The indirect corticopontine pathway relays perioral sensory signals to the cerebellum via the mesodiencephalic junction

Reika Kubo; Takayuki Yoshida; Kenji Yamaoka; Kouichi Hashimoto

doi:10.1016/j.isci.2023.107301

The indirect corticopontine pathway relays perioral sensory signals to the cerebellum via the mesodiencephalic junction

iScience. 2023 Jul 11;26(8):107301. doi: 10.1016/j.isci.2023.107301. eCollection 2023 Aug 18.

Authors

Reika Kubo¹, Takayuki Yoshida¹, Kenji Yamaoka¹, Kouichi Hashimoto¹

Affiliation

¹ Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.

Abstract

In the cerebro-cerebellar loop, outputs from the cerebral cortex are thought to be transmitted via monosynaptic corticopontine gray (PG) pathways and subsequently relayed to the cerebellum. However, it is unclear whether this pathway is used constitutively for cerebro-cerebellar transduction. We examined perioral sensory pathways by unit recording from Purkinje cells in ketamine/xylazine-anesthetized mice. Infraorbital nerve stimulations enhanced simple spikes (SSs) with short and long latencies (first and second peaks), followed by SS inhibition. The second peak and SS inhibition were suppressed by muscimol (a GABA_A agonist) injections into not only the PG but also the mesodiencephalic junction (MDJ). The pathway from the secondary somatosensory area (SII) to the MDJ, but not the cortico-PG pathway, transmitted the second peak signals. SS inhibition was processed in the SII and primary motor area. Thus, the indirect cortico-PG pathway, via the MDJ, is recruited for perioral sensory transduction.

Keywords: Neuroscience; Sensory neuroscience.