Gamma-band synchronization is abundant in nervous systems. Typically, the strength or precision of gamma-band synchronization is studied. However, the precise phase with which individual neurons are synchronized to the gamma-band rhythm might have interesting consequences for their impact on further processing and for spike timing-dependent plasticity. Therefore, we investigated whether the spi...

When subjects monitor a single spatial location, target detection depends on the pre-target phase of an ~8 Hz brain rhythm. When multiple locations are monitored, performance decrements suggest a division of the 8 Hz rhythm over the number of locations. This suggests that different locations are sequentially sampled. Indeed, when subjects monitor two locations, performance benefits alternate at...

Cortical and hippocampal gamma oscillations have been implicated in many behavioral tasks. The hippocampus is required for spatial navigation where animals run at varying speeds. Hence we tested the hypothesis that the gamma rhythm could encode the running speed of mice. We found that the amplitude of slow (20-45 Hz) and fast (45-120 Hz) gamma rhythms in the hippocampal local field potential (L...

Gamma components of the local field potential (LFP) are elevated during cognitive and perceptual processes. It has been suggested that gamma power indicates the strength of neuronal population synchrony, which influences the relaying of signals between cortical areas. However, the relationship between coordinated spiking activity and gamma remains unclear, and the influence on corticocortical s...

Cell assemblies have long been thought to be associated with brain rhythms, notably the gamma rhythm. Here, we use a computational model to show that the beta1 frequency band, as found in rat association cortex, has properties complementary to the gamma band for the creation and manipulation of cell assemblies. We focus on the ability of the beta1 rhythm to respond differently to familiar and n...

Neural oscillations are electrical activities of the brain measurable at different frequencies. This paper studies interaction between fast and slow processes in brain. We recorded signals intracranially from simple Wistar rats, performed signal processing, computed correlation envelopes high-frequency gamma rhythm a low-frequency signal. The analysis shows that (delta rhythm) modulates with sm...

Synchronous activity among synaptically connected interneurons is thought to organize temporal patterns such as gamma and theta rhythms in cortical circuits. Interactions between distinct interneuron circuits may underlie more complex patterns, such as nested rhythms. Here, we demonstrate such an interaction between two groups of CA1 interneurons, GABA(A,slow) and GABA(A,fast) cells, that may c...

Under static gamma stimulations, Ia afferents may discharge in a highly irregular way or may be driven. However, the genesis of the highly irregular form of discharge is unclear. We offer an interpretation of irregular discharge behavior. Twenty-three primary (Ia) muscle spindle afferents from the tibial anterior muscle of the cat were subjected to static gamma stimulation, the stimulation freq...

We study the coexistence of different rhythms in a local network of one inhibitory and two excitatory nerve cells for a wide range of the excitatory synapse strength and of the slow K+-channel conductance. The dynamic features of spike trains in the presence of noise are discussed. It is found that noise can both cause switching between different states and induce coherent firing events.

We describe a simple computational model, based on generic features of cortical local circuits, that links cholinergic neuromodulation, gamma rhythmicity, and attentional selection. We propose that cholinergic modulation, by reducing adaptation currents in principal cells, induces a transition from asynchronous spontaneous activity to a "background" gamma rhythm (resembling the persistent gamma...