TY - JOUR
T1 - Bilateral receptive field neurons in the hindlimb region of the postcentral somatosensory cortex in awake macaque monkeys
AU - Taoka, M.
AU - Toda, T.
AU - Iriki, A.
AU - Tanaka, M.
AU - Iwamura, Y.
N1 - Funding Information:
Acknowledgements This research was supported by the Ministry of Education, Science and Culture of Japan and by the JSPS (Japan Society for the Promotion of Science) Research for the Future program.
PY - 2000
Y1 - 2000
N2 - Single-neuron activities were recorded in the hindlimb region of the primary somatosensory cortex and part of area 5 in awake Japanese monkeys. A total of 1050 units were isolated from five hemispheres of four animals. Receptive fields (RFs) and submodalities were identified for 90% of isolated neurons in areas 3a and 3b. The percentage decreased as the recoding site moved to the more caudal areas. Deep or skin submodality neurons were dominant in area 3a or area 3b, respectively. Deep submodality neurons increased in more caudal areas and were the majority in areas 2 and 5. These observations were consistent with those in the hand and/or digit or arm and/or trunk region. The identified neurons were classified by their RF positions into four types: the foot, leg, foot and leg, or hindlimb and other body parts type. Among 831 identified neurons, 33 neurons had bilateral RFs, 14 had ipsilateral RFs, and the rest (N = 784) had contralateral RFs. The relative incidence of neurons with bilateral or ipsilateral RFs among identified neurons was less than 1% in areas 3a, 3b, and 1, and 16% or 25% in areas 2 or 5, respectively. Within areas 2 and 5, the percentage of neurons with bilateral or ipsilateral RFs was significantly smaller in the foot type (5%) than in other RF types (24-57%). RFs of the foot type were on the sole or single toe but never on multiple toes. These observations contrasted with the previous findings that neurons with bilateral RFs were more frequently seen in the hand and/or digit region and that RFs on multiple digit tips were dominant there. The present study thus demonstrated that neurons with bilateral RFs do exist in the hindlimb region. Similarly to the forelimb region, they were found mostly in areas 2 and 5, the caudalmost areas of the postcentral gyrus and hierarchically higher stages in information processing. The relative paucity of neurons with bilateral RFs on the foot, especially those with RFs on multiple toes, may reflect functional differences between the foot and the hand.
AB - Single-neuron activities were recorded in the hindlimb region of the primary somatosensory cortex and part of area 5 in awake Japanese monkeys. A total of 1050 units were isolated from five hemispheres of four animals. Receptive fields (RFs) and submodalities were identified for 90% of isolated neurons in areas 3a and 3b. The percentage decreased as the recoding site moved to the more caudal areas. Deep or skin submodality neurons were dominant in area 3a or area 3b, respectively. Deep submodality neurons increased in more caudal areas and were the majority in areas 2 and 5. These observations were consistent with those in the hand and/or digit or arm and/or trunk region. The identified neurons were classified by their RF positions into four types: the foot, leg, foot and leg, or hindlimb and other body parts type. Among 831 identified neurons, 33 neurons had bilateral RFs, 14 had ipsilateral RFs, and the rest (N = 784) had contralateral RFs. The relative incidence of neurons with bilateral or ipsilateral RFs among identified neurons was less than 1% in areas 3a, 3b, and 1, and 16% or 25% in areas 2 or 5, respectively. Within areas 2 and 5, the percentage of neurons with bilateral or ipsilateral RFs was significantly smaller in the foot type (5%) than in other RF types (24-57%). RFs of the foot type were on the sole or single toe but never on multiple toes. These observations contrasted with the previous findings that neurons with bilateral RFs were more frequently seen in the hand and/or digit region and that RFs on multiple digit tips were dominant there. The present study thus demonstrated that neurons with bilateral RFs do exist in the hindlimb region. Similarly to the forelimb region, they were found mostly in areas 2 and 5, the caudalmost areas of the postcentral gyrus and hierarchically higher stages in information processing. The relative paucity of neurons with bilateral RFs on the foot, especially those with RFs on multiple toes, may reflect functional differences between the foot and the hand.
KW - Awake monkeys
KW - Bilateral receptive field
KW - Foot
KW - Hierarchical information processing
KW - Hindlimb
KW - Postcentral gyrus
UR - http://www.scopus.com/inward/record.url?scp=0033811295&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033811295&partnerID=8YFLogxK
U2 - 10.1007/s002210000464
DO - 10.1007/s002210000464
M3 - Article
C2 - 11037280
AN - SCOPUS:0033811295
VL - 134
SP - 139
EP - 146
JO - Experimental Brain Research
JF - Experimental Brain Research
SN - 0014-4819
IS - 2
ER -