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.

<ol>
	<li>Mathews, A., MacLeod, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cognitive+vulnerability+to+emotional+disorders.">Cognitive vulnerability to emotional disorders.</a> Annual Review of Clinical Psychology. 1, 167-195 (2005).</li><li>Mathews, A., MacLeod, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cognitive+approaches+to+emotions.">Cognitive approaches to emotions.</a> Anual Review of Psychology. 45 (1), 25-50 (1994).</li><li>Blanchette, I., Richards, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+affect+on+higher+level+cognition:+A+review+of+research+on+interpretation,+judgement,+decision+making+and+reasoning.">The influence of affect on higher level cognition: A review of research on interpretation, judgement, decision making and reasoning.</a> Cognition and Emotion. 24 (4), 561-595 (2010).</li><li>MacLeod, C., Cohen, I. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anxiety+and+the+interpretation+of+ambiguity:+A+text+comprehension+study.">Anxiety and the interpretation of ambiguity: A text comprehension study.</a> Journal of Abnormal Psychology. 102 (2), 238-247 (1993).</li><li>Everaert, J., Podina, I. R., Koster, E. H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comprehensive+meta-analysis+of+interpretation+biases+in+depression.">A comprehensive meta-analysis of interpretation biases in depression.</a> Clinical Psychology Review. 58, 33-48 (2017).</li><li>Haselton, M. G., Nettle, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+paranoid+optimist:+An+integrative+evolutionary+model+of+cognitive+biases.">The paranoid optimist: An integrative evolutionary model of cognitive biases.</a> Personality and Social Psychology Review. 10 (1), 47-66 (2006).</li><li>Mendl, M., Paul, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Getting+to+the+heart+of+animal+welfare.+The+study+of+animal+emotion.">Getting to the heart of animal welfare. The study of animal emotion.</a> Stichting Animales. , (2017).</li><li>Harding, E. J., Paul, E. S., Mendl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cognitive+bias+and+affective+state.">Cognitive bias and affective state.</a> Nature. 427 (6972), 312 (2004).</li><li>Douglas, C., Bateson, M., Walsh, C., B&#233;du&#233;, A., Edwards, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Environmental+enrichment+induces+optimistic+cognitive+biases+in+pigs.">Environmental enrichment induces optimistic cognitive biases in pigs.</a> Applied Animal Behaviour Science. 139 (1-2), 65-73 (2012).</li><li>Paul, E. S., Harding, E. J., Mendl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+emotional+processes+in+animals:+The+utility+of+a+cognitive+approach.">Measuring emotional processes in animals: The utility of a cognitive approach.</a> Neuroscience and Biobehavioral Reviews. 29 (3), 469-491 (2005).</li><li>Mendl, M., Burman, O. H. P., Parker, R. M. A., Paul, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cognitive+bias+as+an+indicator+of+animal+emotion+and+welfare:+Emerging+evidence+and+underlying+mechanisms.">Cognitive bias as an indicator of animal emotion and welfare: Emerging evidence and underlying mechanisms.</a> Applied Animal Behaviour Science. 118 (3-4), 161-181 (2009).</li><li>Rygula, R., Pluta, H., Popik, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laughing+rats+are+optimistic.">Laughing rats are optimistic.</a> PLoS ONE. 7 (12), 51959 (2012).</li><li>Boissy, A., 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=Assessment+of+positive+emotions+in+animals+to+improve+their+welfare.">Assessment of positive emotions in animals to improve their welfare.</a> Physiology and Behavior. 92 (3), 375-397 (2007).</li><li>Ross, M., Garland, A., Harlander-Matauschek, A., Kitchenham, L., Mason, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Welfare-improving+enrichments+greatly+reduce+hens'+startle+responses,+despite+little+change+in+judgment+bias.">Welfare-improving enrichments greatly reduce hens' startle responses, despite little change in judgment bias.</a> Scientific Reports. 9 (1), 1-14 (2019).</li><li>Lagisz, 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=Optimism,+pessimism+and+judgement+bias+in+animals:+A+systematic+review+and+meta-analysis.">Optimism, pessimism and judgement bias in animals: A systematic review and meta-analysis.</a> Neuroscience and Biobehavioral Reviews. 118, 3-17 (2020).