A general mechanism for perceptual decision-making in the

A general mechanism for perceptual decision-making in the human brain Isaeva K. Zhestereva E. Bultseva M. Lysenko A. Vilegzhanina M.

Hypothesis • Comparison of the outputs of different pools of selectively tuned neurons could be a general mechanism by which the human brain computes perceptual decisions.

Studies with monkeys

Shadlen et al. proposed that perceptual decisions are made by integrating the difference in spike rates pools of neurons selectively tuned to different perceptual choices

• Somatosensory task for monkey: which of 2 vibratory stimuli has a higher frequency

• A decision can be formed by subtracing the activities of 2 populations of sensory neurons that prefer low and high frequencies.

“Face/house study”

Theoretical background • Single-unit recordings on monkeys showed that neuronal activity in areas involved in decision-making gradually increases and then remains elevated untill a response is given, with the rate of increase being slower during more difficult trials.

• DLPFC might form a decision by comparing the outputs of pools of selectively tuned lowerlevel sensory neurons.

Hypothesis • 1. Higher-level cortical regions should show the greatest activity in which the evidence for a given perceptual category is the greatest. • 2. Their activity should be correlated with the difference between the output signals of 2 brain regions.

z=-17

• • Greater response for perithreshold: Bromann area Supplementary eye field Inparietal sulcus

For suprathreshold • Region in the depth of the superior frontal sulcus • Posterior portion of DLPFC • Posterior cingulate cortex • Superior frontal gyrus

• The only region fulfilling for both conditions was located in the depth of the left superior frontal sulcus in the posterior portion of the DLPFC