T19_Decision Making

The experimenter controls the duration of the monkey

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: nential distribution. The experimenter controls the duration of The monkey can respond whenever he is ready Response time: behavior The monkey decides to view for longer (and has a lower percent correct) when the sensory evidence is more uncertain Information is not collected for a fixed time but for a time that depends on how difficult the task is Also suggests an “evidence accumulator” Neurons Dot discrimination in LIP: reaction time task The monkey can respond whenever he is ready Just as a reference, this is how MT responds .... MT “receptive field” Just as a reference, this is how MT responds .... MT “receptive field” After a non-selective “onset”, MT cells maintain a steady firing rate that reflects motion strength and direction Neurons Dot discrimination in LIP: reaction time task First, map the response field B rea (LIP) as ips tal sulcus lcus Temporal sulcus ulcus 15 spikes/s k513 Motion Spikes/s Target flash Sac 50 0 1s D RT (msec) Weʼll only talk about the LIP neurons with “memory” activity during the Choose target in RF delayed saccade task Neurons Dot discrimination in LIP: reaction time task The monkey can respond whenever he is ready LIP responses when the dots are on (and the monkey is accumulating evidence) Tin Solid lines Tout Dotted lines Average of 54 neurons LIP responses when the dots are on (and the monkey is accumulating evidence) Tin Solid lines Tout Dotted lines Average of 54 neurons Firing rate ramps with time (like an “accumulator”) Tin Solid lines Tout Dotted lines Average of 54 neurons Firing rate ramps with time (like an “accumulator”) Tin Solid lines Tout Firing ramps up for Tin decisions and down for Tout decisions Dotted lines Average of 54 neurons Firing rate ramps with time (like an “accumulator”) Tin Solid lines Tout Firing ramps up for Tin decisions and down for Tout decisions Dotted lines Average of 54 neurons Ramps are steeper (faster) when there is more evidence Tin Align on time that the saccade happened Tout Average of 54 neurons Tin Align on time that the saccade happened Firing rates all drop at the same out T peak (“bound”) Average of 54 neurons Summary: LIP during dot discrimination Behavioral evidence suggests that monkeys accumulate evidence over time The responses of MT neurons reflect the dot direction and dot strength (sensory information) and are “steady” as long as the stimulus is on The responses of LIP neurons ramp with time to a criterion firi...
View Full Document

Ask a homework question - tutors are online