Article 1: NMDA receptor antagonist ketamine distorts object recognition by reducing feedback to early visual cortex

Question 1

Relation between mooney and grayscale image

Answer 1

Recognition increases the correlation between the two, making them more similar. This occurrs in V1 too, proving presence of feedback processing.

Question 2

Main results of article about ketamine and object recognition

Answer 2

• Using ketamine decreases feedback
• After session, the subjects were better at mooney identification
• Categorization into animal or not improves

Question 3

Results higher visual cortex (article 1)

Answer 3

• Recognition increased the dissimilarity in high level visual cortex
• Unrecognizable mooney images (M1) look more similar and different neural representations arise after recognition (M2)
• No effect of ketamine

Question 4

Results early visual cortex (article 1)

Answer 4

• Recognition increased the dissimilarity also in V1
• Ketamine abolishes this effect, Mooney 1 and Mooney 2 do not differ

Question 5

Conclusions of article 1

Answer 5

• Recognition changes neural object representations
• Ketamine reduced the effect of mooney recognition specifically in V1
• This suggests that reduction of feedback by ketamine reduced the effect of object recognition in early visual areas
• Unrecognized mooney images all look the same whereas recognized mooneys look different
• Feedforward processing is unaffected by NMDA blocking, feedback processing is affected.