</li><li>. Canadian Council on Animal Care CCAC Animal Data Report 2019 Available from: <a target="_blank" href="https://ccac.ca/Documents/AUD/2019-Animal-Data-Report.pdf">https://ccac.ca/Documents/AUD/2019-Animal-Data-Report.pdf</a> (2019)</li><li>Report From the Commission to the European Parlaiment and the Council. European Commission Available from: <a target="_blank" href="https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:52020DC0016&amp;from=EN">https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:52020DC0016&amp;from=EN</a> (2020)</li><li>Cryan, J. F., Holmes, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Model+organisms:+The+ascent+of+mouse:+Advances+in+modelling+human+depression+and+anxiety.">Model organisms: The ascent of mouse: Advances in modelling human depression and anxiety.</a> Nature Reviews Drug Discovery. 4 (9), 775-790 (2005).</li><li>Resasco, A., 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=Cancer+blues?+A+promising+judgment+bias+task+indicates+pessimism+in+nude+mice+with+tumors.">Cancer blues? A promising judgment bias task indicates pessimism in nude mice with tumors.</a> Physiology and Behavior. 238, 113465 (2021).</li><li>Percie du Sert, N., 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=The+ARRIVE+guidelines+2.0:+Updated+guidelines+for+reporting+animal+research.">The ARRIVE guidelines 2.0: Updated guidelines for reporting animal research.</a> Journal of Cerebral Blood Flow and Metabolism. 40 (9), 1769-1777 (2020).</li><li>Gouveia, K., Hurst, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimising+reliability+of+mouse+performance+in+behavioural+testing:+The+major+role+of+non-aversive+handling.">Optimising reliability of mouse performance in behavioural testing: The major role of non-aversive handling.</a> Scientific Reports. 7, 44999 (2017).</li><li>Gygax, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+A+to+Z+of+statistics+for+testing+cognitive+judgement+bias.">The A to Z of statistics for testing cognitive judgement bias.</a> Animal Behaviour. 95, 59-69 (2014).</li><li>Gaskill, B. N., Garner, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Power+to+the+people:+Power,+negative+results+and+sample+size.">Power to the people: Power, negative results and sample size.</a> Journal of the American Association for Laboratory Animal Science: JAALAS. 59 (1), 9-16 (2020).</li><li>MacLellan, A., Adcock, A., Mason, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+biology+of+mice.">Behavioral biology of mice.</a> Behavioral Biology of Lab Animals. , 89-111 (2021).</li><li>Walker, 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=Mixed-strain+housing+for+female+C57BL/6,+DBA/2,+and+BALB/c+mice:+Validating+a+split-plot+design+that+promotes+refinement+and+reduction.">Mixed-strain housing for female C57BL/6, DBA/2, and BALB/c mice: Validating a split-plot design that promotes refinement and reduction.</a> BMC Medical Research Methodology. 16 (11), (2016).</li><li>Weber, E. M., Dallaire, J. A., Gaskill, B. N., Pritchett-Corning, K. R., Garner, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aggression+in+group-housed+laboratory+mice:+Why+can't+we+solve+the+problem.">Aggression in group-housed laboratory mice: Why can't we solve the problem.</a> Lab Animal. 46 (4), 157-161 (2017).</li><li>Nip, 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=Why+are+enriched+mice+nice+Investigating+how+environmental+enrichment+reduces+agonism+in+female+C57BL+/+6,+DBA+/+2,+and+BALB+/+c+mice.">Why are enriched mice nice Investigating how environmental enrichment reduces agonism in female C57BL / 6, DBA / 2, and BALB / c mice.</a> Applied Animal Behaviour Science. 217, 73-82 (2019).</li><li>Tilly, S. C., Dallaire, J., Mason, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Middle-aged+mice+with+enrichment-resistant+stereotypic+behaviour+show+reduced+motivation+for+enrichment.">Middle-aged mice with enrichment-resistant stereotypic behaviour show reduced motivation for enrichment.</a> Animal Behaviour. 80 (3), 363-373 (2010).</li><li>Fureix, C., 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=Stereotypic+behaviour+in+standard+non-enriched+cages+is+an+alternative+to+depression-like+responses+in+C57BL/6+mice.">Stereotypic behaviour in standard non-enriched cages is an alternative to depression-like responses in C57BL/6 mice.</a> Behavioural Brain Research. 305, 186-190 (2016).</li><li>Nip, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The long-term effects of environmental enrichment on agonism in female C57BL/6, BALB/c, and DBA/2 mice. Thesis Dissertation. , (2018).</li><li>Wei, J., Carroll, R. J., Harden, K. K., Wu, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparisons+of+treatment+means+when+factors+do+not+interact+in+two-factorial+studies.">Comparisons of treatment means when factors do not interact in two-factorial studies.