Name: assessment of mouse judgment bias through an olfactory digging task
Uploaded: 2022-03-04T14:00:00.000+00:00
Duration: 12 min 10 s
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.

<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 which over 15 past attempts to develop and implement a mouse JB task have failed19. Here, multiple components played an essential role in meeting these technical criteria and contributed to the success and utility of the task.
First, the ethological design of the task promoted successful discrimination learning since both the discriminative cues and required responses were biologically relevant: mice have impressive olfactory abilities, making them capable of rapid learning and considerable memory spans when presented with odor stimuli33, and they are naturally driven to perform digging for general exploration, foraging, and burrow construction24,34. Further, counterbalancing DS+ odors revealed differences in the ways that Vanilla DS+ and Mint DS+ mice interpreted the ambiguous mixture, confirming that the ambiguous cue was interpreted as intermediate for Vanilla DS+ mice, but not for Mint DS+ mice. It is therefore recommended that only Vanilla is used as the DS+ for any future work utilizing the extract brands and mouse strains used here. Importantly, though counterbalancing yielded successful outcomes in the present experiment, we urge researchers to conduct pilot tests to identify appropriate ambiguous mixtures if implementing changes, since counterbalancing can sometimes add considerable noise to the data, increasing the risk of masking treatment effects35.
Even when these essential criteria are met, JB is not always easy to detect, perhaps owing to the small treatment effect sizes that these experiments commonly yield15. Thus, to ensure task sensitivity, a unique Go/Go design is used since this approach has been shown to be more sensitive to changes in animal affect than Go/No-Go designs in other species15. However, the use of an unscented arm containing a low-value reward in all trials differentiates this task from previous failed attempts to validate a Go/Go JB task for mice36,37,38. Here, during positive trials mice choose between a high-value reward in the DS+ arm and a low-value reward in the unscented arm; and in negative trials, they choose between no reward in the DS- arm and a low-value reward in the unscented arm. Although this requires mice to learn a more complex task (i.e., discriminating between cues predicting different values of reward, rather than simply reward presence or absence), it appears that having a consistent option, where a low-value reward was always present, may have made training and testing less stressful for mice and enhanced learning (with 86% of mice meeting learning criteria). While mice are often assumed to be challenging to train or unable to learn difficult tasks18, results here suggest that their abilities should not be underestimated, and that designing low stress, ethological tasks may be a more effective approach for detecting changes in affect than simpler tasks or those with harsher consequences (e.g., involving punishment like air puffs or white light instead of simply reward absence39,40,41).
Finally, to further reduce stressors that might otherwise interfere with treatment effects and introduce unwanted variability, humane handling methods were implemented21. Here, mice were only handled via cup or tunnel methods throughout their lives (including to and from transport cages and the JB apparatus) to avoid the aversive effects of traditional tail handling21. In addition to this, EH animals were trained to voluntarily enter an annex cage for handling, thus avoiding stressful &#39;chasing&#39; through complex environments. Together, this approach led to the detection of pessimistic judgment biases in CH mice through longer latencies in response to ambiguous cues. Future researchers should similarly consider whether aspects of their treatments of interest, housing, or husbandry practices have the potential to mask treatment effects or induce floor effects (i.e., where all animals show marked pessimism, negating the ability of the task to detect more subtle treatment differences) so that these can be prevented or mitigated.
Further replication and refinement of this promising task are now needed. To date, this JB task has only been applied to animals experiencing long-term, low-arousal negative affect (as a result of restrictive housing or chronic disease19). It is therefore important that future work aims to test the sensitivity of this task to acute stressors and high-arousal negative affective states. Furthermore, maximizing the value of this task would also involve replicate studies investigating test-retest reliability of individuals to the same, or multiple ambiguous probes. Re-testing with the same probes would allow researchers to test hypotheses regarding changes in affect over time, while exposing subjects to a spectrum of ambiguous cues (i.e., near positive, intermediate, and near negative) could potentially allow for the identification of different types of negative states (particularly depression- versus anxiety-like conditions)11,42. Additional validation experiments should also study the value of shorter protocols, as well as potential differences between strains and sexes (though the original publication does address these issues, successfully employing a shorter protocol to assess affect in male mice19). Indeed, this task could potentially be extended to any rodents intrinsically motivated to make burrows43,44 provided appropriate size modifications are made, and validation is confirmed. Such replication and refinements are important since no other valid JB tasks have been developed for mice to date and since JB tasks are sensitive to both the valence and intensity of affective states (as outlined in the introduction), something that most indicators of animal affect fail to do (e.g., hypothalamic-pituitary-adrenal activity can be altered in response to both positive and negative experiences7,45).
Overall, the development of a mouse JB task represents a promising new tool and opens the door for great progress in the assessment of mouse affect. Mice are the most widely used vertebrates in both basic and translational research17, and this task provides a means to answer essential questions about the welfare of these tens of millions of animals used globally, as well as the links between affect and the diseases or conditions they are used to model. Though the use of this task is not recommended for day-to-day welfare assessment, experimental investigation of housing and husbandry practices could help identify refinements that promote mouse welfare and aid in identifying more subtle signs of animal suffering that can be observed cageside. Given the humane and potentially enriching nature of this task, and the low economic cost of implementing the protocol, this novel JB task has great utility.

