Motion Psychophysics Task
Objective: Measure motion perception thresholds in rhesus monkeys using direction discrimination on dynamic random dot displays with varying motion signal intensity
Protocol Steps
Train monkeys on motion psychophysics task
Rhesus monkeys were trained on psychophysical tasks to assess their sensitivity to motion
Note: Training enabled assessment of motion sensitivity
View evidence from paper
“We trained rhesus monkeys on psychophysical tasks that enabled us to assess their sensitivity to motion”
Present dynamic random dot displays
Present dynamic random dot displays with varying intensity of motion signal in the midst of masking motion noise
Note: Motion signal intensity is varied to measure perception thresholds
View evidence from paper
“a dynamic random dot display that permitted us to vary the intensity of a motion signal in the midst of masking motion noise”
Measure motion discrimination threshold
Measure the threshold intensity for which the monkey could successfully complete a direction discrimination task
Note: Threshold is the minimum signal intensity for successful performance
View evidence from paper
“We measured the threshold intensity for which the monkey could successfully complete a direction discrimination”
Perform contrast discrimination task
Measure the threshold contrast for which monkeys could successfully discriminate the orientation of stationary gratings
Note: Contrast task serves as control to assess specificity of motion perception effects
View evidence from paper
“In the contrast task, we measured the threshold contrast for which the monkeys could successfully discriminate the orientation of stationary gratings”
Inject ibotenic acid into MT
Perform chemical lesions of the middle temporal visual area (MT) using ibotenic acid injections
Note: Lesions are used to examine the causal role of MT in motion perception
View evidence from paper
“Injections of ibotenic acid into MT caused striking elevations in motion thresholds”
Reassess motion and contrast thresholds
Measure motion and contrast thresholds again following MT lesions to assess changes in perception
Note: Post-lesion thresholds are compared to baseline to determine MT's role in motion perception
View evidence from paper
“Injections of ibotenic acid into MT caused striking elevations in motion thresholds, but had little or no effect on contrast thresholds”