M72. Cortical Plasticity in Schizophrenia: Associations With Cognition and Community Functioning

Background: Long-term potentiation (LTP) is a basic synaptic mechanism underlying cortical plasticity (ie, malleability of neural organization in response to experience or brain injury). Abnormalities in LTP are hypothesized to underlie cognitive impairment in schizophrenia. However, because it was not possible to evaluate human LTP-like plasticity in vivo until recently, the extent to which it is impacted in schizophrenia is unclear. Furthermore, little is known about the real-world consequences of abnormal LTP-like plasticity for individuals with schizophrenia. Here, we examine associations between a newly-developed EEG paradigm that permits noninvasive assessment of LTP-like plasticity in the visual cortex, with measures of learning and memory and community functioning in schizophrenia. Methods: Thirty people with schizophrenia and 19 healthy comparison subjects completed an EEG assessment. Visual evoked potentials (VEP) were recorded in response to a line grating stimulus before and after high-frequency stimulation (ie, line grating flashed at 8.9 Hz). In addition, participants with schizophrenia completed a cognitive assessment (MATRICS Consensus Cognitive Battery; MCCB) and a measure of community functioning (Role Functioning Scale). Results: There was a nonsignificant tendency for reduced plasticity of VEP following high frequency stimulation in schizophrenia ( F (1,47) = 2.650, P = .110); amplitude of the N1b VEP component was increased following high frequency stimulation in healthy comparison subjects ( t (18) = 2.577, P = .019), but not in the schizophrenia group ( t (29) = 1.396, P = .173). Within the schizophrenia group, increased plasticity of the N1b VEP was associated with better MCCB Visual Learning performance ( r = .367, P = .046), and better community functioning ( r = .487, P = .006). An indirect effect between visual plasticity and community functioning, through visual learning, was statistically significant (indirect effect β = .141, P = .049). Conclusion: These data suggest that LTP-like plasticity of the visual cortex may be diminished in schizophrenia, and LTP-like plasticity is associated with important cognitive and functional outcomes in this clinical population. In schizophrenia, the relationship between cortical plasticity and community functioning is partially mediated by cognition. Funding support: This research was supported by a VA Desert Pacific VISN 22 Mental Illness Research, Education, and Clinical Center Pala