Electrophysiological Models for the Study of Cognition Enhancers

Abstract

Electrophysiological approaches range from global EEG studies to single unit recordings. Quantified EEG studies indicate that cognition enhancers increase the power of fast-frequency (beta) EEG activity in humans and the duration of hippocampal theta in animals. A problem here is the distinction between improved cognition and increases in general arousal, although the two might have the same end effect. A second global approach is the use of the evoked potential or even the conditioned evoked potential, for example the P 300 wave. This approach, using defined brain circuits, would appear to be more specific than global EEG models. Both approaches can be used in parallel studies in animals and man. Studies at more cellular levels can only be used in animals and suffer from severe constraints. The most precise approach, single cell recording, cannot be conducted in freely behaving animals, whereas multi-unit approaches in awake animals tend to produce many artefacts. However, techniques using microintophoretically applied drugs in freely moving rodents and monkeys can contribute to the understanding of mechanisms of action. In vitro studies, for example long-term potentiation in hippocampal slices, may represent a neuronal model of learning but its role in normal brain function has still not been elucidated.

Acute Nicotine Administration in Alzheimer’s Disease: An Exploratory EEG Study

“…The rationale for the study objective of profiling the neuroelectric response to acute nicotine administration in DAT was based in part on the general premise that electrophysiological probes can provide the necessary neurophysiological data-linking behavioral and molecular approaches in the study of cognitive enhancers in gerontopsychopharmacology [66]. Quantitative EEG has not only proven to be useful in the acute prolifing of new cognitiveenhancing agents and in therapeutic assessment of clinical trials in dementia [43][44][45][46], it has also been of use in the diagnoses of DAT in that it has addressed aspects of cerebral electrical potential disturbances which are not easily appreciated visually in the traditional clinical EEG [40,67].…”

Quantitative EEG Changes in Alzheimer Patients during Long-Term Donepezil Therapy

“…The effect of several classes of drugs acting at the brain level has been studied by qEEG [6][7][8], including those employed in the treatment of dementia [9].…”

Dopaminergic regulation of cortical acetylcholine release

“…Cortical acetylcholine (ACh) release correlates positively with EEG desynchrony (Celesia and Jasper, 1966;Kainai and Szerb, 1965) and locomotor activity (Day et al, 1991). Given the association between cortical ACh release and these measures of arousal, and because cortical arousal may be required for a wide variety of cognitive functions (Delacour et al, 1990;Penttila et al, 1985;Riekkinen et al, 1991;Simon and Emmons, 19561, the neuronal control of the cortically projecting basal forebrain cholinergic system is of considerable interest.…”