title: Brain correlates of experience-dependent changes in stimulus discrimination based on the amount and schedule of exposure.
abstract: One product of simple exposure to similar visual stimuli is that they become easier to distinguish. The early visual cortex and other brain areas (such as the prefrontal cortex) have been implicated in such perceptual learning effects, but the anatomical specificity within visual cortex and the relationship between sensory cortex and other brain areas has yet to be examined. Moreover, while variations in the schedule (rather than merely the amount) of exposure influence experience-dependent improvement in discrimination, the neural sequelae of exposure schedule have not been fully investigated. In an event-related fMRI study, participants were exposed to confusable pairs of faces, scenes and dot patterns, using either intermixed or blocked presentation schedules. Participants then performed same/different judgements with exposed and novel pairs of stimuli. Stimulus independent activation, which was correlated with experience-dependent improvement in discrimination, was seen in frontal areas (e.g. frontal and supplementary eye fields and dorsolateral prefrontal cortex) and in early visual cortex (V1-4). In all regions, the difference in activation between exposed and novel stimuli decreased as a function of the degree of discrimination improvement. Overall levels of BOLD activation differed across regions, consistent with the possibility that, as a consequence of experience, processing shifts from initial engagement of early visual regions to higher order visual areas. Similar relationships were observed when contrasting intermixed with blocked exposure, suggesting that the schedule of exposure primarily influences the degree of, rather than the mechanisms for, discrimination performance.
authors: Wales Institute of Cognitive Neuroscience (WICN), School of Psychology, Cardiff University, Cardiff, United Kingdom; Monash University, School of Psychological Sciences, Melbourne, Victoria, Australia.
authors: Matthew E
authors: ME
authors: Mundy
authors: Wales Institute of Cognitive Neuroscience (WICN), School of Psychology, Bangor University, Gwynedd, United Kingdom.
authors: Paul E
authors: PE
authors: Downing
authors: School of Psychology, Cardiff University, Cardiff, United Kingdom.
authors: Robert C
authors: RC
authors: Honey
authors: Cardiff University Brain Imaging Research Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom.
authors: Krish D
authors: KD
authors: Singh
authors: Wales Institute of Cognitive Neuroscience (WICN), School of Psychology, Cardiff University, Cardiff, United Kingdom.
authors: Kim S
authors: KS
authors: Graham
authors: School of Psychology, Cardiff University, Cardiff, United Kingdom; School of Psychology, University of New South Wales, Sydney, New South Wales, Australia.
authors: Dominic M
authors: DM
authors: Dwyer
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004193:Discrimination Learning; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception; D055815:Young Adult