title: Perirhinal cortex lesions in rats: Novelty detection and sensitivity to interference.
abstract: Rats with perirhinal cortex lesions received multiple object recognition trials within a continuous session to examine whether they show false memories. Experiment 1 focused on exploration patterns during the first object recognition test postsurgery, in which each trial contained 1 novel and 1 familiar object. The perirhinal cortex lesions reduced time spent exploring novel objects, but did not affect overall time spent exploring the test objects (novel plus familiar). Replications with subsequent cohorts of rats (Experiments 2, 3, 4.1) repeated this pattern of results. When all recognition memory data were combined (Experiments 1-4), giving totals of 44 perirhinal lesion rats and 40 surgical sham controls, the perirhinal cortex lesions caused a marginal reduction in total exploration time. That decrease in time with novel objects was often compensated by increased exploration of familiar objects. Experiment 4 also assessed the impact of proactive interference on recognition memory. Evidence emerged that prior object experience could additionally impair recognition performance in rats with perirhinal cortex lesions. Experiment 5 examined exploration levels when rats were just given pairs of novel objects to explore. Despite their perirhinal cortex lesions, exploration levels were comparable with those of control rats. While the results of Experiment 4 support the notion that perirhinal lesions can increase sensitivity to proactive interference, the overall findings question whether rats lacking a perirhinal cortex typically behave as if novel objects are familiar, that is, show false recognition. Rather, the rats retain a signal of novelty but struggle to discriminate the identity of that signal.
authors.affiliation: School of Psychology, Cardiff University.
authors.forename: Mathieu M
authors.initials: MM
authors.lastname: Albasser
authors.affiliation: School of Psychology, Cardiff University.
authors.forename: Cristian M
authors.initials: CM
authors.lastname: Olarte-Sánchez
authors.affiliation: School of Psychology, Cardiff University.
authors.forename: Eman
authors.initials: E
authors.lastname: Amin
authors.affiliation: MRC Centre for Synaptic Plasticity, Department of Physiology and Pharmacology, University of Bristol Medical School.
authors.forename: Malcolm W
authors.initials: MW
authors.lastname: Brown
authors.affiliation: School of Psychology, Cardiff University.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kinnavane
authors.affiliation: School of Psychology, Cardiff University.
authors.forename: John P
authors.initials: JP
authors.lastname: Aggleton
mesh_terms: D000818:Animals; D015331:Cohort Studies; D005106:Exploratory Behavior / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D051381:Rats; D021641:Recognition, Psychology / Q000502:physiology*; D013702:Temporal Lobe / Q000293:injuries / Q000503:physiopathology*