Ripple While You Walk, and You May Get Lost: Pathological High-Frequency Activity Can Alter Spatial Navigation Circuits.

Ripple While You Walk, and You May Get Lost: Pathological High-Frequency Activity Can Alter Spatial Navigation Circuits.
Epilepsy Curr. 2019 Sep 02;:1535759719871275
Authors: Brennan EKW, Ahmed OJ
Abstract
The Impact of Pathological High-frequency Oscillations on Hippocampal Network Activity in Rats With Chronic Epilepsy. Ewell LA, Fischer KB, Leibold C, Leutgeb S, Leutgeb JK. eLIFE. 2019;8:pii: e42148. doi: 10.7554/eLife.42148. PMID: 30794155 In epilepsy, brain networks generate pathological high-frequency oscillations (pHFOs) during interictal periods. To understand how pHFOs differ from normal oscillations in overlapping frequency bands and potentially perturb hippocampal processing, we performed high-density single unit and local field potential recordings from hippocampi of behaving rats with and without chronic epilepsy. In epileptic animals, we observed 2 types of co-occurring fast oscillations that by comparison to control animals could be classified as "ripple-like" or "pHFO." We compared their spectral characteristics, brain state dependence, and cellular participants. Strikingly, pHFO occurred irrespective of brain state, were associated with interictal spikes, engaged distinct subnetworks of principal neurons compared to ripple-like events, increased the sparsity of network activity, and initiated both general and immediate disruptions in spatial information coding. Taken together, our findings suggest that events that re...

Source: Epilepsy Currents - September 4, 2019 Category: Neurology Tags: Epilepsy Curr Source Type: research