Glissandi: transient fast electrocorticographic oscillations of steadily increasing frequency, explained by temporally increasing gap junction conductance.

Purpose: We describe a form of very fast oscillation (VFO) in patient electrocorticography (ECoG) recordings, that can occur prior to ictal events, in which the frequency increases steadily from ≈ 30-40 to >120 Hz, over a period of seconds. We dub these events "glissandi" and describe a possible model for them.

Methods: Four patients with epilepsy had presurgical evaluations (with ECoG obtained in two of them), and excised tissue was studied in vitro, from three of the patients.

Dual γ rhythm generators control interlaminar synchrony in auditory cortex.

Rhythmic activity in populations of cortical neurons accompanies, and may underlie, many aspects of primary sensory processing and short-term memory. Activity in the gamma band (30 Hz up to >100 Hz) is associated with such cognitive tasks and is thought to provide a substrate for temporal coupling of spatially separate regions of the brain. However, such coupling requires close matching of frequencies in co-active areas, and because the nominal gamma band is so spectrally broad, it may not constitute a single underlying process.

Circuits and brain rhythms in schizophrenia: a wealth of convergent targets.

Few common neurological illnesses trace back to single molecular disturbances. Many disparate putative causes may co-associate with a single disease state. However, uncovering functional, hierarchical networks of underlying mechanisms can provide a framework in which many primary pathologies converge on more complex, single higher level correlates of disease.

Cholinergic neuromodulation controls directed temporal communication in neocortex in vitro.

Acetylcholine is the primary neuromodulator involved in cortical arousal in mammals. Cholinergic modulation is involved in conscious awareness, memory formation and attention - processes that involve intercommunication between different cortical regions. Such communication is achieved in part through temporal structuring of neuronal activity by population rhythms, particularly in the beta and gamma frequency ranges (12-80 Hz).

A nonsynaptic mechanism underlying interictal discharges in human epileptic neocortex.

Very fast oscillations (VFOs, >80 Hz) are important for physiological brain processes and, in excess, with certain epilepsies. Putative mechanisms for VFO include interneuron spiking and network activity in coupled pyramidal cell axons. It is not known whether either, or both, of these apply in pathophysiological conditions.