1999 Volume 43 Issue 3 Pages 538-550
Single neuronal activities responded to low-threshold mechanical stimulation (stimulus intensity:<0.05 N) of the tooth (PDN) were intracellularly recorded from the primary somatosensory cortex (SI) in the cat anesthetized with α-chloralose and halothane. After identification of their response characteristics, neurobiotin was injected iontophoretically and morphological features of neurons were accurately analyzed.
PDNs responded to low-threshold mechanical stimulation (<0.05 N) of the tooth and received dominantly periodontal afferent without input from other intraoral structures. Most of them received periodontal input from the ipsilateral side and showed directional selectivity to mechanical stimulation.
Most PDNs intracellulary stained were classified as pyramidal neurons according to their morphological properties (13 Pyramidal and 1 non-pyramidal PDNs). Each pyramidal PDN had different morphological features. Mainly, axons of lamina III PDNs ran through relatively superficial regions of the subcortical white matter, whereas those of lamina V ran deep into the subcortical areas. The results suggested that lamina III pyramidal PDNs send periodontal sensory information to the other cortical regions and lamina V pyramidal PDNs send them to the far regions of the CNS such as the medulla and spinal cord.
