Recurrent perseveration correlates with abnormal repetitive locomotion in adult mink but is not reduced by environmental enrichment

Abstract

a b s t r a c tWe analysed the relationship between abnormal repetitive behaviour (ARB), the presence/absence of environmental enrichment, and two types of behavioural disinhibition in farmed American mink, Neovison vison. The first type, recurrent perseveration, the inappropriate repetition of already completed responses, was assessed using three indices of excessive response repetition and patterning in a biascorrected serial two-choice guessing task. The second type, disinhibition of prepotent responses to reward cues, a form of impulsivity, was tested in a locomotive detour task adapted from primate reaching tasks: subjects were required to walk around, rather than directly into, a transparent barrier behind which food was visible. In older adult females, recurrent perseveration positively predicted pre-feeding abnormal repetitive locomotion (ARL) in Non-enriched housing. High-ARL subjects also performed repeated (same-choice) responses more rapidly than low-ARL animals, even when statistically controlling for alternated (different-choice) response latency. Mink performed much less ARL following transfer to Enriched housing, but there was no corresponding change in recurrent perseveration. Thus, elevated recurrent perseveration is not sufficient for frequent ARL; and while captive environments do determine ARL frequency, in mink, they do not necessarily do so by modifying levels of perseveration. Disinhibition of prepotent responses to reward cues, meanwhile, did not predict ARL. In a separate sample of differentially housed young adults, neither type of behavioural disinhibition predicted ARL, and again, whether or not housing was enriched did not affect behavioural disinhibition despite affecting ARL. Thus, the relationship between recurrent perseveration and ARB may only develop with age; longitudinal studies are now required for confirmation.

Feed intake, growth, and behavioral assessment of mink fed a clam-based diet

“…mink fed thiaminase-containing diets also did not observe central nervous system symptoms, although significant loss of appetite did occur and thiamine supplements were required, indicating thiaminase activity (Rouvinen et al 1997). Motivational or learning differences may account for mink that never completed the task, or that stopped making attempts later in the study as shown in other studies where some individual mink never completed the assigned task Dallaire et al 2011).…”

“…Locomotor stereotypy, which might indicate neurological damage (Mason 2006), showed some variation between groups, but this was inconsistent across the first 5 wk, negating firm conclusions. Environmental enrichment provided to adult mink will decrease levels of stereotypic behaviors, possibly acting on neurological pathways (Dallaire et al 2011), but enrichment is more effective when provided at a younger age (Dallaire et al 2011). Therefore, it is possible that stronger effects would have been seen on the stereotypies of juveniles fed thiaminase-containing feedstuffs over adult mink on these diets.…”

Individual differences in stereotypic behaviour predict individual differences in the nature and degree of enrichment use in caged American mink

“…First, unlike Locomotor SB, it often appears to be directed at other mink, and previous authors have reported that similar "scratching" seems to be an attempt to enter areas to which access is denied (nest box: Hansen and Jeppesen, 2000;mother: Houbak andJeppesen, 1987, cited in Akre et al, 2008). Second, unlike Locomotor SB, it does not correlate with recurrent perseveration (Dallaire et al, 2011). Third, unlike Locomotor SB, Scrabbling is not widely reported across captive Carnivora.…”

“…Furthermore, two potential confounding variables are well understood in mink. We have previously shown that the first potential confound, perseveration, does not directly predict the response of SB to EE in mink (Dallaire et al, 2011), but more subtle effects are possible: highly perseverative subjects may still show reduced use of enrichments due to limited behavioural flexibility, potentially contributing to less effective SB reduction. We screened our mink for perseveration to test whether perseverative tendencies compromise EE use.…”

“…Proximate causes of SB involve the frustration of specific, highly-motivated behaviour patterns (e.g. Latham and Mason, 2010), along with perseveration: tendencies to repeat actions inappropriately (Dallaire et al, 2011;Garner and Mason, 2002) which become exaggerated by abnormal rearing conditions and/or high levels of stress (e.g. Mason, 2006).…”