Evidence for a relationship between cage stereotypies and behavioural disinhibition in laboratory rodents

Abstract

Cage stereotypies */abnormal, repetitive, unvarying and apparently functionless behaviours */are common in many captive animals, sometimes resulting in self-injury or decreased reproductive success. However, a general mechanistic or neurophysiological understanding of cage stereotypies has proved elusive. In contrast, stereotypies in human mental disorder, or those induced by drugs or brain lesions, are well understood, and are thought to result from the disinhibition of behavioural selection by the basal ganglia. In this study, we found that the cage stereotypies of captive bank voles also correlate with signs of altered response selection by the basal ganglia. Stereotypic bar-mouthing in the caged voles correlated with inappropriate responding in extinction learning, impairments of response timing, evidence of a knowledge-action dissociation, increased rates of behavioural activation, and hyperactivity. Furthermore, all these signs intercorrelated, implicating a single underlying deficit consistent with striatal disinhibition of response selection. Bar-mouthing thus appears fundamentally similar to the stereotypies of autists, schizophrenics, and subjects treated with amphetamine or basal ganglial lesions. These results represent the first evidence for a neural substrate of cage stereotypy. They also suggest that stereotypic animals may experience novel forms of psychological distress, and that stereotypy might well represent a potential confound in many behavioural experiments. #

Frustration and perseveration in stereotypic captive animals: Is a taste of enrichment worse than none at all?

“…A further result of interest was that impaired behavioural inhibition (as would induce perseveration) was statistically independent of the frustration-related measures. In addition, in contrast with other studies that have found a relationship between stereotypic and perseverative behaviour [11,61] it had no main effects on stereotypic behaviour, nor did it increase the variance explained in the multiple regression models. However, it usefully partitioned out variance in some GLM models, suggesting that it was playing some minor and subtle role in the aetiology of stereotypic behaviour.…”

“…[5,23,48]), does not predict their performance of stereotypic behaviour, and (b) our enriched-reared subjects display more normal behavioural inhibition, as inferred from perseveration under test (e.g. [52]) -a proxy measure of basal ganglia dysfunction [11,61] -than non-enrichedraised mice ('Protection Hypothesis'). In contrast, if early enrichment increases the stereotypic behaviour our subjects display after transfer to non-enriched conditions compared to mice raised in such conditions, we should find that (a) frustration post-transfer does predict their performance of stereotypic behaviour, while (b) behavioural inhibition should be no more normal in our enriched-reared subjects than in non-enriched-raised mice ('Frustration Hypothesis').…”

“…We assessed stereotypic behaviour at Day 88, from videos of the home cage during the first 4 h of the dark period (when mice were most active). We used one-zero sampling (sample intervals of 1 min) to score activity and stereotypic behaviour [11]. Consistent with other authors (e.g.…”

“…[11,61]). We food-deprived the mice for 3 h from dusk, and then initially trained mice in a spatial discrimination task (shown schematically in Fig.…”

“…During the extinction phase mice were therefore rewarded for the first five correct responses but then not rewarded for any further correct responses in any subsequent daily sessions (cf. [11]). Mice reached the 'extinction criterion' when they chose the previously correct arm on ≤65% of visits on 2 consecutive days (NSD from chance).…”