title: Cortical and subcortical contributions to state- and strength-based perceptual judgments.
abstract: Perceptual judgments can be made on the basis of different kinds of information: state-based access to specific details that differentiate two similar images, or strength-based assessments of relational match/mismatch. We explored state- and strength-based perception in eleven right-hemisphere stroke patients, and examined lesion overlap images to gain insight into the neural underpinnings of these different kinds of perceptual judgments. Patients and healthy controls were presented with pairs of scenes that were either identical or differed in that one scene was slightly expanded or contracted relative to the other. Same/different confidence judgments were used to plot receiver-operating characteristics and estimate the contributions of state- and strength-based perception. The patient group showed a significant and selective impairment of strength-based, but not state-based, perception. This finding was not an artifact of reduced levels of overall performance, because matching perceptual discriminability levels between controls and patients revealed a double dissociation, with higher state-based, and lower strength-based, perception in patients vs.
  
  
  
  We then conducted exploratory follow-up analyses on the patient group, based on the observation of substantial individual differences in state-based perception - differences that were masked in analyses based on the group mean. Patients who were relatively spared in state-based perception (but impaired in strength-based perception) had damage that was primarily in temporo-parietal cortical regions. Patients who were relatively impaired in both state- and strength-based perception had overlapping damage in the thalamus, putamen, and adjacent white matter. These patient groups were not different in any other measure, e.g., presence of spatial neglect symptoms, age, education, lesion volume, or time since stroke. These findings shed light on the different roles of right hemisphere regions in high-level perception, suggesting that the thalamus and basal ganglia play a critical role in state- and strength-based perception, whereas temporo-parietal cortical regions are important for intact strength-based perception.
authors.affiliation: Department of Psychology, University of California, Davis, Davis, CA 95616, United States. Electronic address: aly@princeton.edu.
authors.forename: Mariam
authors.initials: M
authors.lastname: Aly
authors.affiliation: Department of Psychology: Cognition and Behavior, University of Liège, Liège B-4000, Belgium.
authors.forename: Murielle
authors.initials: M
authors.lastname: Wansard
authors.affiliation: Cyclotron Research Centre, University of Liège, Liège B-4000, Belgium.
authors.forename: Fermín
authors.initials: F
authors.lastname: Segovia
authors.affiliation: Department of Psychology, University of California, Davis, Davis, CA 95616, United States.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Yonelinas
authors.affiliation: Cyclotron Research Centre, University of Liège, Liège B-4000, Belgium.
authors.forename: Christine
authors.initials: C
authors.lastname: Bastin
mesh_terms: D000368:Aged; D001479:Basal Ganglia / Q000000981:diagnostic imaging / Q000502:physiology*; D002545:Brain Ischemia / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D002543:Cerebral Hemorrhage / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000502:physiology*; D010468:Perceptual Disorders / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D013028:Space Perception / Q000502:physiology*; D020521:Stroke / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology; D013788:Thalamus / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D014796:Visual Perception / Q000502:physiology*
keywords: Basal ganglia; Change detection; Parietal cortex; Scene perception; Spatial neglect; State-based perception; Strength-based perception; Thalamus