patients were recruited for this study involving the evaluation of cognition and walking ability and multitask gait analysis. Multitask ...

Scalp Acupuncture Synchronizing Dual Task Gait for Enhancing Prefrontal Cortex Response

Studies have shown that motor-cognitive dual task can greatly improve motor/cognitive function. However, the therapeutic effect of motor-cognitive dual task is still limited. How to improve dual-task performance is the key to solving this problem. Scalp acupuncture is a non-drug intervention method of traditional Chinese medicine to treat brain-derived diseases by acupuncturing the corresponding projection area of cerebral cortex function on the scalp. Studies have shown that scalp acupuncture helps improve neuronal damage and cognitive dysfunction and plays a neuroprotective function in central nervous system diseases. However, no relevant studies have discussed the synergistic gain effect of motor-cognitive dual task and scalp acupuncture. Therefore, this protocol aims to demonstrate the standardized operation of scalp acupuncture synchronizing motor-cognitive dual task and motor-cognitive dual task and compares the differences between these two tasks in healthy subjects through a randomized cross-over trial. This protocol initially revealed the possible influence mechanism of scalp acupuncture synchronizing motor-cognitive dual task on cognitive performance, gait control, and cortical brain function, which can provide new ideas and a theoretical basis for clinical exploration of new and effective non-drug treatment of integrated Chinese and Western medicine.

This protocol demonstrates the standardized procedure of scalp acupuncture synchronizing motor-cognitive dual task and motor-cognitive dual task. This can provide an important reference for the clinical exploration of the new and effective non-drug treatment of integrated Chinese and Western medicine.

Studies have shown that motor-cognitive dual task can greatly improve motor/cognitive function. However, the therapeutic effect of motor-cognitive dual ...

The Split Brain

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
The study of how damage to the brain affects cognitive functioning has historically been one of the most important tools for cognitive neuroscience. While the brain is one of the most well protected parts of the body, there are many events that can affect the functioning of the brain. Vascular issues, tumors, degenerative diseases, infections, blunt force traumas, and neurosurgery are just some of the underlying causes of brain damage, all of which may produce different patterns of tissue damage that affect brain functioning in different ways.
The history of neuropsychology is marked by several well-known cases that led to advances in the understanding of the brain. For instance, in 1861 Paul Broca observed how damage to the left frontal lobe resulted in aphasia, an acquired language disorder. As another example, a great deal about memory has been learned from patients with amnesia, such as the famous case of Henry Molaison, known for many years in the neuropsychology literature as &#34;H.M.,&#34; whose temporal lobe surgery led to a profound deficit in forming certain kinds of new memories.
While the observation and testing of patients with focal brain damage has provided neuroscience with insight into the functioning of the brain, great care must be taken in designing tests to reveal the specific nature of the deficit. Also, because the brain is a complex network of interconnected neurons, damage to one brain region can affect functioning in regions far away from the damage. To demonstrate how brain damage can affect connections among brain regions, this video examines the case of the so-called split brain.
The corpus callosum is a large bundle of fibers that connects the left and right hemispheres of the brain. It is one of the largest white matter tracts in the brain and can be easily recognized on a sagittal view of the midline of the brain. In the 1960s, neurosurgeons discovered that cutting the corpus callosum could be a successful treatment for certain kinds of epilepsy, which involves uncontrollable neural activity spreading through the brain. People who underwent the split-brain operation had their two hemispheres surgically separated, such that the left and right hemispheres were no longer able to communicate. This condition allowed experimenters to probe the functions of the left and right hemisphere independently, to learn about the relative abilities, and about the nature of communication between them.
This video demonstrates how to test a split-brain patient to reveal some of the differences between the two hemispheres of the brain and to see some dramatic consequences of such a disconnection. The original versions of these experiments were developed by Michael Gazzaniga and colleagues1, 2 and later were elaborated upon by others;3 the version presented here incorporates more recent modernizations of the methodology.

Testing Cognitive Abilities in Split-brain Patients Using Visual Stimuli

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
The study of how damage to the brain affects cognitive ...

Dual-Task Stroop Paradigm for Detecting Cognitive Deficits in High-Functioning Stroke Patients

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