Accurate and Rapid Estimation of Phosphene Thresholds (REPT)

Abrahamyan, Arman; Clifford, Colin W. G.; Ruzzoli, Manuela; Phillips, Dan; Arabzadeh, Ehsan; Harris, Justin A.

doi:10.1371/journal.pone.0022342

Cited by 36 publications

(29 citation statements)

References 55 publications

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“…At the beginning of each session phosphene threshold (i.e. TMS stimulus intensity) was determined using a staircase method (Abrahamyan et al, 2011). TMS intensity was then increased to 140% of phosphene threshold for the remainder of that session.…”

Section: Methodsmentioning

confidence: 99%

Phosphene-guided transcranial magnetic stimulation of occipital but not parietal cortex suppresses stimulus visibility

et al. 2014

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Transcranial magnetic stimulation (TMS) applied over the occipital lobe approximately 100 ms after the onset of a stimulus decreases its visibility if it appears in the location of the phosphene. Because phosphenes can also be elicited by stimulation of the parietal regions, we asked if the same procedure that is used to reduce visibility of stimuli with occipital TMS will lead to decreased stimulus visibility when TMS is applied to parietal regions. TMS was randomly applied at 0 to 130 ms after the onset of the stimulus (SOA) in steps of 10 ms in occipital and parietal regions. Participants responded to the orientation of the line stimulus and rated its visibility. We replicate previous reports of phosphenes from both occipital and parietal TMS. As previously reported, we also observed visual suppression around the classical 100 ms window both in the objective line orientation and subjective visibility responses with occipital TMS. Parietal stimulation, on the other hand, did not consistently reduce stimulus visibility in any time window.

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Section: Methodsmentioning

confidence: 99%

Phosphene-guided transcranial magnetic stimulation of occipital but not parietal cortex suppresses stimulus visibility

et al. 2014

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“…For the remaining participants, stimulations were applied randomly within the defined window on the scalp. We applied stimulation at 80 % stimulator output, approximately 130 % of the average phosphene threshold reported in previous studies using the same stimulator and coil model (Abrahamyan et al 2011; Stokes et al 2013). …”

Section: Methodsmentioning

confidence: 99%

“…For each participant, we defined an excitation threshold, using the REPT adaptive staircase method (Abrahamyan et al 2011). REPT estimates excitation thresholds from 30 stimulations.…”

Section: Methodsmentioning

confidence: 99%

Mapping the visual brain areas susceptible to phosphene induction through brain stimulation

Schaeffner

Welchman

2016

Exp Brain Res

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Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique whose effects on neural activity can be uncertain. Within the visual cortex, phosphenes are a useful marker of TMS: They indicate the induction of neural activation that propagates and creates a conscious percept. However, we currently do not know how susceptible different areas of the visual cortex are to TMS-induced phosphenes. In this study, we systematically map out locations in the visual cortex where stimulation triggered phosphenes. We relate this to the retinotopic organization and the location of object- and motion-selective areas, identified by functional magnetic resonance imaging (fMRI) measurements. Our results show that TMS can reliably induce phosphenes in early (V1, V2d, and V2v) and dorsal (V3d and V3a) visual areas close to the interhemispheric cleft. However, phosphenes are less likely in more lateral locations (hMT+/V5 and LOC). This suggests that early and dorsal visual areas are particularly amenable to TMS and that TMS can be used to probe the functional role of these areas.

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“…To estimate phosphene thresholds accurately, we used the "rapid estimation of phosphene thresholds" (REPT) procedure [17]. REPT programmatically adjusts the stimulator's pulse intensity based on a Bayesian adaptive staircase procedure [11] to estimate phosphene thresholds at 60%, which corresponds to the threshold parameter of a Weibull function fitted to the proportion of phosphene responses between 0 and 1 with a lapse rate of 4%.…”

Section: Phosphene Thresholdmentioning

confidence: 99%