Size matters
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Size matters : effects of stimulus size, duration and eccentricity on the visual gamma-band response. / Busch, Niko A; Debener, Stefan; Kranczioch, Cornelia; Engel, Andreas K; Herrmann, Christoph S.
In: CLIN NEUROPHYSIOL, Vol. 115, No. 8, 01.08.2004, p. 1810-20.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Size matters
T2 - effects of stimulus size, duration and eccentricity on the visual gamma-band response
AU - Busch, Niko A
AU - Debener, Stefan
AU - Kranczioch, Cornelia
AU - Engel, Andreas K
AU - Herrmann, Christoph S
PY - 2004/8/1
Y1 - 2004/8/1
N2 - OBJECTIVE: The effects of stimulus size, duration and eccentricity on the visual gamma-band response (GBR) in human EEG were investigated and compared to visual evoked potentials (VEPs) in order to differentiate in future (and past) experiments whether changes in GBRs are due to stimulus-related (exogenous) or cognitive effects.METHODS: EEG was recorded from 23 subjects while they performed a simple choice reaction time task requiring discrimination of squares and circles. In separate blocks stimulus size, duration, and eccentricity were manipulated. EEG was recorded from 64 electrodes. A wavelet transform based on Morlet wavelets was employed for the analysis of gamma-band activity.RESULTS: Amplitude of the GBR was diminished for small and peripheral stimuli. With short stimulus durations ON and OFF responses of the GBR merged into one peak. In comparison, VEP amplitudes were less susceptible to stimulus features. In contrast to VEP latencies, however, GBR latency did not show a lateralization for eccentric stimuli.CONCLUSIONS: In addition to previous experiments which have shown a modulation of the GBR by various cognitive processes, the present results demonstrate the susceptibility of the GBR in human EEG to exogenous factors, as numerous intracortical recordings in non-human primates have shown before. The results suggest that the human GBR resides in early visual areas.SIGNIFICANCE: The demonstration of the susceptibility of the GBR to stimulus properties implies that studies aimed at exploring the involvement of the GBR in information processing have to be designed carefully. It also constrains the localization of the human GBR.
AB - OBJECTIVE: The effects of stimulus size, duration and eccentricity on the visual gamma-band response (GBR) in human EEG were investigated and compared to visual evoked potentials (VEPs) in order to differentiate in future (and past) experiments whether changes in GBRs are due to stimulus-related (exogenous) or cognitive effects.METHODS: EEG was recorded from 23 subjects while they performed a simple choice reaction time task requiring discrimination of squares and circles. In separate blocks stimulus size, duration, and eccentricity were manipulated. EEG was recorded from 64 electrodes. A wavelet transform based on Morlet wavelets was employed for the analysis of gamma-band activity.RESULTS: Amplitude of the GBR was diminished for small and peripheral stimuli. With short stimulus durations ON and OFF responses of the GBR merged into one peak. In comparison, VEP amplitudes were less susceptible to stimulus features. In contrast to VEP latencies, however, GBR latency did not show a lateralization for eccentric stimuli.CONCLUSIONS: In addition to previous experiments which have shown a modulation of the GBR by various cognitive processes, the present results demonstrate the susceptibility of the GBR in human EEG to exogenous factors, as numerous intracortical recordings in non-human primates have shown before. The results suggest that the human GBR resides in early visual areas.SIGNIFICANCE: The demonstration of the susceptibility of the GBR to stimulus properties implies that studies aimed at exploring the involvement of the GBR in information processing have to be designed carefully. It also constrains the localization of the human GBR.
KW - Adult
KW - Analysis of Variance
KW - Electric Stimulation
KW - Electroencephalography
KW - Evoked Potentials, Visual
KW - Female
KW - Humans
KW - Male
KW - Photic Stimulation
KW - Reaction Time
KW - Time Factors
U2 - 10.1016/j.clinph.2004.03.015
DO - 10.1016/j.clinph.2004.03.015
M3 - SCORING: Journal article
C2 - 15261860
VL - 115
SP - 1810
EP - 1820
JO - CLIN NEUROPHYSIOL
JF - CLIN NEUROPHYSIOL
SN - 1388-2457
IS - 8
ER -