This research was funded by Washington College's Provost's Office, Middendorf Fund, Hodson Trust, and Franklin and Marshall's Hackman Fund and College of Grants. We thank E. Counihan, S. Giordano, F. Rauh, and A. Roth for assistance in the field. We thank M. Conner, R. Fleegle, and D. Startt at Chesapeake Farms, and Chino Farms for permission and access. The Washington College GIS Program helped with the preparation of maps.

All procedures involving animal subjects were approved by the Institutional Animal Care and Use Committees of Franklin and Marshall and Washington Colleges and followed all local, state, and federal regulations.
1. Capture and Handling
<ol>
	<li>Place hoop traps in the target body of water that is known to contain turtles. Identify water depth ensuring that 4 - 5 inches of the trap remains above water to allow trapped turtles to surface and breathe. Be certain to expand and secure hoop traps to their maximum length with the cross beams to prevent trap collapse. Stake traps into the bed of the body of water to prevent drift.</li>
	<li>Bait traps with several dead fish, chicken livers, or chicken necks, a can of cat food, and/or a can of vegetables25.</li>
	<li>Check traps twice daily and remove turtles. When removing turtles from traps, hold animal by the side and use caution to avoid injury from claws or beak.
	<ol>
		<li>Release by-catch. Reset traps if continued trapping is desired. Assess state of bait. If the bait had been consumed, add more. Pull traps to shore if additional trapping is not desired.</li>
	</ol>
	</li>
	<li>Determine the sex and age of turtles if desired26, 27.</li>
	<li>Place turtle in a holding bag and measure body mass with a spring scale to the nearest g.</li>
	<li>Transport turtles to the lab in climate-controlled transport boxes with a small amount of water. House animals singly in aquaria with untreated pond water held at approximately 25 &#176;C and deep enough to cover the head only.</li>
</ol>
2. Affixing Radio Transmitter
<ol>
	<li>To maximize transmitter life and output, choose the largest radio transmitter possible that does not exceed 5% of the animal&#39;s body mass28.</li>
	<li>Identify the location of transmitter placement on the carapace approximately halfway between the midline and lateral edge of the carapace approximately 1/3 of the length up from the rear edge of the carapace.</li>
	<li>Prepare area by removing mud, debris, and algal growth with a dry cloth. Swab area with 70% isopropanol.</li>
	<li>Attach transmitter with a small amount of 5 min epoxy. Orient the transmitter to maximize contact with the surface of the carapace. Position the antenna so that it trails behind the animal parallel to the long axis of the body.</li>
	<li>Once suitably positioned, cover the entire transmitter and approximately 1 cm of the surrounding carapace surface with 5 min epoxy.</li>
	<li>Return the turtle to the aquarium and allow the epoxy to cure overnight.</li>
</ol>
3. Pharmacological Preparation
Caution: Scopolamine hydrobromide and scopolamine methylbromide are potent acetylcholine antagonists. When working with these drugs, consult the Materials Safety Data Sheet, use proper personal protective equipment (e.g., gloves, fume hood), and follow laboratory safety protocols to avoid accidental contact.
<ol>
	<li>Using sterile and antipyrogenic supplies, compound a stock solution of scopolamine hydrobromide. Weigh out the desired quantity of the drug on an analytical balance. Mix the scopolamine with injection saline in a conical tube to the concentration of 1 mg/ml. Vortex solution until dissolved. Ensure that chemical purity of the base chemicals meets or exceeds United States Pharmacopeia (USP) formulation when possible11.</li>
	<li>Repeat step 3.1 with scopolamine methylbromide.</li>
	<li>Process solution through a 0.22 &#181;m pore nylon or mixed cellulose esters syringe filter into a sterile sealed serum vial.</li>
	<li>Store at room temperature. Use within 24 hr.</li>
</ol>
4. Track Turtle Movements Using Radio Telemetry11, 12
<ol>
	<li>Move to the general location of the target animal, remaining at least 25 m from the animal. Using a directional Yagi antenna and setting the receiver gain at medium, scan the horizon to determine the rough direction and location of the animal. When receiving interference or a weak signal, find a new position. Increase elevation or hold Yagi aloft when possible to enhance signal.</li>
	<li>Once a suitable location is found to take a bearing, record your position with a GPS.</li>
	<li>Using the null/peak method28, determine the bearings of the left and right nulls.
	<ol>
		<li>Identify the direction of the strongest signal. Turn the gain down as far as possible while still receiving a detectable signal. Use the attenuator switch on the receiver if so equipped. Move the antenna to the left and record the compass bearing at which the signal is lost.</li>
		<li>Repeat the previous step for the right bearing.</li>
	</ol>
	</li>
	<li>Repeat step 4.3 from at least two additional locations for the same animal. 
	NOTE: These additional points should be taken in such a manner as to surround the animal.
	<ol>
		<li>When a set of bearings is taken from a great distance or with unavoidable interference, take at least two additional bearings to increase accuracy. Collect sets of bearings used to estimate a single location as quickly as possible, particularly if the animal is moving. 
		NOTE: Alternatively, multiple personnel can coordinate to take multiple independent bearings on the same animal simultaneously.</li>
	</ol>
	</li>
	<li>Record locations of animals digitally or by hand every 10 - 15 min using above steps.</li>
	<li>Manipulation of cognitive processing
	<ol>
		<li>Once the unmanipulated animal&#39;s path is documented (a within-subjects control), provide a dose of either scopolamine or methylscopolamine. Using the mass collected in step 1.5, calculate the amount of drug to be given to the animal to achieve a reptile-specific final dose of 6.4 mg/kg of scopolamine or 6.8 mg/kg of methylscopolamine19, 20.</li>
		<li>Deliver the drug directly into the peritoneum via the caudal peritoneal sinus using a 1.0 ml syringe with a 22 gauge needle. Ensure that the total volume delivered does not exceed 1 ml.</li>
		<li>Release animal as soon as possible at its site of capture.</li>
		<li>Continue monitoring the animal&#39;s movement every 10 - 15 min until it reaches its projected destination.</li>
	</ol>
	</li>
</ol>
5. Spatial Analysis
<ol>
	<li>Calculate estimates of animal location.
	<ol>
		<li>For each set of null bearings, bisect the angle (by hand or via software) to find the resultant transmitter bearing. Repeat for all bearings at a given time point.</li>
		<li>Using triangulation software according to manufacturer&#39;s protocol, estimate the animal&#39;s position and associated error with the multiple transmitter bearings. Convert position estimates to x/y coordinates if software provides different output.</li>
	</ol>
	</li>
	<li>Repeat steps 5.1 for all sets of bearings.</li>
	<li>Calculate the spatial precision of movement.
	<ol>
		<li>Calculate the cumulative geometric mean (i.e., mean path) of unmanipulated animals (negative control) as they move towards their goal12.</li>
		<li>For each individual in the treatment and positive control groups, calculate the cumulative number of points that overlap successively larger swaths from the geometric mean line in 5 m intervals until 100% of all points have been included11, 12.</li>
		<li>Calculate the mean and standard error at each swath distance for all individuals in each group.</li>
		<li>Statistically analyze the data, comparing among the treatment groups either for the interval to accommodate 100% of the points or the points of overlap at a given interval, depending upon the question.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

