Adult Neurogenesis: Beyond Learning and Memory

Cameron, Heather A.; Glover, Lucas R.

doi:10.1146/annurev-psych-010814-015006

Cited by 242 publications

(185 citation statements)

References 168 publications

(253 reference statements)

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“…However, a common ground of many studies seems to be the assumption that the interaction between hippocampus, amygdala, and dorsal striatum and their respective projections into neocortical areas are important in order to allow assessment and prioritizing of external stimuli and internal needs, as well as the creation of appropriate responses in order to react to stimuli and needs according to their importance (Hirsh 1974;Simonov 1991;White et al 2013;Cameron and Glover 2015). As a consequence, disruption of this network leads to a variety of complex behavioural changes.…”

Section: Discussionmentioning

confidence: 99%

Procedural Performance Benefits after Excitotoxic Hippocampal Lesions in the Rat Sequential Reaction Time Task

Busse

Schwarting

2015

Neurotox Res

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It is widely agreed upon that hippocampal function is linked to episodic-like and spatial memory across various species, for example, rodents. However, the interplay between hippocampal function and other types of learning and memory, like procedural stimulus-response or sequential learning, is less clear. Recently (Eckart et al. in Hippocampus 22:1202-1214, 2012), we showed that excitotoxic hippocampal lesions, which mainly affected its dorsal part, led not only to the expected deficits in a spatial and episodic-like memory task, namely the object place recognition test, but also to substantial improvements in terms of speed and accuracy in a rat adaption of the human sequential reaction time task (SRTT). The design of that experiment, however, which included fixed test durations per training day, led to the fact that lesioned animals gained more instrumental experience, which may partly have accounted for their enhanced performance. In order to rule out such a potential confound, we performed the present experiment on rats with similar ibotenic lesions aiming at the dorsal hippocampus, but we now kept the amount of correct instrumental responses and reinforcements on the same level as in controls. Our data revealed that lesioned animals were still able to complete the SRTT in a substantially smaller amount of time, when compared to control and sham-operated animals, although no differences were observable in terms of speed or accuracy. Also, the animals with lesions showed impaired extinction in a subsequent test where rewards were omitted. The former effect can primarily be attributed to shorter post-reinforcement pauses in the lesioned animals, and the possible mechanisms of this and the extinction effect will be addressed in the discussion.

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Section: Discussionmentioning

confidence: 99%

Procedural Performance Benefits after Excitotoxic Hippocampal Lesions in the Rat Sequential Reaction Time Task

Busse

Schwarting

2015

Neurotox Res

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“…The past two decades have witnessed tremendous experimental and theoretical investigation of the functions of adult hippocampal neurogenesis in cognition and multiple theories have been proposedCameron and Glover, 2015) including pattern separation to modulate interference(Wiskott et al, 2006;Becker and Wojtowicz, 2007;Sahay et al, 2011a;McAvoy et al, 2014), cognitive flexibility(Kempermann, 2008;Burghardt et al, 2012), pattern integration, encoding of temporal contexts(Aimone et al, 2006;Rangel et al, 2013), memory resolution(Aimone et al, 2011), decay of remote memories(Arruda-Carvalho et al, 2011;McAvoy et al, 2014;Wang et al, 2014) and…”

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confidence: 99%

Adult Hippocampal Neurogenesis, Fear Generalization, and Stress

Besnard

Sahay

2015

Neuropsychopharmacol

192

159

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The generalization of fear is an adaptive, behavioral, and physiological response to the likelihood of threat in the environment. In contrast, the overgeneralization of fear, a cardinal feature of posttraumatic stress disorder (PTSD), manifests as inappropriate, uncontrollable expression of fear in neutral and safe environments. Overgeneralization of fear stems from impaired discrimination of safe from aversive environments or discernment of unlikely threats from those that are highly probable. In addition, the time-dependent erosion of episodic details of traumatic memories might contribute to their generalization. Understanding the neural mechanisms underlying the overgeneralization of fear will guide development of novel therapeutic strategies to combat PTSD. Here, we conceptualize generalization of fear in terms of resolution of interference between similar memories. We propose a role for a fundamental encoding mechanism, pattern separation, in the dentate gyrus (DG)-CA3 circuit in resolving interference between ambiguous or uncertain threats and in preserving episodic content of remote aversive memories in hippocampal-cortical networks. We invoke cellular-, circuit-, and systems-based mechanisms by which adult-born dentate granule cells (DGCs) modulate pattern separation to influence resolution of interference and maintain precision of remote aversive memories. We discuss evidence for how these mechanisms are affected by stress, a risk factor for PTSD, to increase memory interference and decrease precision. Using this scaffold we ideate strategies to curb overgeneralization of fear in PTSD.

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“…The generation of new neurons continues throughout adulthood in the subgranular zone of the dentate gyrus of the hippocampus. It is well accepted that adult hippocampal neurogenesis is involved in memory and learning (Aimone et al, 2014) and various aspects of emotion and the stress response (Cameron and Glover, 2015). Thus, disruption of hippocampal neurogenesis could have profound effects on a wide range of behaviors.…”

Section: Funding and Disclosurementioning

confidence: 99%