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><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 &quot;Menta (Soluci&amp;oacute;n)&quot;. 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 &quot;Vainilla (Soluci&amp;oacute;n)&quot;. 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 used in another experiment. Here, the use of female mice allowed group housing of this social species with environmental enrichment, while avoiding the elevated aggression and resource guarding that can occur in male mice26 (although note that the task has also been applied in non-enriched male nude mice19). CH mice were kept in open-top, transparent polyethylene cages (27L x 16W x 12H cm; n = 9) with corn cob bedding, two types of nesting material (crinkled paper strips and cotton nestlets; Figure 2A), and a paper cup &#39;shelter&#39;. EH cages were opaque plastic, measuring 60L x 60W x 30H cm3 with one red plexiglass window for observations (n = 9; Figure 2B,C). These conditions are known to improve welfare: containing diverse enrichments (as described previously by Nip et al.27) that mice are motivated to access28, and which reduce behaviors indicative of poor welfare (e.g., stereotypic behavior, aggression, and depression-like inactivity27,28,29). Each EH cage also included an attached &#39;annex&#39; cage (identical to CH cages but containing only bedding), which mice could freely access via a tunnel (Figure 2C). Annex cages allowed for ease of catching and handling EH mice trained to enter this attachment for food rewards when a cup full of sweet oat cereal was shaken. Once a mouse entered the annex cage, the access tunnel could be blocked and mice could be easily removed from cages using cup or tunnel handling21. This approach thus avoided stressful &#39;chasing&#39; through complex enriched environments30. Food and water were available ad libitum and the colony room was maintained at 21 &#177; 1 &#176;C and 35%-55% relative humidity, on a reverse 12:12 h light cycle (lights off at 06:00 and on at 18:00). Mice were differentially housed for 5 weeks prior to commencement of digging training in the apparatus (see timeline in Figure 2D).
Mice underwent training and testing in the JB task as outlined in the Protocol above. Latency to dig in the scented arm during the first and full 2 min of positive, negative, and ambiguous test trials was used to test for housing effects on JB. Here, data were analyzed using Generalized Linear Mixed Models, applying transformations where necessary to meet assumptions of normality and homogeneity. See Resasco et al.19 for a detailed description of analyses (e.g., model selection). Briefly, the repeated measures models always included Trial Type, Housing, Strain, Trial Type x Housing, DS+ Odor, Trial Type x Strain, Trial Type x DS+ Odor, Trial Type x Housing x DS+ Odor, Cage (a random effect nested in Housing and DS+ Odor), and Mouse ID (a random effect nested in Cage, Housing, DS+ Odor and Strain). The simple effects of Housing on latency were determined from the Trial Type x Housing when calculating the Least Squares Means31. Note, two-tailed p-values are reported throughout to demonstrate investigation of treatment effects, but the original validation work by Resasco et al.19 used one-tailed p-values where appropriate32 since one specific response was required to validate the task (see Resasco et al.19 for validation discussion).
Before judgment bias can be assessed in any animal task, it is crucial that two technical criteria be met: first, animals must successfully discriminate between positive and negative cues (i.e., meet learning criteria). For animals meeting this criterion, it must then be demonstrated that the ambiguous cue is interpreted as intermediate. If either of these is not met, then inferences cannot be made about judgment bias and corresponding affective states. In this experiment,&#160;all but four C57 mice met learning criteria and one C57 was removed before testing for barbering a cagemate (n = 31). In both the first and full 2 min of testing, Trial Type x DS+ Odor was significant (1 min: F2,62 = 5.67, p = 0.006; 2 min: F2,62 = 5.74, p = 0.005), revealing that Mint DS+ mice unexpectedly interpreted the ambiguous odor mixtures as positive (as if 100% mint), while Vanilla DS+ mice treated the same ambiguous odor mixtures as intermediate (Figure 3A,B). This finding indicated that only Vanilla DS+ mice met the technical requirement of treating the scent mixture as intermediate between the DS+ and DS-, and thus Mint DS+ mice were excluded from subsequent JB analyses.
For Vanilla DS+ mice, simple effects of housing were calculated from the Trial Type x Housing term31. Within this group, Housing influenced digging latencies with CH animals being slower than EH to dig in ambiguous trials, but not in positive or negative trials. This was true after 1 min (ambiguous: t = 2.27, d.f. = 92.94, p = 0.014, Cohen&#39;s d = 1.148; positive: t = 0.22, d.f. = 92.94, p = 0.414, Cohen&#39;s d = 0.110; negative: t = 0.80, d.f. = 92.94, p = 0.214, Cohen&#39;s d = 0.404; see Figure 4A) and after the full 2 min (ambiguous: t = 2.14, d.f. = 91.89, p = 0.018, Cohen&#39;s d = 1.083; positive: t = 0.39, d.f. = 91.89, p = 0.348, Cohen&#39;s d = 0.198; negative: t = 0.61, d.f. = 91.89, p = 0.273, Cohen&#39;s d = 0.308; see Figure 4B), even though Trial Type x Housing x DS+ Odor (1 min: F3,65.37 = 0.36, p = 0.7835; 2 min: F3,65.37 = 0.49, p = 0.688) and Trial Type x Housing (1 min: F2,62 = 1.66, p = 0.198; 2 min: F2,62 = 1.41, p = 0.252) did not account for significant variation. These pessimistic interpretations of ambiguous cues by CH mice reflect negative judgement biases indicative of negative affect.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/63426/63426fig02.jpg" /> 
Figure 2: Housing treatments and experiment timeline. (A) CH laboratory cage. (B) Overhead view of EH. (C) Front view of EH with attached &#39;annex&#39; cage to facilitate mouse catching/handling. (D) Experimental timeline and summary of positive, negative, and ambiguous training and test trials. DS(+): positive discriminative stimulus, DS(-): negative discriminative stimulus, AMB: ambiguous mixture (50% vanilla-50% mint), B: banana chip, C: Rodent diet (&#39;chow&#39;), X: no food rewards. Reprinted from Resasco et al.19&#160;with permission from Elsevier. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/63426/63426fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/63426/63426fig03.jpg" /> 
Figure 3: Determining whether mice meet requirements for JB assessment. Digging latency least-square means (&#177;standard error) during positive, negative, and ambiguous test trials. (A) 1 min digging latency in mice receiving mint (M, n = 15) or vanilla (V, n = 16) as the positive discriminative stimulus (DS+) (data Box Cox transformed). (B) 2 min digging latency in the same subjects (data logarithmically transformed). During both time periods, Vanilla DS+ mice met the technical requirement of interpreting ambiguous cues as intermediate. Mint DS+ mice failed to do so (instead interpreting the ambiguous cue as positive) and were consequentially eliminated from subsequent JB analyses. Reprinted from Resasco et al.19&#160;with permission from Elsevier. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/63426/63426fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/63426/63426fig04.jpg" /> 
Figure 4: Impact of housing treatment on affect-modulated JB. Digging latency least-square means (&#177;standard error) during positive, negative and ambiguous test trials. (A) 1 min digging latency in Vanilla DS+ mice from conventional (CH, n = 7) or enriched (EH, n = 9) housing (data Box Cox transformed). (B) 2 min digging latency in the same subjects (data logarithmically transformed). During both time periods, CH animals demonstrated significantly longer latencies to dig during ambiguous trials than EH conspecifics, indicating negative JB. Reprinted from Resasco et al.19&#160;with permission from Elsevier. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/63426/63426fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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 ...

