RT Journal Article
SR Electronic
T1 Homeostatic mechanisms may shape the type and duration of oscillatory modulation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 615450
DO 10.1101/615450
A1 Erik J. Peterson
A1 Bradley Voytek
YR 2019
UL http://biorxiv.org/content/early/2019/04/22/615450.abstract
AB Neural oscillations are observed ubiquitously in the mammalian brain. However the stability of oscillations is highly variable. Some oscillations are tonic, lasting for seconds or even minutes; others are unstable, appearing only as a single-cycle burst. In a model of hippocampal neurons, we use numerical simulations to show how these different forms of rhythm stability can interact with activity-dependent homeostasis to profoundly alter the modulatory effect of neural oscillations. Under homeostasis, tonic oscillations that are synaptically excitatory have a paradoxical effect; they decrease excitability and desynchronizing firing. Tonic oscillations that are synaptically inhibitory–like those in a real hippocampus–fail to generate new action potentials and so provoke no homeostatic response. This may explain why the theta rhythm in hippocampus is synaptically inhibitory: inhibitory oscillations don’t raise the firing threshold, as excitatory oscillations do, and so can preserve each cell’s dynamic range. Based on these simulations, we also speculate that homeostasis may explain why excitatory intra-cortical and intra-layer oscillations often appear as bursts. In our model bursts minimally interact with the slow homeostasis time constant and so retain typical excitatory effects.