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Changes in Neuronal Membrane Properties Lead to Suppression of Hippocampal Ripples

By Eric D. Melonakos, John A. White, and Fernando R. Fernandez, Department of Bioengineering

Center for High Performance Computing resources were used to study the effects of cholinergic inputs to the hippocampus on patterns of brain activity.

Ripples (140–220 Hz) are patterns of brain activity, seen in the local field potential of the hippocampus, that are important for memory consolidation. Cholinergic inputs to the hippocampus from neurons in the medial septum-diagonal band of Broca cause a marked reduction in ripple incidence as rodents switch from memory consolidation to memory encoding behaviors. The mechanism for this disruption in ripple power is not fully understood. Among the major effects of acetylcholine (or carbachol, a cholinomimetic) on hippocampal neurons are 1) an increase in membrane potential, 2) a decrease in the size of spike after hyperpolarization (AHP), and 3) an increase in membrane resistance. Using an existing model of hippocampal ripples that includes 5000 interconnected neurons (Brunel and Wang, 2003), we manipulated these parameters and observed their effects on ripple power. Shown here, the network firing rate and ripple power of the original model (top row; pyramidal neuron data is shown in red, interneuron data is shown in black) undergo marked changes following a decrease in pyramidal neuron AHP size, as well as an increase in the membrane voltage of both types of neurons. These changes could be the means whereby cholinergic input suppresses hippocampal ripples.

System Status

last update: 07/23/17 2:23 pm
General Nodes
system procs % util.
ember 348/984 35.37%
kingspeak 692/880 78.64%
lonepeak 256/256 100%
Restricted Nodes
system procs % util.
ash 2940/7448 39.47%
apexarch Status Unavailable
ember 952/1284 74.14%
kingspeak 4812/7168 67.13%

Cluster Utilization

Last Updated: 7/18/17