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

Nanyang Technological University

Research

JoVE Journal

Behavior

2.5K 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  ...

The Attentional Set Shifting Task: A Measure of Cognitive Flexibility in Mice

Cognitive impairment, particularly involving dysfunction of circuitry within the prefrontal cortex (PFC), represents a core feature of many neuropsychiatric and neurodevelopmental disorders, including depression, post-traumatic stress disorder, schizophrenia and autism spectrum disorder. Deficits in cognitive function also represent the most difficult symptom domain&#160;to successfully treat, as serotonin reuptake inhibitors and tricyclic antidepressants have only modest effects. Functional neuroimaging studies and postmortem analysis of human brain tissue implicate the PFC as being a primary region of dysregulation in patients with these disorders. However, preclinical behavioral assays used to assess these deficits in mouse models which can be readily manipulated genetically and could provide the basis for studies of new treatment avenues have been underutilized. Here we describe the adaptation of a behavioral assay, the attentional set shifting task (AST), to be performed in mice to assess prefrontal cortex mediated cognitive deficits. The neural circuits underlying behavior during the AST are highly conserved across humans, nonhuman primates and rodents, providing excellent face, construct and predictive validity.

The goal of this protocol is to perform a behavioral assay such as the attentional set shifting task (AST) to assess prefrontal cortex-mediated cognitive flexibility in mice.

Cognitive impairment, particularly involving dysfunction of circuitry within the prefrontal cortex (PFC), represents a core feature of many ...

Testing for Odor Discrimination and Habituation in Mice

This video demonstrates a technique to establish the presence of a normally functioning olfactory system in a mouse. The test helps determine whether the mouse can discriminate between non-social odors and social odors, whether the mouse habituates to a repeatedly presented odor, and whether the mouse demonstrates dishabituation when presented with a novel odor. Since many social behavior tests measure the experimental animal&#8217;s response to a familiar or novel mouse, false positives can be avoided by establishing that the animals can detect and discriminate between social odors. There are similar considerations in learning tests such as fear conditioning that use odor to create a novel environment or olfactory cues as an associative stimulus. Deficits in the olfactory system would impair the ability to distinguish between contexts and to form an association with an olfactory cue during fear conditioning. 
In the odor habitation/dishabituation test, the mouse is repeatedly presented with several odors. Each odor is presented three times for two minutes. The investigator records the sniffing time directed towards the odor as the measurement of olfactory responsiveness. A typical mouse shows a decrease in response to the odor over repeated presentations (habituation). The experimenter then presents a novel odor that elicits increased sniffing towards the new odor (dishabituation). After repeated presentation of the novel odor the animal again shows habituation. This protocol involves the presentation of water, two or more non-social odors, and two social odors. In addition to reducing experimental confounds, this test can provide information on the function of the olfactory systems of new knockout, knock-in, and conditional knockout mouse lines.

This manuscript describes a protocol to examine the olfactory system of rodents. The olfactory habituation/dishabituation test will allow investigators to determine whether a mouse habituates to a repeatedly presented odor and whether the mouse demonstrates dishabituation when presented a novel odor.

This video demonstrates a technique to establish the presence of a normally functioning olfactory system in a mouse. The test helps determine whether the ...

