Dataset Information

Biophysical model for gamma rhythms in the olfactory bulb via subthreshold oscillations.

ABSTRACT: Gamma oscillations in the olfactory bulb can be produced as an interaction of subthreshold oscillations (STOs) in the mitral cells (MCs) with inhibitory granule cells (GCs). The mechanism does not require that the GCs spike, and we work in a regime in which the MCs fire at rates lower than the fast gamma rhythm they create. The frequency of the network is that of the STOs, allowing the gamma to be modulated in amplitude with only small changes in frequency. Gamma oscillations could also be obtained with spiking GCs, but only for GCs firing close to population rate. Our mechanism differs from the more standard description of the gamma oscillation, in which the the decay time of the inhibitory cells is critical to the frequency of the network.

SUBMITTER: Brea JN

PROVIDER: S-EPMC2799880 | biostudies-other | 2009 Dec

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Biophysical model for gamma rhythms in the olfactory bulb via subthreshold oscillations.

Brea Jorge N JN Kay Leslie M LM Kopell Nancy J NJ

Proceedings of the National Academy of Sciences of the United States of America 20091208 51

Gamma oscillations in the olfactory bulb can be produced as an interaction of subthreshold oscillations (STOs) in the mitral cells (MCs) with inhibitory granule cells (GCs). The mechanism does not require that the GCs spike, and we work in a regime in which the MCs fire at rates lower than the fast gamma rhythm they create. The frequency of the network is that of the STOs, allowing the gamma to be modulated in amplitude with only small changes in frequency. Gamma oscillations could also be obtai ...[more]

PMID: 19996171

Similar Datasets

Project description:BackgroundBefore the deposition of amyloid-beta plaques and the onset of learning memory deficits, patients with Alzheimer's disease (AD) experience olfactory dysfunction, typified by a reduced ability to detect, discriminate, and identify odors. Rodent models of AD, such as the Tg2576 and APP/PS1 mice, also display impaired olfaction, accompanied by aberrant in vivo or in vitro gamma rhythms in the olfactory pathway. However, the mechanistic relationships between the electrophysiological, biochemical and behavioral phenomena remain unclear.MethodsTo address the above issues in AD models, we conducted in vivo measurement of local field potential (LFP) with a combination of in vitro electro-olfactogram (EOG), whole-cell patch and field recordings to evaluate oscillatory and synaptic function and pharmacological regulation in the olfactory pathway, particularly in the olfactory bulb (OB). Levels of protein involved in excitation and inhibition of the OB were investigated by western blotting and fluorescence staining, while behavioral studies assessed olfaction and memory function.ResultsLFP measurements demonstrated an increase in gamma oscillations in the OB accompanied by altered olfactory behavior in both APP/PS1 and 3xTg mice at 3-5 months old, i.e. an age before the onset of plaque formation. Fewer olfactory sensory neurons (OSNs) and a reduced EOG contributed to a decrease in the excitatory responses of M/T cells, suggesting a decreased ability of M/T cells to trigger interneuron GABA release indicated by altered paired-pulse ratio (PPR), a presynaptic parameter. Postsynaptically, there was a compensatory increase in levels of GABAAR α1 and β3 subunits and subsequent higher amplitude of inhibitory responses. Strikingly, the GABA uptake inhibitor tiagabine (TGB) ameliorated abnormal gamma oscillations and levels of GABAAR subunits, suggesting a potential therapeutic strategy for early AD symptoms. These findings reveal increased gamma oscillations in the OB as a core indicator prior to onset of AD and uncover mechanisms underlying aberrant gamma activity in the OB.ConclusionsThis study suggests that the concomitant dysfunction of both olfactory behavior and gamma oscillations have important implications for early AD diagnosis: in particular, awareness of aberrant GABAergic signaling mechanisms might both aid diagnosis and suggest therapeutic strategies for olfactory damage in AD.

Dataset Information

Biophysical model for gamma rhythms in the olfactory bulb via subthreshold oscillations.

Publications

Biophysical model for gamma rhythms in the olfactory bulb via subthreshold oscillations.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets