The three-dimensional organization of the hippocampal formation: A review of anatomical data

Amaral, David G.; Witter, Menno P.

doi:10.1016/0306-4522(89)90424-7

Cited by 1,896 publications

(1,526 citation statements)

References 47 publications

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“…Moreover, UP-state-associated sleep spindles are associated with the spindle-frequency currents in the CA1 str. lacunosum-moleculare and the dentate molecular layer (Sirota et al, 2003), the targets of the entorhinal inputs (Amaral and Witter, 1989). As expected, granule cells and other neurons of the dentate area fire coherently with the input from the entorhinal neurons during the slow oscillation (Fig.…”

Section: Hippocampal Network Patterns Are Affected By Slow Oscillationssupporting

confidence: 70%

Interaction between neocortical and hippocampal networks via slow oscillations

Sirota

Buzsáki

2005

THL

234

219

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Both the thalamocortical and limbic systems generate a variety of brain state-dependent rhythms but the relationship between the oscillatory families is not well understood. Transfer of information across structures can be controlled by the offset oscillations. We suggest that slow oscillation of the neocortex, which was discovered by Mircea Steriade, temporally coordinates the self-organized oscillations in the neocortex, entorhinal cortex, subiculum and hippocampus. Transient coupling between rhythms can guide bidirectional information transfer among these structures and might serve to consolidate memory traces.

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Section: Hippocampal Network Patterns Are Affected By Slow Oscillationssupporting

confidence: 70%

Interaction between neocortical and hippocampal networks via slow oscillations

Sirota

Buzsáki

2005

THL

234

219

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“…In line with this view it has been shown that electrical stimuli delivered in the perirhinal cortex do not evoke field potential responses in the entorhinal cortex (Fig. 15A), even though anatomical studies demonstrated that these two structures are strongly reciprocally connected (Amaral and Witter, 1989;Witter et al, 1989;Witter, 1993). Massive propagation of synchronous activity between these two regions can, however, be released when seizure activity is repeatedly generated within the hippocampal-entorhinal region, as demonstrated in the isolated guinea pig brain in vitro preparation (Uva et al, 2005).…”

Section: Control Of Spread Of Synchronous Activitymentioning

confidence: 67%

GABAergic synchronization in the limbic system and its role in the generation of epileptiform activity

Avoli¹,

Curtis²

2011

Progress in Neurobiology

227

253

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GABA is the main inhibitory neurotransmitter in the adult forebrain, where it activates ionotropic type A and metabotropic type B receptors. Early studies have shown that GABA A receptormediated inhibition controls neuronal excitability and thus the occurrence of seizures. However, more complex, and at times unexpected, mechanisms of GABAergic signaling have been identified during epileptiform discharges over the last few years. Here, we will review experimental data that point at the paradoxical role played by GABA A receptor-mediated mechanisms in synchronizing neuronal networks, and in particular those of limbic structures such as the hippocampus, the entorhinal and perirhinal cortices, or the amygdala. After having summarized the fundamental characteristics of GABA A receptor-mediated mechanisms, we will analyze their role in the generation of network oscillations and their contribution to epileptiform synchronization. Whether and how GABA A receptors influence the interaction between limbic networks leading to ictogenesis will be also reviewed. Finally, we will consider the role of altered inhibition in the human epileptic brain along with the ability of GABA A receptor-mediated conductances to generate synchronous depolarizing events that may lead to ictogenesis in human epileptic disorders as well.

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“…Despite its convoluted appearance and complex 3D structure (Amaral & Witter, 1989), the HC may be considered as a relatively simple infolded cortical sheet of cytoarchitecturally distinct neurons, well suited for folded out 2D representations. Our 2D maps can be made using relatively simple plotting software like SigmaPlot and can provide useful visual and graphic means for regional analysis of surface area and topology along the A-P axis and in the mediallateral direction.…”

Section: Discussion Useful Features Of Regional 2d Mapsmentioning

confidence: 99%

Novel two-dimensional morphometric maps and quantitative analysis reveal marked growth and structural recovery of the rat hippocampal regions from early hypothyroid retardation

Farahvar

Meisami

2007

Experimental Neurology

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Effects of postnatal hypothyroidism and recovery from this condition on regional growth of the rat hippocampus (HC) were studied using two-dimensional (2D) foldout, morphometric maps of HC and its constituent CA1-CA4 regions. The maps were derived from unfolding serial coronal sections of the rat forebrain, consisting of the entire rostrocaudal extent of HC pyramidal cell layer in the normal control and hypothyroid weanling (P25, postnatal day 25) and young adult (P90) male rats, as well as animals allowed to recover from hypothyroid-induced growth retardation at weaning. The maps revealed novel views of HC regions for assessment of topological relationships and measurement of surface areas of the HC cortical sheet (pyramidal cell layer). In normal control P90 rats, the unfolded HC on each side extended 4 times more laterally than rostrocaudally; total HC surface area was about 40 mm 2 , compared to 30 mm 2 in the weanling, indicating 35% growth from P25 to P90; CA1 took up 52% of the total HC surface area, followed by CA3 (31%) and CA2 and CA4, 8% each. Hypothyroidism resulted in significant (p<0.01) 11% and 20% reductions in the HC surface area in P25 and P90 rats respectively; CA1 and CA4 regions suffered the most reductions while CA3 and CA2 regions the least. Recovering rats examined at P90, exhibited remarkable growth plasticity and recovery in HC regions, as evident by their near normal HC cortical surface area values, compared to age-matched controls. The 2-D maps also revealed growth deficits in all HC regions of the hypothyroid rats; recovery in these parameters occurred across all dimensions, although the anterior-posterior growth was more severely affected than the mediolateral one. These results are confirmed and extended by volumetric analysis of laminar volumes of HC regions presented in a companion paper (Farahvar et al., 2006). These results imply that HC regions, in contrast to whole brain, possess exceptional growth plasticity, as shown by ability to dramatically recover from early hypothyroid retardation; also 2D morphometric maps are useful tools to visualize complex and convoluted regional sheet of HC cortex and depict quantitative aspects of growth in normal and experimental conditions.

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The three-dimensional organization of the hippocampal formation: A review of anatomical data

Cited by 1,896 publications

References 47 publications

Interaction between neocortical and hippocampal networks via slow oscillations

Interaction between neocortical and hippocampal networks via slow oscillations

GABAergic synchronization in the limbic system and its role in the generation of epileptiform activity

Novel two-dimensional morphometric maps and quantitative analysis reveal marked growth and structural recovery of the rat hippocampal regions from early hypothyroid retardation

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