title: Visual cortex activity predicts subjective experience after reading books with colored letters.
abstract: One of the most astonishing properties of synesthesia is that the evoked concurrent experiences are perceptual. Is it possible to acquire similar effects after learning cross-modal associations that resemble synesthetic mappings? In this study, we examine whether brain activation in early visual areas can be directly related to letter-color associations acquired by training. Non-synesthetes read specially prepared books with colored letters for several weeks and were scanned using functional magnetic resonance imaging. If the acquired letter-color associations were visual in nature, then brain activation in visual cortex while viewing the trained black letters (compared to untrained black letters) should predict the strength of the associations, the quality of the color experience, or the vividness of visual mental imagery. Results showed that training-related activation of area V4 was correlated with differences in reported subjective color experience. Trainees who were classified as having stronger 'associator' types of color experiences also had more negative activation for trained compared to untrained achromatic letters in area V4. In contrast, the strength of the acquired associations (measured as the Stroop effect) was not reliably reflected in visual cortex activity. The reported vividness of visual mental imagery was related to veridical color activation in early visual cortex, but not to the acquired color associations. We show for the first time that subjective experience related to a synesthesia-training paradigm was reflected in visual brain activation.
authors.affiliation: Brain and Cognition, Department of Psychology, University of Amsterdam, Weesperplein 4, 1018 XA Amsterdam, The Netherlands. Electronic address: o.colizoli@uva.nl.
authors.forename: Olympia
authors.initials: O
authors.lastname: Colizoli
authors.affiliation: Brain and Cognition, Department of Psychology, University of Amsterdam, Weesperplein 4, 1018 XA Amsterdam, The Netherlands.
authors.forename: Jaap M J
authors.initials: JMJ
authors.lastname: Murre
authors.affiliation: Brain and Cognition, Department of Psychology, University of Amsterdam, Weesperplein 4, 1018 XA Amsterdam, The Netherlands; Amsterdam Brain and Cognition Center, Institute for Interdisciplinary Studies, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: H Steven
authors.initials: HS
authors.lastname: Scholte
authors.affiliation: Cognitive Psychology, Vrije Universiteit, van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: van Es
authors.affiliation: Cognitive Psychology, Vrije Universiteit, van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands.
authors.forename: Tomas
authors.initials: T
authors.lastname: Knapen
authors.affiliation: Brain and Cognition, Department of Psychology, University of Amsterdam, Weesperplein 4, 1018 XA Amsterdam, The Netherlands.
authors.forename: Romke
authors.initials: R
authors.lastname: Rouw
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011932:Reading; D057190:Stroop Test; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult
keywords: Individual differences; Learning; Memory; Mental imagery; Reading; Synesthesia; Training