Spatio-temporal modeling of evoked brain activity during memory encoding and target comparison in visual tasks.
In this paper, the temporal pattern of activity and approximate locations of brain areas related to selective attention and visual working memory processes were studied with event related potential (ERP) recordings in healthy humans. Three experimental series included pairs of the following conditions: Face comparison (familiar faces), Pattern comparison (abstract dot patterns), and Passive viewing. Participants compared pairs of consecutive targets presented in composite images on a computer screen. Spatio-temporal multiple dipole models were developed for 128-channel ERPs. Keeping dipole locations and orientations constant, we compared the source activities for ERPs recorded (1) in different tasks for task-specificity of activations, (2) after the first and second stimuli in the pair, i.e. on the encoding and comparison stages of the task, and (3) after the first stimulus in different series to compare encoding in different conditions. Sources located in the inferotemporal brain areas, especially in the left hemisphere, showed increased activity after 200 ms from the first stimulus onset that may indicate encoding into visual working memory. The anterior sources, located near midline and showing activity around or after 300 ms, presumably reflect non-specific memory processes and attentional control. Major task-specific differences were observed in the temporo-parieto-occipital region in 250-500 ms.
Mnatsakanian
Elena V
EV
Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str, Moscow 117485, Russia. mnazak@aha.ru
Tarkka
Ina M
IM
D000328:Adult; D003627:Data Interpretation, Statistical; D004569:Electroencephalography / Q000706:statistics & numerical data*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D008959:Models, Neurological; D015233:Models, Statistical; D011597:Psychomotor Performance / Q000502:physiology*