Journal ArticleDOI
Modulation of Induced Gamma Band Responses in a Perceptual Learning Task in the Human EEG
TLDR
It is concluded that induced GBRs might represent a signature of synchronized neural activity in a Hebbian cell assembly, activated by the fragmented picture after perceptual learning took place.Abstract:
Fragmented pictures of an object, which appear meaningless when seen for the first time, can easily be identified after the presentation of an unfragmented version of the same picture. The neuronal mechanism for such a rapid perceptual learning phenomenon is largely unknown. Recently, induced gamma band responses (GBRs) have been discussed as a possible physiological correlate of activity in cell assemblies formed by learning. The present study was designed to investigate the modulation of induced GBRs in a perceptual learning task by using a 128-channel EEG montage. In the first sequence of the experiment, fragmented pictures from the Snodgrass and Vandervart inventory were presented. The fragmentation of the pictures was selected that subjects were unable to identify them. In the second experimental sequence - the perceptual learning sequence - half of the pictures were displayed in their unfragmented version. In the third sequence, all pictures were presented again in the fragmented version. Now, subjects had to rate whether or not they could identify the images. Results showed an increase in spectral gamma power at parietal electrode sites for identified pictures. In addition, neural activity in the gamma band was highly synchronized between posterior electrodes. For pictures not presented in their complete version, we found no such pattern in the third sequence. From our results, we concluded that induced GBRs might represent a signature of synchronized neural activity in a Hebbian cell assembly, activated by the fragmented picture after perceptual learning took place. No difference between identified and unidentified pictures was found in the visual evoked potential in the same time range and in the evoked GBR in the same frequency range as the induced response.read more
Citations
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Journal ArticleDOI
Cognitive functions of gamma-band activity: memory match and utilization
TL;DR: A new framework is proposed that relates gamma oscillations observed in human, as well as in animal, experiments to two underlying processes: the comparison of memory contents with stimulus-related information and the utilization of signals derived from this comparison.
Journal ArticleDOI
Human EEG gamma oscillations in neuropsychiatric disorders.
TL;DR: A hypothesis of a gamma axis of these disorders mainly based on the significance of gamma oscillations for memory matching is formulated, probably reflecting both cortical excitation and perceptual distortions such as déjà vu phenomena frequently observed in epilepsy.
Journal ArticleDOI
Interneuron Diversity series: Inhibitory interneurons and network oscillations in vitro
TL;DR: This review concentrates on recent in vitro evidence revealing a division of labour among different subclasses of interneurons with respect to the frequency of persistent rhythms, and the crucial dependence on gap-junction-mediated intercellular communication for the generation and maintenance of these rhythms.
Journal ArticleDOI
Attention Modulates Gamma-band Oscillations Differently in the Human Lateral Occipital Cortex and Fusiform Gyrus
TL;DR: It is suggested that the functional role of gamma oscillations depends on the area in which they occur, both in their time-course (preparatory period and/or stimulus processing) and direction of modulation ( increase or decrease).
Journal ArticleDOI
Oscillatory Brain Activity Dissociates between Associative Stimulus Content in a Repetition Priming Task in the Human EEG
Thomas Gruber,Matthias M. Müller +1 more
TL;DR: Event related potentials (ERPs) showed a decrease in amplitude independent of the stimuli's associative content, and seem to play a complementary role in repetition priming as compared to high-frequency brain dynamics.
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