Changes in spatial selectivity of pattern-ERG components with stimulus contrast

AbstractFeedback in the brain is thought to convey contextual information that underlies our flexibility to perform different tasks. Empirical and computational work on the visual system suggests this is achieved by targeting task-relevant neuronal subpopulations. We combine two tasks, each resulting in selective modulation by feedback, to test whether the feedback reflected the combination of both selectivities. We used visual feature-discrimination specified at one of two possible locations and uncoupled the decision formation from motor plans to report it, while recording in macaque mid-level visual areas. Here we show that although the behavior is spatially selective, using only task-relevant information, modulation by decision-related feedback is spatially unselective. Population responses reveal similar stimulus-choice alignments irrespective of stimulus relevance. The results suggest a common mechanism across tasks, independent of the spatial selectivity these tasks demand. This may reflect biological constraints and facilitate generalization across tasks. Our findings also support a previously hypothesized link between feature-based attention and decision-related activity.

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Blue light blind-spot stimulation upregulates b-wave and pattern ERG activity in myopes

Scientific Reports ◽

10.1038/s41598-021-88459-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ana Amorim-de-Sousa ◽

Tim Schilling ◽

Paulo Fernandes ◽

Yeshwanth Seshadri ◽

Hamed Bahmani ◽

...

Keyword(s):

Optic Nerve ◽

Electrical Activity ◽

Blue Light ◽

Optic Nerve Head ◽

Plexiform Layer ◽

Pattern Electroretinogram ◽

Blind Spot ◽

Inner Plexiform Layer ◽

Pattern Erg ◽

Myopia Progression

AbstractUpregulation of retinal dopaminergic activity may be a target treatment for myopia progression. This study aimed to explore the viability of inducing changes in retinal electrical activity with short-wavelength light targeting melanopsin-expressing retinal ganglion cells (ipRGCs) passing through the optic nerve head. Fifteen healthy non-myopic or myopic young adults were recruited and underwent stimulation with blue light using a virtual reality headset device. Amplitudes and implicit times from photopic 3.0 b-wave and pattern electroretinogram (PERG) were measured at baseline and 10 and 20 min after stimulation. Relative changes were compared between non-myopes and myopes. The ERG b-wave amplitude was significantly larger 20 min after blind-spot stimulation compared to baseline (p < 0.001) and 10 min (p < 0.001) post-stimulation. PERG amplitude P50-N95 also showed a significant main effect for ‘Time after stimulation’ (p < 0.050). Implicit times showed no differences following blind-spot stimulation. PERG and b-wave changes after blind-spot stimulation were stronger in myopes than non-myopes. It is possible to induce significant changes in retinal electrical activity by stimulating ipRGCs axons at the optic nerve head with blue light. The results suggest that the changes in retinal electrical activity are located at the inner plexiform layer and are likely to involve the dopaminergic system.

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Qualitative speed-accuracy tradeoff effects can be explained by a diffusion/fast-guess mixture model

Scientific Reports ◽

10.1038/s41598-021-94451-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Roger Ratcliff ◽

Inhan Kang

Keyword(s):

Mixture Model ◽

Diffusion Model ◽

Response Times ◽

Model Fit ◽

Orientation Discrimination ◽

Model Parameters ◽

Stimulus Contrast ◽

Accuracy Stress ◽

Speed Accuracy ◽

Selective Influence

AbstractRafiei and Rahnev (2021) presented an analysis of an experiment in which they manipulated speed-accuracy stress and stimulus contrast in an orientation discrimination task. They argued that the standard diffusion model could not account for the patterns of data their experiment produced. However, their experiment encouraged and produced fast guesses in the higher speed-stress conditions. These fast guesses are responses with chance accuracy and response times (RTs) less than 300 ms. We developed a simple mixture model in which fast guesses were represented by a simple normal distribution with fixed mean and standard deviation and other responses by the standard diffusion process. The model fit the whole pattern of accuracy and RTs as a function of speed/accuracy stress and stimulus contrast, including the sometimes bimodal shapes of RT distributions. In the model, speed-accuracy stress affected some model parameters while stimulus contrast affected a different one showing selective influence. Rafiei and Rahnev’s failure to fit the diffusion model was the result of driving subjects to fast guess in their experiment.

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