Article

When Doors of Perception Close: Bottom-up Models of Disrupted Cognition in Schizophrenia

Schizophrenia Research Center, Nathan Kline Institute for Psychiatric Research/New York University School of Medicine, Orangeburg, NY 10962, USA.
Annual Review of Clinical Psychology (Impact Factor: 12.67). 02/2009; 5(1):249-75. DOI: 10.1146/annurev.clinpsy.032408.153502
Source: PubMed

ABSTRACT

Schizophrenia is a major mental disorder that affects approximately 1% of the population worldwide. Cognitive deficits are a key feature of schizophrenia and a primary cause of long-term disability. Current neurophysiological models of schizophrenia focus on distributed brain dysfunction with bottom-up as well as top-down components. Bottom-up deficits in cognitive processing are driven by impairments in basic perceptual processes that localize to primary sensory brain regions. Within the auditory system, deficits are apparent in elemental sensory processing, such as tone matching following brief delay. Such deficits lead to impairments in higher-order processes such as phonological processing and auditory emotion recognition. Within the visual system, deficits are apparent in functioning of the magnocellular visual pathway, leading to higher-order deficits in processes such as perceptual closure, object recognition, and reading. In both auditory and visual systems, patterns of deficit are consistent with underlying impairment of brain N-methyl-d-aspartate receptor systems.

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    • "Stage 1 APS scores that were averaged across a range of auditory stimuli were further associated with executive functioning , whereas APS scores averaged across the entire hour of training (Hour 1 metrics) were also moderately associated with baseline verbal memory. These findings are consistent with previous research demonstrating relationships between auditory perception and performance in complex cognitive domains (Javitt, 2009; Kawakubo et al., 2006; Leitman et al., 2005; Light et al., 2007; Rissling et al., 2014). As evidenced by their moderate-to-strong associations with all cognitive domains, the composite metrics calculated after a full hour of training appear to provide a more robust indicator of auditory perceptual efficiency than do metrics derived from Level 1 or Stage 1. "
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    • "Our study thus provides the first direct evidence for temporally facilitated responses to chromatic and, thus, putatively parvocellularbiased , stimuli. While the neurophysiologic bases for this latency difference as well as for the discrepancies between single-unit and population-based levels of quantification remain to be fully resolved in future research, the present results lay grounds for further investigations of the visual system dynamics and of the 'division of labour' between the two pathways and, thus, for a better understanding of their contribution to visual processing deficits in clinical populations (e.g.,Javitt, 2009). That said, it is important to also note that peak latency and amplitude of VEP components, such as P1 and N1, are strongly influenced by low-level stimulus features, including contrast (e.g.Butler et al., 2007), the number and distribution of pixels within an image (Doniger et al., 2002;Foxe et al., 2001), and stimulus location within the visual field (Clark et al., 1995;Murray et al., 2001). "
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    • "The highlighting of sensorimotor systems is in contrast to the frequent emphasis on dysfunction of executive and highlevel association areas, which intuitively may be more related to cardinal symptoms of the disease. Sensory and motor impairments are nevertheless indicated by multiple lines of research (Butler et al., 2008; Javitt, 2009; Walther and Strik, 2012). Motor cortex, like prefrontal cortex, has lower neuronal density in schizophrenia when measured post-mortem (Benes et al., 1986) and imaging studies have shown alterations in cortical and subcortical motor areas (Dazzan et al., 2004; Honey et al., 2005). "
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