Neurocognitive Dysfunction in Schizophrenia Attention/Vigilance - PowerPoint PPT Presentation

Neurocognitive Dysfunction in Schizophrenia Attention/Vigilance Immediate Memory Secondary Memory Verbal Fluency, Learning Spatial Working Memory Motor Reaction Time Processing Speed Executive Functions Visual-motor Skills

Early Visual Processing Deficits in Schizophrenia: Evidence for Sensory Dysfunction

Perceptual/Sensory Dysfunction in Schizophrenia: Visual System • Abnormal Smooth Pursuit Eye Movements • ↓ Amplitude of ssVEPs to magnocellular-biased stimuli, but not parvocellular-biased stimuli • ↑ Sensitivity to Backward Masking • Impaired Motion Perception • Impaired Spatial Localization • Impaired Detection of Simple Visual Stimuli • Impaired Stereopsis (binocular depth perception) • ↑ Visual Thresholds

Sensory Dysfunction in Early Visual Processing • Eye tracking dysfunction ↓ Acceleration (open loop gain)/delayed initiation Impaired Motion Perception - ↑ velocity discrimination thresholds ↑ Velocity discrimination thresholds correlated with ↓ pursuit acceleration

Sensory Dysfunction in Early Visual Processing • Eye tracking dysfunction ↓ Acceleration (open loop gain)/ delayed initiation Impaired Motion Perception - ↑ velocity discrimination thresholds ↑ Velocity discrimination thresholds correlated with ↓ pursuit acceleration

Sensory Dysfunction in Early Visual Processing • Eye tracking dysfunction ↓ Acceleration (open loop gain)/ delayed initiation Impaired Motion Perception - ↑ velocity discrimination thresholds ↑ Velocity Discrimination Threshold ( ↓ contrast sensitivity) correlated with ↓ pursuit acceleration

Chen et al, 2006

Sensory Dysfunction in Early Visual Processing • ↓ Amplitude of ssVEPs to magnocellular-biased stimuli - - but not to parvocellular-biased stimuli

Butler et al, 2001

Sensory Dysfunction in Early Visual Processing ↓ Amplitude of ssVEPs to magnocellular-biased stimuli correlates with velocity discrimination thresholds Not true for parvocellular-biased stimuli

Kim et al, 2006

Butler et al, 2005

Increased Sensitivity to Backward Masking -- Persistence of Masking Effect

Green et al. 1994

Perceptual/Sensory Dysfunction in Schizophrenia: Magnocellular Input to Dorsal Stream • ↑ Sensitivity to Backward Masking • Impaired Motion Perception • ↓ Acceleration (open loop gain) • ↓ ssVEP Amplitude

References Butler, P.D. et al. Dysfunction in early-stage visual processing in schizophrenia. Am J Psychiatry, 2001; 158:1126-1133. Butler, P.D. et al. Early-stage visual processing and cortical amplification deficits in schizophrenia. Arch Gen Psychiatry, 2005; 62: 495-504. Chen, Y. et al. Psychophysical isolation of a motion processing deficit in schizophrenics and their relatives and its association with impaired smooth pursuit. Proc Nat'l Acad Sci, 1999; 96: 4724-4729. Green, M.F. et al. Backward masking in schizophrenia and mania: I. Specifying a mechanism . Arch Gen Psychiatry, 1994; 51: 939-944. Holzman, P.S. and D.L. Levy, Eye tracking dysfunction and mental illness . Encyclopedia of Neuroscience, ed. G. Adelman and B. Smith. 2003: Elsevier. (CD ROM and Book). Kim, D. et al. Dysfunction in early-stage visual processing in schizophrenia: harmonic analysis. Schiz Res, 2005. 76 : p. 55-65. Kim, D. et al. Magnocellular contributions to impaired motion processing in schizophrenia. Schiz Res, 2006. 82 : p. 1-8. Levy, D.L. et al. Eye tracking dysfunction and schizophrenia: A critical perspective. Schiz Bull, 1993. 19 : p. 461-536. Schechter, I. et al A new dimension of sensory dysfunction: Stereopsis deficits in schizophrenia. Biol Psychiatry, 2006; on-line.