Simple and Computer-assisted Olfactory Testing for Mice

Olfaction is highly conserved among species and is required for reproduction and survival.
In humans, olfaction is also one of the senses that is affected with aging and is a strong predictor of neurodegenerative diseases. Thus, olfaction testing is used as a non-invasive diagnostic method to detect neurological deficits early on. In order to understand the mechanisms underlying olfactory network susceptibility, olfactory research in rodents has gained momentum in the past decade.
Here, we present a very simple, time efficient and reproducible olfactory testing method of innate odor perception and sensitivity in mice without the need of any prior food or water restriction. The tests are performed in a familiar environment to the mice, require only the scents and a 2 min session of odorant exposure. The analysis is performed, post-hoc, using computer-assisted commands on ImageJ and can be, therefore, carried out from start to end by one researcher.
This protocol does not require any special hardware or setup and is indicated for any laboratory interested in testing olfactory perception and sensitivity.

We present a simple and unbiased olfactory test in mice. With this protocol olfactory discrimination, preference, avoidance and sensitivity to a novel odor as compared to water can be assessed in single behavioral sessions. This method is indicated for a single experimenter and analysis is based on computer-assisted video processing.

Olfaction is highly conserved among species and is required for reproduction and survival.
In humans, olfaction is also one of the senses that is affected ...

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 ...

Olfactory Behavioral Testing in the Adult Mouse

The rodent olfactory system is of increasing interest to scientists, studied, in part, in systems biology because of its stereotyped, yet accessible circuitry. In addition, this area's unique ability to generate new neurons throughout an organism's lifetime makes it an attractive system for developmental and regenerative biologists alike. Such interest necessitates a means for a quick, yet reliable assessment of olfactory function. Many tests of olfactory ability are complex, variable or not specifically designed for mice. Also, some tests are sensitive to memory deficits as well as defects in olfactory abilities, confounding obtained results.
Here, we describe a simple battery of tests designed to identify defects in olfactory sensitivity and preference. First, an initial general health assessment allows for the identification of animals suitable for further testing. Second, mice are exposed to various dilutions of scents to ascertain whether there is a threshold difference. Third, mice are presented with various scents, both attractive and aversive, that allow for the assessment of olfactory preference. These simple studies should make the initial characterization of olfactory behavior accessible for labs of varied resources and expertise.

Fundamental, yet unique properties of the rodent olfactory system have led to its increasing study among biologists. A relatively simple assessment of its function is then also needed. Here we describe sensitive tests for the characterization of mouse olfactory sensitivity and preference.

The rodent olfactory system is of increasing interest to scientists, studied, in part, in systems biology because of its stereotyped, yet accessible ...

Biology

Assessing Olfactory Impairment in Mice Due to Inhaled Environmental Pollutants

Studying the Effects of Inhaled Environmental Pollutants on Olfactory Function in Mice

Olfactory impairment is a significant public health problem and independently predicts the risk of neurodegenerative diseases. Inhaled environmental pollutants exposure may impair olfaction; thereby, there is an urgent need for methods to evaluate the effects of inhaled environmental pollutants exposure on olfaction. Mice are ideal models for olfactory experiments because of their highly developed olfactory system and behavioral characteristics. To assess the effects of inhaled environmental pollutants exposure on olfactory function in mice, a detailed buried food test and social odor discrimination experiment is provided, including the experiment preparation, the selection and construction of experimental facilities, the testing process, and indexes of time. Meanwhile, timekeeping equipment, operational details, and the experimental environment are discussed to ensure the success of the assay. Zinc sulfate is used as the treatment to demonstrate the feasibility of the experimental approach. The protocol provides a simple and clear operational process for assessing the effects of inhaled environmental pollutants on olfactory function in mice.

Author Spotlight: Assessing the Olfactory Effects of Airborne Pollutants &#8212; Buried Food and Social Odor Tests

This paper provides a detailed description of the buried food test and social odor discrimination experiment to assess the effects of inhaled environmental pollutants exposure on olfactory function in mice.

