bee Flashcards
(25 cards)
What is the aim of the study on neural correlates of perceptual learning?
To understand the neural mechanisms of perceptual learning
What are the learning objectives of the study?
Understand how visual information is represented and read-out in visual cortex, evaluate evidence of changes in representation and read-out due to perceptual learning
At what levels of the cortical visual hierarchy is visual input represented?
Different levels of the cortical visual hierarchy
What is necessary to make a motor or perceptual decision regarding visual input?
The representation of visual input in visual cortex has to be read out or decoded
Which brain areas are involved in decoding neural signals from visual cortex?
Lateral intraparietal (LIP), frontal eye fields (FEF), prefrontal (area 46) cortex
What does a typical neural model of visual discrimination include?
- Visual representation
- Decision unit
- Internal noise
- Weights
How is visual input encoded in visual cortex?
By the pattern of firing across a population of neurons
What does perceptual decision-making involve in terms of neural responses?
Different patterns of responses generated by Direction A and Direction B
What is the role of weights in the readout process?
Assign negative weights to neurons encoding A and positive weights to neurons encoding B
What does specificity of learning for low-level visual characteristics suggest?
Neurons in early visual cortex are malleable or ‘plastic’
Does perceptual learning necessarily change the representation in visual cortex?
No, specificity of perceptual learning does not necessarily indicate changes in representation
What could perceptual learning change in terms of individual neurons?
Responses, preferences, width of tuning functions, or amplitude of response
What was observed in monkeys regarding orientation discrimination performance?
Improvement correlated with changes in the slope of orientation tuning curves at the trained location
Did the learned improvement in monkeys correlate with changes in V1 or V2 tuning curves?
No correlation with bandwidth, amplitude, peak response, or response variability
What changes were observed in V4 neurons after perceptual learning?
Stronger responses and narrower orientation tuning curves at the trained location
How do correlated neuronal responses affect information encoded by neurons?
Responses of neurons with similar tuning preferences are more strongly correlated
What was found regarding correlations between neurons in the medial superior temporal (MST) area?
Correlated responses were significantly weaker in trained animals
Does perceptual learning change the neuronal representation of visual stimuli?
Yes, it changes responses, tuning, and correlated responses, but may not account for behavioral changes
How could perceptual learning optimize the read-out of visual information?
By giving more weight to the neurons providing the most reliable information
What did the study by Law and Gold (2008) investigate?
Whether perceptual learning changes the representation or read-out of visual motion
What changes occurred in LIP neurons during training on visual motion tasks?
Responses grew in strength as performance on the task improved
What effect did training on fine depth discrimination have on MT’s contribution to coarse depth discrimination?
Reversible inactivation of MT devastated performance on coarse depth discrimination
What was the effect of muscimol injection into MT after training on fine depth discrimination?
No effect on coarse or fine depth discrimination, but abolished direction discrimination performance
What do substantive alterations to the read-out explain?
Changes to the perception of visual motion
