Eye closure in darkness animates sensory systems.
Single subject and group analyses (n = 12) showed that the eyes-open and eyes-closed states in complete darkness considerably and consistently differ in the patterns of associated brain activation in fMRI. During nonchanging external stimulation, ocular motor and attentional systems were activated when the eyes were open; the visual, somatosensory, vestibular, and auditory systems were activated when the eyes were closed. These data suggest that there are two different states of mental activity: with the eyes closed, an "interoceptive" state characterized by imagination and multisensory activity and with the eyes open, an "exteroceptive" state characterized by attention and ocular motor activity. Our study also shows that the chosen baseline condition may have a considerable impact on activation patterns and on the interpretation of brain activation studies.
Marx
Esther
E
Center for Sensorimotor Research, Department of Neurology, Ludwig-Maximilians University, 81377 Munich, Germany. emarx@nefo.med.uni-muenchen.de
Stephan
Thomas
T
Nolte
Annina
A
Deutschländer
Angela
A
Seelos
Klaus C
KC
Dieterich
Marianne
M
Brandt
Thomas
T
D000328:Adult; D001931:Brain Mapping; D003624:Darkness; D004584:Electronystagmography; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009799:Ocular Physiological Phenomena; D010100:Oxygen / Q000097:blood; D013003:Somatosensory Cortex / Q000502:physiology*
D010100:Oxygen