Olfactory impairment is a significant public health problem and independently predicts the risk of neurodegenerative diseases. Inhaled environmental ...

Environment

Olfactory Assays for Mouse Models of Neurodegenerative Disease

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process and may be a useful behavioral marker for early detection. Earlier detection in neurodegenerative disease is a major goal in the field because this is when neuroprotective therapies have the best potential to be effective. Therefore, in preclinical studies testing novel neuroprotective strategies in rodent models of neurodegenerative disease, olfactory assessment could be highly useful in determining therapeutic potential of compounds and translation to the clinic. In the present study we describe a battery of olfactory assays that are useful in measuring olfactory function in mice. The tests presented in this study were chosen because they measure olfaction abilities in mice related to food odors, social odors, and non-social odors. These tests have proven useful in characterizing novel genetic mouse models of Parkinson&#8217;s disease as well as in testing potential disease-modifying therapies.

Impairment in olfactory function is a common feature in many neurodegenerative disorders including Parkinson, Alzheimer, and Huntington diseases. In the present article, we describe a set of tests for assessing olfaction discrimination and detection in mice that can be used to measure olfactory abilities in mouse models of neurodegenerative diseases.

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process ...

Neuroscience

Designing a Flexible, Cost-Effective Olfactometer for Rodent Olfactory Experiments

Constructing an Olfactometer for Rodent Olfactory Behavior Studies

The use of olfactometers to study rodent behavior and brain activity during olfactory tasks is crucial for understanding brain circuits. These sophisticated devices allow researchers to precisely control and deliver odor stimuli, enabling the investigation of complex olfactory processes in rodents. Although commercially available olfactometers are convenient, they present challenges when technical issues arise, often requiring costly assistance and potentially disrupting research timelines. This article details the construction of a custom olfactometer specifically designed for mouse olfactory behavior experiments, providing a comprehensive list of parts and step-by-step instructions. The olfactometer is controlled through MATLAB, offering a user-friendly interface for researchers. Importantly, the open-source code allows users to modify and adapt the system, tailoring behavioral tasks to meet specific experimental needs. Building a customized olfactometer empowers users with the knowledge and capability to perform custom experimental design and troubleshooting independently, saving both time and resources. This approach not only enhances research flexibility but also fosters a deeper understanding of the equipment's functionality, ultimately leading to more robust and reliable olfactory studies in rodents.

Constructing an Olfactometer for Rodent Olfactory Behavior Studies Near-Infrared Spectroscopy Hyperscanning Study in Psychological Counseling

This protocol describes the construction of an olfactometer for go/no-go olfactory behavior experiments. Step-by-step instructions, along with images, are provided to ensure the successful construction of the olfactometer. Information for troubleshooting issues encountered during the process is also included.

The use of olfactometers to study rodent behavior and brain activity during olfactory tasks is crucial for understanding brain circuits. These ...

An Objective and Reproducible Test of Olfactory Learning and Discrimination in Mice

Olfaction is the predominant sensory modality in mice and influences many important behaviors, including foraging, predator detection, mating, and parenting. Importantly, mice can be trained to associate novel odors with specific behavioral responses to provide insight into olfactory circuit function. This protocol details the procedure for training mice on a Go/No-Go operant learning task. In this approach, mice are trained on hundreds of automated trials daily for 2&#8211;4 weeks and can then be tested on novel Go/No-Go odor pairs to assess olfactory discrimination, or be used for studies on how odor learning alters the structure or function of the olfactory circuit. Additionally, the mouse olfactory bulb (OB) features ongoing integration of adult-born neurons. Interestingly, olfactory learning increases both the survival and synaptic connections of these adult-born neurons. Therefore, this protocol can be combined with other biochemical, electrophysiological, and imaging techniques to study learning and activity-dependent factors that mediate neuronal survival and plasticity.

Here, we train mice on an associative learning task to test odor discrimination. This protocol also allows for studies on learning-induced structural changes in the brain.