RT Journal Article
SR Electronic
T1 Optical Imaging of SI Topography in Anesthetized and Awake Squirrel Monkeys
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 7648
OP 7659
DO 10.1523/JNEUROSCI.1990-05.2005
VO 25
IS 33
A1 Li Min Chen
A1 Robert Mark Friedman
A1 Anna Wang Roe
YR 2005
UL http://www.jneurosci.org/content/25/33/7648.abstract
AB Orderly topographic maps in the primary somatosensory cortex (SI) serve as an anchor for our understanding of somatosensory cortical organization. However, this view is mostly based on data collected in the anesthetized animal. Less is known about these topographies in the awake primate. Even less is known about the relative activations of different subdivisions of SI (areas 3a, 3b, 1, and 2). Toward the goal of understanding the functional activation of SI, we conducted intrinsic signal optical imaging of areas 3b and 1 in awake squirrel monkeys. Monkeys were imaged repeatedly for a period of >2 years in awake and anesthetized states in response to vibrotactile and electrocutaneous stimuli presented to individual fingerpads. During this period, we found stable somatotopic maps in both the anesthetized and awake states, consistent with electrophysiologically recorded maps in areas 3b and 1 in the anesthetized state. In the awake animal, signal sizes were larger, but variability was greater, leading to decreased signal-to-noise ratios. Topographic activations were larger (in both area and amplitude) in the awake animal, suggesting either a less precise topography and/or more complex integration. This brings into question the role of a precise topographic map during behavior. In addition, whereas in the anesthetized animal strongest imaging signals were obtained from area 3b, in the awake animal, area 1 activation dominated over that in area 3b. Differences in relative dominance of area 3b versus area 1 suggest that inter-areal interactions in the alert animal differ substantially from that in the anesthetized animal.