| 1. |
- Orekhova, E. V., et al.
(författare)
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Gamma oscillations point to the role of primary visual cortex in atypical motion processing in autism
- 2023
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 18:2
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Tidskriftsartikel (refereegranskat)abstract
- Neurophysiological studies suggest that abnormal neural inhibition may explain a range of sensory processing differences in autism spectrum disorders (ASD). In particular, the impaired ability of people with ASD to visually discriminate the motion direction of small-size objects and their reduced perceptual suppression of background-like visual motion may stem from deficient surround inhibition within the primary visual cortex (V1) and/or its atypical top-down modulation by higher-tier cortical areas. In this study, we estimate the contribution of abnormal surround inhibition to the motion-processing deficit in ASD. For this purpose, we used a putative correlate of surround inhibition-suppression of the magnetoencephalographic (MEG) gamma response (GR) caused by an increase in the drift rate of a large annular high-contrast grating. The motion direction discrimination thresholds for the gratings of different angular sizes (1 degrees and 12 degrees) were assessed in a separate psychophysical paradigm. The MEG data were collected in 42 boys with ASD and 37 typically developing (TD) boys aged 7-15 years. Psychophysical data were available in 33 and 34 of these participants, respectively. The results showed that the GR suppression in V1 was reduced in boys with ASD, while their ability to detect the direction of motion was compromised only in the case of small stimuli. In TD boys, the GR suppression directly correlated with perceptual suppression caused by increasing stimulus size, thus suggesting the role of the top-down modulations of V1 in surround inhibition. In ASD, weaker GR suppression was associated with the poor directional sensitivity to small stimuli, but not with perceptual suppression. These results strongly suggest that a local inhibitory deficit in V1 plays an important role in the reduction of directional sensitivity in ASD and that this perceptual deficit cannot be explained exclusively by atypical top-down modulation of V1 by higher-tier cortical areas.
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| 2. |
- Manyukhina, V. O., et al.
(författare)
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Globally elevated excitation-inhibition ratio in children with autism spectrum disorder and below-average intelligence
- 2022
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Ingår i: Molecular Autism. - : Springer Science and Business Media LLC. - 2040-2392. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Altered neuronal excitation-inhibition (E-I) balance is strongly implicated in ASD. However, it is not known whether the direction and degree of changes in the E-I ratio in individuals with ASD correlates with intellectual disability often associated with this developmental disorder. The spectral slope of the aperiodic 1/f activity reflects the E-I balance at the scale of large neuronal populations and may uncover its putative alternations in individuals with ASD with and without intellectual disability. Methods Herein, we used magnetoencephalography (MEG) to test whether the 1/f slope would differentiate ASD children with average and below-average (< 85) IQ. MEG was recorded at rest with eyes open/closed in 49 boys with ASD aged 6-15 years with IQ ranging from 54 to 128, and in 49 age-matched typically developing (TD) boys. The cortical source activity was estimated using the beamformer approach and individual brain models. We then extracted the 1/f slope by fitting a linear function to the log-log-scale power spectra in the high-frequency range. Results The global 1/f slope averaged over all cortical sources demonstrated high rank-order stability between the two conditions. Consistent with previous research, it was steeper in the eyes-closed than in the eyes-open condition and flattened with age. Regardless of condition, children with ASD and below-average IQ had flatter slopes than either TD or ASD children with average or above-average IQ. These group differences could not be explained by differences in signal-to-noise ratio or periodic (alpha and beta) activity. Limitations Further research is needed to find out whether the observed changes in E-I ratios are characteristic of children with below-average IQ of other diagnostic groups. Conclusions The atypically flattened spectral slope of aperiodic activity in children with ASD and below-average IQ suggests a shift of the global E-I balance toward hyper-excitation. The spectral slope can provide an accessible noninvasive biomarker of the E-I ratio for making objective judgments about treatment effectiveness in people with ASD and comorbid intellectual disability.
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| 3. |
- Orekhova, Elena V, 1967, et al.
(författare)
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Input-dependent modulation of MEG gamma oscillations reflects gain control in the visual cortex
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-band oscillations arise from the interplay between neural excitation (E) and inhibition (I) and may provide a non-invasive window into the state of cortical circuitry. A bell-shaped modulation of gamma response power by increasing the intensity of sensory input was observed in animals and is thought to reflect neural gain control. Here we sought to find a similar input-output relationship in humans with MEG via modulating the intensity of a visual stimulation by changing the velocity/temporal-frequency of visual motion. In the first experiment, adult participants observed static and moving gratings. The frequency of the MEG gamma response monotonically increased with motion velocity whereas power followed a bell-shape. In the second experiment, on a large group of children and adults, we found that despite drastic developmental changes in frequency and power of gamma oscillations, the relative suppression at high motion velocities was scaled to the same range of values across the life-span. In light of animal and modeling studies, the modulation of gamma power and frequency at high stimulation intensities characterizes the capacity of inhibitory neurons to counterbalance increasing excitation in visual networks. Gamma suppression may thus provide a non-invasive measure of inhibitory-based gain control in the healthy and diseased brain.
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| 4. |
- Stroganova, T. A., et al.
(författare)
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High-frequency oscillatory response to illusory contour in typically developing boys and boys with autism spectrum disorders
- 2012
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Ingår i: Cortex. - : Elsevier BV. - 0010-9452. ; 48:6, s. 701-717
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Tidskriftsartikel (refereegranskat)abstract
- Illusory contour (IC) perception, a fruitful model for studying the automatic contextual integration of local image features, can be used to investigate the putative impairment of such integration in children with autism spectrum disorders (ASD). We used the illusory Kanizsa square to test how the phase-locked (PL) gamma and beta electroencephalogram (EEG) responses of typically developing (TD) children aged 3-7 years and those with ASD were modulated by the presence of IC in the image. The PL beta and gamma activity strongly differentiated between IC and control figures in both groups of children (IC effect). However, the timing, topography, and direction of the IC effect differed in TD and ASD children. Between 40 msec and 120 msec after stimulus onset, both groups demonstrated lower power of gamma oscillations at occipital areas in response to IC than in response to the control figure. In TD children, this relative gamma suppression was followed by relatively higher parieto-occipital gamma and beta responses to IC within 120-270 msec after stimulus onset. This second stage of IC processing was absent in children with ASD. Instead, their response to IC was characterized by protracted (40-270 msec) relative reduction of gamma and beta oscillations at occipital areas. We hypothesize that children with ASD rely more heavily on lower-order processing in the primary visual areas and have atypical later stage related to higher-order processes of contour integration. (C) 2011 Elsevier Srl. All rights reserved.
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| 5. |
- Manyukhina, V. O., et al.
(författare)
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Visual gamma oscillations predict sensory sensitivity in females as they do in males
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Gamma oscillations are driven by local cortical excitatory (E)-inhibitory (I) loops and may help to characterize neural processing involving excitatory-inhibitory interactions. In the visual cortex reliable gamma oscillations can be recorded with magnetoencephalography (MEG) in the majority of individuals, which makes visual gamma an attractive candidate for biomarkers of brain disorders associated with E/I imbalance. Little is known, however, about if/how these oscillations reflect individual differences in neural excitability and associated sensory/perceptual phenomena. The power of visual gamma response (GR) changes nonlinearly with increasing stimulation intensity: it increases with transition from static to slowly drifting high-contrast grating and then attenuates with further increase in the drift rate. In a recent MEG study we found that the GR attenuation predicted sensitivity to sensory stimuli in everyday life in neurotypical adult men and in men with autism spectrum disorders. Here, we replicated these results in neurotypical female participants. The GR enhancement with transition from static to slowly drifting grating did not correlate significantly with the sensory sensitivity measures. These findings suggest that weak velocity-related attenuation of the GR is a reliable neural concomitant of visual hypersensitivity and that the degree of GR attenuation may provide useful information about E/I balance in the visual cortex.
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| 6. |
- Stroganova, Tatiana A, et al.
