Sensory perception during sleep in humans: a magnetoencephalograhic study.
We reported the changes of brain responses during sleep following auditory, visual, somatosensory and painful somatosensory stimulation by using magnetoencephalography (MEG). Surprisingly, very large changes were found under all conditions, although the changes in each were not the same. However, there are some common findings. Short-latency components, reflecting the primary cortical activities generated in the primary sensory cortex for each stimulus kind, show no significant change, or are slightly prolonged in latency and decreased in amplitude. These findings indicate that the neuronal activities in the primary sensory cortex are not affected or are only slightly inhibited during sleep. By contrast, middle- and long-latency components, probably reflecting secondary activities, are much affected during sleep. Since the dipole location is changed (auditory stimulation), unchanged (somatosensory stimulation) or vague (visual stimulation) between the state of being awake and asleep, different regions responsible for such changes of activity may be one explanation, although the activated regions are very close to each other. The enhancement of activities probably indicates two possibilities, an increase in the activity of excitatory systems during sleep, or a decrease in the activity of some inhibitory systems, which are active in the awake state. We have no evidence to support either, but we prefer the latter, since it is difficult to consider why neuronal activities would be increased during sleep.
Kakigi
Ryusuke
R
Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan. kakigi@nips.ac.jp
Naka
Daisuke
D
Okusa
Tomohiro
T
Wang
Xiohong
X
Inui
Koji
K
Qiu
Yunhai
Y
Tran
Tuan Diep
TD
Miki
Kensaku
K
Tamura
Yohei
Y
Nguyen
Thi Binh
TB
Watanabe
Shoko
S
Hoshiyama
Minoru
M
D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*