Topic > A role for hippocampal neurogenesis in learning and memory

Inflammatory modulation of learning and memory: a role for hippocampal neurogenesis? Hippocampal Neurogenesis Neurogenesis is the birth of new neurons. It is a multistep process that consists of the asymmetric division of neural stems that ultimately leads to the generation of new neurons. In the hippocampus, neurogenesis occurs predominantly during embryonic development and also during adulthood (Altman and Das, 1965). In the human brain, adult neurogenesis occurs in the subgranular zone of the dentate gyrus throughout life (Eriksson et al., 1998). Newly formed cells in the subgranular layer then migrate into the granular layer of the dentate gyrus where they express a neuronal phenotype (Kuhn et al., 1996). These adult-formed granule cells are integrated into existing hippocampal circuits where they participate in hippocampal function after several weeks (Jessberger and Kempermann, 2003). The role of hippocampal neurogenesis in learning and memory The extent to which hippocampal neurogenesis plays a role in learning and memory is an active area of ​​research. Evidence suggests that learning enhances adult hippocampal neurogenesis. The effects of associative learning on hippocampal neurogenesis in adult rats were determined by labeling new cells with the thymidine analog bromodeoxyuridine (BrdU) and analyzing these cells after specific behavioral tasks. The number of BrdU-labeled cells increased markedly in the dentate gyrus following specific hippocampus-dependent tasks, whereas no significant increase occurred after completing hippocampus-independent tasks ( Gould et al., 1999 ). The object localization test (OLT) is a behavioral test to evaluate a rodent's ability to distinguish between a familiar and a new spatial location... half of article ...... blocks many effects of IL -1 beta in the central nervous system (Cragnolini et al., 2004). TNF alpha is believed to be involved in the cognitive effects associated with AIDS Dementia Complex. Young adult rats were subjected to a chronic infusion of TNF alpha before their spatial memory was tested in the Morris water maze. After four consecutive daily training sessions during which the platform in the pool was visible, the rats' spatial memory was tested in a 60-second probe trial without the platform. Recorded data showed that rats that received TNF alpha spent significantly less time in the previous platform quadrant than rats that did not receive the TNF alpha infusion (Bjugstad et al., 1998). Since TNF alpha is known to suppress neurogenesis, suppression of neurogenesis may be responsible for spatial memory impairments associated with inflammation.