The Retrosplenial Cortex: Intrinsic Connectivity and Connections with the (Para)Hippocampal Region in the Rat. An Interactive Connectome

Sugar, Jørgen; Witter, Menno P.; Strien, Niels van; Cappaert, Natalie L.M.

doi:10.3389/fninf.2011.00007

Cited by 206 publications

(236 citation statements)

References 83 publications

(256 reference statements)

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“…While the entorhinal cortex is the major excitatory input to the dentate (2, 3), it is certainly not the only input. The dentate gyrus receives input from the presubiculum and parasubiculum; the postrhinal and perirhinal cortex; backprojections from CA1 and CA3; commissural connections; GABAergic & cholinergic, noradrenergic, dopaminergic, and serotonergic input from the septum, locus coeruleus, ventral tegmental area, and raphe; and GABAergic and glutamatergic input from the supramammillary nucleus (3,4,5). One or more of these other sources of input (specifically, those that would not be damaged by perforant path transection) to the dentate may drive seizures.…”

Section: The Gate and The Source? The Dentate Gyrus Takes Central Stamentioning

confidence: 99%

The Gate and the Source? the Dentate Gyrus Takes Central Stage in Temporal Lobe Epilepsy

Krook-Magnuson¹

2017

Epilepsy Curr

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CommentaryIn healthy tissue, dentate granule cells respond to entorhinal input with very sparse activation, limiting the flow of excitation through the hippocampal circuit. This 'gating' function of the dentate can be impaired in temporal lobe epilepsy, such that even normal input from the entorhinal cortex might produce greater levels of activity in the dentate. This greater dentate output would then feed through the circuit and be proictogenic. A recent study by Norwood and colleagues adds an interesting twist to the classic dentate gate hypothesis of temporal lobe epilepsy; their findings reported in Meyer et al. suggest that entorhinal input may not be necessary for ictogenesis.Meyer et al. used the perforant path stimulation model to induce temporal lobe epilepsy in rats. In this model, after 2 priming days of 30-min stimulation, the perforant path is stimulated for 8 hours in awake animals at a subconvulsive level [1]. This results in immediate hippocampal cell damage and loss, and the appearance of spontaneous dentate discharges. Spontaneous behavioral seizures arise in this model 2 to 3 weeks after the 8-hour performant path stimulation insult.The spontaneous discharges in the dentate, which appear immediately after the 8 hours of perforant path stimulation are remarkably similar to potentials directly evoked by stimulation of the entorhinal input to the dentate. This similarity caused Norwood and colleagues to previously note "the first spontaneous potentials closely resembled what would be expected from the granule cell layer if the seizures originated in the entorhinal cortex" and, holding with the classic view of the dentate gate hypothesis, "the available evidence is consistent with spontaneous 'hippocampal-onset' granule cell seizure discharges that may have been preceded and driven by spontaneous and synchronized entorhinal cortex discharges" (1). Thus, a reasonable interpretation was that the spontaneous discharges in the dentate were driven by the entorhinal cortex. A similar scenario was suggested for the spontaneous behavioral seizures that later develop in the model: "We hypothesize that the seizures in this model begin outside the hippocampus… and that only when the originating seizure activity recruits epileptiform discharges from disinhibited dentate granule cells do clinical seizures occur" (1). Previous findings were thus consistent with the hypothesis that input from the entorhinal cortex ultimately drove seizure expression. And so, in Meyer et al., they did a simple test-immediately after perforant path stimulation, they physically cut off the entorhinal input to the dentate. The effect? Nothing. Removing Entorhinal Cortex Input to the Dentate Gyrus Does not Impede Low Frequency Oscillations, an EEGbiomarker of Hippocampal Epileptogenesis.Meyer M, Kienzler-Norwood F, Bauer S, Rosenow F, Norwood BA. Sci Rep 2016;6:25660.Following prolonged perforant pathway stimulation (PPS) in rats, a seizure-free "latent period" is observed that lasts around 3 weeks. During this time, aberrant neurona...

