Now? Later? Brain cells help us make the call

We all prefer receiving large rewards right away, but we typically must choose between small, quick payoffs and bigger ones that occur later. Neuroscientists have determined that a brain region called the basal ganglia is crucial in helping us evaluate the size and timing of such incentives.

As reported in the January 13 issue of Neuron, a team led by Daeyeol Lee, Ph.D., associate professor of neurobiology and psychology, determined which basal ganglia structures govern these choices. Lee and colleagues recorded the activity of neurons in the caudate nucleus and ventral striatum of the basal ganglia in monkeys that shifted their gaze toward different patterns on a computer screen to receive either a tiny amount of apple juice delivered instantly or a larger quantity provided seconds later. The team found that the caudate nucleus contributed more to these judgments than did the ventral striatum. Neurons in the caudate seemed to compare the values of the treats based on their delay and magnitude, revealing a new role of this brain region in decision-making.

The work may help to explain psychiatric conditions characterized by a bias toward immediate gratification. “We don’t know the anatomical basis of . . . problem gambling or impulsive behavior,” Lee says. “Now we are starting to pinpoint those areas, even down to individual neurons.”