19th biennial IPEG Meeting

Abstract

Neuropsychiatric Electrophysiology 2016, 2(Suppl 1):A1 In waking and sleeping states, thalamocortical system generates a variety of oscillations ranging from 0.1 Hz to hundreds of Hz. Most of them are present during NREM sleep, but slower activities prevail in this state of vigilance. Thalamocortical network is organized in a loop in which thalamocortical cells excite reticular thalamic and neocor-tical cells, reticular thalamic cells inhibit thalamocortical cells and corticothalamic cells excite thalamocortical and reticular thalamic cells. Despite stable anatomical connectivity, different types of oscil-lations preferentially originate either in neocortex or in thalamus. During sleep stage 2, spindle oscillation (9–15 Hz) is a dominant type of activity. It is well accepted that spindles originate in the thalamus via interplay of firing of reticular thalamic and thalamocortical neurons, but neocortex controls spindle generation. Spindles can be divided on fast and slow. Several properties of slow spindles do not match known mechanisms of their thalamic origin. Slow oscillation (about 1 Hz) dominates slow-wave sleep stage. Each slow wave is composed of hyperpolarized or silent and depolarized and active state. Active states may be accompanied by spindles and higher frequency activities. Slow waves originate mainly in deep cortical layers from which they propagate to more superficial layers and they also propagate horizontally. Full expression of slow wave activities requires the presence of thalamus, although slow oscillation can be recorded in athalamic preparations. Therefore, despite the fact of preferential origin of different sleep oscillations in either neocortex or in thalamus, only the full thalamo-cortical network can generate sleep activities with known properties. Support: CIHR and NSERC. A2 Electropsychopharmacology: applying EEG and ERP to psychopharmacology Leon Kenemans Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, Netherlands Neuropsychiatric Electrophysiology 2016, 2(Suppl 1):A2 Electroencephalography (EEG), in particular event-related or evoked potentials (ERPs), as well as their magnetic counterparts, can yield useful supplementary information when interpreting effects of psy-choactive substances on behavior. They can be used to elucidate the neurocognitive mechanisms that underlie pharmacological modula-tion of behavior, or they may provide additional sensitivity to detect neurocognitive effects that are not readily observable in behavioral measures. This will be illustrated by means of pertinent examples. These include elucidating the mechanisms of stimulant action re-mediating deficient impulse control and the role of the cannabinoid system in human working memory, as well as drug effects on sensory gating and specific aspects of visual-spatial attention. Other examples concern the added sensitivity of EEG and ERP measures, relative to that of performance measures, in detecting effects of alco-hol, and more generally in monitoring and predicting vigilance and the ability to detect external signals in the immediate future. Rela-tions between brain signals and cognitive competences are revealed by either comparing different individuals, or moment-to-moment fluctuations within individuals, or differences in state (e.g., drug-induced) within individuals.