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Section: The Gate and The Source? The Dentate Gyrus Takes Central Stamentioning

confidence: 99%

The Gate and the Source? the Dentate Gyrus Takes Central Stage in Temporal Lobe Epilepsy

Krook-Magnuson¹

2017

Epilepsy Curr

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“…Building upon their earlier work in the hippocampus (van Strien et al, 2009), Sugar et al (2011 present an interactive connectome of hippocampal and parahippocampal connections. The authors have extracted ∼2600 descriptions of hippocampal connections from 226 published reports, and assembled them into a versatile, searchable application providing a comprehensive description of all known network elements in this region ( Figure 1P).…”

Section: Progress Made and Main Challengesmentioning

confidence: 99%

“…Several groups have invested in further ambitious data mining projects to aggregate connectome data from legacy data (Sugar et al, 2011;Tallis et al, 2011;Bota et al, 2012). Over several years, Bota and co-workers have developed a publicly available neuroinformatics system, called the brain architecture knowledge management system (BAMS), which currently contains >50,000 connectivity reports from the rat brain ( Figure 1O).…”

Section: Progress Made and Main Challengesmentioning

confidence: 99%

Mapping the connectome: Multi-level analysis of brain connectivity

2013

Frontiers Research Topics

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“…These retrosplenial areas are closely connected with the hippocampal formation, the parahippocampal region, and anterior thalamic nuclei. Each of these areas is characterized by distinct connectivity patterns (Jones and Witter 2007, van Groen and Wyss 1992, 2003, Sugar et al 2011, Shibata 1993. The morphological and connectional heterogeneity of RSC subdivisions provides a basis for their functional diversity.…”

Section: Introductionmentioning

confidence: 99%

Spatial memory formation differentially affects c-Fos expression in retrosplenial areas during place avoidance training in rats

Malinowska¹,

Niewiadomska²,

Wesierska³

2016

Acta Neurobiologiae Experimentalis

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Authors' contributions: M.M. designed the research; M.M. and M.W. performed the research, analyzed the data and wrote the paper; M.N. performed ~20% of the research.The retrosplenial cortex is involved in spatial memory function, but the contribution of its individual areas is not well known. To elucidate the involvement of retrosplenial cortical areas 29c and 30 in spatial memory, we analyzed the expression of c-Fos in these areas in the experimental group of rats that were trained in a spatial place avoidance task, i.e. to avoid shocks presented in an unmarked sector of a stable arena under light conditions. Control rats were trained in the same context as the experimental rats either without (Control-noUS) or with shocks (Control-US) that were delivered in a random, noncontingent manner for three days. On the first day of place avoidance learning, the experimental group exhibited c-Fos induction in area 29c, similar to both control groups. In area 30, similarly high levels of c-Fos expression were observed in the experimental and Control-US groups. On the third day of training, when the experimental group efficiently avoided c-Fos expression in areas 29c and 30 was lower compared with the first day of training. In area 29c c-Fos level was also lower in the experimental group in comparison to the Control-US group. In area 30, c-Fos expression in the experimental group was lower than in both control groups. In conclusion, areas 29c and 30 appear to be activated during spatial memory acquisition on the first day of training, whereas area 30 seems suppressed during long-term memory functioning on the third day of training when rats effectively avoid.

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The Retrosplenial Cortex: Intrinsic Connectivity and Connections with the (Para)Hippocampal Region in the Rat. An Interactive Connectome

Cited by 206 publications

References 83 publications

The Gate and the Source? the Dentate Gyrus Takes Central Stage in Temporal Lobe Epilepsy

The Gate and the Source? the Dentate Gyrus Takes Central Stage in Temporal Lobe Epilepsy

Mapping the connectome: Multi-level analysis of brain connectivity

Spatial memory formation differentially affects c-Fos expression in retrosplenial areas during place avoidance training in rats

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