A general mechanism for perceptual decision-making in the human brain

Abstract

Findings from single-cell recording studies suggest that a comparison of the outputs of different pools of selectively tuned lower-level sensory neurons may be a general mechanism by which higher-level brain regions compute perceptual decisions. For example, when monkeys must decide whether a noisy field of dots is moving upward or downward, a decision can be formed by computing the difference in responses between lower-level neurons sensitive to upward motion and those sensitive to downward motion. Here we use functional magnetic resonance imaging and a categorization task in which subjects decide whether an image presented is a face or a house to test whether a similar mechanism is also at work for more complex decisions in the human brain and, if so, where in the brain this computation might be performed. Activity within the left dorsolateral prefrontal cortex is greater during easy decisions than during difficult decisions, covaries with the difference signal between face- and house-selective regions in the ventral temporal cortex, and predicts behavioural performance in the categorization task. These findings show that even for complex object categories, the comparison of the outputs of different pools of selectively tuned neurons could be a general mechanism by which the human brain computes perceptual decisions.

Spatial maps in frontal and prefrontal cortex

“…Response times were also slower for the identity task (0.81 T 0.13 s vs. 0.66 T 0.13 ms., P < 10 À5 , paired t test). A previous study, however, has shown that increased difficulty alone does not increase DLPFC activity (Barch et al, 1997;Heekeren et al, 2004). The increased activity may instead be due to additional working memory load or recruitment of neurons specialized for object working memory.…”

Immediate memory for “when, where and what”: Short‐delay retrieval using dynamic naturalistic material

“…We also assessed the effect of difficulty using the Temporal and Spatial tasks in Exp 2. The contrast “hard > easy” Temporal trials revealed one single activation cluster in the supplementary frontal eye field, which has been associated with difficult decision making [Heekeren et al, 2004]. None of the critical task‐specific regions (Figs 2, 3, 4) was activated by this “hard > easy” comparison.…”

Assessing cognitive dysfunction in Parkinson's disease: An online tool to detect visuo‐perceptual deficits

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