Visual sensory processing deficits in Schizophrenia and their relationship to disease state

The Cognitive Neurophysiology Laboratory, St. Vincent's Hospital, Richmond Road, Fairview, Dublin 3, Ireland.
European Archives of Psychiatry and Clinical Neuroscience (Impact Factor: 3.53). 06/2008; 258(5):305-16. DOI: 10.1007/s00406-008-0802-2
Source: PubMed


Visual Evoked Potential (VEP) abnormalities have been a fairly consistent finding in patients with schizophrenia, and it has been suggested that electrophysiological markers of early sensory processing may be useful as trait markers for the illness, and for development as potential diagnostic measures.
Clear amplitude reductions in the occipital P1 component of the VEP (approximately 100 ms), have been repeatedly demonstrated in patients with schizophrenia. Here, we investigated whether the extent of this deficit was related to age, clinical symptoms, medication status and length of illness, in a large cohort of ethnically homogenous patients.
VEP responses to simple isolated-check stimuli were examined in 52 DSM-IV diagnosed patients with schizophrenia, and compared with responses from 26 healthy age-matched control subjects. Using high-density electrical scalp recordings, we assessed the integrity of the visual P1 component across the two groups. This study was conducted at St.Vincent's Psychiatric Hospital in Fairview, Dublin, Ireland.
Substantially reduced P1 amplitude was demonstrated in the patient group compared to controls. The deficit was not linked to age, length of illness or medication status. A small positive correlation, accounting for about 11% of the variance, was found between P1 amplitude and clinical symptoms scales (BPRS and SANS). In addition, we found that a slightly later (~110 ms) fronto-central component was relatively increased in the patient group, and was inversely correlated with the occipital P1 amplitude in the patients, but not in the healthy control subjects.
Our findings clearly demonstrate a deficit in early visual processing in patients with schizophrenia (with a large effect size; Cohen's d = 0.7) that is unrelated to chronicity. The results are consistent with recent findings showing that the P1 deficit is endophenotypic of the disorder and related to genetic risk factors rather than the disease process itself.

