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Posted by
btel
- Last updated: 2004-07-06
| Title |
Article.2004.07.06.16
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| File | ANE-60-247.pdf |
| Short Description |
Beta activity: a carrier for visual attention.
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| Description | The alpha (8-13 Hz), beta (15-25 Hz) and gamma (30-60 Hz) bands of the EEG have been long studied in clinical research because of their putative functional importance. Old experimental results indicated that repetitive stimulation of the visual pathway evoked synchronous responses at the cortical level with gain depending on frequency: oscillations within relevant bands were less damped at subsequent processing levels then others. Our current results show that in the cat, cortico-geniculate feedback has a build-in potentiation mechanism acting at around the beta frequency which activates thalamic cells and may thus lower the threshold for visual information transmission. We have also shown that enhanced beta activity is propagated along this feedback pathway solely during attentive visual behavior. This activity consists of 300 ms to 1 s long bursts which tend to correlate in time with gamma oscillatory events. Beta bursting activity spreads to all investigated visual centers, including the lateral posterior and pulvinar complex and higher cortical areas. Other supporting data on enhanced beta activity during attentive-like behavior of various species including man, are discussed. Finally, we put forward a general hypothesis which attributes the appearance of oscillations within the alpha, beta and gamma bands to different activation states of the visual system. According to this hypothesis, alpha activity characterizes idle arousal of the system, while beta bursts shift the system to an attention state that consequently allows for gamma synchronization and perception. |
| Bibliographic Information | Acta Neurobiol. Exp. 60: 247-260 |
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| Original Release Date |
2004/04/19 20:26:00 GMT+2
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