title: Unconscious and conscious processing of color rely on activity in early visual cortex: a TMS study.
abstract: Chromatic information is processed by the visual system both at an unconscious level and at a level that results in conscious perception of color. It remains unclear whether both conscious and unconscious processing of chromatic information depend on activity in the early visual cortex or whether unconscious chromatic processing can also rely on other neural mechanisms. In this study, the contribution of early visual cortex activity to conscious and unconscious chromatic processing was studied using single-pulse TMS in three time windows 40-100 msec after stimulus onset in three conditions: conscious color recognition, forced-choice discrimination of consciously invisible color, and unconscious color priming. We found that conscious perception and both measures of unconscious processing of chromatic information depended on activity in early visual cortex 70-100 msec after stimulus presentation. Unconscious forced-choice discrimination was above chance only when participants reported perceiving some stimulus features (but not color).
authors: Department of Psychology, University of Turku, 20014 Turku, Finland. henry.railo@utu.fi
authors: Henry
authors: H
authors: Railo
authors: Niina
authors: N
authors: Salminen-Vaparanta
authors: Linda
authors: L
authors: Henriksson
authors: Antti
authors: A
authors: Revonsuo
authors: Mika
authors: M
authors: Koivisto
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology*; D003243:Consciousness; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D011930:Reaction Time; D050781:Transcranial Magnetic Stimulation; D014474:Unconsciousness; D014793:Visual Cortex / Q000098:blood supply / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen