This work was supported by the Department of Veterans Affairs Rehab R&#38;D Service Career Development Awards (CDA-1, RX002111; CDA-2; RX002928) to RSA and (CDA-2, RX002342) to AJF and the National Institutes of Health (NIH-NICHD F31 HD097918 to DACT and NIH-NIEHS T32 ES012870 to DACT) and NEI Core Grant P30EY006360.

All procedures were approved by the Atlanta Veterans Affairs Institutional Animal Care and Use Committee and conformed to the National Institutes of Health guide for the care and use of laboratory animals (NIH Publications, 8th edition, updated 2011).
1. The optomotor response (OMR)
<ol>
	<li>Set up the OMR apparatus (details on apparatus and software in Table of Materials)
	<ol>
		<li>Choose the appropriate-sized platform for the rodent: mouse, rat, or large/impa...

<ol>
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Y., 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=Retinal+microvascular+abnormalities+and+incident+stroke:+the+Atherosclerosis+Risk+in+Communities+Study.">Retinal microvascular abnormalities and incident stroke: the Atherosclerosis Risk in Communities Study.</a> The Lancet. 358 (9288), 1134-1140 (2001).</li><li>Marqui&#233;, M., 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=Association+between+retinal+thickness+and+&#946;-amyloid+brain+accumulation+in+individuals+with+subjective+cognitive+decline:+Fundaci&#243;+ACE+Healthy+Brain+Initiative.">Association between retinal thickness and &#946;-amyloid brain accumulation in individuals with subjective cognitive decline: Fundaci&#243; ACE Healthy Brain Initiative.</a> Alzheimer's Research &amp; Therapy. 12 (1), 37 (2020).</li><li>Thomas, B. B., Seiler, M. J., Sadda, S. R., Coffey, P. J., Aramant, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optokinetic+test+to+evaluate+visual+acuity+of+each+eye+independently.">Optokinetic test to evaluate visual acuity of each eye independently.</a> Journal of Neuroscience Methods. 138 (1-2), 7-13 (2004).</li><li>Prusky, G. T., Alam, N. M., Beekman, S., Douglas, R. 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M., 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=Independent+visual+threshold+measurements+in+the+two+eyes+of+freely+moving+rats+and+mice+using+a+virtual-reality+optokinetic+system.">Independent visual threshold measurements in the two eyes of freely moving rats and mice using a virtual-reality optokinetic system.</a> Visual Neuroscience. 22 (5), 677-684 (2005).</li><li>Feola, A. J., 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=Menopause+exacerbates+visual+dysfunction+in+experimental+glaucoma.">Menopause exacerbates visual dysfunction in experimental glaucoma.</a> Experimental Eye Research. 186, 107706 (2019).</li><li>Allen, R. S., 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=TrkB+signalling+pathway+mediates+the+protective+effects+of+exercise+in+the+diabetic+rat+retina.">TrkB signalling pathway mediates the protective effects of exercise in the diabetic rat retina.</a> European Journal of Neuroscience. 47 (10), 1254-1265 (2018).</li><li>Allen, R. S., 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=Retinal+deficits+precede+cognitive+and+motor+deficits+in+a+rat+model+of+type+II+diabetes.">Retinal deficits precede cognitive and motor deficits in a rat model of type II diabetes.</a> Investigative Ophthalmology &amp; Visual Science. 60 (1), 123-133 (2019).</li><li>Prusky, G. T., Harker, K. T., Douglas, R. M., Whishaw, I. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variation+in+visual+acuity+within+pigmented,+and+between+pigmented+and+albino+rat+strains.">Variation in visual acuity within pigmented, and between pigmented and albino rat strains.</a> Behavioural Brain Research. 136 (2), 339-348 (2002).</li><li>Hwang, C. K., 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=Circadian+rhythm+of+contrast+sensitivity+is+regulated+by+a+dopamine-neuronal+PAS-domain+protein+2-adenylyl+cyclase+1+signaling+pathway+in+retinal+ganglion+cells.">Circadian rhythm of contrast sensitivity is regulated by a dopamine-neuronal PAS-domain protein 2-adenylyl cyclase 1 signaling pathway in retinal ganglion cells.</a> Journal of Neuroscience. 33 (38), 14989-14997 (2013).</li><li>Mui, A. M., 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=Daily+visual+stimulation+in+the+critical+period+enhances+multiple+aspects+of+vision+through+BDNF-mediated+pathways+in+the+mouse+retina.">Daily visual stimulation in the critical period enhances multiple aspects of vision through BDNF-mediated pathways in the mouse retina.</a> PLoS One. 13 (2), 0192435 (2018).</li><li>Feola, A. J., 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=Menopause+exacerbates+visual+dysfunction+in+experimental+glaucoma.">Menopause exacerbates visual dysfunction in experimental glaucoma.</a> Experimental Eye Research. 186, 107706 (2019).</li><li>Allen, R. S., 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=Long-term+functional+and+structural+consequences+of+primary+blast+overpressure+to+the+eye.">Long-term functional and structural consequences of primary blast overpressure to the eye.</a> Journal of Neurotrauma. 35 (17), 2104-2116 (2018).</li><li>Maaswinkel, H., Li, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatio-temporal+frequency+characteristics+of+the+optomotor+response+in+zebrafish.">Spatio-temporal frequency characteristics of the optomotor response in zebrafish.</a> Vision Research. 43 (1), 21-30 (2003).</li><li>Benkner, B., Mutter, M., Ecke, G., M&#252;nch, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterizing+visual+performance+in+mice:+an+objective+and+automated+system+based+on+the+optokinetic+reflex.">Characterizing visual performance in mice: an objective and automated system based on the optokinetic reflex.</a> Behavioral Neuroscience. 127 (5), 788-796 (2013).</li><li>Lehmann, K., Schmidt, K. 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The authors have nothing to disclose.

The OMR and the Y-maze allow for the non-invasive assessment of visual function and cognitive function deficits in rodents over time. In this protocol, the OMR and the Y-maze were demonstrated to track visual and cognitive deficits in rodent models of diabetes.
Critical steps in the protocol
The OMR
Some important points to consider when performing the OMR to assess visual function are the testing parameters used, experim...

An erratum was issued for:&#160;<a href="https://www.jove.com/t/61806">Behavioral Assessment of Visual Function via Optomotor Response and Cognitive Function via Y-Maze in Diabetic Rats</a>. The author list was updated.
The author list was updated from:
Kaavya Gudapati*1,2, Anayesha Singh*1,3, Danielle Clarkson-Townsend1,4, Andrew J. Feola1,2, Rachael S. Allen1,2 
1Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, 
2Department of Biomedical Engineering, Georgia Institute of Technology, 
3Department of Neuroscience, Emory University, 
4Gangarosa Department of Environmental Health, Emory University 
* These authors contributed equally
to:
Kaavya Gudapati*1,2, Anayesha Singh*1,3, Danielle Clarkson-Townsend1,4, Stephen Q. Phillips1, Amber Douglass1, Andrew J. Feola1,2, Rachael S. Allen1,2 
1Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, 
2Department of Biomedical Engineering, Georgia Institute of Technology, 
3Department of Neuroscience, Emory University, 
4Gangarosa Department of Environmental Health, Emory University 
* These authors contributed equally

An erratum was issued for:&#160;<a href="https://www.jove.com/t/61806">Behavioral Assessment of Visual Function via Optomotor Response and Cognitive Function via Y-Maze in Diabetic Rats</a>. The author list was updated.

Erratum: Behavioral Assessment of Visual Function via Optomotor Response and Cognitive Function via Y-Maze in Diabetic Rats

Over 463 million people live with diabetes, making it one of the largest global disease epidemics1. One of the serious complications that arises from diabetes is diabetic retinopathy (DR), a leading cause of blindness for working-age American adults2. In the next 30 years, the percentage of the population at risk for DR is projected to double, so it is crucial to find new ways of diagnosing DR in its earlier stages to prevent and mitigate DR development3. DR has conventionally been thought to be a vascular disease4,5,6. However, now with evidence of neuronal dysfunction and apoptosis in the retina that precedes vascular pathology, DR is defined to have neuronal and vascular components4,5,6,7,8,9. One way to diagnose DR would be to examine neural abnormalities in the retina, a tissue that may be more vulnerable to oxidative stress and metabolic strain from diabetes than other neural tissue10.
Declines in cognitive and motor function also occur with diabetes and are often correlated with retinal changes. Older individuals with Type II diabetes portray worse baseline cognitive performance and show more exacerbated cognitive decline than control participants11. Additionally, the retina has been established as an extension of the central nervous system and pathologies can manifest in the retina12. Clinically, the relationship between retina and brain has been studied in the context of Alzheimer&#8217;s and other diseases but is not commonly explored with diabetes12,13,14,15,16. Changes in the brain and retina during the progression of diabetes can be explored using animal models, including the STZ rat (a model of Type I diabetes in which the toxin, streptozotocin or STZ, is used to damage pancreatic beta cells) and the Goto-Kakizaki rat (a polygenic model of Type II diabetes in which animals develop hyperglycemia spontaneously at around 3 weeks of age). In this protocol, a description for the Y-maze and the optomotor response to assess cognitive and visual changes in diabetic rodents, respectively, is provided. The optomotor response (OMR) assesses spatial frequency (similar to visual acuity) and contrast sensitivity by monitoring characteristic reflexive head tracking movements to gauge visual thresholds for each eye17. Spatial frequency refers to the thickness or fineness of the bars, and contrast sensitivity refers to how much contrast there is between the bars and the background (Figure 1E). Meanwhile, the Y-maze tests short-term spatial memory and exploratory function, observed through spontaneous alternations and entries through the arms of the maze.
Both tests can be performed in awake, non-anesthetized animals and have the advantage of capitalizing on innate responses of the animals, meaning that they do not require training. Both are relatively sensitive, in that they can be used to detect deficits early in the progression of diabetes in rodents, and reliable, in that they produce results that correlate with other visual, retinal, or behavioral tests. Additionally, using the OMR and the Y-maze in conjunction with tests such as electroretinogram and optical coherence tomography scans can provide information on when retinal, structural, and cognitive changes develop relative to each other in disease models. These investigations could be useful in identifying neural degenerations that occur due to diabetes. Ultimately, this could lead to new diagnostic methods that effectively identify DR in early stages of progression.
The OMR and the Y-maze systems used to develop this protocol are described in the Table of Materials. Previous research on the OMR, by Prusky et al.18, and the Y-maze, by Maurice et al.19, was used as the starting point to develop this protocol.

