Abstract
Horses displaying an oral stereotypy were tested on an instrumental choice paradigm to examine differences in learning from non-stereotypic counterparts. Stereotypic horses are known to have dysfunction of the dorsomedial striatum, and lesion studies have shown that this region may mediate response-outcome learning. The paradigm was specifically applied in order to examine learning that requires maintenance of response-outcome judgements. The non-stereotypic horses learned, over three sessions, to choose a more immediate reinforcer, whereas the stereotypic horses failed to do so. This suggests an initial behavioural correlate for dorsomedial striatum dysregulation in the stereotypy phenotype. (C) 2008 Elsevier B.V. All rights reserved.