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EEG findings of reduced neural synchronization during visual integration in schizophrenia.

Wynn JK, Roach BJ, Lee J, Horan WP, Ford JM, Jimenez AM, Green MF - PLoS ONE (2015)

Bottom Line: Compared to controls, patients failed to show increased phase locking to illusory versus no contours between 40-60 Hz.These results suggest that the pattern of results across visual processing conditions is similar in patients and controls.However, patients have deficits in neural synchronization in the gamma range during basic processing of illusory contours when attentional demand is limited.

View Article: PubMed Central - PubMed

Affiliation: Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, United States of America; Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, CA, United States of America.

ABSTRACT
Schizophrenia patients exhibit well-documented visual processing deficits. One area of disruption is visual integration, the ability to form global objects from local elements. However, most studies of visual integration in schizophrenia have been conducted in the context of an active attention task, which may influence the findings. In this study we examined visual integration using electroencephalography (EEG) in a passive task to elucidate neural mechanisms associated with poor visual integration. Forty-six schizophrenia patients and 30 healthy controls had EEG recorded while passively viewing figures comprised of real, illusory, or no contours. We examined visual P100, N100, and P200 event-related potential (ERP) components, as well as neural synchronization in the gamma (30-60 Hz) band assessed by the EEG phase locking factor (PLF). The N100 was significantly larger to illusory vs. no contour, and illusory vs. real contour stimuli while the P200 was larger only to real vs. illusory stimuli; there were no significant interactions with group. Compared to controls, patients failed to show increased phase locking to illusory versus no contours between 40-60 Hz. Also, controls, but not patients, had larger PLF between 30-40 Hz when viewing real vs. illusory contours. Finally, the positive symptom factor of the BPRS was negatively correlated with PLF values between 40-60 Hz to illusory stimuli, and with PLF between 30-40 Hz to real contour stimuli. These results suggest that the pattern of results across visual processing conditions is similar in patients and controls. However, patients have deficits in neural synchronization in the gamma range during basic processing of illusory contours when attentional demand is limited.

No MeSH data available.


Related in: MedlinePlus

Example of stimuli, comprised either real figures (square or diamond) or no figures.Real figures were composed of either real contours (RC) or illusory contours (IC). No figure stimuli contained no contours (NC). A small fixation dot at the center of the stimulus changed from black to red and vice versa periodically.
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pone.0119849.g001: Example of stimuli, comprised either real figures (square or diamond) or no figures.Real figures were composed of either real contours (RC) or illusory contours (IC). No figure stimuli contained no contours (NC). A small fixation dot at the center of the stimulus changed from black to red and vice versa periodically.

Mentions: In healthy samples, visual integration, in particular Gestalt processing, can be examined through the use of illusory contours (IC), known as Kanizsa figures [6] (see Fig. 1). The neural mechanisms of Kanizsa shape perception are well-described in non-clinical animal and human samples. Electroencephalography (EEG) and functional magnetic resonance imaging studies have shown that illusory contour processing is localized to bilateral lateral occipital cortex (LO) [7,8]. However, it has also been demonstrated that recurrent feedback information from LO to V1 and V2 [9] and even from V2 to V1 is also necessary for completion of illusory processing [10].


EEG findings of reduced neural synchronization during visual integration in schizophrenia.

Wynn JK, Roach BJ, Lee J, Horan WP, Ford JM, Jimenez AM, Green MF - PLoS ONE (2015)

Example of stimuli, comprised either real figures (square or diamond) or no figures.Real figures were composed of either real contours (RC) or illusory contours (IC). No figure stimuli contained no contours (NC). A small fixation dot at the center of the stimulus changed from black to red and vice versa periodically.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4364708&req=5

pone.0119849.g001: Example of stimuli, comprised either real figures (square or diamond) or no figures.Real figures were composed of either real contours (RC) or illusory contours (IC). No figure stimuli contained no contours (NC). A small fixation dot at the center of the stimulus changed from black to red and vice versa periodically.
Mentions: In healthy samples, visual integration, in particular Gestalt processing, can be examined through the use of illusory contours (IC), known as Kanizsa figures [6] (see Fig. 1). The neural mechanisms of Kanizsa shape perception are well-described in non-clinical animal and human samples. Electroencephalography (EEG) and functional magnetic resonance imaging studies have shown that illusory contour processing is localized to bilateral lateral occipital cortex (LO) [7,8]. However, it has also been demonstrated that recurrent feedback information from LO to V1 and V2 [9] and even from V2 to V1 is also necessary for completion of illusory processing [10].

Bottom Line: Compared to controls, patients failed to show increased phase locking to illusory versus no contours between 40-60 Hz.These results suggest that the pattern of results across visual processing conditions is similar in patients and controls.However, patients have deficits in neural synchronization in the gamma range during basic processing of illusory contours when attentional demand is limited.

View Article: PubMed Central - PubMed

Affiliation: Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, United States of America; Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, CA, United States of America.

ABSTRACT
Schizophrenia patients exhibit well-documented visual processing deficits. One area of disruption is visual integration, the ability to form global objects from local elements. However, most studies of visual integration in schizophrenia have been conducted in the context of an active attention task, which may influence the findings. In this study we examined visual integration using electroencephalography (EEG) in a passive task to elucidate neural mechanisms associated with poor visual integration. Forty-six schizophrenia patients and 30 healthy controls had EEG recorded while passively viewing figures comprised of real, illusory, or no contours. We examined visual P100, N100, and P200 event-related potential (ERP) components, as well as neural synchronization in the gamma (30-60 Hz) band assessed by the EEG phase locking factor (PLF). The N100 was significantly larger to illusory vs. no contour, and illusory vs. real contour stimuli while the P200 was larger only to real vs. illusory stimuli; there were no significant interactions with group. Compared to controls, patients failed to show increased phase locking to illusory versus no contours between 40-60 Hz. Also, controls, but not patients, had larger PLF between 30-40 Hz when viewing real vs. illusory contours. Finally, the positive symptom factor of the BPRS was negatively correlated with PLF values between 40-60 Hz to illusory stimuli, and with PLF between 30-40 Hz to real contour stimuli. These results suggest that the pattern of results across visual processing conditions is similar in patients and controls. However, patients have deficits in neural synchronization in the gamma range during basic processing of illusory contours when attentional demand is limited.

No MeSH data available.


Related in: MedlinePlus