To verify our hypothesis on complex regulatory functions of pallidal glucose-sensitive (GS) cells, extracellular single neuron activity was recorded in the globus pallidus (GP) rhesus monkeys during: (1) microelectrophoretic administration of chemicals (glucose, glutamate, catecholamines, Ach, GABA, etc.), (2) gustatory and (3) olfactory stimulations. The overall proportion of GS neurons was 17% in the primate GP. Gustatory and olfactory units (14% and 7%, respectively) formed a well localized population of pallidal neurons in the ventralmedial region of the structure. The GS cells proved to be especially very likely to change in firing rate in response to tastes and smells: more than two-thirds of the chemosensitive neurons responded to exogenous chemosensory stimuli. While displaying heterogeneous activity changes to microiontophoretically applied neurotransmitters in general, the GS taste- and smellresponsive cells showed distinct dopamine and norepinephrine sensitivities compared to the glucose-insensitive, non-chemosensory units. Our present findings, along with previous data from the lateral hypothalamic area and amygdaloid body, demonstrate a substantial overlap of the central gustatory representations and the hierarchically organized glucose-monitoring neural network. Constituents of these complex systems, the chemosensitive neurons, appear to possess integrative roles in the central feeding control.
ASJC Scopus subject areas
- Nutrition and Dietetics