Article

Oscillatory brain activity dissociates between associative stimulus content in a repetition priming task in the human EEG.

Institut für Allgemeine Psychologie, Universität Leipzig, Leipzig, Germany.
Cerebral Cortex (impact factor: 6.54). 02/2005; 15(1):109-16. DOI:10.1093/cercor/bhh113 pp.109-16
Source: PubMed

ABSTRACT The retrieval and formation of cortical object representations seem to require the activation of neuronal cell assemblies, correlated by synchronized neuronal activity in the gamma band range (>20 Hz). In the present electroencephalogram (EEG) study we have analysed induced gamma band activity during the repetition of familiar (meaningful) and unfamiliar (meaningless) line drawings. Results showed a broad posterior distribution of induced gamma band responses (GBRs) after the initial presentation of a familiar stimulus. Repeated presentations of the same picture resulted in a decrease of GBRs, accompanied by a decrease in the number of electrode pairs exhibiting significant phase-locking values. These effects might be linked to a 'sharpening' mechanism within a cell assembly representing a familiar object. In contrast, the re-presentation of primed unfamiliar stimuli was associated with an augmentation of gamma power and an increase in significantly phase-locked pairs of electrodes. These findings might be a signature of the formation of a new cortical network representing an object. Event related potentials (ERPs) showed a decrease in amplitude independent of the stimuli's associative content, and, thus, seem to play a complementary role in repetition priming as compared to high-frequency brain dynamics.

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Keywords

'sharpening' mechanism
 
amplitude independent
 
broad posterior distribution
 
cell assembly
 
electrode pairs
 
electrodes
 
familiar stimulus
 
gamma band range
 
gamma power
 
induced gamma band responses
 
initial presentation
 
meaningful
 
neuronal cell assemblies
 
new cortical network
 
phase-locked pairs
 
Repeated presentations
 
repetition priming
 
significant phase-locking values
 
stimuli's associative content
 
unfamiliar stimuli