Mika Koivisto

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Electrophysiological recordings during visual tasks can shed light on the temporal dynamics of the subjective experience of seeing, visual awareness. This paper reviews studies on electrophysiological correlates of visual awareness operationalized as the difference between event-related potentials (ERPs) in response to stimuli that enter awareness and(More)
Electrophysiological correlates of change detection and change blindness were studied in 12 observers. The ERP difference between detected changes and undetected changes was considered an electrophysiological correlate of visual awareness. Two distinct electrophysiological responses correlated with the awareness of change. First, awareness was associated(More)
The present study examined possible influences of a 902 MHz electromagnetic field emitted by cellular telephones on cognitive functioning in 48 healthy humans. A battery of 12 reaction time tasks was performed twice by each participant in a counterbalanced order: once with and once without the exposure to the field. The results showed that the exposure to(More)
The influence of pulsed radiofrequency (RF) electromagnetic fields of digital GSM mobile phones on working memory in healthy subjects were studied. Memory load was varied from 0 to 3 items in an n-back task. Each subject was tested twice within a single session, with and without the RF exposure (902MHz, 217Hz). The RF field speeded up response times when(More)
Event-related potential (ERP) studies have attempted to discover the processes that underlie conscious visual perception by contrasting ERPs produced by stimuli that are consciously perceived with those that are not. Variability of the proposed ERP correlates of consciousness is considerable: the earliest proposed ERP correlate of consciousness (P1)(More)
OBJECTIVES To examine the effects of working memory load on the event-related desynchronization (ERD) and synchronization (ERS) of several narrow EEG frequency bands. METHODS ERD/ERS responses of the 4-6, 6-8, 8-10 and 10-12 Hz EEG frequency bands were studied in 24 normal subjects performing a visual sequential letter task (so-called n-back task) in(More)
The effects of electromagnetic fields (EMF) emitted by cellular phones on the ERD/ERS of the 4-6 Hz, 6-8 Hz, 8-10 Hz and 10-12 Hz EEG frequency bands were studied in 16 normal subjects performing an auditory memory task. All subjects performed the memory task both with and without exposure to a digital 902 MHz EMF in counterbalanced order. The exposure to(More)
PURPOSE To examine the effects of electromagnetic fields (EMF) emitted by cellular phones on the event-related desynchronization/synchronization (ERD/ERS) responses of the 4-6, 6-8, 8-10 and 10-12Hz EEG frequency bands during cognitive processing. MATERIALS AND METHODS Twenty-four subjects performed a visual sequential letter task (n-back task) with three(More)
Interhemispheric processing may either increase or decrease the processing power of the brain. The two experiments presented here examined in normal subjects whether hemispheric interaction would be useful or not in semantic categorization of pictures. It was tested whether the advantages of dividing the processing between the hemispheres would increase(More)