Abstract
Sensory neural inputs during developmental period from outer world are important for maturation of brain functions. Paying attention to oral sensory system, sensory inputs from teeth and tooth-related organs may also be important for maturation of oral sensory system. Here we investigated whether multiple tooth losses during the developmental period disturb age-dependent appearance of the network oscillation in the neocortex, by applying caffeine to rat brain slices. Electrical stimulation was delivered to the white matter and field potentials were recorded from layer II/III. In control animals, synchronized population oscillation at the frequency of alpha-range appeared during postnatal weeks 2 to 3, and was observed in mature periods in both oral somatosensory cortex and visual cortex. In multiple tooth loss rats, in contrast, the oscillation appeared during postnatal weeks 2 to 3 in the visual cortex, but did not appear in the oral somatosensory cortex even in mature periods. Induction and maintenance of the oscillation were dependent on NMDA receptor activities. Thus, sufficient neural information from the teeth may be important for development of neural activities in the oral somatosensory cortex, suggesting that the brain has the critical period for tooth-related sensory system. [Jpn J Physiol 55 Suppl:S146 (2005)]