The protocol presented here allows the experimenter to document and quantify the role of cognition in navigation. Manipulating cognition in the field has proven difficult, as most approaches leave experimenters unable to know which specific aspects of the animal&#39;s behavior are being manipulated. However, the protocol presented here allows the experimenter to accurately manipulate and thus assess the role of cognition in navigation. The technique further allows experimenters to monitor animal navigation in real-time with exceptionally high spatial and temporal resolution, thereby empowering researchers to clearly document the behavioral ramifications of experimental manipulation of cognition in wild animals.
Within this context, radio telemetry provides the ability to precisely monitor animal movements over great distances, yielding both high-quality spatial and behavioral data. Although this application of telemetry is by no means new28, the majority of studies use this technique to address coarse questions in ecology and behavior (e.g., habitat use, home range size, etc.). The frequent monitoring of the animal location (4 - 5 times per hr) described here combined with fine scale spatial analyses provide a more detailed behavioral component to an animal&#39;s location in space. Note that the optimal tracking distance will be a function of the transmitter strength and the equipment sensitivity. Generally it is best practice to remain at least 25 m away from the animal to avoid disturbing it, although when the animal is located in open vegetation, the distance needed to avoid such disturbance might be larger.
In the current application, high-precision radio telemetry offers unique advantages over the use of animal-mounted GPS recorders. Transmitters can be smaller, are less expensive, and have longer battery life than GPS units28. Moreover, the temporal resolution of remote triangulation via radio telemetry is far superior to animal-mounted GPS. Temporally, animal-mounted GPS units are limited by battery life (i.e., a finite number of measurements can be taken, thereby constraining their frequency). High-precision tracking with GPS would require a large battery to obtain high frequency position over a long period of time. The substantial mass of these batteries preclude them from use in small animal-mounted GPS units28. Furthermore, high-precision radio telemetry is not constrained by expensive data retrieval costs, or limited by on-board memory storage. However, radio telemetry is not optimal for tracking animals with particularly large movement ranges (e.g., during long-distance migration), in deep water or fossorial species, or those in steep montane habitats. In addition, high-precision radio tracking can be very time intensive and requires a relatively large field crew, particularly for fast-moving species; therefore, this approach may not suitable for all questions.
Pharmacological manipulation with scopolamine and methylscopolamine offers specific advances for the study of cognition in a natural setting. Behavior can be hard to interpret, especially under field conditions, thereby limiting the scope of potential inquiry. Scopolamine allows the manipulation of specific receptors that influence cognitive processes, enabling the researcher to ask questions specifically about the manipulation of cognition. Furthermore, as scopolamine easily crosses the blood-brain barrier and methylscopolamine does not, researchers can control for peripheral effects of scopolamine thereby dissociating cognitive-based from non-cognitive behaviors. These benefits of pharmacological manipulation allow for the generation and subsequent testing of clear behavioral predictions and afford the use of complex experimental designs under field conditions. However, scopolamine is a very general acetylcholine antagonist that can have unintended effects on other behavioral, sensory, and cognitive systems21-24. Therefore, it is possible that the use of scopolamine can produce effects that can interfere with the interpretation of complex behaviors (e.g., pupil dilation, thermal sensitivity21-24, 29, 30); no such confounding effects have been detected in this or previous studies11-13, 19, 20.
Common problems encountered while radio tracking include weak signal, loss of signal, and interference. To combat a weak signal, increase gain, change antenna orientation, move closer to the animal (being careful to avoid disturbing the anima), and elevate the antenna28. If the signal is lost completely, search with the gain and antenna as high as possible in an outwardly spiraling area restricted search28. Interference can be combated by decreasing gain, using the attenuator or noise cancelling filter (if so equipped), and changing antenna orientation. If interference cannot be overcome by these means, future work at the study site should focus on bandwidths that are not affected by interference.
Overall, pharmacological manipulation in conjunction with high-precision telemetry provides unique insight into the role that cognition plays in the origin and manifestation of navigation. The novelty of this unique method allows researchers to better understand the underlying neurological mechanisms that give rise to cognition in navigation. Moreover, these techniques can be used for additional studies of cognition in the wild with particular applicability to spatially explicit behaviors (e.g., navigation, migration, foraging, and dispersal)11-13, 33, the evolution of cognition1, 7, and conservation (e.g., translocation, reintroduction)31, 32. This technique is useful for a wide range of taxa in a wide range of habitats and will be vital to understanding phylogenic patterns in cognition.

Cognition (herein defined as &#34;all processes involved in acquiring, storing, and using information from the environment&#34; 1) is central to an array of complex navigation tasks2. For example, Sandhill cranes (Grus canadensis) show a marked improvement in migratory precision with experience3, and sea turtle species imprint on their natal beaches as hatchlings and return as adults4-6. Similarly, successful migration, dispersal, and foraging hinge on an animal&#39;s ability to gather information about their spatial environment7,8. Some animals appear to learn navigational routes in relation to specific landscape features9 and may use spatial cognition when moving between nesting and foraging areas10. Recent work on Eastern Painted turtles (Chrysemys picta) suggests a critical period in navigation, where successful navigation of upland habitat as adults hinges on juvenile experience within a narrow age range (&#60; 4 years old11-13). Though together these studies demonstrate the progress that has been made in understanding the role of learning in navigation4-6, 14-16, the mechanisms that underlie such behaviors and the full role of cognition in navigation remain enigmatic, especially in vertebrates8, 17, 18.
Field investigations into the role of cognition in navigation are rare2, 8, 18, due largely to the methodological difficulties involved in monitoring, manipulating, and tracking wild animals. For example, the large spatial and temporal scales on which many animals navigate often preclude investigating both type of information that those animals potentially learn and how that information is acquired. Experimenters often face the logistical difficulties of detecting and locating animals when monitoring behavior over such large areas and time frames, thereby limiting the type of data that can be collected and the conclusions that can be drawn. Although the use of animal-mounted global positioning system (GPS) recorders may improve the probability of detection of widely ranging animals, spatial data collected by these means are generally of very coarse resolution and lack a detailed behavioral component. Consequently, the data that can be collected under such circumstances are of limited value for examining subtle variation in behavior among different groups or experimental treatments. Similarly, the direct, controlled manipulation of target behaviors is often prohibited by the spatial and temporal scales typical of navigation behaviors, as well as by inherent logistical constraints of field studies. Finding animals in their natural habitat, catching and manipulating them, and then collecting behavioral data without inadvertently producing spurious behaviors are major challenges of working with animals in the field. Therefore, the design of experiments on free-ranging animals is often constrained and the ability to conduct rigorous, controlled field experiments on the role of cognition in navigation is limited.
The present study circumvents many of the previous difficulties of investigating the relationship between cognition and navigation in the field by using a novel combination of pharmacological manipulation and high-resolution tracking of freely navigating animals under field conditions. Scopolamine, a muscarinic acetylcholine receptor (mAChR) antagonist, has been shown to block spatial memory formation and recall by blocking cholinergic activity in the brains of a variety of vertebrate taxa18-24. Scopolamine can be used effectively on free-ranging animals under field conditions11, 18 and has a marked but temporary effect (e.g., 6 - 8 hr in reptiles). Methylscopolamine, a mAChR antagonist that does not cross the blood-brain-barrier19-21, can be used to control for the possible peripheral effects of scopolamine and for non-cognitive aspects of behavior11. Pharmacology allows for the precise manipulation of cognition by directly affecting receptors, and high-precision radio telemetry allows for the observation of the resulting effects on behavior. Measurements taken via remote triangulation with both high spatial (&#177; 2.5 m) and temporal (15 min) resolution allow for the precise documentation and quantification of animal behavior relative to the experimental manipulation of cognition.
This study11 was conducted between May and August 2013 and 2014 at Chesapeake Farms, a 3,300 acre wildlife management and agriculture research area in Kent Co., MD, USA (39.194&#176;N, 76.187&#176;W). The protocol involves five main steps: (1) capturing and handling animals (2) affixing radio transmitters (3) preparing the pharmacological agents (4) monitoring and manipulating animal movements, and (5) analyzing spatial data. The study described herein focused on the Eastern painted turtle (Chrysemys picta). Turtles in the focal population engage in annual overland movements in which they leave their home ponds and navigate to alternative aquatic habitats using one of four very precise (&#177; 3.5 m), complex, and highly predictable routes11, 12. Pharmacological manipulation of animals in this system paired with high-resolution radio telemetry sheds light on the role of cognition in freely navigating wild animals.

<table><tbody><tr><td>Scopolamine bromide</td><td>Sigma</td><td>S0929</td><td>USP</td></tr><tr><td>Scopolamine methylbromide</td><td>Sigma</td><td>S8502, 1421009</td><td>USP and non USP versions</td></tr><tr><td>Saline</td><td>Hanna Pharmaceutical Supply Co., Inc.</td><td>409488850</td><td>USP, formulated as an injectable&amp;nbsp;</td></tr><tr><td>Syringe filter</td><td>Fisher</td><td>09-720-004</td><td></td></tr><tr><td>Syringe</td><td>Fisher</td><td>14-823-30</td><td></td></tr><tr><td>Hypodermic needle</td><td>Fisher</td><td>14-823-13</td><td></td></tr><tr><td>Antenna</td><td>Wildlife Materials</td><td>3 Element Folding Yagi</td><td>Antennae with additional elements are available, but can be cumbersome in the field.&amp;nbsp;</td></tr><tr><td>Radio Receiver</td><td>Wildlife Materials</td><td>TRX-2000S</td><td>Water resistant models are also available.</td></tr><tr><td>Compass</td><td>Brunton&amp;nbsp;</td><td>Truarc 15</td><td></td></tr><tr><td>Radio transmitters</td><td>Holohil Inc.</td><td>BD-2, PD-2, RI-2B</td><td>Transmitter models vary in lifespan and signal output as a function of battery size and pulse rate settings, which can be customized based on the study question and organism.</td></tr><tr><td>GPS</td><td>Garmin</td><td>eTrex Venture</td><td></td></tr><tr><td>Coaxial cable</td><td>newegg.com</td><td>C2G 40026</td><td>BNC connections are necessary.</td></tr><tr><td>Hoop net</td><td>Memphis Net and Twine&amp;nbsp;</td><td>TN325</td><td>Net mesh size should be chosen based on the minimum size of the target animal.&amp;nbsp;</td></tr></tbody></table>

using pharmacological manipulation and high-precision radio telemetry to study the spatial cognition in free-ranging animals

An animal&#39;s ability to perceive and learn about its environment plays a key role in many behavioral processes, including navigation, migration, dispersal and foraging. However, the understanding of the role of cognition in the development of navigation strategies and the mechanisms underlying these strategies is limited by the methodological difficulties involved in monitoring, manipulating the cognition of, and tracking wild animals. This study describes a protocol for addressing the role of cognition in navigation that combines pharmacological manipulation of behavior with high-precision radio telemetry. The approach uses scopolamine, a muscarinic acetylcholine receptor antagonist, to manipulate cognitive spatial abilities. Treated animals are then monitored with high frequency and high spatial resolution via remote triangulation. This protocol was applied within a population of Eastern painted turtles (Chrysemys picta) that has inhabited seasonally ephemeral water sources for ~100 years, moving between far-off sources using precise (&#177; 3.5 m), complex (i.e., non-linear with high tortuosity that traverse multiple habitats), and predictable routes learned before 4 years of age. This study showed that the processes used by these turtles are consistent with spatial memory formation and recall. Together, these results are consistent with a role of spatial cognition in complex navigation and highlight the integration of ecological and pharmacological techniques in the study of cognition and navigation.

Using the above protocol, the role of cognition in navigation was assessed in a population of Eastern painted turtles (Chrysemys picta) that has experienced seasonal ephemeral water sources for ~100 years. This population inhabits a mix of ephemeral (drained annually and rapidly - in several hr) and permanent aquatic habitats (Figure 1). Previous studies suggest that after their ponds are drained, resident turtles navigate to alternative water sources with high precision (&#177; 3.5 m) using complex, predictable routes learned before 4 years of age11-13 (Figure 1).
This study showed that the processes used by these turtles are consistent with spatial memory formation and recall11. Scopolamine blocked cholinergic activity in the brains of animals (including spatial memory formation and recall19-21) during navigation. Experienced adults treated with scopolamine diverted from their precise historic routes while na&#239;ve juveniles lacking experience (and thus memory) were unaffected by scopolamine, suggesting no effect of scopolamine on perceptual or non-spatial cognitive processes11 (Figures 1 and 2). Further, neither adult nor juvenile navigation was affected by the methylscopolamine control. Adult animals (i.e., those with previous experience at the site) injected with scopolamine lost their ability to follow the historic paths and the juveniles that use local cues to navigate and those adults injected with the drug that does not cross the blood-brain barrier were unaffected. Therefore, navigation in adults in this system seems to be cognitive in nature. Together, these results are consistent with the idea that turtles have a critical period during which they must learn paths and use cholinergic-dependent cognitive systems (spatial memory) to navigate as adults11-13.
<img alt="Figure 1" src="/files/ftp_upload/54790/54790fig1.jpg" /> 
Figure 1. Navigation is Based on Cognitive Processing in Adult Turtles. Representative movements of (a) experienced adults and (b) na&#239;ve juveniles (1 - 3 years) from temporary (T) to permanent (P) ponds while treated with either scopolamine or methylscopolamine. All adults receiving scopolamine (a, yellow, n = 9) drifted dramatically away (over 200 m) from the traditional routes (red, p&#60; 0.001), while all na&#239;ve juveniles treated with the drug (b, yellow, n = 7) maintained movement exactly within traditional routes (p &#62; 0.999). All control adults (a, white, n = 9) and control na&#239;ve juveniles (b, white, n = 6) followed traditional routes (p &#62; 0.999). Each line of points represents one individual. All turtles from all groups maintained high precision prior to injection (p &#62; 0.999). Data from Roth and Krochmal11. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54790/54790fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54790/54790fig2.jpg" /> 
Figure 2. The Precision of Navigation is a Function of Cognitive Processing in Adult Turtles. a) All turtles demonstrated high precision of movement prior to injection of the treatment (scopolamine) or control (methylscopolamine; p &#62; 0.999). b) After injection, adults in the scopolamine treatment deviated significantly (p &#60; 0.001) from their traditional routes. In contrast, all other groups continued to navigate with high precision (&#177; 3.5 m; p &#62; 0.999). Inserts show detail of overlap from 0.5 - 3.5 m. Points are means &#177; SEM. Data from Roth and Krochmal11. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54790/54790fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Using Pharmacological Manipulation and High-precision Radio Telemetry to Study the Spatial Cognition in Free-ranging Animals at JoVE.com

Using Pharmacological Manipulation and High-precision Radio Telemetry to Study the Spatial Cognition in Free-ranging Animals

This paper describes a novel protocol that combines the pharmacological manipulation of memory and radio telemetry to document and quantify the role of cognition in navigation.

An animal&#39;s ability to perceive and learn about its environment plays a key role in many behavioral processes, including navigation, migration, ...

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Nanyang Technological University

Research

JoVE Journal

Environment

6.7K Views.  Franklin and Marshall College.  Dit document beschrijft een nieuw protocol dat de farmacologische manipulatie van het geheugen en radio telemetrie te documenteren en te kwantificeren de rol van cognitie in de navigatie combineert. 

Video: Using Pharmacological Manipulation and High-precision Radio Telemetry to Study the Spatial Cognition in Free-ranging Animals

The Double-H Maze: A Robust Behavioral Test for Learning and Memory in Rodents

Spatial cognition research in rodents typically employs the use of maze tasks, whose attributes vary from one maze to the next. These tasks vary by their behavioral flexibility and required memory duration, the number of goals and pathways, and also the overall task complexity. A confounding feature in many of these tasks is the lack of control over the strategy employed by the rodents to reach the goal, e.g., allocentric (declarative-like) or egocentric (procedural) based strategies. The double-H maze is a novel water-escape memory task that addresses this issue, by allowing the experimenter to direct the type of strategy learned during the training period. The double-H maze is a transparent device, which consists of a central alleyway with three arms protruding on both sides, along with an escape platform submerged at the extremity of one of these arms.
Rats can be trained using an allocentric strategy by alternating the start position in the maze in an unpredictable manner (see protocol 1; &#167;4.7), thus requiring them to learn the location of the platform based on the available allothetic cues. Alternatively, an egocentric learning strategy (protocol 2; &#167;4.8) can be employed by releasing the rats from the same position during each trial, until they learn the procedural pattern required to reach the goal. This task has been proven to allow for the formation of stable memory traces.
Memory can be probed following the training period in a misleading probe trial, in which the starting position for the rats alternates. Following an egocentric learning paradigm, rats typically resort to an allocentric-based strategy, but only when their initial view on the extra-maze cues differs markedly from their original position. This task is ideally suited to explore the effects of drugs/perturbations on allocentric/egocentric memory performance, as well as the interactions between these two memory systems.

The goal of this protocol is to investigate spatial cognition in rodents. The double-H water maze is a novel test, which is particularly useful to elucidate the different components of learning, consolidation and memory, as well as the interplay of memory systems.

Spatial cognition research in rodents typically employs the use of maze tasks, whose attributes vary from one maze to the next. These tasks vary by their ...

Behavior

Quantifying Cognitive Decrements Caused by Cranial Radiotherapy

With the exception of survival, cognitive impairment stemming from the clinical management of cancer is a major factor dictating therapeutic outcome. For many patients afflicted with CNS and non-CNS malignancies, radiotherapy and chemotherapy offer the best options for disease control. These treatments however come at a cost, and nearly all cancer survivors (~11 million in the US alone as of 2006) incur some risk for developing cognitive dysfunction, with the most severe cases found in patients subjected to cranial radiotherapy (~200,000/yr) for the control of primary and metastatic brain tumors1. Particularly problematic are pediatric cases, whose long-term survival plagued with marked cognitive decrements results in significant socioeconomic burdens2. To date, there are still no satisfactory solutions to this significant clinical problem.
We have addressed this serious health concern using transplanted stem cells to combat radiation-induced cognitive decline in athymic rats subjected to cranial irradiation3. Details of the stereotaxic irradiation and the in vitro culturing and transplantation of human neural stem cells (hNSCs) can be found in our companion paper (Acharya et al., JoVE reference). Following irradiation and transplantation surgery, rats are then assessed for changes in cognition, grafted cell survival and expression of differentiation-specific markers 1 and 4-months after irradiation. To critically evaluate the success or failure of any potential intervention designed to ameliorate radiation-induced cognitive sequelae, a rigorous series of quantitative cognitive tasks must be performed. To accomplish this, we subject our animals to a suite of cognitive testing paradigms including novel place recognition, water maze, elevated plus maze and fear conditioning, in order to quantify hippocampal and non-hippocampal learning and memory. We have demonstrated the utility of these tests for quantifying specific types of cognitive decrements in irradiated animals, and used them to show that animals engrafted with hNSCs exhibit significant improvements in cognitive function3.
The cognitive benefits derived from engrafted human stem cells suggest that similar strategies may one day provide much needed clinical recourse to cancer survivors suffering from impaired cognition. Accordingly, we have provided written and visual documentation of the critical steps used in our cognitive testing paradigms to facilitate the translation of our promising results into the clinic.

Cognitive impairment resulting from the radiotherapeutic management of brain tumors represents a clinically intractable condition that adversely impacts quality of life. The capability to critically evaluate potential interventions for ameliorating radiation-induced cognitive decrements ultimately depends on the capability to undertake rigorous quantitative assessments of cognition.

With the exception of survival, cognitive impairment stemming from the clinical management of cancer is a major factor dictating therapeutic outcome. For ...

Medicine

Survivable Stereotaxic Surgery in Rodents 

The ability to measure extracellular basal levels of neurotransmitters in the brain of awake animals allows for the determination of effects of different systemic challenges (pharmacological or physiological) to the CNS. For example, one can directly measure how the animal's midbrain dopamine projections respond to dopamine-releasing drugs like d-amphetamine or natural stimuli like food. In this video, we show you how to implant guide cannulas targeting specific sites in the rat brain, how to insert and implant a microdialysis probe and how to use high performance liquid chromatography coupled with electrochemical detection (HPLC-EC) to measure extracellular levels of oxidizable neurotransmitters and metabolites. Local precise introduction of drugs through the microdialysis probe allows for refined work on site specificity in a compound s mechanism of action. This technique has excellent anatomical and chemical resolution but only modest time resolution as microdialysis samples are usually processed every 20-30 minutes to ensure detectable neurotransmitter levels. Complementary ex vivo tools (i.e., slice and cell culture electrophysiology) can assist with monitoring real-time neurotransmission.

Survivable Stereotaxic Surgery in Rodents

The monitoring of extracellular neurotransmitter levels in distinct brain regions of freely moving animals offers insights on the link between neurotransmitter release and behavior. In vivo microdialysis coupled with electrochemical detection provides excellent anatomical and chemical resolution; and information on how basal neurotransmission is altered by pharmacological or physiological manipulations.

The ability to measure extracellular basal levels of neurotransmitters in the brain of awake animals allows for the determination of effects of different ...

Biology

A Behavioral Assay for Investigating the Role of Spatial Memory During Instinctive Defense in Mice

Evolution has selected a repertoire of defensive behaviors that are essential for survival across all animal species. These behaviors are often stereotyped actions elicited in response to innately aversive sensory stimuli, but their success requires enough flexibility for adapting to different spatial environments, which can change rapidly. Here, we describe a behavioral assay to evaluate the influence of learned spatial knowledge on defensive behaviors in mice. We have adapted the widely used Barnes maze spatial memory assay to investigate how mice navigate to a shelter during escape responses to innately aversive sensory stimuli in a novel environment, and how they adapt to acute changes in the environment. This new assay is an ethological paradigm that does not require training and exploits the natural exploration patterns and navigation strategies in mice. We propose that the set of protocols described here are a powerful means of studying goal-directed behaviors and stimulus-triggered navigation, which should be of interest to both the fields of instinctive behaviors and spatial memory.

This protocol describes a behavioral assay, based on the Barnes maze test, to study how instinctive defensive actions are modified by the knowledge of spatial environment.

Evolution has selected a repertoire of defensive behaviors that are essential for survival across all animal species. These behaviors are often ...

Analyzing Spatial Learning and Prosocial Behavior in Mice Using the Barnes Maze and Damsel-in-Distress Paradigms

The Barnes maze is a reliable measure of spatial learning and memory that does not require food restriction or exposure to extremely stressful stimuli. The Barnes maze can also assess other mouse behaviors, such as general motivation to escape from the maze platform and exploratory behavior. The Barnes maze can measure whether a genetic mutation or environmental variable can impact the acquisition and retention of spatial memories, as well as provide information about the search strategy employed by the mice. Here we use the Barnes maze to detect a memory deficit in adult mice following a single developmental ethanol exposure event. The newly described Damsel-in-Distress paradigm exposes a male mouse to a female mouse trapped in a chamber in the open center field of the arena. It provides an opportunity for the mouse to socially respond to the trapped female and exhibit prosocial behavior. The Damsel-in-Distress paradigm can also be used to examine mouse behavior in a novel arena and measure locomotor activity. Both the Barnes Maze and the Damsel-in-Distress protocols require minimal financial investment and most aspects of the tests can be constructed from common lab supplies. These flexible and accessible tools can also be used to detect behavioral changes over the course of development.