<table>
	<tbody>
		<tr>
			<td>OptoMotry HD</td>
			<td>CerebralMechanics Inc.</td>
			<td></td>
			<td>OMR apparatus &#38; software</td>
		</tr>
		<tr>
			<td>Timer</td>
			<td>Thomas Scientific</td>
			<td>810029AR</td>
			<td></td>
		</tr>
		<tr>
			<td>Y-Maze apparatus</td>
			<td>San Diego Instruments</td>
			<td>7001-043</td>
			<td>Available specifically for rats</td>
		</tr>
	</tbody>
</table>

behavioral assessment of visual function via optomotor response and cognitive function via y-maze in diabetic rats

The optomotor response and the Y-maze are behavioral tests useful for assessing visual and cognitive function, respectively. The optomotor response is a valuable tool to track changes in spatial frequency (SF) and contrast sensitivity (CS) thresholds over time in a number of retinal disease models, including diabetic retinopathy. Similarly, the Y-maze can be used to monitor spatial cognition (as measured by spontaneous alternation) and exploratory behavior (as measured by a number of entries) in a number of disease models that affect the central nervous system. Advantages of the optomotor response and the Y-maze include sensitivity, speed of testing, the use of innate responses (training is not needed), and the ability to be performed on awake (non-anesthetized) animals. Here, protocols are described for both the optomotor response and the Y-maze and examples of their use shown in models of Type I and Type II diabetes. Methods include preparation of rodents and equipment, performance of the optomotor response and the Y-maze, and post-test data analysis.

The OMR is considered successful if spatial frequency and contrast sensitivity thresholds can be obtained from a rodent. Here, the use of the OMR to assess spatial frequency is illustrated in na&#239;ve control Brown-Norway and Long-Evans rats, both young (3&#8211;6 months) and aged (9&#8211;12 months). Brown-Norway rats typically show a higher baseline spatial frequency than Long-Evans rats. Additionally, an aging effect on spatial frequency was observed in the Long-Evans rats (Figure 3A). ...

Watch this Scientific Journal Video about Behavioral Assessment of Visual Function via Optomotor Response and Cognitive Function via Y-Maze in Diabetic Rats at JoVE.com

Behavioral Assessment of Visual Function via Optomotor Response and Cognitive Function via Y-Maze in Diabetic Rats

Neural degeneration in both eyes and brain as a result of diabetes can be observed through behavioral tests carried out on rodents. The Y-maze, a measure of spatial cognition, and the optomotor response, a measure of visual function, both provide insight into potential diagnoses and treatments.

The optomotor response and the Y-maze are behavioral tests useful for assessing visual and cognitive function, respectively. The optomotor response is a ...

