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Andreas Marzoll, Isha Chavva, Takeo Watanabe; A new type of long-lasting adaptation that is feature-unspecific, task-specific and occurs only in a plastic state. Journal of Vision 2019;19(10):293c. doi: https://doi.org/10.1167/19.10.293c.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies found that visual high- and low-frequency stimulation (dubbed “LTP/LTD-like”) can facilitate or impair perceptual abilities (Beste et al., 2011; Marzoll, Saygi & Dinse, 2018). Here we report that LTP-like and LTD-like stimulation results in an adaptation that has never been reported. After 7 days of training on an orientation detection task which led to perceptual learning (Watanabe & Sasaki, 2015; Sasaki, Náñez, & Watanabe, 2010), LTP-like or LTD-like stimulation was applied to subjects (n=12 for LTP-like and n=12 for LTD-like). The stimulation consisted of a Gabor flickering on and off either intermittently at 10 Hz (LTP-like stim.: 1 s stimulus train, 5 s break) or continuously (LTD-like stim.: 1 Hz). 90 min and 1 d after the stimulation, signal-to-noise thresholds were measured in both groups for both the stimulated orientation and for an orthogonal control orientation. We found the following aspects. First, threshold elevation did not occur until 90 min after stimulation offset and lasted for at least ~180 min after offset. Second, correlative analysis of individual data suggests a persistence for the subjects most strongly affected on the previous day (ϱs = .63; p < .001), ruling out mere fatigue. Third, on the following day, performance returned to baseline levels on the population level. Fourth, significant threshold elevations were obtained not only for the stimulated orientation (LTP-like: +66%; LTD-like: +27%) but also for the control orientation (LTP-like: +81%; LTD-like: +27%). Fifth, the threshold elevation was obtained only when the stimulation was given after detection performance was enhanced due to detection training (ϱs = −.45; p < .03). These properties are contrasted to the orientation aftereffect (OA), which is strongest after the offset of stimulus exposure and is highly specific for the exposed orientation. This new type of adaptation by LTP/LTD-like stimulation thus differs markedly from the OA.
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