Separate circuitries encode the hedonic and nutritional values of sugar

Area of Science:

• Neuroscience
• Neurobiology of Feeding
• Reward System

Background:

• Sugar's reinforcing effects are mediated by both taste (hedonic) and post-ingestive (nutritional) signals.
• The specific brain networks engaged by these distinct sugar pathways remain largely uncharacterized.

Purpose of the Study:

• To investigate whether sweetness and nutritional signals activate segregated brain circuits to motivate sugar ingestion.
• To elucidate the role of dopamine signaling within the basal ganglia in mediating the hedonic and nutritional aspects of sugar reward.

Main Methods:

• Utilized mouse models to investigate the neural circuitry underlying sugar motivation.
• Employed techniques including dopamine level monitoring, cell-specific ablation, and optogenetics in distinct striatal regions (ventral and dorsal).
• Assessed the impact of manipulating specific neural pathways on the motivation to ingest unpalatable solutions.

Main Results:

• Separate basal ganglia circuitries were identified for the hedonic and nutritional actions of sugar.
• Suppression of hedonic value affected dopamine release in the ventral striatum, while suppression of nutritional value affected the dorsal striatum.
• Selective ablation or stimulation of dopamine-excitable cells in the dorsal striatum, but not the ventral striatum, altered the motivation for sugar intake, prioritizing energy over taste.

Conclusions:

• Sugar engages a distributed dopamine-excitable striatal circuitry.
• Distinct pathways within the striatum mediate the hedonic and nutritional value of sugar.
• This circuitry prioritizes energy-seeking behavior over sensory (taste) quality.