TY - JOUR
T1 - Functional roles of descending projections from the cerebral cortex to the trigeminal spinal subnucleus caudalis in orofacial nociceptive information processing
AU - Kobayashi, Masayuki
AU - Nakaya, Yuka
AU - Kobayashi, Satomi
N1 - Publisher Copyright:
© 2024
PY - 2024/6
Y1 - 2024/6
N2 - Background: The trigeminal spinal subnucleus caudalis (Sp5C), also known as the medullary dorsal horn, receives orofacial somatosensory inputs, particularly nociceptive inputs, from the trigeminal nerve. In the Sp5C, excitatory and inhibitory neurons, glutamatergic and GABAergic/glycinergic neurons, respectively, form the local circuits. The axons of the glutamatergic neurons in lamina I ascend toward the thalamic and parabrachial nuclei, and this projection is the main pathway of orofacial nociception. Additionally, the axons of the higher brain regions, including the locus coeruleus, dorsal raphe, and cerebral cortex, are sent to the Sp5C. Highlight: Among these descending projections, this review focuses on the functional profiles of the corticotrigeminal projections to the Sp5C, along with their anatomical aspects. The primary and secondary somatosensory and insular cortices are of particular interest. Conclusion: Corticotrigeminal projections from the somatosensory cortex to the Sp5C play a suppressive role in nociceptive information processing, whereas recent studies have demonstrated a facilitative role of the insular cortex in nociceptive information processing at the Sp5C level.
AB - Background: The trigeminal spinal subnucleus caudalis (Sp5C), also known as the medullary dorsal horn, receives orofacial somatosensory inputs, particularly nociceptive inputs, from the trigeminal nerve. In the Sp5C, excitatory and inhibitory neurons, glutamatergic and GABAergic/glycinergic neurons, respectively, form the local circuits. The axons of the glutamatergic neurons in lamina I ascend toward the thalamic and parabrachial nuclei, and this projection is the main pathway of orofacial nociception. Additionally, the axons of the higher brain regions, including the locus coeruleus, dorsal raphe, and cerebral cortex, are sent to the Sp5C. Highlight: Among these descending projections, this review focuses on the functional profiles of the corticotrigeminal projections to the Sp5C, along with their anatomical aspects. The primary and secondary somatosensory and insular cortices are of particular interest. Conclusion: Corticotrigeminal projections from the somatosensory cortex to the Sp5C play a suppressive role in nociceptive information processing, whereas recent studies have demonstrated a facilitative role of the insular cortex in nociceptive information processing at the Sp5C level.
KW - Insular cortex
KW - Optogenetics
KW - Pain
KW - Somatosensory cortex
UR - http://www.scopus.com/inward/record.url?scp=85194141358&partnerID=8YFLogxK
U2 - 10.1016/j.job.2024.05.004
DO - 10.1016/j.job.2024.05.004
M3 - Review article
C2 - 38734177
AN - SCOPUS:85194141358
SN - 1349-0079
VL - 66
SP - 304
EP - 307
JO - Journal of Oral Biosciences
JF - Journal of Oral Biosciences
IS - 2
ER -