| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
The regulation of food and fluid intake is primarily vital for animal's survival. So far, the neural mechanisms of the taste-guided motivated behavior have been investigated along the taste pathway. However, it is still unclear which neural systems are responsible for the emotional information processing of taste. In the present research, we have examined the function of the ventral tegmental area, which is the pivot of the mesocorticolimbic dopaminergic projection and the rewarding neural system, and its related structures on the palatability-induced ingestion of taste fluids. Because the pedunculopontine tegmental area, which is one of the cholinergic neural system of the brainstem, is recently considered to be involved in various motivated behaviors, we focused on the nucleus and its afferents and efferents. Behavioral and neuroanatomical experiments yielded the following results. 1) The lesions of the pedunculopontine tegmental nucleus as well as the ventral tegmental area did not
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affect the perceived payability of taste fluids but severely diminished the consumption of normally preferred taste fluids. 2) The neuroanatomical findings of the present study and other investigators support the notion that the inputs from the pedunculopontine tegmental nucleul to the ventral tegmental area facilitate the selective oversonsumption of normally preferred taste fluids. 3) The lesions of the ventral pallidum, which sends efferent fibers to the pedunculopontine tegmental nucleus, disturbed the palatability-induced overconsumption of normally preferred taste fluids, indicating that the ventral pallidum presumably modulate the ventral tegmental area via the pedunculopontine tegmental nucleus. In addition, the electrophysiological experiment indicates that neurons in the parabrachial nucleus, the second taste relay, differentially respond to preferred and aversive taste stimuli. These results suggest that the cholinergic neurons in the brainstem, especially in the pedunculopontine tegmental nucleus, are critically involved in the taste-motivated ingestion of food and fluid. Less
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