Young and excitable: new neurons in memory networks

Bischofberger, Josef

doi:10.1038/nn0307-273

Cited by 41 publications

(31 citation statements)

References 14 publications

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“…Here we demonstrate that the temporal pattern of innervation of the CA2 region by newborn granule neurons follows the time course of that of CA3 region (Zhao et al, 2006), although a slight delay can be observed in the case of CA2 innervation as compared to that of CA3. CA2 MFTs of newborn neurons are found at around 3 weeks of cell age, coincident with the period of highest electrophysiological plasticity of newborn granule neurons (Bischofberger, 2007). However, the data obtained here suggest that the maturation of the MFT follows a different time course in the CA2 and the CA3 fields.…”

Section: Discussionmentioning

confidence: 46%

Novel connection between newborn granule neurons and the hippocampal CA2 field

Llorens‐Martin

Jurado‐Arjona

Ávila

et al. 2015

Experimental Neurology

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Newborn neurons are continuously added to the hippocampal dentate gyrus (DG) throughout life. Mature and immature granule neurons are believed to send their axonal projections exclusively to the hippocampal CA3 field. However, recent data point to an alternative trisynaptic circuit, involving a direct axonal projection from mature granule neurons to the CA2 field. Whether this circuit takes place only in mature granule neurons or, on the contrary, whether immature granule neurons also contribute to this novel connection is unknown. We used various retroviral vectors to show that immature granule neurons send axonal processes to and establish synaptic contacts with CA2 pyramidal neurons and that axonal growth follows a similar time course to that described for CA3 innervation. In addition, we provide experimental evidence demonstrating that the pathway connecting newborn granule neurons and the CA2 field can be modulated by physiological and deleterious stimuli.

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Section: Discussionmentioning

confidence: 46%

Novel connection between newborn granule neurons and the hippocampal CA2 field

Llorens‐Martin

Jurado‐Arjona

Ávila

et al. 2015

Experimental Neurology

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“…After the appearance of dendritic spines, the number, volume and complexity of these structures increase until reaching a plateau at 8-10 weeks of cell age [35]. Growing evidence indicates that newborn neurons are important for hippocampal function, not only when they are mature but also during the transient period in which they are young and excitable [36]. In general terms, it is considered that immature neurons are required for pattern separation [37], whereas mature ones are necessary for pattern completion [38].…”

Section: Discussionmentioning

confidence: 99%

Retroviral induction of GSK-3β expression blocks the stimulatory action of physical exercise on the maturation of newborn neurons

Llorens‐Martin

Teixeira

Jurado‐Arjona

et al. 2016

Cell. Mol. Life Sci.

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Adult hippocampal neurogenesis (AHN) is a key process for certain types of hippocampal-dependent learning. Alzheimer's disease (AD) is accompanied by memory deficits related to alterations in AHN. Given that the increased activity of GSK-3β has been related to alterations in the population of hippocampal granule neurons in AD patients, we designed a novel methodology by which to induce selective GSK-3β overexpression exclusively in newborn granule neurons. To this end, we injected an rtTA-IRES-EGFP-expressing retrovirus into the hippocampus of tTO-GSK-3β mice. Using this novel retroviral strategy, we found that GSK-3β caused a cell-autonomous impairment of the morphological and synaptic maturation of newborn neurons. In addition, we examined whether GSK-3β overexpression in newborn neurons limits the effects of physical activity. While physical exercise increased the number of dendritic spines, the percentage of mushroom spines, and the head diameter of the same in tet-OFF cells, these effects were not triggered in tet-ON cells. This observation suggests that GSK-3β blocks the stimulatory actions of exercise. Given that the activity of GSK-3β is increased in the brains of individuals with AD, these data may be relevant for non-pharmacological therapies for AD.

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“…All of these network models share a relative emphasis on memory storage rather than processing (or learning), and often do not yet offer a satisfactory explanation why the problem might not be solvable at lower cost with the help of synaptic plasticity [31]. Several lines of reasoning focus on the particularity that the new neurons have a lower threshold for the induction of long-term potentiation than older cells, often leading to concepts that favor a transient function of the new cells [32,33].…”

Section: Possible Functions Of Adult Hippocampal Neurogenesis On the mentioning

confidence: 99%

The neurogenic reserve hypothesis: what is adult hippocampal neurogenesis good for?

Kempermann¹

2008

Trends in Neurosciences

338

243

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MDC Repository | http://edoc.mdc-berlin.de/9409/ 1 ABSTRACT | Several theories have proposed possible functions of adult neurogenesis in learning processes on a systems level, such as the avoidance of catastrophic interference and the encoding of temporal and contextual information, and in emotional behavior. Under the assumption of such functionality of new neurons, the question arises: what are the consequences of adult hippocampal neurogenesis beyond the temporally immediate computational benefit? What might provide the evolutionary advantage of maintaining neurogenesis in the dentate gyrus but almost nowhere else? I propose that over the course of life, activity-dependently regulated adult neurogenesis reveals its true significance in the retained ability for lasting and cumulative network adaptations. The hippocampal precursor cells that generate new neurons with their particular acute function represent a 'neurogenic reserve': the potential to remain flexible and plastic in hippocampal learning when the individual is exposed to novelty and complexity.

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Young and excitable: new neurons in memory networks

Cited by 41 publications

References 14 publications

Novel connection between newborn granule neurons and the hippocampal CA2 field

Novel connection between newborn granule neurons and the hippocampal CA2 field

Retroviral induction of GSK-3β expression blocks the stimulatory action of physical exercise on the maturation of newborn neurons

The neurogenic reserve hypothesis: what is adult hippocampal neurogenesis good for?

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