Interaction between perirhinal and medial prefrontal cortex is required for temporal order but not recognition memory for objects in rats - PubMed (original) (raw)

Interaction between perirhinal and medial prefrontal cortex is required for temporal order but not recognition memory for objects in rats

Darren K Hannesson et al. J Neurosci. 2004.

Abstract

The present study investigated the roles of the perirhinal cortex, medial prefrontal cortex, and intrahemispheric interactions between them in recognition and temporal order memory for objects. Experiment 1 assessed the effects of bilateral microinfusions of the sodium channel blocker lidocaine into either the anterior perirhinal or medial prefrontal cortex immediately before memory testing in a familiarity discrimination task and a recency discrimination task, both of which involved spontaneous exploration of objects. Inactivation of the perirhinal cortex disrupted performance in both tasks, whereas inactivation of the medial prefrontal cortex disrupted performance in the recency, but not the familiarity, discrimination task. In a second experiment, the importance of intrahemispheric interactions between these structures in temporal order memory were assessed by comparing the effects of unilateral inactivation of either structure alone with those of crossed unilateral inactivation of both structures on the recency discrimination task. Crossed unilateral inactivation of both structures produced a significant impairment, whereas inactivation of either structure alone produced little or no impairment. Collectively, these findings suggest that the perirhinal cortex, but not the medial prefrontal cortex, contributes to retrieval of information necessary for long-term object recognition, whereas both structures, via intrahemispheric interactions between them, contribute to retrieval of information necessary for long-term object temporal order memory. These data are consistent with models in which attributed information is stored in posterior cortical sites and supports lower-order mnemonic functions (e.g., recognition memory) but can also be retrieved and further processed via interactions with the prefrontal cortex to support higher-order mnemonic functions (e.g., temporal order memory).

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Figures

Figure 1.

Figure 1.

Location of the injection needles (lines) in rats in the mPFC group included in the behavioral analyses (plates located anterior to bregma and adapted from Paxinos and Watson, 1998). Acg, Anterior cingulate cortex; IL, infralimbic cortex; PL, prelimbic cortex.

Figure 2.

Figure 2.

Location of the injection needles (lines) in rats in the Prh group included in the behavioral analyses (plates located posterior to bregma and adapted from Paxinos and Watson, 1998). Ent, Entorhinal cortex; Prh, perirhinal cortex; TeA, temporal association cortex.

Figure 3.

Figure 3.

Differences in the amount of exploration directed at novel versus familiar (familiarity discrimination task) or old familiar versus recent familiar (recency discrimination task) objects after sham or lidocaine (Lido) infusions into the mPFC in experiment 1. A, Difference score (D1) calculated as time spent exploring the novel (or old familiar) object less time spent exploring the familiar (or recent familiar) object. B, Weighted difference score (D2) calculated as D1 divided by the time spent exploring both objects. **p < 0.01, one-tailed, relative to chance performance (i.e., 0, indicated by the dashed line); ##p < 0.01, one-tailed, sham versus lidocaine.

Figure 4.

Figure 4.

Differences in the amount of exploration directed at novel versus familiar (familiarity discrimination task) or old familiar versus recent familiar (recency discrimination task) objects after sham or lidocaine (Lido) infusions into the anterior Prh in experiment 1. A, Difference score (D1) calculated as time spent exploring the novel (or old familiar) object less time spent exploring the familiar (or recent familiar) object. B, Weighted difference score (D2) calculated as D1 divided by the time spent exploring both objects. **p < 0.01, one-tailed, relative to chance performance (i.e., 0, indicated by the dashed line); #p < 0.05 and ##p < 0.01, one-tailed, sham versus lidocaine.

Figure 5.

Figure 5.

Differences in the amount of exploration directed at old familiar versus recent familiar (recency discrimination task) objects after sham, unilateral, or crossed unilateral infusions into anterior Prh and/or mPFC in experiment 2. A, Difference score (D1) calculated as time spent exploring the old familiar object less time spent exploring the recent familiar object. B, Weighted difference score (D2) calculated as D1 divided by the time spent exploring both objects. *p < 0.05 and **p < 0.01, one-tailed, relative to chance performance (i.e., 0, indicated by the dashed line); #p < 0.05 and ##p < 0.01, one-tailed, sham versus lidocaine.

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