Neuronal firing rate, inter-neuron correlation and synchrony in area MT are correlated with directional
choices during stimulus and reward expectation
A.Thiele & K.-P. Hoffmann
Exp.Brain Res. 188:559-577, 2008
- Sensation, memories, and predictions contribute to choices in everyday life, and their relative impact should
change with task constraints. To investigate how the impact from sensory cortex on decision making varies with
task constraints we trained macaque monkeys in a direction discrimination task where they could maximize reward
by waiting for sensory visual information early in a trial, while focusing on memory and reward prediction as a
trial progressed. The task constraints caused animals to indicate decisions in complete absence of visual motion
stimuli (stimulus independent decisions), as 25% of the trials were 'no stimulus' trials. On 'no stimulus' trials
reward delivery depended on the current decision in relation to the decision history. Stimulus independent decisions
occurred during an epoch when a stimulus could in principle have been presented, or afterwards when stimuli could
not occur anymore. Stimulus independent decisions were significantly different during these two periods. Reward
exploitation was more efficient late in the trial, but it was not associated with systematic activity changes in
directionally selective neurons in area MT. Conversely, systematic changes of neuronal activity and firing rate
correlation in directionally selective middle temporal area (MT) neurons were restricted to a short time period
before early decisions. Changing task constraints in the course of a single trial thus determines how neurons in
sensory areas contribute to decision making.
|
