Name: assessment of mouse judgment bias through an olfactory digging task
Uploaded: 2022-03-04T14:00:00
Description: Watch this Scientific Journal Video about Assessment of Mouse Judgment Bias through an Olfactory Digging Task at JoVE.com

The authors are grateful to Miguel Ayala, Lindsey Kitchenham, Dr. Michelle Edwards, Sylvia Lam and Stephanie Dejardin for their contributions to the Reseasco et al.19 validation work which this protocol is based on. We would also like to thank the mice and our wonderful animal care technicians, Michaela Randall and Michelle Cieplak.

Experiments were approved by the University of Guelph&#39;s Animal Care Committee (AUP #3700), conducted in compliance with Canadian Council on Animal Care guidelines, and reported in accordance with ARRIVE (Animal Research: Reporting of In Vivo Experiments)20 requirements.
1. Experiment preparation
<ol>
	<li>Experimental design (see Table 1). 
	NOTE: This behavioral test is a scent-based Go/Go digging task, in which mic...

<ol>
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The scent-based digging protocol and results outlined here demonstrate the ability of this novel JB task to detect changes in mouse affective state. The task thus presents a valuable tool for diverse fields of research. Similar to any JB task, to assess animal affect it is critical that animals first learn to discriminate between cues (step 4.7.3) and that the ambiguous stimulus is interpreted as intermediate (step 5.3). Though simple, meeting these requirements can be challenging, particularly in laboratory mice for whi...

Measuring affectively modulated judgment bias (henceforth JB) has proven to be a useful tool for studying the emotional states of animals. This innovative approach borrows from human psychology since humans experiencing positive or negative affective states (emotions and longer-term moods) reliably demonstrate differences in the way they process information1,2,3. For example, humans experiencing anxiety or depression might interpret neutral facial expressions as negative, or neutral sentences as threatening4,5. It is likely that these biases have an adaptive value and are therefore conserved across species6,7. Researchers aiming to assess animal affect have cleverly taken advantage of this phenomenon, operationalizing optimism as the increased expectation of reward in response to neutral or ambiguous cues, and pessimism as the increased expectation of punishment or reward absence8,9. Thus, in an experimental setting, optimistic and pessimistic responses to ambiguous stimuli can be interpreted as indicators of positive and negative affect, respectively10,11.
Compared to other indicators of animal affect, JB tasks have the potential to be particularly valuable tools since they are capable of detecting both the valence and intensity of affective states10,11. The ability of JB tasks to detect positive states (e.g., Rygula et al.12) is especially useful since most indicators of animal affect are limited to the detection of negative states13. During JB tasks, animals are typically trained to respond to a positive discriminative cue predicting reward (e.g., high-frequency tone) and a negative discriminative cue predicting punishment (e.g.,&#160;low-frequency tone), before being presented with an ambiguous cue (e.g., intermediate tone)8. If in response to ambiguous cues an animal &#39;optimistically&#39; performs the trained response for the positive cue (as if expecting reward), this indicates a positive judgment bias. Alternatively, if animals demonstrate the negative trained response to avoid punishment, this is indicative of &#39;pessimism&#39; or negative judgment bias.
Since the development of the first successful JB task for animals by Harding and colleagues8, several JB tasks have been developed for a wide range of species across diverse research fields7. But despite their increasing popularity, animal JB tasks are often labor-intensive. Moreover, perhaps because they are methodologically different from the human tasks that inspired them, they sometimes produce null or counterintuitive results14 and commonly yield only small treatment effect sizes15. As a result, JB tasks can be challenging to develop and implement. In fact, for laboratory mice, the most widely used vertebrates in research16,17 and a species heavily relied upon to model affective disorders18, only one JB task has been successfully validated as sensitive to changes in affective state19 despite many attempts over the past decade (see supplementary material of Resasco et al.19&#160;for a summary). This article describes the recently validated murine JB task, detailing its biologically relevant design, and highlighting the ways that this humane task can be applied to test important hypotheses relevant to mouse affect. Overall, the protocol can be implemented to investigate the affective effects of any variable of interest on JB in mice. This would include categorical treatment variables as described here (drug or disease effects, environmental conditions, genetic background, etc.), or relationships with continuous variables (physiological changes, home cage behaviors, etc.).

