Abstract
Somatosensory and chemical information from the oral cavity is important for feeding behavior. Recently, we proposed that interactions of neural information between gustatory insular (GI) cortex and oral somatosensory (OS) cortex of rats are strengthened age-dependently, suggesting that somatosensory and chemical information is liable to be integrated in adult age than in young age. In the present study, we focused attention on the roles of neural information from the teeth for the development of the reciprocal interaction between GI and OS cortices. All teeth of upper jaw were extracted at 2-3 weeks old, and raised with fluid feeding. Control animals were raised with normal feeding. Brain slices containing both GI and OS cortices were made at 6-8 weeks old, and optical recordings with voltage sensitive dye and field potential recordings were made. In control animals, signals elicited by electrical stimulation propagated along upper layer between GI and OS cortices, and the propagation was reciprocal. The horizontal propagation was dependent on intracellular ryanodine-sensitive calcium release. In animals with losses of teeth, in contrast, signal propagation was restricted within GI or OS cortex. These results suggest that multiple losses of teeth disturbed development of signal interaction between GI and OS cortices. Sufficient neural information from the teeth may be important for development of neocortical function. [Jpn J Physiol 54 Suppl:S162 (2004)]
