The influence of defocus on multifocal visual evoked potentials

Pieh, Christina; Hoffmann, Michael B.; Bach, Michael

doi:10.1007/s00417-004-0969-9

Cited by 19 publications

(11 citation statements)

References 18 publications

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“…(2) Motivated by related work (Normann et al, 2007), we added catch trials during the probe and potentiation periods to monitor attention, thus ensuring subjects attended to the task and focused constantly, as it has been shown that defocus diminishes VEP responses significantly (Pieh et al, 2005). (3) The probe sessions were shorter.…”

Section: Discussionmentioning

confidence: 99%

Heterogeneity of stimulus-specific response modificationâ€”an fMRI study on neuroplasticity

Lahr

Peter

Bach

et al. 2014

Front. Hum. Neurosci.

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Long-term potentiation (LTP) is a key element of synaptic plasticity. At the macroscopic level, similar effects can be induced in the human brain using repetitive stimulation with identical stimuli. High-frequency stimulation (HFS) can increase neuronal responses whereas low-frequency stimulation may produce the opposite effect. Optimal stimulation frequencies and characteristics for inducing stimulus-specific response modification (SRM) differ substantially from those applied to brain tissue slices but have been explored in recent studies. In contrast, the individual manifestation of this effect in terms of its spatial location and extent are unclear. Using functional magnetic resonance imaging (fMRI) in 18 subjects (mean age 25.3 years), we attempted to induce LTP-like effects by HFS with checkerboard flashes at 9 Hz for 120 s. As expected, flashes induced strong activation in primary and secondary visual cortices. Contrary to our expectations, we found clusters of decreased activations induced by pattern flashes after HFS in the primary and secondary visual cortices. On the level of the individual subject, some showed significantly increased activations in the post-HFS session while the majority showed significant decreases. The locations of areas showing altered activations before and after HFS were only partly overlapping. No association between location, extent and direction of the HFS-effect was observed. The findings are unexpected in the light of existing HFS-studies, but mirror the high inter-subject variability, concerning even the directionality of the induced effects shown for other indices of LTP-like plasticity in the human brain. As this variability is not observed in LTP at the cellular level, a better understanding of LTP-like mechanisms on the macroscopic level is essential for establishing tools to quantify individual synaptic plasticity in-vivo.

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Section: Discussionmentioning

confidence: 99%

Heterogeneity of stimulus-specific response modificationâ€”an fMRI study on neuroplasticity

Lahr

Peter

Bach

et al. 2014

Front. Hum. Neurosci.

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“…Studies on visual blurring found that monocular‐induced defocus reduces foveal VEP to ∼60%, whereas defocus had no effect at eccentricities over 7° (Pieh et al . ). When defocus is induced binocularly, the amplitude of the P1 component is larger and peaks earlier than during monocular‐induced defocus (Plainis et al .…”

Section: Introductionmentioning

confidence: 97%

Immediate cortical adaptation in visual and non‐visual areas functions induced by monovision

Zeri

Berchicci

Naroo

et al. 2017

The Journal of Physiology

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A common and often successful option to correct presbyopia with contact lenses is monovision. This is an unbalanced correction across the two eyes where one eye is corrected for far vision and the other eye is corrected for near vision. Monovision is therefore a form of acquired anisometropia that causes a superimposition of an in-focus image with a blurred image. In spite of this visual anisometropia, monovision has been successfully used for many decadesl however the brain mechanism supporting monovision is not well understood. The present study aimed to measure the visual evoked potentials with a high-density electrode array (64-channel) in a group of presbyopes and to provide a detailed spatiotemporal analysis of the cortical activity after a short period of adaptation to monovision with contact lenses. When compared with a balanced eye near correction, monovision produced both a clear reduction of the earliest visual evoked potential components, the C1 and the N1, and an amplitude increase of the P1 and pP1. These results indicate that the unilateral blurring induced by wearing monovision contact lenses reduces feed-forward activity in the primary visual area and feedback activity in extrastriate areas (C1 and N1 reduction). Interestingly, other brain activities in both extrastriate visual areas (the P1 component) and in the anterior insula (the pP1 component) appear to compensate for this dysfunction, increasing their activity during monovision. These changes confirm the presence of fluid brain adaptation in visual and non-visual areas during monocular interferences.

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“…21 Procedure Stimuli were viewed monocularly corrected for the viewing distance. 22 For this purpose, an infrared eye camera refractor system (Electro-Diagnostic Imaging, Inc.) was used that also provided a magnified video image of the coaxial view of the pupil of the stimulated eye to monitor ocular alignment and fixation stability during recordings. The patients viewed the stimuli through filters inserted in trial frames, and multifocal VEPs were recorded for 2 conditions: neutral filtering and blue filtering.…”

Section: Patientsmentioning

confidence: 99%

Effect of blue-light filtering on multifocal visual-evoked potentials

Hoffmann¹,

Behrens–Baumann²,

Langenbucher³

et al. 2012

Journal of Cataract and Refractive Surgery

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The influence of defocus on multifocal visual evoked potentials

Abstract: The results suggest that, in contrast to the mfERG, the mfVEP requires optimal refraction to correctly assess the cortical responses.

Cited by 19 publications

References 18 publications

Heterogeneity of stimulus-specific response modificationâ€”an fMRI study on neuroplasticity

Heterogeneity of stimulus-specific response modificationâ€”an fMRI study on neuroplasticity

Immediate cortical adaptation in visual and non‐visual areas functions induced by monovision

Effect of blue-light filtering on multifocal visual-evoked potentials

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