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Coexistence of gamma and high‐frequency oscillations in rat medial entorhinal cortex in vitro
Author(s) -
Cunningham M. O.,
Halliday David M.,
Davies Ceri H.,
Traub Roger D.,
Buhl Eberhard H.,
Whittington Miles A.
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.068973
Subject(s) - neocortex , neuroscience , entorhinal cortex , excitatory postsynaptic potential , local field potential , hippocampus , carbenoxolone , pyramidal cell , gap junction , biology , physics , inhibitory postsynaptic potential , intracellular , microbiology and biotechnology
High frequency oscillations (> 80–90 Hz) occur in neocortex and hippocampus in vivo where they are associated with specific behavioural states and more classical EEG frequency bands. In the hippocampus in vitro these oscillations can occur in the absence of pyramidal neuronal somatodendritic compartments and are temporally correlated with on‐going, persistent gamma frequency oscillations. Their occurrence in the hippocampus is dependent on gap‐junctional communication and it has been suggested that these high frequency oscillations originate as collective behaviour in populations of electrically coupled principal cell axonal compartments. Here we demonstrate that the superficial layers of medial entorhinal cortex can also generate high frequency oscillations associated with gamma rhythms. During persistent gamma frequency oscillations high frequency oscillations occur with a high bispectral coherence with the field gamma activity. Bursts of high frequency oscillations are temporally correlated with both the onset of compound excitatory postsynaptic potentials in fast‐spiking interneurones and spikelet potentials in both pyramidal and stellate principal neurones. Both the gamma frequency and high frequency oscillations were attenuated by the gap junction blocker carbenoxolone. These data suggest that high frequency oscillations may represent the substrate for phasic drive to interneurones during persistent gamma oscillations in the medial entorhinal cortex.