[Laminar distribution of excitatory responses to acetylcholine in rat somatic sensory cortex: a microionophoretic study].

The laminar distribution of excitatory responses to iontophoretically applied acetylcholine (ACh) was studied in the first somatic sensory cortex (SI) of the Rat, using extracellular dye deposits for reconstruction of the electrode tracks. Most of the responses were recorded from neurons located in the lower half of the cortex, namely in layers V and VI. ACh sensitive neurons were found in two locations: one encompassing layer V and upper part of VI and the other at the border between cortex and white matter. The functional significance of this distribution is discussed.