Suppression of afferent visual information in a patient with dissociative identity disorder and state-dependent blindness

Abstract

he neural basis of conscious vision is still elusive despite numerous experimental and clinical studies. Here, we present the case of patient BT suffering from Dissociative identity disorder after trauma who had been diagnosed as legally blind by neuro-ophthalmic examination including visual evoked potentials (VEPs). After 15 years of blindness, she regained sight and showed normal VEPs in one of her personality states although VEPs are still absent in a remaining blind state. Retinotopic mapping with functional MRI revealed that V1 and thalamic activity were absent during the blind but normal during the sighted state. Findings suggest that BT responded to her trauma with a blind personality state that was attained by complete suppression of visual input at the thalamic level. This case demonstrates a fundamental ability of the brain to block early visual processing in rapid response to personality changes to prevent conscious visual processing at cortical levels