Studies of human visual pathophysiology with visual evoked potentials

Tobimatsu, Shozó; Celesia, Gastone G.

doi:10.1016/j.clinph.2006.01.004

Cited by 174 publications

(149 citation statements)

References 198 publications

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“…Thus, the information about complex objects must be processed by many different neuronal assemblies in distinct brain areas (Felleman and Van Essen, 1991;Tobimatsu and Celesia, 2006). However, our visual experiences of the environment are integrated percepts despite the spatial segregation of visual processing in the brain.…”

Section: Introductionmentioning

confidence: 99%

“…After a phase of synaptic overproduction and pruning (e.g., Huttenlocher and de Courten, 1987), occipital areas show relatively little senescence-related changes compared to, for example, prefrontal regions (Sowell et al, 2003;Raz et al, 2005), and provide the main input for higher order cognitive processes requiring visual information (Tobimatsu and Celesia, 2006). Therefore, we chose gamma-band synchronization in early visual perception as a target mechanism.…”

Section: Introductionmentioning

confidence: 99%

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EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

Werkle‐Bergner

Shing

Müller

et al. 2009

Clinical Neurophysiology

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a b s t r a c tObjective: To investigate lifespan age differences in neuronal mechanisms of visual coding in the context of perceptual discrimination. Methods: We recorded EEG from 17 children (10-12 years), 16 younger adults (20-26 years), and 17 older adults (70-76 years) during a simple choice-reaction task requiring discrimination of squares and circles of different sizes. We examined age-group differences in the effect of stimulus size on early ERP components, evoked gamma-band power, and inter-trial phase-stability in the gamma band as assessed by the phase-locking index (PLI). Results: In the absence of age differences in discrimination accuracy, we observed reliable age differences in patterns of ERP, evoked gamma power, and PLI. P1 and N1 peak amplitudes were larger and the peak latencies longer in children than in adults. Children also showed lower levels of evoked power and PLI than adults. Older adults showed smaller increments in evoked power with increasing stimulus size than younger adults, but similar amounts of phase locking for small-and medium-sized stimuli as younger adults. Conclusions: The relative importance of different coding mechanisms in early visual areas changes from childhood to old age. Due to synaptic overproduction and immature myelination, the visual system of children is less entrained by incoming information, resulting in less synchronized neuronal responses. Adults primarily rely on sparse representations formed through experience-dependent temporally synchronized neuronal interactions. In old age, senescent decline in neuronal density and neurotransmitter availability further increase the reliance on temporally synchronized processing. Significance: Findings from this study defy the notion that sensory aging consists in a reversal of sensory development in childhood, and point to a high degree of age specificity in mechanisms of visual coding.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

Werkle‐Bergner

Shing

Müller

et al. 2009

Clinical Neurophysiology

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“…Generators of microsaccade-related brain potentials were modeled with equivalent current dipoles in BESA (Brain Electromagnetic Source Analysis, v5.1, Megis) using a four-shell spherical head model. Both one-and two-dipole models have been used to model the lambda response following macrosaccades (Kazai and Yagi, 2003) and the P1 visual evoked potential (VEP) (Tobimatsu and Celesia, 2006); here we used a pair of dipoles with the constraint of a bihemispheric mirror-symmetric location (Di Russo et al, 2005). First, two regional sources (each consisting of three orthogonal dipoles) were fitted to the maximum in global field power (GFP; the SD across electrodes) between 75 and 125 ms after microsaccade onset.…”

Section: Experiments 1: Checkerboard Fixationmentioning

confidence: 99%

Human Microsaccade-Related Visual Brain Responses

Dimigen

Valsecchi²,

Sommer³

et al. 2009

J. Neurosci.

162

192

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Microsaccades are very small, involuntary flicks in eye position that occur on average once or twice per second during attempted visual fixation. Microsaccades give rise to EMG eye muscle spikes that can distort the spectrum of the scalp EEG and mimic increases in gamma band power. Here we demonstrate that microsaccades are also accompanied by genuine and sizeable cortical activity, manifested in the EEG. In three experiments, high-resolution eye movements were corecorded with the EEG: during sustained fixation of checkerboard and face stimuli and in a standard visual oddball task that required the counting of target stimuli. Results show that microsaccades as small as 0.15°generate a field potential over occipital cortex and midcentral scalp sites 100 -140 ms after movement onset, which resembles the visual lambda response evoked by larger voluntary saccades. This challenges the standard assumption of human brain imaging studies that saccade-related brain activity is precluded by fixation, even when fully complied with. Instead, additional cortical potentials from microsaccades were present in 86% of the oddball task trials and of similar amplitude as the visual response to stimulus onset. Furthermore, microsaccade probability varied systematically according to the proportion of target stimuli in the oddball task, causing modulations of late stimulus-locked event-related potential (ERP) components. Microsaccades present an unrecognized source of visual brain signal that is of interest for vision research and may have influenced the data of many ERP and neuroimaging studies.

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“…UMAN visual system is made up of multiple, parallel channels which process different information, and each channel comprises a set of the sequential processing centers [1,2]. Light increments (ON) and decrements (OFF), motion, stereoscopic depth, color, shape, and other parameters of visual stimuli are processed separately and simultaneously [1].…”

Section: Parallel Visual Pathways In Humanmentioning

confidence: 99%

Abstract of the 12th International Meeting of Physical Therapy Science in Korea

2013

J Phys Ther Sci

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Studies of human visual pathophysiology with visual evoked potentials

Cited by 174 publications

References 198 publications

EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

EEG gamma-band synchronization in visual coding from childhood to old age: Evidence from evoked power and inter-trial phase locking

Human Microsaccade-Related Visual Brain Responses

Abstract of the 12th International Meeting of Physical Therapy Science in Korea

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