When a large combat unit, widely dispersed in dense jungle, goes to battle, no single soldier knows precisely how his actions are affecting the unit’s success or failure. But in modern armies, every soldier is connected via an audio link that can instantly receive broadcasts — reporting both positive and negative surprises — based on new intelligence. The real-time broadcasts enable dispersed troops to learn from these reports and can be critical since no solider has an overview of the entire unit’s situation.

Similarly, as neuroscientists at Cold Spring Harbor Laboratory (CSHL) have just discovered, there are a set of dedicated neurons in the basal forebrain that broadcast a message throughout the cerebral cortex, rapidly informing multiple distributed subregions of any surprising rewards or punishments — what scientists call reinforcers.

The neurons in question are cholinergic, and the team, led by Associate Professor Adam Kepecs, has succeeded in recording their activity for the first time in behaving animals (mice).

Cholinergic neurons form one of the brain’s several neuromodulatory systems — they send signals in the form of the neurotransmitter acetylcholine to broad swaths of the brain. Although they have been thought to play an important role in arousal, attention and learning, their precise role in behavior has remained mysterious — in part, because of the technical difficulty in recording from them in vivo. Degeneration and loss of cholinergic neurons in the basal forebrain has been implicated in Alzheimer’s disease, age-related cognitive decline, and other cognitive disorders and dementias.

In a…

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