The optomotor response and the Y-maze are behavioral tests that are useful in measuring visual function and cognitive function respectively in a wide variety of disease models. Advantages of these tests include sensitivity, speed of testing, the use of innate responses such that training isn't needed, and the ability to perform the tests on awake non-anesthetized animals. OMR and Y-maze can be used along with other tests to identify temporal appearance of retinal and brain dysfunction in diseases like diabetes with the goal being earlier diagnosis.Demonstrating the Y-maze will be Stephen Phillips, a research technician from my laboratory. Demonstrating the optomotor response or OMR procedure will be Amber Douglass, a research technician in the Allen and Viola Labs. To set up the OMR apparatus, first select an appropriate-sized platform for the experimental animal species to be used and open the OMR software.Zoom in or out with the video camera as needed so that the platform and its surroundings are visible and click the asterisk and rotating stripes icons so that both the green asterisk and green rotating stripes disappear from the live feed. Click the compass icon so that a green circle and two perpendicular lines appear and stretch the green circle so that it aligns perfectly with the black circle on the platform. When the OMR is completely aligned, re-click the compass, asterisk, and rotating stripes icons.Note that the green stripes will rotate in the same direction as the stripes in the drum. Under the testing tab, click the psychophysics tab. To measure spatial frequency, under threshold, select frequency.Under testing, click presets and select the default settings for the experimental animal being used. Click the blanking tab and check the blank on tracking box to pause the stripes and blank out the computer screens in the drum whenever the mouse is right-clicked. Then click the results tab to open the window in which the results of the test will be displayed.To assess spatial frequency, place the rodent onto the circular platform in the center of a virtual reality chamber comprised of four computer monitors showing vertical sine wave gradings circling the chamber at a velocity of 12 degrees per second. The video camera positioned at the top of the chamber should project the rodent's behavior live on the computer monitor. Look for the presence or absence of reflexive actions by the rodent's head as the gradings move in a clockwise or counterclockwise direction.Make sure that illustrated bars are visible in the program as they will show the direction of the grading movement. Watch for the rodent's head to move in the same direction as the gradings. When there is a smooth pursuit, not erratic bursts of head motion, count this movement as tracking.Click on yes or no as appropriate. Spatial frequency will start at 0.042 cycle or degree and adjust with each yes and no click to become easier or more difficult. As the rodent is tested, make sure to keep the asterisk positioned over the rodent's head and watch for the system to say done when the rodent's spatial frequency threshold is reached.Note that the yes and no buttons will no longer be able to be clicked. Then open the results tab to view the spatial frequency for the left, right, and combined eyes. To measure contrast sensitivity, in the testing and psychophysics tabs, select contrast single.Open the stimulus and gradings tabs and enter the appropriate value into the spatial frequency box to start gradings with the spatial frequency constant at the peak of the contrast sensitivity curve. Begin the contrast at 100%and look for the same reflexive head movements as observed during spatial frequency testing. Note that the contrast will decrease as the testing progresses until the rodent no longer has reflexive head movements in response to the stimulus.When the contrast sensitivity threshold has been reached, open the results tab to view the contrast sensitivity values for the left, right, and combined eyes. To conduct a Y-maze analysis, first label the initial arm of the Y-maze as B and the other two arms as A and C and place the rodent in the B arm near the center of the maze. Immediately start the timer and allow the rodent to explore the Y-maze for eight minutes.Sit several feet away from the maze, keeping it in sight and avoiding making any noise while taking recordings and noting any observations. Record the starting location as B.Each time the rodent makes an entry into a new arm, record the new location of the rodent. If the rodent remains in the same spot for more than 60 seconds and does not appear to show exploratory behavior, move the rodent toward the center of the Y-maze and continue the trial.After at the end of each trial, remove any feces and clean the maze with sanitizing solution. Calculate the exploratory behavior as the total number of entries made over the eight minutes of the trial. The spatial cognition is calculated as the number of successful alternations divided by the total number of entries.Here, the use of the OMR to assess spatial frequency is illustrated in naive controlled Brown Norway and Long-Evans rats. Brown Norway rats typically show a higher baseline spatial frequency than Long-Evans rats. Additionally, an aging effect on spatial frequency is observed in the Long-Evans rats.Using the OMR to assess contrast sensitivity reveals significant deficits in contrast sensitivity in type one diabetic rats. Exercise treatment reduces these deficits, demonstrating that the OMR is useful both for detecting and tracking retinal deficits over time with and without intervention. Using a Y-maze to assess cognitive function and exploratory behavior in a type two model of diabetes shows significant deficits in spatial cognition as measured by spontaneous alternation and exploratory behavior as measured by number of entries in Goto-Kakizaki rats compared with Wistar control animals beginning at seven weeks of age.Learning how to identify a tracking head movement in step 3.4 is the most difficult part of OMR. Learning what a smooth pursuit movement looks like is critical. The OMR and Y-maze paved the way for IM brain researchers to quickly and reliably measure visual and cognitive function without training and with minimal stress to the animals.

behavioral-assessment-visual-function-via-optomotor-response

Research

JoVE Journal

Behavior

5.3K Views.  Atlanta VA Medical Center. The optomotor response and the Y-maze are behavioral tests that are useful in measuring visual function and cognitive function respectively in a wide variety of disease models. Advantages of these tests include sensitivity, speed of testing, the use of innate responses such that training isn't needed, and the ability to perform the tests on awake non-anesthetized animals. OMR and Y-maze can be used along with other tests to identify temporal appearance of retinal and brain dysfunction in dise...