Convergence of input from tongue and palate to the parabrachial nucleus neurons of rats.

Receptive fields (RFs) in the oral cavity were examined for 24 taste and 20 mechanoreceptive neurons in the parabrachial nucleus (PB) of anesthetized rats. All of the units studied had an RF on the ipsilateral half of the oral cavity. About half of the units in each category had at least two separate RFs. Most of the 'taste neurons', i.e. units receiving taste inputs, were activated by mechanical stimulation and some of them had a complex RF, e.g. separated into two parts, one on the tongue for taste and one on the palate for mechanical stimulation. The present findings show that the afferent inputs of two modalities from the tongue and palate converge on the PB neurons.