Differential innervation within a transverse plane of spinal gray matter by sensorimotor cortices,with special reference to the somatosensory cortices |
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Authors: | Hiroshi Kameda Naoyuki Murabe Kaoru Odagaki Hiroaki Mizukami Keiya Ozawa Masaki Sakurai |
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Institution: | 1. Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan;2. Division of Genetic Therapeutics, Jichi Medical University, Tochigi, Japan;3. Division of Genetic Therapeutics, Jichi Medical University, Tochigi, Japan
Division of Genetic Therapeutics, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan |
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Abstract: | The corticospinal (CS) neurons projecting to the cervical cord distribute not only in motor-related cortical areas, but also in somatosensory areas, including the primary somatosensory cortex (S1). The exact functions of these widely distributed CS neurons are largely unknown, however. In this study, we injected mice with adeno-associated virus encoding membrane-binding fluorescent proteins to investigate the distribution of axons from CS neurons in different regions within a broad cortical area. We found that CS axons from the primary motor cortex (M1), the rostral part of S1 (S1r), and the caudal part of S1 (S1c) differentially project to specific compartments within the spinal gray matter of the seventh cervical cord segment: (a) M1 projects mainly to intermediate and ventral areas, (b) S1r to the mediodorsal area, and (c) S1c to the dorsolateral area. We also found that the projection from S1r, which corresponds to the forelimb area, largely overlaps the cutaneous afferent terminals from the forepaw (hand) in the dorsal horn, and we detected a similar relation between S1c and the trunk. Our findings suggest the existence of considerably fine somatotopic compartments within the dorsal horn that process somatosensation and descending information, which is provided mainly by S1 CS neurons and contribute to delicate control of sensory information in generation of movement. |
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Keywords: | adeno-associated virus cervical cord cholera toxin subunit B primary afferent RRID:AB_10013220 RRID:AB_10013483 RRID:AB_141637 RRID:AB_2301751 RRID:AB_2336881 RRID:AB_2340398 RRID:AB_2534120 RRID:AB_2535792 RRID:AB_591819 RRID:SCR_000325 RRID:SCR_001905 RRID:SCR_003070 RRID:SCR_007370 RRID:SCR_014312 RRID:SCR_016137 sensorimotor integration |
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