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eNeuro. 2016 Nov 18;3(6). pii: ENEURO.0284-16.2016. eCollection 2016 Nov-Dec.

Altered Oscillatory Dynamics of CA1 Parvalbumin Basket Cells during Theta-Gamma Rhythmopathies of Temporal Lobe Epilepsy.

Author information

1
Instituto Cajal, Consejo Superior de Investigaciones Científicas , 28002 Madrid, Spain.
2
Departamento de Ingeniería Biomédica, Universidad de los Andes , 111711 Bogotá, Colombia.
3
Instituto Cajal, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain; Villaviciosa de Odón Campus, Universidad Europea de Madrid, 28670 Madrid, Spain.

Abstract

Recent reports in human demonstrate a role of theta-gamma coupling in memory for spatial episodes and a lack of coupling in people experiencing temporal lobe epilepsy, but the mechanisms are unknown. Using multisite silicon probe recordings of epileptic rats engaged in episodic-like object recognition tasks, we sought to evaluate the role of theta-gamma coupling in the absence of epileptiform activities. Our data reveal a specific association between theta-gamma (30-60 Hz) coupling at the proximal stratum radiatum of CA1 and spatial memory deficits. We targeted the microcircuit mechanisms with a novel approach to identify putative interneuronal types in tetrode recordings (parvalbumin basket cells in particular) and validated classification criteria in the epileptic context with neurochemical identification of intracellularly recorded cells. In epileptic rats, putative parvalbumin basket cells fired poorly modulated at the falling theta phase, consistent with weaker inputs from Schaffer collaterals and attenuated gamma oscillations, as evaluated by theta-phase decomposition of current-source density signals. We propose that theta-gamma interneuronal rhythmopathies of the temporal lobe are intimately related to episodic memory dysfunction in this condition.

KEYWORDS:

episodic memory; hippocampus; silicon probes; tetrodes; theta-gamma

PMID:
27896315
PMCID:
PMC5114702
DOI:
10.1523/ENEURO.0284-16.2016
[Indexed for MEDLINE]
Free PMC Article

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