(författare)
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Inverted event-related potentials response to illusory contour in boys with autism.
- 2007
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Ingår i: Neuroreport. - 0959-4965. ; 18:9, s. 931-5
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Tidskriftsartikel (refereegranskat)abstract
- We examined the hypothesis of lower-level processing abnormalities related to perceptual grouping in boys with autism aged 3-6 years. We investigated event-related potentials response to visual elements that either formed perceptually coherent illusory contour or were arranged in a noncoherent way. The results showed that in healthy boys the illusory contour as compared with control stimulus elicited enhanced negativity of N1 peak (C effect), which has been previously found in adults. Autistic boys demonstrated the reliable inverted illusory contour effect, that is, more positive N1 amplitude to illusory contour. We hypothesized that boys with autism were sensitive to difference between illusory contour and control figures basing on collinearity processing mechanisms implemented in neural circuitry of primary visual cortex.
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| 7. |
- Stroganova, T. A., et al.
(författare)
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Left hemispheric deficit in the sustained neuromagnetic response to periodic click trains in children with ASD
- 2020
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Ingår i: Molecular Autism. - : Springer Science and Business Media LLC. - 2040-2392. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Deficits in perception and production of vocal pitch are often observed in people with autism spectrum disorder (ASD), but the neural basis of these deficits is unknown. In magnetoencephalogram (MEG), spectrally complex periodic sounds trigger two continuous neural responses-the auditory steady state response (ASSR) and the sustained field (SF). It has been shown that the SF in neurotypical individuals is associated with low-level analysis of pitch in the 'pitch processing center' of the Heschl's gyrus. Therefore, alternations in this auditory response may reflect atypical processing of vocal pitch. The SF, however, has never been studied in people with ASD. Methods We used MEG and individual brain models to investigate the ASSR and SF evoked by monaural 40 Hz click trains in boys with ASD (N = 35) and neurotypical (NT) boys (N = 35) aged 7-12-years. Results In agreement with the previous research in adults, the cortical sources of the SF in children were located in the left and right Heschl's gyri, anterolateral to those of the ASSR. In both groups, the SF and ASSR dominated in the right hemisphere and were higher in the hemisphere contralateral to the stimulated ear. The ASSR increased with age in both NT and ASD children and did not differ between the groups. The SF amplitude did not significantly change between the ages of 7 and 12 years. It was moderately attenuated in both hemispheres and was markedly delayed and displaced in the left hemisphere in boys with ASD. The SF delay in participants with ASD was present irrespective of their intelligence level and severity of autism symptoms. Limitations We did not test the language abilities of our participants. Therefore, the link between SF and processing of vocal pitch in children with ASD remains speculative. Conclusion Children with ASD demonstrate atypical processing of spectrally complex periodic sound at the level of the core auditory cortex of the left-hemisphere. The observed neural deficit may contribute to speech perception difficulties experienced by children with ASD, including their poor perception and production of linguistic prosody.
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| 8. |
- Stroganova, T. A., et al.
(författare)
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Effects of the Periodicity and Vowelness of Sounds on Auditory Cortex Responses in Children
- 2022
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Ingår i: Neuroscience and Behavioral Physiology. - : Springer Science and Business Media LLC. - 0097-0549 .- 1573-899X. ; 52:3, s. 395-404
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of the human brain decoding speech sounds are of fundamental and applied interest in many areas of neuroscience. This study addresses the roles of periodicity and the speech nature (fixed formant structure) of vowel sounds in modulating auditory cortex activity in typically developing children. We proposed that both of these characteristics are typical of the vowel sounds of speech and that they are processed by different neural networks in the auditory cortex. To test this hypothesis, we constructed a set of acoustic stimuli by manipulating their periodicity and vowelness separately and used magnetoencephalography combined with individual models of the cortical surface to evaluate the cortical topography of the sources of auditory cortex responses and their strengths. The cohort consisted of nine typically developing children aged 7–12 years. We found that early auditory cortex responses (50–150 msec after stimulus onset) were highly sensitive to both the periodicity and vowelness of sounds, with independent tuning of neural networks to each of these properties of speech sounds. Differences in the locations, time dynamics, and hemisphere asymmetry of these differential responses indicated that “sound vowelness zones” in the temporal cortex constitute the earliest level in the speech information processing hierarchy at which processing of the acoustic properties of a periodic signal is transformed into decoding of speech sounds. These results allow the specific features and roles of possible impairments to the processing of the low-level properties of speech sounds and difficulties in speech perception in children with pervasive developmental disorders to be evaluated.
