The brain of many species including humans, harbors stem cells that continue to generate new neurons up into adulthood. This form of structural plasticity occurs in a limited number of brain regions, i.e. the subventr...The brain of many species including humans, harbors stem cells that continue to generate new neurons up into adulthood. This form of structural plasticity occurs in a limited number of brain regions, i.e. the subventricular zone and the hippocampal dentate gyrus and is regulated by environmental and hormonal factors. In this minireview, we provide an overview of the effects of stress and glucocorticoid hormones on adult hippocampal neurogenesis and discuss how these effects may be relevant for cognitive function and possibly, brain disease. While its exact functional role remains elusive, adult neurogenesis has been implicated in learning and memory, fear and mood regulation and recently, adult-born neurons were found to be involved in specific cognitive functions such as pattern separation （i.e. the ability to form unique memory representations） and cognitive flexibility. The process of adult neurogenesis is influenced by several factors; whereas e.g. exercise stimulates, exposure to stress and stress hormones generally inhibit neurogenesis. Effects of acute, mild stress are generally short-lasting and recover quickly, but chronic or severe forms of stress can induce lasting reductions in adult neurogenesis. Some of the inhibitory effects of stress can be rescued by exercise, by allowing a period of recovery from stress, by drugs that target the stress system, or by some, but not all, antidepressants. Stress may, partly through its effects on adult neurogenesis, alter structure and plasticity of the hippocampal circuit. This can lead to subsequent changes in stress responsivity and aspects of memory processing, which may be particularly relevant for stress related psychopathology or brain diseases that involve perturbed memory processing.展开更多
The ability to discriminate and store similar inputs as distinct representations in memory is thought to rely on a process called pattern separation in the dentate gyrus of the hippocampus. Recent computational and em...The ability to discriminate and store similar inputs as distinct representations in memory is thought to rely on a process called pattern separation in the dentate gyrus of the hippocampus. Recent computational and empirical findings support a role for adult-born granule neurons in spatial pattern separation. We reviewed rodent studies that have manipulated both hippocampal adult neurogenesis and assessed pattern separation. The majority of studies report a supporting role of adult born neurons in pattern separation as measured at the behavioral level. However, closer evaluation of the published findings reveals variation in both pattern separation tasks and in the interpretation of behavioral performance that, taken together, suggests that the role of hippocampal adult neurogenesis in pattern separation may be less established than is currently assumed. Assessment of pattern separation at the network level through the use of immediate early gene expression, optogenetic, pharmacogenetic and/or in vivo electrophysiology studies could be instrumental in further confirming a role of adult born neurons in pattern separation further. Finally, hippocampal adult neurogenesis and pattern separation are not an exclusive pair, as evidence for hippocampal adult neurogenesis contributing to the temporal separation of events in memory, forgetting and cognitive flexibility has also been found. We conclude that whereas current empirical evidence for the involvement of hippocampal adult neurogenesis in pattern separation seems supportive, there is a need for careful interpretation of behavioral findings and an integration of the various proposed functions of adult born neurons.展开更多
文摘The brain of many species including humans, harbors stem cells that continue to generate new neurons up into adulthood. This form of structural plasticity occurs in a limited number of brain regions, i.e. the subventricular zone and the hippocampal dentate gyrus and is regulated by environmental and hormonal factors. In this minireview, we provide an overview of the effects of stress and glucocorticoid hormones on adult hippocampal neurogenesis and discuss how these effects may be relevant for cognitive function and possibly, brain disease. While its exact functional role remains elusive, adult neurogenesis has been implicated in learning and memory, fear and mood regulation and recently, adult-born neurons were found to be involved in specific cognitive functions such as pattern separation （i.e. the ability to form unique memory representations） and cognitive flexibility. The process of adult neurogenesis is influenced by several factors; whereas e.g. exercise stimulates, exposure to stress and stress hormones generally inhibit neurogenesis. Effects of acute, mild stress are generally short-lasting and recover quickly, but chronic or severe forms of stress can induce lasting reductions in adult neurogenesis. Some of the inhibitory effects of stress can be rescued by exercise, by allowing a period of recovery from stress, by drugs that target the stress system, or by some, but not all, antidepressants. Stress may, partly through its effects on adult neurogenesis, alter structure and plasticity of the hippocampal circuit. This can lead to subsequent changes in stress responsivity and aspects of memory processing, which may be particularly relevant for stress related psychopathology or brain diseases that involve perturbed memory processing.
文摘The ability to discriminate and store similar inputs as distinct representations in memory is thought to rely on a process called pattern separation in the dentate gyrus of the hippocampus. Recent computational and empirical findings support a role for adult-born granule neurons in spatial pattern separation. We reviewed rodent studies that have manipulated both hippocampal adult neurogenesis and assessed pattern separation. The majority of studies report a supporting role of adult born neurons in pattern separation as measured at the behavioral level. However, closer evaluation of the published findings reveals variation in both pattern separation tasks and in the interpretation of behavioral performance that, taken together, suggests that the role of hippocampal adult neurogenesis in pattern separation may be less established than is currently assumed. Assessment of pattern separation at the network level through the use of immediate early gene expression, optogenetic, pharmacogenetic and/or in vivo electrophysiology studies could be instrumental in further confirming a role of adult born neurons in pattern separation further. Finally, hippocampal adult neurogenesis and pattern separation are not an exclusive pair, as evidence for hippocampal adult neurogenesis contributing to the temporal separation of events in memory, forgetting and cognitive flexibility has also been found. We conclude that whereas current empirical evidence for the involvement of hippocampal adult neurogenesis in pattern separation seems supportive, there is a need for careful interpretation of behavioral findings and an integration of the various proposed functions of adult born neurons.
