Regions of the human brain affected during a liquid-meal taste perception in the fasting state: a positron emission tomography study.

BACKGROUND: The sensation of taste provides reinforcement for eating and is of possible relevance to the clinical problem of obesity.
OBJECTIVE: Positron emission tomography (PET) was used to explore regions of the brain that were preferentially affected during the taste perception of a liquid meal by 11 right-handed, lean men in the fasting state.
DESIGN: After subjects had fasted for 36 h, 2 measurements of regional cerebral blood flow (rCBF) obtained immediately after subjects retained and swallowed 2 mL of a flavored liquid meal (the taste condition) were compared with 2 measurements of rCBF obtained immediately after subjects retained and swallowed 2 mL of water (the baseline condition).
RESULTS: Compared with the baseline condition, taste was associated with increased rCBF (P < 0.005) in the left dorsolateral prefrontal cortex and superior temporal gyrus; the right ventrolateral prefrontal cortex, supramarginal gyrus, and anterior thalamus; and bilaterally in the hippocampal formation, posterior cingulate, midbrain, occipital cortex, and cerebellum. Taste was also associated with decreased rCBF (P < 0.005) in the right dorsolateral prefrontal cortex, superior temporal gyrus, and supplementary motor area, and bilaterally in the medial prefrontal cortex and inferior parietal lobule.
CONCLUSIONS: This exploratory study provides additional evidence that the temporal cortex, thalamus, cingulate cortex, caudate, and hippocampal formation are preferentially affected by taste stimulation. The asymmetric pattern of activity in the dorsolateral prefrontal cortex and superior temporal gyrus may contribute to the taste perception of a liquid meal perceived as pleasant. Additional studies are required to determine how these regions are affected in patients with obesity or anorexia.