Back to Search
Start Over
Hierarchical equivalence of somatosensory areas I and II for tactile processing in the cerebral cortex of the marmoset monkey.
- Source :
-
Journal of neurophysiology [J Neurophysiol] 2001 May; Vol. 85 (5), pp. 1823-35. - Publication Year :
- 2001
-
Abstract
- Responsiveness of the first somatosensory area (SI) of the cerebral cortex was investigated in the marmoset monkey (Callithrix jacchus) in association with cooling-induced, reversible inactivation of the second somatosensory area, SII. The aim was to determine whether SI responsiveness to peripheral tactile stimulation depends on SII and therefore whether SI and SII in the marmoset occupy hierarchically equivalent positions in a parallel organizational scheme for thalamocortical tactile processing as appears to be the case in nonprimate mammals. Inactivation of SII was achieved when the temperature over SII was lowered to < or =12 degrees C, as indicated by abolition of the SII-evoked potentials generated by brief tap stimuli to the hand or foot, and by abolition of tactile responses in single SII neurons located at the margin beneath the block. The effect of SII inactivation on SI-evoked potentials was examined in 16 experiments by simultaneous recording of the SI- and SII-evoked potentials. SI-evoked potentials were never abolished and remained unaffected in 11 cases. In three experiments there was a small reduction in amplitude and inconsistent effects in the remaining two. Responsiveness to controlled tactile stimuli was examined quantitatively in 31 individual SI neurons of different functional classes before, during, and after the inactivation of SII. Tactile responsiveness in individual SI neurons was never abolished by SII inactivation, remaining unchanged in 20 neurons (65%) while undergoing some reduction in the remaining 11 SI neurons (35%). This reduction of tactile responsiveness in one-third of SI neurons is most likely attributable to a removal of a facilitatory influence emanating from SII, based on the observation that background activity of the affected neurons was also reduced. Furthermore, phase locking of SI responses to vibrotactile stimulation was unchanged when SII was inactivated. The retention of responsiveness in SI neurons when SII was inactivated by cooling in the marmoset demonstrates that tactile inputs can reach SI without traversing an indirect, serially organized path through SII. The present results, together with our previous observations that responsiveness in the majority of SII neurons survived SI inactivation, demonstrate that there is a parallel organization of the SI and SII areas for tactile processing in the marmoset monkey and that SI and SII occupy hierarchically equivalent positions in a parallel processing network. There is therefore no longer justification for the view that there are fundamental differences in the organization of thalamocortical tactile processing for SI and SII between simian primates, in general, and other mammals.
- Subjects :
- Afferent Pathways anatomy & histology
Afferent Pathways physiology
Animals
Callithrix anatomy & histology
Cold Temperature
Evoked Potentials, Somatosensory
Female
Male
Mammals anatomy & histology
Mammals physiology
Models, Neurological
Neurons physiology
Somatosensory Cortex anatomy & histology
Species Specificity
Stress, Mechanical
Ventral Thalamic Nuclei cytology
Ventral Thalamic Nuclei physiology
Vibration
Brain Mapping
Callithrix physiology
Foot innervation
Forearm innervation
Hand innervation
Somatosensory Cortex physiology
Touch physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0022-3077
- Volume :
- 85
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Journal of neurophysiology
- Publication Type :
- Academic Journal
- Accession number :
- 11352999
- Full Text :
- https://doi.org/10.1152/jn.2001.85.5.1823