Neural circuitry for rat recognition memory.
Bottom Line: Information concerning the roles of different brain regions in recognition memory processes is reviewed.Particular emphasis is given to the potential roles of different regions in the circuit of interacting structures involving the perirhinal cortex, hippocampus, medial prefrontal cortex and medial dorsal thalamus in recognition memory for the association of objects and places.It is concluded that while all structures in this circuit play roles critical to such memory, these roles can potentially be differentiated and differences in the underlying synaptic and biochemical processes involved in each region are beginning to be uncovered.
Affiliation: School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom. Electronic address: email@example.com.Show MeSH
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Mentions: As this review will focus on experimental evidence from rodent studies, we will briefly outline object recognition paradigms in the rat. Object recognition memory tasks depend on the use of this species’ instinctive tendency to explore novel items or a novel location. These tasks thus avoid lengthy training regimes or reinforcement schedules [11,12]. Four recognition memory procedures have been used in our studies, to explore the effects of specific neural manipulations of different aspects of recognition memory. These recognition memory procedures all involve an acquisition (sample) phase, in which a rat familiarises itself with one or more objects, or objects in a particular places. After a delay, the sample phase is followed by a choice (test) phase. In the test phase, the time spent exploring what has been encountered in the sample phase is compared with the time spent exploring a new object or object–location configuration. The four recognition memory tasks (shown in Fig. 1) are: (a) novel object preference (OR), in which the rats’ exploration of a novel object is compared with that of a familiar object; (b) object location (OL), which tests the animals’ ability to detect the movement of a familiar object to a novel location; (c) object-in-place (OiP) in which animals’ discriminate between familiar objects that have been previously associated and those that are newly associated with particular places; (d) temporal order (TO) which examines the animals’ ability to differentiate between familiar objects presented at different times previously.
Affiliation: School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom. Electronic address: firstname.lastname@example.org.