Biomedical subjects

Allison N McCoy

Publications and source records attributed to Allison N McCoy.

3 recordsLinked to original sources

PubMed2005

Risk-sensitive neurons in macaque posterior cingulate cortex.

People and animals often demonstrate strong attraction or aversion to options with uncertain or risky rewards, yet the neural substrate of subjective risk preferences has rarely been investigated. Here we show that monkeys systematically preferred the risky target in a visual gambling task in which they chose between two targets offering the same mean reward but differing in reward uncertainty. Neuronal activity in posterior cingulate cortex (CGp), a brain area linked to visual orienting and reward processing, increased when monkeys made risky choices and scaled with the degree of risk. CGp activation was better predicted by the subjective salience of a chosen target than by its actual value. These data suggest that CGp signals the subjective preferences that guide visual orienting.

Action Potentials↗

PubMed2004

Expectations and outcomes: decision-making in the primate brain.

Success in a constantly changing environment requires that decision-making strategies be updated as reward contingencies change. How this is accomplished by the nervous system has, until recently, remained a profound mystery. New studies coupling economic theory with neurophysiological techniques have revealed the explicit representation of behavioral value. Specifically, when fluid reinforcement is paired with visually-guided eye movements, neurons in parietal cortex, prefrontal cortex, the basal ganglia, and superior colliculus-all nodes in a network linking visual stimulation with the generation of oculomotor behavior-encode the expected value of targets lying within their response fields. Other brain areas have been implicated in the processing of reward-related information in the abstract: midbrain dopaminergic neurons, for instance, signal an error in reward prediction. Still other brain areas link information about reward to the selection and performance of specific actions in order for behavior to adapt to changing environmental exigencies. Neurons in posterior cingulate cortex have been shown to carry signals related to both reward outcomes and oculomotor behavior, suggesting that they participate in updating estimates of orienting value.

Action Potentials↗

PubMed2003

Saccade reward signals in posterior cingulate cortex.

Movement selection depends on the outcome of prior behavior. Posterior cingulate cortex (CGp) is strongly connected with both limbic and oculomotor circuitry, and CGp neurons respond following saccades, suggesting a role in signaling the motivational outcome of gaze shifts. To test this hypothesis, single CGp neurons were studied in monkeys while they shifted gaze to visual targets for liquid rewards that varied in size or were delivered probabilistically. CGp neurons responded following saccades as well as following reward delivery, and these responses were correlated with reward size. CGp neurons also responded following the omission of predicted rewards. The timing of CGp activation and its modulation by reward could provide signals useful for updating representations of expected saccade value.

Animals↗