</a> Amino Acids. 42 (5), 2031-2035 (2012).</li><li>Ruxton, G. D., Neuh&#228;user, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=When+should+we+use+one-tailed+hypothesis+testing.">When should we use one-tailed hypothesis testing.</a> Methods in Ecology and Evolution. 1 (2), 114-117 (2010).</li><li>Young, J. W., 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=The+odour+span+task:+A+novel+paradigm+for+assessing+working+memory+in+mice.">The odour span task: A novel paradigm for assessing working memory in mice.</a> Neuropharmacology. 52 (2), 634-645 (2007).</li><li>Latham, N., Mason, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+house+mouse+to+mouse+house:+The+behavioural+biology+of+free-living+Mus+musculus+and+its+implications+in+the+laboratory.">From house mouse to mouse house: The behavioural biology of free-living Mus musculus and its implications in the laboratory.</a> Applied Animal Behaviour Science. 86 (3-4), 261-289 (2004).</li><li>Jones, 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=Assessing+animal+affect:+an+automated+and+self-initiated+judgement+bias+task+based+on+natural+investigative+behaviour.">Assessing animal affect: an automated and self-initiated judgement bias task based on natural investigative behaviour.</a> Scientific Reports. 8 (1), 12400 (2018).</li><li>Novak, 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=Effects+of+stereotypic+behaviour+and+chronic+mild+stress+on+judgement+bias+in+laboratory+mice.">Effects of stereotypic behaviour and chronic mild stress on judgement bias in laboratory mice.</a> Applied Animal Behaviour Science. 174, 162-172 (2016).</li><li>Krakenberg, V., von Kortzfleisch, V. T., Kaiser, S., Sachser, N., Richter, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+effects+of+serotonin+transporter+genotype+on+anxiety-like+behavior+and+cognitive+judgment+bias+in+mice.">Differential effects of serotonin transporter genotype on anxiety-like behavior and cognitive judgment bias in mice.</a> Frontiers in Behavioral Neuroscience. 13, 263 (2019).</li><li>Krakenberg, V., 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=Technology+or+ecology?+New+tools+to+assess+cognitive+judgement+bias+in+mice.">Technology or ecology? New tools to assess cognitive judgement bias in mice.</a> Behavioural Brain Research. 362, 279-287 (2019).</li><li>Krakenberg, V., 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=Effects+of+different+social+experiences+on+emotional+state+in+mice.">Effects of different social experiences on emotional state in mice.</a> Scientific Reports. 10, 15255 (2020).</li><li>Bra&#269;i&#263;, M., Bohn, L., Krakenberg, V., Schielzeth, H., Kaiser, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Once+an+optimist,+always+an+optimist?+Studying+cognitive+judgment+bias+in+mice.">Once an optimist, always an optimist? Studying cognitive judgment bias in mice.</a> EcoEvoRxiv. , (2021).</li><li>Jones, S., Paul, E. S., Dayan, P., Robinson, E. S. J., Mendl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pavlovian+influences+on+learning+differ+between+rats+and+mice+in+a+counter-balanced+Go/NoGo+judgement+bias+task.">Pavlovian influences on learning differ between rats and mice in a counter-balanced Go/NoGo judgement bias task.</a> Behavioural Brain Research. 331, 214-224 (2017).</li><li>Roelofs, S., Boleij, H., Nordquist, R. E., vander Staay, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Making+decisions+under+ambiguity:+Judgment+bias+tasks+for+assessing+emotional+state+in+animals.">Making decisions under ambiguity: Judgment bias tasks for assessing emotional state in animals.</a> Frontiers in Behavioral Neuroscience. 10 (119), 1-16 (2016).</li><li>Sherwin, C. M., Haug, E., Terkelsen, N., Vadgama, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+motivation+for+burrowing+by+laboratory+mice.">Studies on the motivation for burrowing by laboratory mice.</a> Applied Animal Behaviour Science. 88 (3-4), 343-358 (2004).</li><li>Deacon, R. M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Burrowing:+A+sensitive+behavioural+assay,+tested+in+five+species+of+laboratory+rodents.">Burrowing: A sensitive behavioural assay, tested in five species of laboratory rodents.</a> Behavioural Brain Research. 200 (1), 128-133 (2009).</li><li>MacDougall-Shackleton, S. A., Bonier, F., Romero, L. M., Moore, I. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucocorticoids+and+&amp;#34;stress&amp;#34;+are+not+synonymous.">Glucocorticoids and &amp;#34;stress&amp;#34; are not synonymous.</a> Integrative Organismal Biology. 1 (1), 1-8 (2019).</li></ol>

