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The many tunes of perisomatic targeting interneurons in the hippocampal network.

Ellender TJ, Paulsen O - Front Cell Neurosci (2010)

Bottom Line: Firstly, it has been shown that, in addition to rhythm generation, GABAergic perisomatic inhibition also serves as a current generator contributing significantly to hippocampal oscillatory EEG signals.Furthermore, GABAergic interneurons have a previously unrecognized role in the initiation of hippocampal population bursts, both in the developing and adult hippocampus.This review is part of the Frontiers in Cellular Neuroscience's special topic entitled "GABA signaling in health and disease" based on the meeting at the CNCR Amsterdam.

View Article: PubMed Central - PubMed

Affiliation: OXION Initiative, Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK.

ABSTRACT
The axonal targets of perisomatic targeting interneurons make them ideally suited to synchronize excitatory neurons. As such they have been implicated in rhythm generation of network activity in many brain regions including the hippocampus. However, several recent publications indicate that their roles extend beyond that of rhythm generation. Firstly, it has been shown that, in addition to rhythm generation, GABAergic perisomatic inhibition also serves as a current generator contributing significantly to hippocampal oscillatory EEG signals. Furthermore, GABAergic interneurons have a previously unrecognized role in the initiation of hippocampal population bursts, both in the developing and adult hippocampus. In this review, we describe these new observations in detail and discuss the implications they have for our understanding of the mechanisms underlying physiological and pathological hippocampal network activities. This review is part of the Frontiers in Cellular Neuroscience's special topic entitled "GABA signaling in health and disease" based on the meeting at the CNCR Amsterdam.

No MeSH data available.


Schematic diagram of hippocampal local field potentials and the underlying current sinks and sources. (A) Recording electrodes placed in the dendritic and somatic regions of the hippocampus show a phase reversal for both evoked responses and oscillatory activity. (B) Excitatory synaptic events at the apical dendrite of pyramidal neurons generate an active current sink as positive ions flow into neurons; a concurrent passive source is recorded from the somatic region. (C) Inhibitory synaptic events at the perisomatic regions of pyramidal neurons generate an active source accompanied by a passive current sink at the dendrites.
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Figure 1: Schematic diagram of hippocampal local field potentials and the underlying current sinks and sources. (A) Recording electrodes placed in the dendritic and somatic regions of the hippocampus show a phase reversal for both evoked responses and oscillatory activity. (B) Excitatory synaptic events at the apical dendrite of pyramidal neurons generate an active current sink as positive ions flow into neurons; a concurrent passive source is recorded from the somatic region. (C) Inhibitory synaptic events at the perisomatic regions of pyramidal neurons generate an active source accompanied by a passive current sink at the dendrites.

Mentions: Although the rhythm generation of many oscillations has been extensively studied, little is known about the currents underlying the observed field events. Field activity is generated by the sum of currents flowing into and out of cells. It has long been thought that excitatory currents contribute predominantly to the recorded field events (see Figures 1A,B). Several recent papers have now challenged this assumption and shown that inhibition, especially arising from perisomatic targeting interneurons, can contribute significantly to the current generation (see Figures 1A,C).


The many tunes of perisomatic targeting interneurons in the hippocampal network.

Ellender TJ, Paulsen O - Front Cell Neurosci (2010)

Schematic diagram of hippocampal local field potentials and the underlying current sinks and sources. (A) Recording electrodes placed in the dendritic and somatic regions of the hippocampus show a phase reversal for both evoked responses and oscillatory activity. (B) Excitatory synaptic events at the apical dendrite of pyramidal neurons generate an active current sink as positive ions flow into neurons; a concurrent passive source is recorded from the somatic region. (C) Inhibitory synaptic events at the perisomatic regions of pyramidal neurons generate an active source accompanied by a passive current sink at the dendrites.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927192&req=5

Figure 1: Schematic diagram of hippocampal local field potentials and the underlying current sinks and sources. (A) Recording electrodes placed in the dendritic and somatic regions of the hippocampus show a phase reversal for both evoked responses and oscillatory activity. (B) Excitatory synaptic events at the apical dendrite of pyramidal neurons generate an active current sink as positive ions flow into neurons; a concurrent passive source is recorded from the somatic region. (C) Inhibitory synaptic events at the perisomatic regions of pyramidal neurons generate an active source accompanied by a passive current sink at the dendrites.
Mentions: Although the rhythm generation of many oscillations has been extensively studied, little is known about the currents underlying the observed field events. Field activity is generated by the sum of currents flowing into and out of cells. It has long been thought that excitatory currents contribute predominantly to the recorded field events (see Figures 1A,B). Several recent papers have now challenged this assumption and shown that inhibition, especially arising from perisomatic targeting interneurons, can contribute significantly to the current generation (see Figures 1A,C).

Bottom Line: Firstly, it has been shown that, in addition to rhythm generation, GABAergic perisomatic inhibition also serves as a current generator contributing significantly to hippocampal oscillatory EEG signals.Furthermore, GABAergic interneurons have a previously unrecognized role in the initiation of hippocampal population bursts, both in the developing and adult hippocampus.This review is part of the Frontiers in Cellular Neuroscience's special topic entitled "GABA signaling in health and disease" based on the meeting at the CNCR Amsterdam.

View Article: PubMed Central - PubMed

Affiliation: OXION Initiative, Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK.

ABSTRACT
The axonal targets of perisomatic targeting interneurons make them ideally suited to synchronize excitatory neurons. As such they have been implicated in rhythm generation of network activity in many brain regions including the hippocampus. However, several recent publications indicate that their roles extend beyond that of rhythm generation. Firstly, it has been shown that, in addition to rhythm generation, GABAergic perisomatic inhibition also serves as a current generator contributing significantly to hippocampal oscillatory EEG signals. Furthermore, GABAergic interneurons have a previously unrecognized role in the initiation of hippocampal population bursts, both in the developing and adult hippocampus. In this review, we describe these new observations in detail and discuss the implications they have for our understanding of the mechanisms underlying physiological and pathological hippocampal network activities. This review is part of the Frontiers in Cellular Neuroscience's special topic entitled "GABA signaling in health and disease" based on the meeting at the CNCR Amsterdam.

No MeSH data available.