One in four people fail to perceive phosphenes during early visual cortex transcranial magnetic stimulation

Phylactou, Phivos; Traikapi, Artemis; Konstantinou, Nikos

doi:10.1016/j.brs.2022.12.012

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…= 16.5%) out of the total (100%) stimulation power of the Magstim Super Rapid 2 stimulator. For participants who failed to perceive phosphenes a fixed power set at 65% of the stimulator maximum output was used, with the coil placed approximately 2 cm above and 0.5 cm laterally, as previously discussed (see Sensory visual cortex stimulation section; see also [ 94 ]). The TMS coil was placed on the right hemisphere of 19 participants and on the left hemisphere of the remaining 17 participants.…”

Section: Resultsmentioning

confidence: 99%

Causal evidence for the role of the sensory visual cortex in visual short-term memory maintenance

2023

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The role of the sensory visual cortex during visual short-term memory (VSTM) remains controversial. This controversy is possibly due to methodological issues in previous attempts to investigate the effects of transcranial magnetic stimulation (TMS) on VSTM. The aim of this study was to use TMS, while covering previous methodological deficits. Sixty-four young adults were recruited to participate in two experiments (Experiment 1: n = 36; Experiment 2: n = 28) using a VSTM orientation change-detection task under TMS. Monocular vision was ensured using red-blue goggles combined with red-blue stimuli. Double-pulse TMS was delivered at different times (Experiment 1: 0, 200 or 1000 ms; Experiment 2: 200, 1000 ms) during a 2 s maintenance phase, on one side of the occipital hemisphere. In Experiment 2, a sham TMS condition was introduced. Decreased detection sensitivity ( d′ ) in the ipsilateral occipital hemisphere to visual hemifield, and in the real TMS (compared with sham TMS) condition indicated inhibitory TMS effects, and thus, a causal involvement of the sensory visual cortex during early (200 ms) and late (1000 ms) maintenance in VSTM. These findings are aligned with sensory recruitment, which proposes that both perceptual and memory processes rely upon the same neural substrates in the sensory visual cortex. The methods used in this study were preregistered and had received in-principle acceptance on 6 June 2022 (Stage 1 protocol can be found in: https://doi.org/10.17605/OSF.IO/EMPDT ).

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Section: Resultsmentioning

confidence: 99%

Causal evidence for the role of the sensory visual cortex in visual short-term memory maintenance

2023

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“…In other words, people may fail to report the "minimal" phosphene if uncertain. This uncertainty is also echoed by the estimation that one in four people will fail to report any reliable phosphenes (Phylactou et al, 2023).…”

Section: Discussionmentioning

confidence: 99%

“…By inducing phosphenes, one can estimate a phosphene threshold (PT), which is the minimum required stimulation intensity to evoke self-reported phosphenes in at least half the trials (e.g., 5 out of 10 stimulations; see Mazzi et al, 2017). The PT has been extensively used to study vision and visual cognition (for recent reviews see Phylactou et al, 2022, 2023), as well as to measure occipital cortex excitability (for reviews see Aurora & Welch, 1998; Brigo et al, 2013).…”

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Phosphene and Motor Transcranial Magnetic Stimulation Thresholds Are Correlated: A Meta-Analytic Investigation

Phylactou,

Pham,

Narskhani

et al. 2023

Preprint

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Transcranial magnetic stimulation (TMS) is commonly delivered at an intensity defined by the resting motor threshold (rMT), which is thought to represent cortical excitability, even if the TMS target area falls outside of the motor cortex. This approach rests on the assumption that cortical excitability, as measured through the motor cortex, represents a ‘global’ measure of excitability. Another common approach to measure cortical excitability relies on the phosphene threshold (PT), measured through the visual cortex of the brain. However, it remains unclear whether either estimate can serve as a singular measure of global cortical excitability. If PT and rMT indeed reflect global cortical excitability, they should be correlated. To test this, we systematically identified previous studies that measured PT and rMT to calculate an overall correlation between the two estimates. Our results, based on 16 effect sizes from eight studies, indicated that PT and rMT are correlated (ρ = .4), and thus one measure could potentially serve as a global cortical excitability measure. Three exploratory meta-analyses revealed that the strength of the correlation is affected by different methodologies, and that PT intensities are higher than rMT. Evidence for a PT-rMT correlation remained robust across all analyses. Further research is necessary for an in-depth understanding of how cortical excitability is reflected through TMS.

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Phosphene and motor transcranial magnetic stimulation thresholds are correlated: A meta-analytic investigation

Phylactou,

Pham,

Narskhani

et al. 2024

Progress in Neuro-Psychopharmacology and Biological Psychiatry

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One in four people fail to perceive phosphenes during early visual cortex transcranial magnetic stimulation

Cited by 3 publications

References 8 publications

Causal evidence for the role of the sensory visual cortex in visual short-term memory maintenance

Causal evidence for the role of the sensory visual cortex in visual short-term memory maintenance

Phosphene and Motor Transcranial Magnetic Stimulation Thresholds Are Correlated: A Meta-Analytic Investigation

Phosphene and motor transcranial magnetic stimulation thresholds are correlated: A meta-analytic investigation

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