The authors have no conflicts of interest to disclose.

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...

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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 ...

assessment-of-mouse-judgment-bias-through-an-olfactory-digging-task

Universidad de Cartagena UDEC

Research

JoVE Journal

Behavior

2.4K Views.  University of Guelph. 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.

Video: Assessment of Mouse Judgment Bias through an Olfactory Digging Task

Assessment of Sensorimotor Function in Mouse Models of Parkinson's Disease

Sensitive and reliable behavioral outcome measures are essential to the evaluation of potential therapeutic treatments in preclinical trials for many neurodegenerative diseases. In Parkinson's disease, sensorimotor tests sensitive to varying degrees of nigrostriatal dysfunction are fundamental for testing the efficacy of potential therapeutics. Reliable and quite elegant sensorimotor measures exist for rats, however many of these tests measure sensorimotor asymmetry within the rat and are not entirely suitable for the newer genetic mouse models of PD. We have put together a battery of sensorimotor tests inspired by the sensitive tests in rats and adapted for mice. The test battery highlighted in this study is chosen for a) its sensitivity in a wide variety of mouse models of PD, b) its ease in implementing into a study, and c) its low expense. These tests have proven useful in characterizing novel genetic mouse models of PD as well as in testing potential disease-modifying therapies.

In Parkinson's disease and movement disorders in general, sensitive and reliable behavioral assays are essential for testing novel potential therapeutics. Here, we describe a manageable battery of sensorimotor tests for mice that are sensitive to varying degrees of injury to the nigrostriatal system and useful for preclinical studies.

Sensitive and  reliable behavioral outcome measures are essential to the evaluation of  potential therapeutic treatments in preclinical trials for many  ...

Measurement of Fronto-limbic Activity Using an Emotional Oddball Task in Children with Familial High Risk for Schizophrenia

Adolescence is a critical developmental period where the early symptoms of schizophrenia frequently emerge. First-degree relatives of people with schizophrenia who are at familial high risk (FHR) may show similar cognitive and emotional changes. However, the neurological changes underlying the emergence of these symptoms remain unclear. This study sought to identify differences in frontal, striatal, and limbic regions in children and adolescents with FHR using functional magnetic resonance imaging. Groups of 21 children and adolescents at FHR and 21 healthy controls completed an emotional oddball task that relied on selective attention and the suppression of task-irrelevant emotional information. The standard oddball task was modified to include aversive and neutral distractors in order to examine potential group differences in both emotional and executive processing. This task was designed specifically to allow for children and adolescents to complete by keeping the difficulty and emotional image content age-appropriate. Furthermore, we demonstrate a technique for suitable fMRI registration for children and adolescent participants. This paradigm may also be applied in future studies to measure changes in neural activity in other populations with hypothesized developmental changes in executive and emotional processing.

This paper describes how to use the emotional oddball task and fMRI to measure brain activation in children and adolescents at familial high risk for schizophrenia (FHR).&#160;FMRI was used to measure differences in fronto-striato-limbic regions during an emotional oddball task. Children with FHR exhibited abnormal functional activation during adolescence.