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Available from: John J Foxe, Oct 07, 2015
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    • "Auditory adaptation deficits represent potentially powerful biomarkers of schizophrenia as they are also seen in a significant proportion of unaffected first-degree biological relatives of patients (Olincy et al., 2010). In a series of experiments, we have shown that visual-sensory processing deficits are particularly robust in patients with schizophrenia (Foxe et al., 2001, 2005; Doniger et al., 2002; Lalor et al., 2008, 2012; Yeap et al., 2008a), a finding that has been observed across multiple labs (Mukundan, 1986; Spencer et al., 2004; Haenschel et al., 2007). Crucially, these deficits are also seen in first-degree relatives (Yeap et al., 2006), first-episode drug-na€ ıve patients (Yeap et al., 2008b) and in young adults with high schizotypy (Koychev et al., 2010; Bedwell et al., 2013), pointing to their potential utility as risk endophenotypes (Gottesman & Gould, 2003; Magno et al., 2008; Foxe et al., 2011). "
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    ABSTRACT: When sensory inputs are presented serially, response amplitudes to stimulus repetitions generally decrease as a function of presentation rate, diminishing rapidly as inter-stimulus intervals (ISIs) fall below 1 s. This 'adaptation' is believed to represent mechanisms by which sensory systems reduce responsivity to consistent environmental inputs, freeing resources to respond to potentially more relevant inputs. While auditory adaptation functions have been relatively well characterized, considerably less is known about visual adaptation in humans. Here, high-density visual-evoked potentials (VEPs) were recorded while two paradigms were used to interrogate visual adaptation. The first presented stimulus pairs with varying ISIs, comparing VEP amplitude to the second stimulus with that of the first (paired-presentation). The second involved blocks of stimulation (N = 100) at various ISIs and comparison of VEP amplitude between blocks of differing ISIs (block-presentation). Robust VEP modulations were evident as a function of presentation rate in the block-paradigm, with strongest modulations in the 130-150 ms and 160-180 ms visual processing phases. In paired-presentations, with ISIs of just 200-300 ms, an enhancement of VEP was evident when comparing S2 with S1, with no significant effect of presentation rate. Importantly, in block-presentations, adaptation effects were statistically robust at the individual participant level. These data suggest that a more taxing block-presentation paradigm is better suited to engage visual adaptation mechanisms than a paired-presentation design. The increased sensitivity of the visual processing metric obtained in the block-paradigm has implications for the examination of visual processing deficits in clinical populations. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
    European Journal of Neuroscience 02/2015; 41(7). DOI:10.1111/ejn.12849 · 3.18 Impact Factor
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    • "However, P100 deficits have not always been reported in patient studies (13, 61–64), or in schizotypy (25). It is also noteworthy that P100 effects have typically been recorded in response to basic visual stimuli (i.e., isolated gray/white check images and line drawings) (50–52, 65, 66), with only a handful of studies demonstrating P100 deficits to (emotional) face stimuli in patients (49, 67), and in those at risk for psychosis (53). Last, antipsychotic agents have known effects on neural activation (68, 69). "
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    ABSTRACT: Background: Face processing impairment in schizophrenia appears to be underpinned by poor configural (as opposed to feature-based) processing; however, few studies have sought to characterize this impairment electrophysiologically. Given the sensitivity of event-related potentials to antipsychotic medications, and the potential for neurophysiological abnormalities to serve as vulnerability markers for schizophrenia, a handful of studies have investigated early visual P100 and face-selective N170 in “at risk” populations. However, this is the first known neurophysiological investigation of configural face processing in a non-clinical schizotypal sample. Methods: Using stimuli designed to engage configural processing in face perception (upright and inverted Mooney and photographic faces), P100 and N170 components were recorded in healthy individuals characterized by high (N = 14) and low (N = 14) schizotypal traits according to the Oxford–Liverpool Inventory of Feelings and Experiences. Results: High schizotypes showed significantly reduced N170 amplitudes to inverted photographic faces. Typical N170 latency and amplitude inversion effects (delayed and enhanced N170 to inverted relative to upright photographic faces, and enhanced amplitude to upright versus inverted Mooney faces), were demonstrated by low, but not high, schizotypes. No group differences were shown for P100 analyses. Conclusions: The findings suggest that neurophysiological deficits in processing facial configurations (N170) are apparent in schizotypy, while the early sensory processing (P100) of faces appears intact. This work adds to the mounting evidence for analogous neural processing anomalies at the healthy end of the psychosis continuum.
    Frontiers in Psychiatry 08/2014; 5(101). DOI:10.3389/fpsyt.2014.00101
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    • "The hypoactive M-pathway is often inferred from a reduced P1 amplitude, which is a transient VEP component occurring approximately 90e140 ms post-stimulus with multiple generators from both the M-and P-pathways (Di Russo et al., 2002; Vanni et al., 2004). Very few of these studies examined symptom relations, and these have been limited to schizophrenia samples with broad symptom total scores e two reported no relationship between P1 amplitude and broad symptom scales (Obayashi et al., 2009; Schechter et al., 2005), while one showed a counterintuitive weak positive correlation between P1 amplitude and broad positive and negative symptom scales (Yeap et al., 2008a). "
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    ABSTRACT: Research has suggested a hypoactive visual magnocellular (M) pathway in individuals with schizophrenia-spectrum disorders and traits, along with a unique response of this pathway to red light. As these abnormalities only appear in a subset of these samples, they may reflect unknown subtypes with unique etiologies and corresponding neuropathologies. The P1 transient visual-evoked component has been found to be influenced by M-pathway activity; therefore, the current study assessed the P1 component in response to a 64% contrast checker stimulus on white, red, and green background conditions. The sample consisted of 28 undergraduate participants (61% male) who endorsed a continuous range of total scores from the Schizotypal Personality Questionnaire (SPQ). Participants with higher total SPQ scores had a reduced P1 mean amplitude with the white (baseline) background, which was primarily related to the SPQ Magical Thinking subscale score. In addition, while participants with lower total SPQ scores showed the expected reduction in P1 amplitude to the red (vs. green) background, participants with higher total SPQ scores showed no change, which was primarily related to the SPQ Ideas of Reference subscale. This differential change to the red background remained after covarying for the P1 amplitude to the green background, thus representing a relatively independent effect. Further confirmation of these early visual processing relationships to particular clusters of symptoms in related psychiatric samples may assist in revealing unique, currently unknown, subtypes of particular psychiatric disorders such as schizophrenia. This can direct treatment efforts toward more homogeneous neuropathology targets.
    Journal of Psychiatric Research 01/2013; 47(4). DOI:10.1016/j.jpsychires.2012.12.012 · 3.96 Impact Factor
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