Frequency of gamma oscillations in humans is modulated by velocity of visual motion.
Gamma oscillations are generated in networks of inhibitory fast-spiking (FS) parvalbumin-positive (PV) interneurons and pyramidal cells. In animals, gamma frequency is modulated by the velocity of visual motion; the effect of velocity has not been evaluated in humans. In this work, we have studied velocity-related modulations of gamma frequency in children using MEG/EEG. We also investigated whether such modulations predict the prominence of the "spatial suppression" effect (Tadin D, Lappin JS, Gilroy LA, Blake R. Nature 424: 312-315, 2003) that is thought to depend on cortical center-surround inhibitory mechanisms. MEG/EEG was recorded in 27 normal boys aged 8-15 yr while they watched high-contrast black-and-white annular gratings drifting with velocities of 1.2, 3.6, and 6.0°/s and performed a simple detection task. The spatial suppression effect was assessed in a separate psychophysical experiment. MEG gamma oscillation frequency increased while power decreased with increasing velocity of visual motion. In EEG, the effects were less reliable. The frequencies of the velocity-specific gamma peaks were 64.9, 74.8, and 87.1 Hz for the slow, medium, and fast motions, respectively. The frequency of the gamma response elicited during slow and medium velocity of visual motion decreased with subject age, whereas the range of gamma frequency modulation by velocity increased with age. The frequency modulation range predicted spatial suppression even after controlling for the effect of age. We suggest that the modulation of the MEG gamma frequency by velocity of visual motion reflects excitability of cortical inhibitory circuits and can be used to investigate their normal and pathological development in the human brain.
The MEG Centre, Moscow State University of Psychology and Education, Moscow, Russia orekhova.elena.v@gmail.com.
Elena V
EV
Orekhova
The MEG Centre, Moscow State University of Psychology and Education, Moscow, Russia.
Anna V
AV
Butorina
The MEG Centre, Moscow State University of Psychology and Education, Moscow, Russia.
Olga V
OV
Sysoeva
The MEG Centre, Moscow State University of Psychology and Education, Moscow, Russia.
Andrey O
AO
Prokofyev
The MEG Centre, Moscow State University of Psychology and Education, Moscow, Russia.
Anastasia Yu
AY
Nikolaeva
The MEG Centre, Moscow State University of Psychology and Education, Moscow, Russia.
Tatiana A
TA
Stroganova
D000293:Adolescent; D000375:Aging / Q000502:physiology; D001921:Brain / Q000254:growth & development / Q000502:physiology*; D002648:Child; D004569:Electroencephalography; D065818:Gamma Rhythm / Q000502:physiology*; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012044:Regression Analysis
electroencephalography; frequency of gamma oscillations; magnetoencephalography; spatial suppression; visual cortex