Abstract

Cortical EEG reflects vigilance level

Cholinergic projection is the most important activating system

The cholinergic system has tonic and phasic influence on EEG

Some well-known EEG events might have cholinergic background

References

Discussion
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Changes in the level of vigilance are reflected in the pattern of the cortical electroencephalogram (EEG). Now it is known that the different patterns are caused by the altered interplay of thalamic and cortical circuits that, in turn, is attributable to changes in the functioning of different ion channels due to variations in the ascending modulatory effects. In addition to the tonic patterns, many other, short-lasting or rhythmically recurring EEG phenomena can be recorded under different circumstances and they might be induced by similar changes in the modulatory effects. To understand the ultimate cause and purpose of the processes underlying these tonic and phasic EEG events, it is very important to clarify the role played by the individual modulatory systems in their generation. The participation of a given modulatory system in these processes can be examined by manipulating of the modulatory system and monitoring EEG changes or by correlating activity in the neurons of the modulatory systems with the cortical EEG changes. Using the latter approach we found strong correlation between tonic and phasic EEG changes and the neuronal activity in the basal forebrain further corroborating the importance of the basal forebrain neurones in the regulation of tonic and phasic EEG phenomena.

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Presentation Number SAdetari0367
Keywords: basal forebrain, cholinergic cells, cortical EEG, unit activity