Adolescence is a critical developmental period where the early symptoms of schizophrenia frequently emerge. First-degree relatives of people with ...

The 5-Choice Serial Reaction Time Task: A Task of Attention and Impulse Control for Rodents

This protocol describes the 5-choice serial reaction time task, which is an operant based task used to study attention and impulse control in rodents. Test day challenges, modifications to the standard task, can be used to systematically tax the neural systems controlling either attention or impulse control. Importantly, these challenges have consistent effects on behavior across laboratories in intact animals and can reveal either enhancements or deficits in cognitive function that are not apparent when rats are only tested on the standard task. The variety of behavioral measures that are collected can be used to determine if other factors (i.e., sedation, motivation deficits, locomotor impairments) are contributing to changes in performance. The versatility of the 5CSRTT is further enhanced because it is amenable to combination with pharmacological, molecular, and genetic techniques.

This protocol describes the 5-choice serial reaction time task, which is an operant based task used to study attention and impulse control in rodents. Test day challenges, which are modifications of the standard task, increase flexibility of the task and can be combined with other manipulations to more fully characterize behavior.

This protocol describes the 5-choice serial reaction time task, which is an operant based task used to study attention and impulse control in rodents. ...

Behavioral Assessment of the Aging Mouse Vestibular System

Age related decline in balance performance is associated with deteriorating muscle strength, motor coordination and vestibular function. While a number of studies show changes in balance phenotype with age in rodents, very few isolate the vestibular contribution to balance under either normal conditions or during senescence. We use two standard behavioral tests to characterize the balance performance of mice at defined age points over the lifespan: the rotarod test and the inclined balance beam test. Importantly though, a custom built rotator is also used to stimulate the vestibular system of mice (without inducing overt signs of motion sickness). These two tests have been used to show that changes in vestibular mediated-balance performance are present over the murine lifespan. Preliminary results show that both the rotarod test and the modified balance beam test can be used to identify changes in balance performance during aging as an alternative to more difficult and invasive techniques such as vestibulo-ocular (VOR) measurements.

Motor control and balance performance are known to deteriorate with age. This paper presents a number of standard noninvasive behavioral tests with the addition of a simple rotary stimulus to challenge the vestibular system and show changes in balance performance in a murine model of aging.

Age related decline in balance performance is associated with deteriorating muscle strength, motor coordination and vestibular function. While a number of ...

fMRI Validation of fNIRS Measurements During a Naturalistic Task

We present a method to compare brain activity recorded with near-infrared spectroscopy (fNIRS) in a dance video game task to that recorded in a reduced version of the task using fMRI (functional magnetic resonance imaging). Recently, it has been shown that fNIRS can accurately record functional brain activities equivalent to those concurrently recorded with functional magnetic resonance imaging for classic psychophysical tasks and simple finger tapping paradigms. However, an often quoted benefit of fNIRS is that the technique allows for studying neural mechanisms of complex, naturalistic behaviors that are not possible using the constrained environment of fMRI. Our goal was to extend the findings of previous studies that have shown high correlation between concurrently recorded fNIRS and fMRI signals to compare neural recordings obtained in fMRI procedures to those separately obtained in naturalistic fNIRS experiments. Specifically, we developed a modified version of the dance video game Dance Dance Revolution (DDR) to be compatible with both fMRI and fNIRS imaging procedures. In this methodology we explain the modifications to the software and hardware for compatibility with each technique as well as the scanning and calibration procedures used to obtain representative results. The results of the study show a task-related increase in oxyhemoglobin in both modalities and demonstrate that it is possible to replicate the findings of fMRI using fNIRS in a naturalistic task. This technique represents a methodology to compare fMRI imaging paradigms which utilize a reduced-world environment to fNIRS in closer approximation to naturalistic, full-body activities and behaviors. Further development of this technique may apply to neurodegenerative diseases, such as Parkinson&#8217;s disease, late states of dementia, or those with magnetic susceptibility which are contraindicated for fMRI scanning.

We present a method to compare functional brain activity recorded during a naturalistic task using fNIRS with activity recorded during fMRI.

We present a method to compare brain activity recorded with near-infrared spectroscopy (fNIRS) in a dance video game task to that recorded in a reduced ...

