Comparison of psychophysical, electrophysiological, and fMRI assessment of visual contrast responses in patients with schizophrenia

Abstract

Perception has been identified by the NIMH-sponsored Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) group as a useful domain for assessing cognitive deficits in patients with schizophrenia. Specific measures of contrast gain derived from recordings of steady-state visual evoked potentials (ssVEP) have demonstrated neural deficits within the visual pathways of patients with schizophrenia. Psychophysical measures of contrast sensitivity have also shown functional loss in these patients. In the current study, functional magnetic resonance imaging (fMRI) was used in conjunction with ssVEP and contrast sensitivity testing to elucidate the neural underpinnings of these deficits. During fMRI scanning, participants viewed 1) the same low and higher spatial frequency stimuli used in the psychophysical contrast sensitivity task, at both individual detection threshold contrast and at a high contrast; and 2) the same stimuli used in the ssVEP paradigm, which were designed to be biased toward either the magnocellular or parvocellular visual pathway. Patients showed significant impairment in contrast sensitivity at both spatial frequencies in the psychophysical task, but showed reduced occipital activation volume for low, but not higher, spatial frequency at the low and high contrasts tested in the magnet. As expected, patients exhibited selective deficits under the magnocellular-biased ssVEP condition. However, occipital lobe fMRI responses demonstrated the same general pattern for magnocellular- and parvocellular-biased stimuli across groups. These results indicate dissociation between the fMRI measures and the psychophysical/ssVEP measures. These latter measures appear to have greater value for the functional assessment of the contrast deficits explored here.

A systematic review comparing sex differences in cognitive function in schizophrenia and in rodent models for schizophrenia, implications for improved therapeutic strategies

“…Interestingly when we compared untreated male and female rats' visual recognition memory in the NOR test at increasing inter-trial intervals, males performed considerably worse than females (Calderone et al, 2013). When we compared their performance in a spatial version of the task males did better than females, supporting the translational nature of these tasks in rodents.…”

Functional hierarchy underlies preferential connectivity disturbances in schizophrenia

“…However, studies examining SCZ repeatedly implicate disturbances across distributed cortical territories, including primary visual (62,63) and auditory circuits (64)(65)(66). Therefore, there exists a tension between findings implicating focal disruptions within higher-order association cortices (2, 3, 9, 31) and cellular-level hypotheses, suggesting widespread synaptic alterations, supported by pharmacological and preclinical studies (20,62). We combined computational modeling and clinical neuroimaging in an attempt to link levels of analysis, from a hypothesized widespread cellular-level neuropathology in SCZ (20,21) to preferential neural network disruption identified via neuroimaging.…”

Schizophrenia and visual backward masking: a general deficit of target enhancement

“…For example, schizophrenic patients show strong deficits in the detection of low contrast stimuli (Slaghuis, 1998, 2004; Kéri et al, 2004; Calderone et al, 2013). It remains an open question whether these visual deficits are restricted to patients with negative symptoms (e.g., Slaghuis, 1998) and to certain stimuli, such as low spatial frequency gratings (Kéri et al, 2004).…”