This protocol measures spatial learning and memory using the Barnes maze. A novel Damsel-in-Distress paradigm is used to assess locomotor activity and prosocial behavior in mice.

The Barnes maze is a reliable measure of spatial learning and memory that does not require food restriction or exposure to extremely stressful stimuli. ...

A Video Demonstration of Preserved Piloting by Scent Tracking but Impaired Dead Reckoning After Fimbria-Fornix Lesions in the Rat

Piloting and dead reckoning navigation strategies use very different cue constellations and computational processes (Darwin, 1873; Barlow, 1964; O&#x2019;Keefe and Nadel, 1978; Mittelstaedt and Mittelstaedt, 1980; Landeau et al., 1984; Etienne, 1987; Gallistel, 1990;
Maurer and S&#233;guinot, 1995). Piloting requires the use of the relationships between relatively stable external (visual, olfactory, auditory) cues, whereas dead reckoning requires the integration of cues generated by self-movement. Animals obtain self-movement information from vestibular receptors, and possibly muscle and joint receptors, and efference copy of commands that generate movement. An animal may also use the flows of visual, auditory, and olfactory stimuli caused by its movements. Using a piloting strategy an animal can use geometrical calculations to determine directions and distances to places in its environment, whereas using an dead reckoning strategy it can integrate cues generated by its previous movements to return to a just left location. Dead reckoning is colloquially called "sense of direction" and "sense of distance."

Although there is considerable evidence that the hippocampus is involved in piloting (O&#x2019;Keefe and Nadel, 1978; O&#x2019;Keefe and Speakman, 1987), there is also evidence from behavioral (Whishaw et al., 1997; Whishaw and Maaswinkel, 1998; Maaswinkel and Whishaw, 1999), modeling (Samsonovich and McNaughton, 1997), and electrophysiological (O&#x2019;Mare et al., 1994; Sharp et al., 1995; Taube and Burton, 1995; Blair and Sharp, 1996; McNaughton et al., 1996; Wiener, 1996; Golob and Taube, 1997) studies that the hippocampal formation is involved in dead reckoning. The relative contribution of the hippocampus to the two forms of navigation is still uncertain, however. Ordinarily, it is difficult to be certain that an animal is using a piloting versus a dead reckoning strategy because animals are very flexible in their use of strategies and cues (Etienne et al., 1996; Dudchenko et al., 1997; Martin et al., 1997; Maaswinkel and Whishaw, 1999). The objective of the present video demonstrations was to solve the problem of cue specification in order to examine the relative contribution of the hippocampus in the use of these strategies. The rats were trained in a new task in which they followed linear or polygon scented trails to obtain a large food pellet hidden on an open field. Because rats have a proclivity to carry the food back to the refuge, accuracy and the cues used to return to the home base were dependent variables (Whishaw and Tomie, 1997). To force an animal to use a a dead reckoning strategy to reach its refuge with the food, the rats were tested when blindfolded or under infrared light, a spectral wavelength in which they cannot see, and in some experiments the scent trail was additionally removed once an animal reached the food. To examine the relative contribution of the hippocampus, fimbria&#x2013;fornix (FF) lesions, which disrupt information flow in the hippocampal formation (Bland, 1986), impair memory (Gaffan and Gaffan, 1991), and produce spatial deficits (Whishaw and Jarrard, 1995), were used.

In a piloting scent tracking task, the ability of the rats to return to a refuge with food using visual an odor trail or using dead reckoning in infrared light, the integrated record of previous movements, demonstrates that the hippocampus is necessary for dead reckoning.

Piloting and dead reckoning navigation strategies use very different cue constellations and computational processes (Darwin, 1873; Barlow, 1964; ...

Simultaneous Monitoring of Wireless Electrophysiology and Memory Behavioral Test as a Tool to Study Hippocampal Neurogenesis

Brainwaves amplitude obtained from electroencephalography (EEG) has been well-recognized as a basis for cognitive capacity, memory, and learning on animals and humans. Adult neurogenesis mechanism is also linked to memory and learning improvement. Traditionally, researchers used to assess learning and memory parameters in rodent models by behavioral tasks. Therefore, the simultaneous monitoring of behavioral changes and EEG is particularly interesting in correlating data between brain activity and task-related behaviors. However, most of the equipment required to perform both studies are either complex, expensive, or uses a wired setup network that hinders the natural animals&#8217; movement. In this study, EEG was recorded with a wireless electrophysiology device along with the execution of a novel object recognition task (NORT). The animal&#8217;s behavior was monitored simultaneously by a video tracking system. Both recordings were analyzed offline by their timestamps which were synched to link EEG signals with the animal&#8217;s actions. Subjects consist of adult Wistar rats after medium-term environmental enrichment treatment. Six skull screw electrodes were fixed in pairs on both hemispheres over frontal, central, and parietal regions and were referenced to an electrode located posterior of the nasal bone. NORT protocol consists of exposing the animal to two identical objects for 10 min. After 2 h and 24 h, one of the objects was replaced with a novel one. Exploration time for each object was monitored by a behavioral tracking software (BTS) and EEG data recording. The analysis of the EEG synced with behavioral data consists of estimations of alpha and beta relative band power and comparisons between novel object recognition versus familiar object exploration, between three experimental stages. In this manuscript, we have discussed electrodes manufacturing process, epidural electrodes implantation surgery, environmental enrichment protocol, NORT protocol, BTS setup, EEG &#8211; BTS coupling for simultaneous monitoring in real-time, and EEG data analysis based on automatic events detection.

