Gustatory Cortex - Functionality and Stimulation

Functionality and Stimulation

There have been many studies done to observe the functionality of the primary gustatory cortex and associated structures with various chemical and electrical stimulations as well as observations of patients with lesions and GC epileptic focus. It has been reported that electrical stimulation of the lingual nerve, chorda tympani, and a lingual branch of the glossopharyngeal nerve elicit evoked field potential in the frontal operculum. Electrical stimulation of the insula in the human elicit gustatory sensations. Gustatory information is conveyed to the orbitofrontal cortex, the secondary gustatory cortex from the AI/FO. Studies have shown that 7.9% of neurons in the orbitofrontal cortex respond to taste stimuli, and a part of these neurons are finely tuned to particular taste stimuli. It has also been shown in monkeys that the responses of orbitofrontal neurons to taste decreased when the monkey eats to satiety. Furthermore neurons in the orbitofrontal cortex respond to the visual,and/or olfactory stimuli in addition to the gustatory stimulus. These results suggest that gustatory neurons in the orbitofrontal cortex may play an important role in food identification and selection. A patient study reported that damage in the rostral part of the insula caused gustatory disturbance, as well as taste recognition and intensity deficits in patients with insular cortex lesions. It has also been reported that a patient who had an epileptic focus in the frontal operculum and epileptic activity in the focus produced a disagreeable taste. Activation in the insula also takes place when exposed to gustatory imagery. Studies compared the activated regions in subjects shown food pictures to those shown location pictures and found that food pictures activated the right insula/operculum and the left orbitofrontal cortex.