Experimental Assessment of Mouse Sociability Using an Automated Image Processing Approach

Mouse is the preferred model organism for testing drugs designed to increase sociability. We present a method to quantify mouse sociability in which the test mouse is placed in a standardized apparatus and relevant behaviors are assessed in three different sessions (called session I, II, and III).
The apparatus has three compartments (see Figure 1), the left and right compartments contain an inverted cup which can house a mouse (called &#34;stimulus mouse&#34;).
In session I, the test mouse is placed in the cage and its mobility is characterized by the number of transitions made between compartments. In session II, a stimulus mouse is placed under one of the inverted cups and the sociability of the test mouse is quantified by the amounts of time it spends near the cup containing the enclosed stimulus mouse vs. the empty inverted cup. In session III, the inverted cups are removed and both mice interact freely. The sociability of the test mouse in session III is quantified by the number of social approaches it makes toward the stimulus mouse and by the number of times it avoids a social approach by the stimulus mouse.
The automated evaluation of the movie detects the nose of the test mouse, which allows the determination of all described sociability measures in session I and II (in session III, approaches are identified automatically but classified manually). To find the nose, the image of an empty cage is digitally subtracted from each frame of the movie and the resulting image is binarized to identify the mouse pixels. The mouse tail is automatically removed and the two most distant points of the remaining mouse are determined; these are close to nose and base of tail. By analyzing the motion of the mouse and using continuity arguments, the nose is identified.
<img alt="Figure 1" src="/files/ftp_upload/52508/52508fig1.jpg" /> 
Figure 1. Assessment of Sociability During 3 sessions. Session I (top): Acclimation of test mouse to the cage. Session II (middle): Test mouse moving freely in the cage while the stimulus mouse is enclosed in an inverted cup. Session III (bottom): Both test mouse and stimulus mouse are allowed to move freely and interact with each other.

This protocol describes a method to quantify mouse sociability. Mice are videotaped as they move and interact in a special cage. Movie processing allows for the automated quantification of sociability with excellent accuracy and reliability.

Mouse is the preferred model organism for testing drugs designed to increase sociability. We present a method to quantify mouse sociability in which the ...

An Operant Intra-/Extra-dimensional Set-shift Task for Mice

Alterations in executive control and cognitive flexibility, such as attentional set-shifting abilities, are core features of several neuropsychiatric diseases. The most widely used neuropsychological tests for the evaluation of attentional set-shifting in human subjects are the Wisconsin Card Sorting Test (WCST) and the CANTAB Intra-/Extra-dimensional set shift task (ID/ED). These tasks have proven clinical relevance and have been modified and successfully adapted for research in animal models. However, currently available tasks for rodents present several limitations, mainly due to their manual-based testing procedures, which are hampering translational advances in psychiatric medicine. To overcome these limitations and to better mimic the original version in primates, we present the development of a novel operant-based two-chamber ID/ED "Operon" task for rodents. We demonstrated the effectiveness of this novel task to measure different facets of cognitive flexibility in mice including attentional set formation and shifting, and reversal learning. Moreover, we show the high flexibility of this task in which three different perceptual dimensions can be manipulated with a high number of stimuli cues for each dimension. This novel ID/ED Operon task can be an effective preclinical tool for drug testing and/or large genetic screening relevant to the study of executive dysfunction and cognitive symptoms found in psychiatric disorders.

Attentional set-shifting cognitive abnormalities are a core feature of many psychiatric diseases. Here, we present the development of a novel automatic system for the effective study of attentional set-shifting abilities, executive functions and other cognitive abilities in mice with high translational validity to human studies.

Alterations in executive control and cognitive flexibility, such as attentional set-shifting abilities, are core features of several neuropsychiatric ...

Measuring Delay Discounting in Humans Using an Adjusting Amount Task

Delay discounting refers to a decline in the value of a reward when it is delayed relative to when it is immediately available. Delay discounting tasks are used to identify indifference points, which reflect equal preference for two dichotomous reward alternatives differing in both delay and magnitude. Indifference points are key to assessing the shape of a delay-discounting gradient because they allow us to isolate the effect of delay on value. For example, if at a 1 week delay and a maximum of $1,000, the indifference point is at $700 we know that, for that participant, a 1-week delay corresponds to a 30% reduction in value. This video outlines an adjusting amount delay-discounting task that identifies indifference points relatively quickly and is inexpensive and easy to administer. Once data have been collected, non-linear regression techniques are typically used to generate discounting curves. The steepness of the discounting curve reflects the degree of impulsive choice of a group or individual. These techniques have been used with a wide range of commodities and have identified populations that are relatively impulsive. For example, people with substance abuse problems discount delayed rewards more steeply than control participants. Although degree of discounting varies as a function of the commodity examined, discounting of one commodity correlates with discounting of other commodities, which suggests that discounting may be a persistent pattern of behavior1.

Delay discounting refers to a decline in the value of a reward when it is delayed relative to when it is immediately available. We outline a computer-based delay discounting task that is easy to implement and allows for the quantification of the degree of delay discounting in human participants.

Delay discounting refers to a decline in the value of a reward when it is delayed relative to when it is immediately available. Delay discounting tasks ...

Determining Pain Detection and Tolerance Thresholds Using an Integrated, Multi-Modal Pain Task Battery

Human pain models are useful in the assessing the analgesic effect of drugs, providing information about a drug&#39;s pharmacology and identify potentially suitable therapeutic populations. The need to use a comprehensive battery of pain models is highlighted by studies whereby only a single pain model, thought to relate to the clinical situation, demonstrates lack of efficacy. No single experimental model can mimic the complex nature of clinical pain. The integrated, multi-modal pain task&#160;battery presented here encompasses the electrical stimulation task, pressure stimulation task, cold pressor task, the UVB inflammatory model which includes a thermal task and a paradigm for inhibitory conditioned pain modulation. These human pain models have been tested for predicative validity and reliability both in their own right and in combination, and can be used repeatedly, quickly, in short succession, with minimum burden for the subject and with a modest quantity of equipment. This allows a drug to be fully characterized and profiled for analgesic effect which is especially useful for drugs with a novel or untested mechanism of action.

Human pain models are valuable tools used to assess the analgesic potential of novel compounds and predict their clinical efficacy, especially when used in an integrated manner. Although implementation of these models is complex, with proper execution, the pain models described in this protocol can provide predictive and reliable results.

Human pain models are useful in the assessing the analgesic effect of drugs, providing information about a drug&#39;s pharmacology and identify ...

Task Interruption and Resumption Paradigm for Testing the Activation and Pursuit of an Abstract Thinking Goal

This protocol is based on the task interruption and resumption paradigm, the premise of which is that active goals lead to persistent behavior and thus a higher resumption rate after a period of delay or interruption. The task interruption and resumption protocol described in this research is tailored to test the activation of cognitive goals (e.g., a goal to think more abstractly). Cognitive goals may be pursued even during the interruption period; thus, to prevent this, the protocol involves cognitive distraction. The protocol consists of several stages. Specifically, the initial stage includes the goal activation process, where the treatment (versus control) condition receives a manipulation to activate the cognitive goal being tested by the researcher. In the next stage, participants are presented with the introduction of a task that is perceived to either satisfy or not satisfy the cognitive goal of interest. Importantly, this task is interrupted a few seconds after it begins. The task interruption forces a delay period and introduces a cognitive distraction to prevent the automatic pursuit and fulfillment of the cognitive goal. After the interruption period, participants are given a choice between resuming the interrupted task and abandoning the interrupted task to complete an alternative task instead. Among participants whose cognitive goals had been activated at the earlier stage, the task resumption rate should be higher if the task was perceived as an opportunity to satisfy (versus not satisfy) the goal. Such a finding would provide empirical evidence that the cognitive goal has been activated and pursued. In previous research, this protocol has been used to test whether causal uncertainty activates an abstract thinking goal. Adapting the protocol to test the activation of other cognitive goals is also discussed.

This protocol was designed to test the activation and pursuit of cognitive goals (e.g., an abstract thinking goal) using the task interruption and resumption paradigm. The protocol is suitable for cognitive goals that are automatically pursued once activated, as the distraction procedure prevents goal pursuit during the interruption period.

This protocol is based on the task interruption and resumption paradigm, the premise of which is that active goals lead to persistent behavior and thus a ...