Magnocellular contributions to impaired motion processing in schizophrenia

Abstract

Patients with schizophrenia show impairments in motion processing, along with deficits in lower level processing primarily involving the magnocellular visual pathway. The present study investigates potential magnocellular contributions to impaired motion processing in schizophrenia using a combined neurophysiological and behavioral approach. As compared to prior motion studies in schizophrenia, thresholds were determined for both incoherent and coherent visual motion. In this study, velocity discrimination thresholds were measured for schizophrenia patients (n = 14) and agematched normal control subjects (n = 16) using a staircase procedure. Early visual processing was evaluated using steady-state visual evoked potentials (ssVEP), with stimuli biased toward activation of either the magnocellular or parvocellular visual pathways through luminance contrast manipulation. Patients with schizophrenia showed poor velocity discrimination for both incoherent and coherent motion, with no significant group × task interaction. Further, when coherent motion performance was measured at individually determined incoherent motion thresholds, accuracy levels for patients were similar to controls, also indicating similarity of deficit for incoherent vs. coherent motion discrimination. Impairments in velocity discrimination correlated significantly with reduced amplitude of ssVEP elicited by magnocellular -but not parvocellular -selective stimuli. This study demonstrates that deficits in motion processing in schizophrenia are significantly related to reduced activation of the magnocellular visual system. Further, this study supports and extends prior reports of impaired motion processing in schizophrenia, and indicates significant bottom-up contributions to higher-order cognitive impairments.

An fMRI study of language processing in people at high genetic risk for schizophrenia

“…Visual processing deficits have been found previously in studies of patients with schizophrenia (e.g. Kim et al, 2006) and in another study related to the genetic vulnerability for developing illness (Green et al, 2006). While our data do not support the latter, it is possible that visual activation differences could implicate visual processing pathways that are relevant to the recognition of language and thus contribute to some of the changes then seen in the processing of words in frontal and temporal lobes.…”

Dissecting the cellular contributions to early visual sensory processing deficits in schizophrenia using the VESPA evoked response

“…In our previous studies, we have consistently posited a magnocellular basis for the observed VEP P1 deficits (e.g. Foxe et al, 2005;Butler et al, 2005Butler et al, , 2007; see also Kim et al, 2005a). The VESPA scalp maps of Fig.…”

Weakened Center-Surround Interactions in Visual Motion Processing in Schizophrenia

“…This result provides additional evidence for the existence of a motion processing deficit in schizophrenia (Stuve et al, 1997;Chen et al, 1999aChen et al, ,b,c, 2003aChen et al, , 2004Chen et al, , 2005Li, 2002;Slaghuis et al, 2005;Kim et al, 2006). More importantly, at high contrast, schizophrenic patients exhibit reduced centersurround suppression.…”