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Stronger Neural Modulation by Visual Motion Intensity in Autism Spectrum Disorders.

Peiker I, Schneider TR, Milne E, Schöttle D, Vogeley K, Münchau A, Schunke O, Siegel M, Engel AK, David N - PLoS ONE (2015)

Bottom Line: A polynomial regression analysis revealed that gamma-band power increased significantly stronger with motion coherence in ASD compared to controls, suggesting excessive visual activation with increasing stimulus intensity originating from motion-responsive visual areas V3, V6 and hMT/V5.Enhanced neural responses with increasing stimulus intensity suggest an enhanced response gain in ASD.Thus, our data suggest that a disturbed excitatory-inhibitory balance underlies enhanced neural responses to coherent motion in ASD.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

ABSTRACT
Theories of autism spectrum disorders (ASD) have focused on altered perceptual integration of sensory features as a possible core deficit. Yet, there is little understanding of the neuronal processing of elementary sensory features in ASD. For typically developed individuals, we previously established a direct link between frequency-specific neural activity and the intensity of a specific sensory feature: Gamma-band activity in the visual cortex increased approximately linearly with the strength of visual motion. Using magnetoencephalography (MEG), we investigated whether in individuals with ASD neural activity reflect the coherence, and thus intensity, of visual motion in a similar fashion. Thirteen adult participants with ASD and 14 control participants performed a motion direction discrimination task with increasing levels of motion coherence. A polynomial regression analysis revealed that gamma-band power increased significantly stronger with motion coherence in ASD compared to controls, suggesting excessive visual activation with increasing stimulus intensity originating from motion-responsive visual areas V3, V6 and hMT/V5. Enhanced neural responses with increasing stimulus intensity suggest an enhanced response gain in ASD. Response gain is controlled by excitatory-inhibitory interactions, which also drive high-frequency oscillations in the gamma-band. Thus, our data suggest that a disturbed excitatory-inhibitory balance underlies enhanced neural responses to coherent motion in ASD.

No MeSH data available.


Related in: MedlinePlus

Experimental design and psychophysics.(A) Motion discrimination task. Trials started with the onset of a central fixation dot. After 500 ms, the motion stimulus was presented for 750 ms in a circular aperture. Motion coherence across stimuli ranged from 0% to 100% with either upward or downward motion direction. Following a fixed delay period, the fixation dot was extinguished and a question mark prompted the participants to report the perceived motion direction (left button = “upwards”, right button = “downwards). Participants were given a brief visual feedback (green = “correct”; red = “incorrect”). The trial ended with a blank inter-trial interval (ITI). (B) Curves represent the group-average logistic function fitted to the average motion detection performance of the control (gray solid lines) and ASD (black dashed lines) group. (C) Bar graphs illustrate the mean motion coherence thresholds (MCTs; i.e., coherence level at which 75% of motion discriminations were correct) for each group, assessed on the basis of logistic functions fitted to the individual data. Error bars represent the standard error of the mean.
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pone.0132531.g001: Experimental design and psychophysics.(A) Motion discrimination task. Trials started with the onset of a central fixation dot. After 500 ms, the motion stimulus was presented for 750 ms in a circular aperture. Motion coherence across stimuli ranged from 0% to 100% with either upward or downward motion direction. Following a fixed delay period, the fixation dot was extinguished and a question mark prompted the participants to report the perceived motion direction (left button = “upwards”, right button = “downwards). Participants were given a brief visual feedback (green = “correct”; red = “incorrect”). The trial ended with a blank inter-trial interval (ITI). (B) Curves represent the group-average logistic function fitted to the average motion detection performance of the control (gray solid lines) and ASD (black dashed lines) group. (C) Bar graphs illustrate the mean motion coherence thresholds (MCTs; i.e., coherence level at which 75% of motion discriminations were correct) for each group, assessed on the basis of logistic functions fitted to the individual data. Error bars represent the standard error of the mean.

Mentions: Global motion perception in ASD was tested with a coarse visual motion direction discrimination task. Each motion stimulus consisted of a weighted average of a signal and a noise component. Both components consisted of normally distributed and spatiotemporally bandpass-filtered luminance noise. The mean of the luminance noise distribution was identical to the luminance of the uniform background gray. The complete black-white dynamic range of the employed video projector was spanned by +/-3 standard deviations of the luminance distribution in each stimulus. The luminance noise was spatiotemporally bandpass-filtered by multiplication in the frequency domain such that each stimulus frame contained spatial frequencies of 1.33–2.66 cycles/deg and that the frame sequence contained motion speeds of 2.4–3.0 deg/s. Each signal component consisted of only upward or downward motion. Each noise component consisted of motion in all directions. The motion coherence of each individual stimulus was set by adjusting the ratio of a signal and noise component, with 0% and 100% motion coherence corresponding to only the noise or signal component, respectively. Stimuli were presented centrally in a circular aperture (diameter: 27 deg). The stimulus was masked with the background color around the fixation dot (dot diameter 0.36 deg, mask diameter 3 deg), to rule out any stimulus interactions with the central fixation dot and to encourage monitoring of the entire stimulus field (see Fig 1A for a schematic stimulus display). Stimuli were constructed off-line using MATLAB (MathWorks Inc., Natick, MA) and presented with the software “Presentation” (Neurobehavioral systems, Albany, CA).


Stronger Neural Modulation by Visual Motion Intensity in Autism Spectrum Disorders.

Peiker I, Schneider TR, Milne E, Schöttle D, Vogeley K, Münchau A, Schunke O, Siegel M, Engel AK, David N - PLoS ONE (2015)

Experimental design and psychophysics.(A) Motion discrimination task. Trials started with the onset of a central fixation dot. After 500 ms, the motion stimulus was presented for 750 ms in a circular aperture. Motion coherence across stimuli ranged from 0% to 100% with either upward or downward motion direction. Following a fixed delay period, the fixation dot was extinguished and a question mark prompted the participants to report the perceived motion direction (left button = “upwards”, right button = “downwards). Participants were given a brief visual feedback (green = “correct”; red = “incorrect”). The trial ended with a blank inter-trial interval (ITI). (B) Curves represent the group-average logistic function fitted to the average motion detection performance of the control (gray solid lines) and ASD (black dashed lines) group. (C) Bar graphs illustrate the mean motion coherence thresholds (MCTs; i.e., coherence level at which 75% of motion discriminations were correct) for each group, assessed on the basis of logistic functions fitted to the individual data. Error bars represent the standard error of the mean.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4492621&req=5

pone.0132531.g001: Experimental design and psychophysics.(A) Motion discrimination task. Trials started with the onset of a central fixation dot. After 500 ms, the motion stimulus was presented for 750 ms in a circular aperture. Motion coherence across stimuli ranged from 0% to 100% with either upward or downward motion direction. Following a fixed delay period, the fixation dot was extinguished and a question mark prompted the participants to report the perceived motion direction (left button = “upwards”, right button = “downwards). Participants were given a brief visual feedback (green = “correct”; red = “incorrect”). The trial ended with a blank inter-trial interval (ITI). (B) Curves represent the group-average logistic function fitted to the average motion detection performance of the control (gray solid lines) and ASD (black dashed lines) group. (C) Bar graphs illustrate the mean motion coherence thresholds (MCTs; i.e., coherence level at which 75% of motion discriminations were correct) for each group, assessed on the basis of logistic functions fitted to the individual data. Error bars represent the standard error of the mean.
Mentions: Global motion perception in ASD was tested with a coarse visual motion direction discrimination task. Each motion stimulus consisted of a weighted average of a signal and a noise component. Both components consisted of normally distributed and spatiotemporally bandpass-filtered luminance noise. The mean of the luminance noise distribution was identical to the luminance of the uniform background gray. The complete black-white dynamic range of the employed video projector was spanned by +/-3 standard deviations of the luminance distribution in each stimulus. The luminance noise was spatiotemporally bandpass-filtered by multiplication in the frequency domain such that each stimulus frame contained spatial frequencies of 1.33–2.66 cycles/deg and that the frame sequence contained motion speeds of 2.4–3.0 deg/s. Each signal component consisted of only upward or downward motion. Each noise component consisted of motion in all directions. The motion coherence of each individual stimulus was set by adjusting the ratio of a signal and noise component, with 0% and 100% motion coherence corresponding to only the noise or signal component, respectively. Stimuli were presented centrally in a circular aperture (diameter: 27 deg). The stimulus was masked with the background color around the fixation dot (dot diameter 0.36 deg, mask diameter 3 deg), to rule out any stimulus interactions with the central fixation dot and to encourage monitoring of the entire stimulus field (see Fig 1A for a schematic stimulus display). Stimuli were constructed off-line using MATLAB (MathWorks Inc., Natick, MA) and presented with the software “Presentation” (Neurobehavioral systems, Albany, CA).

Bottom Line: A polynomial regression analysis revealed that gamma-band power increased significantly stronger with motion coherence in ASD compared to controls, suggesting excessive visual activation with increasing stimulus intensity originating from motion-responsive visual areas V3, V6 and hMT/V5.Enhanced neural responses with increasing stimulus intensity suggest an enhanced response gain in ASD.Thus, our data suggest that a disturbed excitatory-inhibitory balance underlies enhanced neural responses to coherent motion in ASD.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

ABSTRACT
Theories of autism spectrum disorders (ASD) have focused on altered perceptual integration of sensory features as a possible core deficit. Yet, there is little understanding of the neuronal processing of elementary sensory features in ASD. For typically developed individuals, we previously established a direct link between frequency-specific neural activity and the intensity of a specific sensory feature: Gamma-band activity in the visual cortex increased approximately linearly with the strength of visual motion. Using magnetoencephalography (MEG), we investigated whether in individuals with ASD neural activity reflect the coherence, and thus intensity, of visual motion in a similar fashion. Thirteen adult participants with ASD and 14 control participants performed a motion direction discrimination task with increasing levels of motion coherence. A polynomial regression analysis revealed that gamma-band power increased significantly stronger with motion coherence in ASD compared to controls, suggesting excessive visual activation with increasing stimulus intensity originating from motion-responsive visual areas V3, V6 and hMT/V5. Enhanced neural responses with increasing stimulus intensity suggest an enhanced response gain in ASD. Response gain is controlled by excitatory-inhibitory interactions, which also drive high-frequency oscillations in the gamma-band. Thus, our data suggest that a disturbed excitatory-inhibitory balance underlies enhanced neural responses to coherent motion in ASD.

No MeSH data available.


Related in: MedlinePlus