Winters BD, Dunnett SB (2000) Combined cholinergic denervation of the hippocampus and posterior cingulate cortex fails to impair working memory performance but may produce deficits in behavioural flexibility in the rat. Neuroscience 2000 Abstracts 563.2. Society for Neuroscience, New Orleans, LA.
Summary: Selective cholinergic denervation of either the hippocampal formation (HPC) or posterior cingulate cortex (pCCX) with the immunotoxin 192 IgG-saporin produces negligible effects on rats’ performance of the delayed nonmatching-to-position (DNMTP) task. Yet, fimbria-fornix transection, which disrupts the cholinergic input to both of these limbic regions, causes a delay-dependent deficit in this working memory task. In the current study, rats were trained in a standard DNMTP procedure and then divided into three groups: Group SAP (n=6) received injections of 192 IgG-saporin into both HPC and pCCX; Group NMDA (n=4) received similar injections of the excitotoxin N-methyl-D-aspartic acid; and Control rats (n=10) received vehicle injections. Following surgery, NMDA rats performed significantly worse than SAP and Control rats at all delays in the DNMTP task (p<0.05); SAP rats did not differ from Controls. All groups then acquired a matching-to-position task (i.e., reversal) over four sessions; however, SAP rats performed significantly more perseverative errors during the first reversal session, resulting in a significant Group x Session interaction (p<0.01). It is suggested that, while the cholinergic projections to the HPC and pCCX are not crucial for working memory performance in the DNMTP task, the cholinergic innervation of these limbic regions may influence behavioural flexibility by modulating a circuit mediating habit-like performance.
Related Products: 192-IgG-SAP (Cat. #IT-01)