The hippocampus—what does it do?

Eichenbaum, Howard; Otto, Tim; Cohen, Neal J.

doi:10.1016/0163-1047(92)90724-i

Cited by 836 publications

(397 citation statements)

References 130 publications

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“…First, the hippocampus mediates spatial and explicit memory function and is integral to performance in the inhibitory avoidance and water maze tasks [17,36]. Second, E 2 produces changes in hippocampal physiology and morphology that has recently been related to cognitive performance [86].…”

Section: Discussionmentioning

confidence: 99%

Estradiol to aged female or male mice improves learning in inhibitory avoidance and water maze tasks

2005

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Although 17β-Estradiol (E 2 ) improves cognitive performance of aged female mice, its mnemonic effects when administered post-training to aged male mice have not been examined. E 2 (10 µg, SC) or oil vehicle was administered to intact, 24-month-old female or male congenic (primarily C57BL/6 background) mice immediately after training in the inhibitory avoidance or water maze tasks. Following behavioral testing, effects of 1 or 24 h of E 2 exposure on hippocampal levels of E 2 and brain-derived neurotrophic factor (BDNF) were examined. Female and male mice administered E 2 showed significantly better performance in the inhibitory avoidance task than did vehicle-administered mice. When tested 24 h after training, mice that received E 2 had significantly longer latencies to cross-over to the shock-associated side of the chamber than did vehicleadministered mice. Female or male mice administered E 2 showed significantly better performance in the reference memory aspect of the spatial water maze task. When tested 30 min after training, mice administered E 2 had shorter latencies to, and spent longer swimming in, the quadrant that the hidden platform had previously been located in. E 2 administration produced physiological levels of E 2 in the hippocampus 1 and 24 h after E 2 . BDNF levels in the hippocampus were decreased following 1 h of E 2 exposure compared to vehicle. These findings suggest that E 2 to female and male mice may overcome age-related deficits in reference memory in an emotional or spatial learning task.

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Section: Discussionmentioning

confidence: 99%

Estradiol to aged female or male mice improves learning in inhibitory avoidance and water maze tasks

2005

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“…For example, androgen and oestrogen receptors and aromatase activity have been detected in the hippocampus of mammals and birds (Gahr et al, 1993;Kerr et al, 1995;Weiland et al, 1997;Saldanha et al, 1999), a brain area known to be involved in relational memory processes (e.g. declarative memory, Eichenbaum et al, 1992;Squire, 1992). Interestingly also in fish androgen receptors have been found in the dorsolateral telencephalon (Gelinas and Callard, 1997) which has recently been demonstrated to be involved in spatial memory formation in goldfish (Vargas et al, 2000).…”

Section: The Adaptive Value Of Androgen Social Modulation: Androgens mentioning

confidence: 99%

Social modulation of androgen levels in male teleost fish

Oliveira

Hirschenhauser

Carneiro

et al. 2002

Comparative Biochemistry and Physiology Part B: Biochemistry an

193

113

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Androgens are classically thought of as the sex steroids controlling male reproduction. However, in recent years evidence has accumulated showing that androgens can also be affected by the interactions between conspecifics, suggesting reciprocal interactions between androgens and behaviour. These results have been interpreted as an adaptation for individuals to adjust their agonistic motivation and to cope with changes in their social environment. Thus, malemale interactions would stimulate the production of androgens, and the levels of androgens would be a function of the stability of its social environment w'challenge hypothesis', Gen. Comp. Endocrinol. 56 (1984) 417x. Here the available data on social modulation of androgen levels in male teleosts are reviewed and some predictions of the challenge hypothesis are addressed using teleosts as a study model. We investigate the causal link between social status, territoriality and elevated androgen levels and the available evidence suggests that the social environment indeed modulates the endocrine axis of teleosts. The association between higher androgen levels and social rank emerges mainly in periods of social instability. As reported in the avian literature, in teleosts the trade-off between androgens and parental care is indicated by the fact that during the parental phase breeding males decreased their androgen levels. A comparison of androgen responsiveness between teleost species with different mating and parenting systems also reveals that parenting explains the variation observed in androgen responsiveness to a higher degree than the mating strategy. Finally, the adaptive value of social modulation of androgens and some of its evolutionary consequences are discussed. ᮊ

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“…Currently, depression may be considered a consequence of stress-induced impairment in the plasticity of several brain areas (Duman, 2002). In particular, the hippocampus, a region critically involved in motivation and emotion processing (Eichenbaum and Otto, 1992), has been shown affected in depressed patients (Bremner et al, 2000;Mervaala et al, 2002;Sheline et al, 2000) and in animals exposed to experimental models of depression (Watanabe et al, 1992;Magariños et al, 1996). Dysfunction of neuronal plasticity could therefore contribute to the pathophysiology of mood disorders and recovery could occur by induction of the appropriate plasticity or remodeling phenomena (Akhondzadeh, 1999;Duman, 2002).…”

Section: Introductionmentioning

confidence: 99%

Maintenance Treatment with Fluoxetine is Necessary to Sustain Normal Levels of Synaptic Markers in an Experimental Model of Depression: Correlation with Behavioral Response

Reinés

Cereseto

Ferrero

et al. 2007

Neuropsychopharmacol

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Dysfunction of hippocampal plasticity has been proposed to play a critical role in the pathophysiology of depression. However, antidepressant drug effects on synaptic plasticity and cytoskeletal remodeling remain controversial. The aim of the present study was to evaluate in animals exposed to the learned helplessness (LH) paradigm, an accepted experimental model of depression, the effect of chronic treatment with fluoxetine (FLX) on synaptic and cytoskeletal proteins known to undergo plastic changes. Synaptophysin (SYN), postsynaptic density 95 (PSD-95), axon growth-associated protein 43 (GAP-43), and cytoskeletal proteins (intermediate neurofilaments and MAP-2) were studied in the hippocampus by immunohistochemistry. Whereas LH animals treated 21 days with saline (LH-S group) displayed diminished SYN and PSD-95 immunostainings in the CA3 but not in the DG, chronic treatment with FLX not only reversed the despaired behavior induced by exposure to LH paradigm, but also fully recovered SYN and PSD-95 labeling to control values. Similar results were obtained for the axonal remodeling marker GAP-43. FLX treatment did not modify either the decreased light neurofilament subunit (NFL) observed in the hippocampus of LH animals or any other cytoskeletal protein studied. When FLX treatment was withdrawn for 90 days in those LH-FLX animals in which reversion of despair had been observed at day 25, recurrence of despaired behavior was found accompanied by decreased SYN, PSD-95, and NFL labelings. Results indicate that the synapse remodeling induced by FLX in the CA3 region could underlie its behavioral efficacy despite the absence of cytoskeletal remodeling and that the stability of synaptic changes would depend on the continuous administration of the drug.

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The hippocampus—what does it do?

Cited by 836 publications

References 130 publications

Estradiol to aged female or male mice improves learning in inhibitory avoidance and water maze tasks

Estradiol to aged female or male mice improves learning in inhibitory avoidance and water maze tasks

Social modulation of androgen levels in male teleost fish

Maintenance Treatment with Fluoxetine is Necessary to Sustain Normal Levels of Synaptic Markers in an Experimental Model of Depression: Correlation with Behavioral Response

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