title: Cortical area inducing chewing-like rhythmical jaw movements and its connections with thalamic nuclei in guinea pigs.
abstract: Repetitive electrical stimulation to the cortical masticatory areas (CMA) evokes rhythmical jaw movements (RJM), whose patterns vary depending on the stimulation site, in various species. In guinea pigs, although alternating bilateral jaw movements are usually seen during natural chewing, it is still unclear which cortical areas are responsible for chewing-like RJM. To address this issue, we first defined the cortical areas inducing chewing-like RJM by intracortical microstimulation. Stimulation of the most lateral area of the CMA, the granular cortex, induced chewing-like RJM, but from the region medial to this area, simple vertical RJM were induced. Subsequently, to reveal the properties of these two areas in the CMA, the connections between the CMA and the dorsal thalamus were examined by neuronal tract-tracing techniques. The area inducing chewing-like RJM possessed strong reciprocal connections, mainly with the medial part of the ventral posteromedial nucleus, which is the sensory-relay thalamus. On the other hand, the simple vertical RJM-inducing area had reciprocal connections with the motor thalamus. The present study suggests that the CMA inducing chewing-like RJM is different from the CMA inducing simple vertical RJM, and plays a role in cortically induced chewing-like RJM under the influence of the sensory thalamus in guinea pigs.
authors.affiliation: Division of Oral Maxillofacial Biology, Institute for Oral Science, Matsumoto Dental University, 1780 Gobara, Hirooka, Shiojiri, Nagano 399-0781, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Isogai
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kato
authors.forename: Masaichiro
authors.initials: M
authors.lastname: Fujimoto
authors.forename: Shoko
authors.initials: S
authors.lastname: Toi
authors.forename: Ayaka
authors.initials: A
authors.lastname: Oka
authors.forename: Tadafumi
authors.initials: T
authors.lastname: Adachi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Maeda
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Morimoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshida
authors.forename: Yuji
authors.initials: Y
authors.lastname: Masuda
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000033:anatomy & histology*; D006168:Guinea Pigs; D007568:Jaw / Q000294:innervation*; D008297:Male; D008409:Mastication / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology*; D013787:Thalamic Nuclei / Q000033:anatomy & histology*