Figure 2.

Ventral pallidum hotspot neurons encode the incentive salience of cues and hedonic value of rewards. (Top) Neurons fire little to a learned cue predicting an unpalatable salt taste, but fire in a phasic burst when the cue gains incentive value after sodium depletion and salt-appetite (raster and histogram traces show an example neuron recorded during baseline homeostasis and another neuron recorded after salt depletion firing in response to the salt cue at time zero) [182]. This dynamic computation integrates prior learned associations and physiological state to update incentive salience ‘on-the-fly’ and prior to ever re-experiencing the predicted taste. (Bottom) Normally, the unpalatable salt taste evokes ‘disliking’ reactions (e.g. oral gaping) and evokes little ventral pallidum firing, but after sodium depletion the same taste evokes ‘liking’ reactions (e.g. tongue protrusions) and bursts of ventral pallidal excitatory firing to compute magnified hedonic impact [180].