Quantitative EEG changes in non‐demented Parkinson's disease patients before and during L‐dopa therapy

Abstract

Nineteen non‐demented Parkinson's disease patients have been studied before and during L‐dopa therapy by quantitative EEG performed at rest with eyes closed (EC) and during attentive (BR) and cognitive (FIX) tasks. The data have been compared by ANOVA analysis with those of 22 age‐matched healthy subjects. In all three conditions a significant increase of the mean δ power as well as a decrease of β1 power was observed in patients before therapy. Abnormal high δ values were observed in 10 out of 19 patients. L‐Dopa therapy did not modify this EEG pattern. After therapy, however, a significant decrease of reactivity to BR and FIX was observed in patients compared to normal subjects. These data confirmed the presence of an EEG synchronization (increase of slow activity and decrease of fast activity) in non‐demented Parkinson's disease patients. This pattern, similar to that of subjects with Alzheimer‐type dementia, might indicate an intellectual impairment at sub‐clinical level. A non‐dopaminergic mechanism could be responsible for this impairment

High Thalamocortical Theta Coherence in Patients with Parkinson's Disease

“…This finding suggests that thalamic and cortical factors are both relevantly contributing to the cortical rhythmicity recorded by scalp EEG (Nunez et al, 2001;Schreckenberger et al, 2004). The pathophysiological effects of PD on the thalamus thus lead to a slowing of scalp EEG in PD patients (Soikkeli et al, 1991;Stanzione et al, 1996;Tanaka et al, 2000). Our results support the notion that the PD symptomatology originates from a disturbance in the thalamocortical interplay (Llinas, 1984;Volkmann et al, 1992Volkmann et al, , 1996Llinas and Pare, 1994;Jeanmonod et al, 1996;Llinas et al, 1999).…”

“…A theta or ␦ power increase may also become measurable in EEG (Fig. 1 A, Table 1) (Soikkeli et al, 1991;Stanzione et al, 1996;Tanaka et al, 2000) and MEG (Llinas et al, 1999;Salenius et al, 2002) and thalamic LFP (Fig. 1 B).…”

Enhanced frontal low and high frequency power and synchronization in the resting EEG of parkinsonian patients

“…1) is in line with a previous report of excess power in all frequency bands (Tanaka et al, 2000) and at variance with other reports of excess power only in specific frequency bands (Bosboom et al, 2006;Neufeld et al, 1994;Salenius et al, 2002;Stanzione et al, 1996;Stoffers et al, 2007). The general increase in power is confirmed if individual electrodes are analysed ( Fig.…”

“…But interpretation of these studies is made difficult by the differences in task performance between studies, and mainly by the fact that we still lack sufficient knowledge of the anomalies of the resting EEG state in PD. Over the years, a few studies have looked at the EEG power spectra in PD patients, showing excess power in either all frequency bands (Tanaka et al, 2000), or only in specific frequency bands (Bosboom et al, 2006;Salenius et al, 2002;Stanzione et al, 1996;Stoffers et al, 2007), or a slowing of the occipital background rhythm (Soikkeli et al, 1991). The localization of the cortical generators at the source of this power excess has not yet been investigated in detail, except in one pioneering MEG work (Moran et al, 2004).…”

An aging brain: morphofunctional aspects

“…Альфа-1-ритм связан с вниманием и трудностью выполня-емого задания, тогда как альфа-2 является нейрофи-зиологическим коррелятом сложной семантической памяти [46]. Одновременно снижается реактивность альфа-ритма на активирующие нагрузки, а мощ-ность бета-активности при функциональных на-грузках возрастает [47]. Н.В.…”