Neurobiology of learning and memory
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Neurobiol Learn Mem · Feb 2015
Postoperative cognitive dysfunction and microglial activation in associated brain regions in old rats.
Research indicates that neuroinflammation plays a major role in postoperative cognitive dysfunction (POCD) in older patients. However, studies have mainly focused on hippocampal neuroinflammation and hippocampal-dependent learning and memory, which does not cover the whole spectrum of POCD. We hypothesized that regional differences in postoperative neuroinflammation in the brain may underlie variation in postoperative cognitive impairment. ⋯ These outcomes suggest that indeed neuroinflammation may be involved in POCD. Moreover, effects of age and surgery on cognition and microglial morphology seem to be area specific and hence cannot be generalized to the whole brain. This underpins the importance for expanding the research of POCD beyond the hippocampus.
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Neurobiol Learn Mem · Feb 2015
Inactivating the infralimbic but not prelimbic medial prefrontal cortex facilitates the extinction of appetitive Pavlovian conditioning in Long-Evans rats.
The infralimbic medial prefrontal cortex (IL) has been posited as a common node in distinct neural circuits that mediate the extinction of appetitive and aversive conditioning. However, appetitive extinction is typically assessed using instrumental conditioning procedures, whereas the extinction of aversive conditioning is customarily studied using Pavlovian assays. The role of the IL in the extinction of appetitive Pavlovian conditioning remains underexplored. ⋯ IL inactivation during a Pavlovian conditioning session in which conditioned stimulus (CS) trials were paired with sucrose did not affect CS-elicited behaviour, but increased responding during intervals that did not contain the CS. The same manipulation did not impact lever pressing for sucrose. These findings suggest that the IL may normally maintain Pavlovian conditioned responding when an anticipated appetitive CS is unexpectedly withheld, and that this region has distinct roles in the expression of Pavlovian conditioning when an appetitive unconditioned stimulus is either presented or omitted.