The protocol presented here provides information on the simultaneous electroencephalography (EEG) and behavioral assessment in real-time. We have discussed all steps involved in this protocol as an attractive solution for researchers in many fields of neuroscience, particularly in learning and memory areas.

Brainwaves amplitude obtained from electroencephalography (EEG) has been well-recognized as a basis for cognitive capacity, memory, and learning on ...

Behavioral Training Procedures for Head-fixed Virtual Reality in Mice

Virtual reality (VR) combined with head-fixation is increasingly being utilized in behavioral neuroscience studies as it allows complex behavioral assays to be performed in head-fixed mice. This enables precise behavioral recordings while incorporating various neurophysiological techniques that require head-fixation to minimize movement-related signal noise during neural recordings. However, despite the growing use of VR, there is little published data on the detailed methodology of how to implement it. In this study, a training protocol is developed whereby male and female C57B16/J mice are trained to run down a virtual linear corridor, the length of which is increased from 1-3 m over multiple training sessions. Building upon this foundation, this study investigated the feasibility of mice performing complex behaviors within VR using a Y-maze paradigm. The task required navigating to the arm with black walls from the choice point in the Y-maze. After reaching a criterion of two consecutive days equal to or greater than 70% correct, the mice progressed to increasingly difficult sensory discrimination. The findings provide important details on the methodologies useful for the successful training of mice in VR and demonstrate that mice exhibit learning capabilities in navigating the Y-maze. The methodology presented not only offers insights into training duration in VR-based assays but also underscores the potential for probing intricate behaviors in mice, opening avenues for more comprehensive neuroscience investigations.

The article describes the experimental procedures for the commonly used linear track virtual reality (VR) paradigm in mice as well as determining the feasibility of running complex VR tasks by testing a Y-shaped signal discrimination task.

Virtual reality (VR) combined with head-fixation is increasingly being utilized in behavioral neuroscience studies as it allows complex behavioral assays ...

Assessing Spatial Learning and Memory in Small Squamate Reptiles

Clinical research has leveraged a variety of paradigms to assess cognitive decline, commonly targeting spatial learning and memory abilities. However, interest in the cognitive processes of nonmodel species, typically within an ecological context, has also become an emerging field of study. In particular, interest in the cognitive processes in reptiles is growing although experimental studies on reptilian cognition are sparse. The few reptilian studies that have experimentally tested for spatial learning and memory have used rodent paradigms modified for use in reptiles. However, ecologically important aspects of the physiology and behavior of this taxonomic group must be taken into account when testing for spatially based cognition. Here, we describe modifications of the dry land Barnes maze and associated testing protocol that can improve performance when probing for spatial learning and memory ability in small squamate reptiles. The described paradigm and procedures were successfully used with male side-blotched lizards (Uta stansburiana), demonstrating that spatial learning and memory can be assessed in this taxonomic group with an ecologically relevant apparatus and protocol.

This paper describes a modification of the Barnes maze, a standard rodent paradigm used to assess spatial memory and learning, for use in small squamate reptiles.

Clinical research has leveraged a variety of paradigms to assess cognitive decline, commonly targeting spatial learning and memory abilities. However, ...

Neuroscience

An Open-Source Virtual Reality System for the Measurement of Spatial Learning in Head-Restrained Mice

Head-restrained behavioral experiments in mice allow neuroscientists to observe neural circuit activity with high-resolution electrophysiological and optical imaging tools while delivering precise sensory stimuli to a behaving animal. Recently, human and rodent studies using virtual reality (VR) environments have shown VR to be an important tool for uncovering the neural mechanisms underlying spatial learning in the hippocampus and cortex, due to the extremely precise control over parameters such as spatial and contextual cues. Setting up virtual environments for rodent spatial behaviors can, however, be costly and require an extensive background in engineering and computer programming. Here, we present a simple yet powerful system based upon inexpensive, modular, open-source hardware and software that enables researchers to study spatial learning in head-restrained mice using a VR environment. This system uses coupled microcontrollers to measure locomotion and deliver behavioral stimuli while head-restrained mice run on a wheel in concert with a virtual linear track environment rendered by a graphical software package running on a single-board computer. The emphasis on distributed processing allows researchers to design flexible, modular systems to elicit and measure complex spatial behaviors in mice in order to determine the connection between neural circuit activity and spatial learning in the mammalian brain.

Here, we present a simplified open-source hardware and software setup for investigating mouse spatial learning using virtual reality (VR). This system displays a virtual linear track to a head-restrained mouse running on a wheel by utilizing a network of microcontrollers and a single-board computer running an easy-to-use Python graphical software package.

Head-restrained behavioral experiments in mice allow neuroscientists to observe neural circuit activity with high-resolution electrophysiological and ...

Using Pharmacological Manipulation and High-precision Radio Telemetry to Study the Spatial Cognition in Free-ranging Animals

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