Hepatic encephalopathy is associated with slowed and delayed stimulus-associated somatosensory alpha activity.

Objective: Hepatic encephalopathy (HE) is associated with motor symptoms and attentional deficits, which are related to pathologically slowed oscillatory brain activity. Here, potential alterations of oscillatory activity in the somatosensory system were investigated.

Methods: 21 patients with liver cirrhosis and varying HE severity and 7 control subjects received electrical stimulation of the right median nerve while brain activity was recorded using magnetoencephalography (MEG).

Pre- and post-stimulus alpha activity shows differential modulation with spatial attention during the processing of pain.

Extensive work using magneto- and electroencephalography (M/EEG) suggests that cortical alpha activity represents a top-down controlled gating mechanism employed by processes like attention across different modalities. However, it is not yet clear to what extent this presumed gating function of alpha activity also applies to the processing of pain. In the current study, a spatial attention paradigm was employed requiring subjects to attend to painful laser stimuli on one hand while ignoring stimuli on the other hand.

Lowered frequency and impaired modulation of gamma band oscillations in a bimodal attention task are associated with reduced critical flicker frequency.

Visual attention is associated with occipital gamma band activity. While gamma band power can be modulated by attention, the frequency of gamma band activity is known to decrease with age. The present study tested the hypothesis that reduced visual attention is associated with a change in induced gamma band activity.

Fluctuations of prestimulus oscillatory power predict subjective perception of tactile simultaneity.

Oscillatory activity is modulated by sensory stimulation but can also fluctuate in the absence of sensory input. Recent studies have demonstrated that such fluctuations of oscillatory activity can have substantial influence on the perception of subsequent stimuli. In the present study, we employed a simultaneity task in the somatosensory domain to study the role of prestimulus oscillatory activity on the temporal perception of 2 events.

Sustained gamma band synchronization in early visual areas reflects the level of selective attention.

Cortical gamma band synchronization is associated with attention. Accordingly, directing attention to certain visual stimuli modulates gamma band activity in visual cortical areas. However, gradual effects of attention and behavior on gamma band activity in early visual areas have not yet been reported.

Transient reduction of tinnitus intensity is marked by concomitant reductions of delta band power.

Background: Tinnitus is an auditory phantom phenomenon characterized by the sensation of sounds without objectively identifiable sound sources. To date, its causes are not well understood. Previous research found altered patterns of spontaneous brain activity in chronic tinnitus sufferers compared to healthy controls, yet it is unknown whether these abnormal oscillatory patterns are causally related to the tinnitus sensation.