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Absolute ethanol</td>
			<td>Commercial alcohol</td>
			<td>P016EAAN</td>
			<td>Dilute to 70% with distilled water, for cleaning</td>
		</tr>
		<tr>
			<td>Centrifuge tubes</td>
			<td>Fischer</td>
			<td>55395</td>
			<td>15 mL tubes used to dilute essences here. However, size may be selected based on total volume required for sample size</td>
		</tr>
		<tr>
			<td>Cheerios (original)</td>
			<td>Cheerios</td>
			<td>N/A</td>
			<td>Commercially available. Used as reward to train animals to enter annex cage for handling</td>
		</tr>
		<tr>
			<td>Corncob bedding</td>
			<td>Envigo</td>
			<td>7092</td>
			<td>Teklad 1/8 corncob bedding used in digging pots and animal cages</td>
		</tr>
		<tr>
			<td>Cotton pads</td>
			<td>Equate</td>
			<td>N/A</td>
			<td>Commercially available. Modified in lab to fit within tissue cassettes for scent dispensing</td>
		</tr>
		<tr>
			<td>Digging pots</td>
			<td>Rubbermaid</td>
			<td>N/A</td>
			<td>Commercially available. Containers were modified to fit the apparatus in the lab</td>
		</tr>
		<tr>
			<td>Dried, sweetened banana chips</td>
			<td>Stock and Barrel</td>
			<td>N/A</td>
			<td>Commercially available. High value reward in JB task</td>
		</tr>
		<tr>
			<td>JB apparatus</td>
			<td></td>
			<td>N/A</td>
			<td>The apparatus was made in the lab</td>
		</tr>
		<tr>
			<td>JWatcher event recording software</td>
			<td>Animal Behavior Laboratory, Macquarie University</td>
			<td>Version 1.0</td>
			<td>Freely available for download online. Used to score digging behavior during JB task</td>
		</tr>
		<tr>
			<td>Mint extract</td>
			<td>Fleibor</td>
			<td>N/A</td>
			<td>Commercially &#34;Menta (Soluci&#243;n)&#34;. Discriminative stimulus odor</td>
		</tr>
		<tr>
			<td>Rodent Diet</td>
			<td>Envigo</td>
			<td>2914</td>
			<td>Teklad global 14% protein rodent maintenance diets. Low value reward in JB task and regular diet in home cage</td>
		</tr>
		<tr>
			<td>SAS statistical software</td>
			<td>SAS</td>
			<td>Version 9.4</td>
			<td>Other comparable software programs (e.g. R) are also appropriate</td>
		</tr>
		<tr>
			<td>Vanilla extract</td>
			<td>Fleibor</td>
			<td></td>
			<td>Commercially available &#34;Vainilla (Soluci&#243;n)&#34;. Discriminative stimulus odor</td>
		</tr>
		<tr>
			<td>Video camera</td>
			<td>Sony</td>
			<td>DCR-SX22</td>
			<td>Sony handycam.</td>
		</tr>
	</tbody>
</table>

assessment of mouse judgment bias through an olfactory digging task

Judgment biases (JB) are differences in the way that individuals in positive and negative affective/emotional states interpret ambiguous information. This phenomenon has long been observed in humans, with individuals in positive states responding to ambiguity 'optimistically' and those in negative states instead showing 'pessimism'. Researchers aiming to assess animal affect have taken advantage of these differential responses, developing tasks to assess judgment bias as an indicator of affective state. These tasks are becoming increasingly popular across diverse species and fields of research. However, for laboratory mice, the most widely used vertebrates in research and a species heavily relied upon to model affective disorders, only one JB task has been successfully validated as sensitive to changes in affective state. Here, we provide a detailed description of this novel murine JB task, and evidence of its sensitivity to mouse affect. Though refinements are still necessary, assessment of mouse JB opens the door for answering both practical questions regarding mouse welfare, and fundamental questions about the impact of affective state in translational research.

Results presented here reflect relevant findings from Experiment 1 of Resasco et al.19. Subjects in this experiment were 18 female C57BL/6NCrl (&#39;C57&#39;) and 18 Balb/cAnNCrl (&#39;Balb&#39;) mice. Animals arrived at the facility at 3-4 weeks of age and were randomly assigned to environmentally enriched or conventional housing treatments (EH or CH, respectively) in mixed strain quartets25. Each cage contained one C57 and one Balb, in addition to two DBA/2NCrl mice being...

Watch this Scientific Journal Video about Assessment of Mouse Judgment Bias through an Olfactory Digging Task at JoVE.com

Assessment of Mouse Judgment Bias through an Olfactory Digging Task

This article provides a detailed description of a novel mouse judgment bias protocol. Evidence of this olfactory digging task's sensitivity to affective state is also demonstrated and its utility across diverse research fields is discussed.

Judgment biases (JB) are differences in the way that individuals in positive and negative affective/emotional states interpret ambiguous information. This ...

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