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| 9. |
- Stroganova, T. A., et al.
(författare)
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THE EFFECT OF PERIODICITY AND "VOWELNESS" OF A SOUND ON CORTICAL AUDITORY RESPONSES IN CHILDREN
- 2021
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Ingår i: Zhurnal Vysshei Nervnoi Deyatelnosti Imeni I.P. Pavlova. - 0044-4677. ; 71:4, s. 563-577
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Tidskriftsartikel (refereegranskat)abstract
- The neural basis of speech decoding is of both fundamental and practical interest for many areas of neuroscience. The discovery of highly specialized areas of the temporal cortex, which perform acoustic analysis of vowels and the pitch of spectrally complex periodic sounds, opens the way for new directions in research on speech signal processing in healthy and diseased brain. Here, we sought to dissect the effects of periodicity and "vowelness" of a sound on the neural response of the auditory cortex in typically developing children aged 7-12 years. We hypothesized that although both of these properties are pertinent to speech vowels, their processing occurs at different levels of cortical ventral auditory stream. To test this hypothesis, we constructed a set of acoustic stimuli, manipulating their periodicity and 'vowelness' separately, and used magnetoencephalography in combination with individual brain models to assess the cortical topography and temporal dynamic of cortical sources, which respond selectively to either sounds' periodicity or to their 'vowelness'. We found that the early auditory responses (50-150 ms) were highly sensitive to both periodicity and 'vowelness' of a sound, although they were separable from each other in terms of response timing, source localization and hemispheric asymmetry. Our findings suggest that the separate neural networks are independently tuned for each of these properties of the speech sound, and that transformation of the respective acoustic properties into a speech feature take place at these earliest stages in the speech processing hierarchy. Our results may help to evaluate the role of specific neural deficits in the processing of low-level properties of speech sounds in language disorders.
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| 10. |
- Orekhova, Elena V, 1967, et al.
(författare)
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Additive effect of contrast and velocity suggests the role of strong excitatory drive in suppression of visual gamma response
- 2020
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 Orekhova et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. It is commonly acknowledged that gamma-band oscillations arise from interplay between neural excitation and inhibition; however, the neural mechanisms controlling the power of stimulus-induced gamma responses (GR) in the human brain remain poorly understood. A moderate increase in velocity of drifting gratings results in GR power enhancement, while increasing the velocity beyond some ‘transition point’ leads to GR power attenuation. We tested two alternative explanations for this nonlinear input-output dependency in the GR power. First, the GR power can be maximal at the preferable velocity/temporal frequency of motion-sensitive V1 neurons. This ‘velocity tuning’ hypothesis predicts that lowering contrast either will not affect the transition point or shift it to a lower velocity. Second, the GR power attenuation at high velocities of visual motion can be caused by changes in excitation/inhibition balance with increasing excitatory drive. Since contrast and velocity both add to excitatory drive, this ‘excitatory drive’ hypothesis predicts that the ‘transition point’ for low-contrast gratings would be reached at a higher velocity, as compared to high-contrast gratings. To test these alternatives, we recorded magnetoencephalography during presentation of low (50%) and high (100%) contrast gratings drifting at four velocities. We found that lowering contrast led to a highly reliable shift of the GR suppression transition point to higher velocities, thus supporting the excitatory drive hypothesis. No effects of contrast or velocity were found in the alpha-beta range. The results have implications for understanding the mechanisms of gamma oscillations and developing gamma-based biomarkers of disturbed excitation/inhibition balance in brain disorders.
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