Separating the effects of response nonlinearity and internal noise psychophysically

Kontsevich, Leonid L.; Chen, Chien‐Chung; Tyler, Christopher W.

doi:10.1016/s0042-6989(02)00091-3

Cited by 73 publications

(79 citation statements)

References 47 publications

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“…As originally formalized by Johnson (27,28), the relationship between JNDs and standard amplitude is determined by the rate-intensity function, which describes how the mean response rate of the activated neuronal population changes as the amplitude changes, and the variance-rate function, which describes how the response variance changes as the mean rate changes (29,30). If these two functions are described as power functions with exponents p and q, respectively, the JND should be related to the standard amplitude I according to the following equation (29,30):…”

Section: Discussionmentioning

confidence: 99%

Behavioral assessment of sensitivity to intracortical microstimulation of primate somatosensory cortex

Kim

Callier

Tabot

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

128

132

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Intracortical microstimulation (ICMS) is a powerful tool to investigate the functional role of neural circuits and may provide a means to restore sensation for patients for whom peripheral stimulation is not an option. In a series of psychophysical experiments with nonhuman primates, we investigate how stimulation parameters affect behavioral sensitivity to ICMS. Specifically, we deliver ICMS to primary somatosensory cortex through chronically implanted electrode arrays across a wide range of stimulation regimes. First, we investigate how the detectability of ICMS depends on stimulation parameters, including pulse width, frequency, amplitude, and pulse train duration. Then, we characterize the degree to which ICMS pulse trains that differ in amplitude lead to discriminable percepts across the range of perceptible and safe amplitudes. We also investigate how discriminability of pulse amplitude is modulated by other stimulation parameters-namely, frequency and duration. Perceptual judgments obtained across these various conditions will inform the design of stimulation regimes for neuroscience and neuroengineering applications.is an important tool to investigate the functional role of neural circuits (1, 2). In a famous example, microstimulation of neurons in the middle temporal area was found to bias the perceived direction of visual motion stimuli, causally implicating these neurons in the computation of visual motion direction (3). Experiments with ICMS of somatosensory cortex showed that changing the frequency of stimulation elicited discriminable percepts, demonstrating that temporal patterning of cortical responses has perceptual correlates (4). Building on the success of these and other studies, ICMS has been proposed as an approach to restore perception in individuals who have lost it, for example in visual neuroprostheses for the blind (5, 6) or somatosensory neuroprostheses for tetraplegic patients (7-11). In the present study, we sought to characterize the psychometric properties of ICMS delivered to primary somatosensory cortex (S1) across a wide range of stimulation regimes. In psychophysical experiments with Rhesus macaques, we first measured the detectability of ICMS pulse trains and assessed its dependence on a variety of stimulation parameters. We then measured the degree to which animals could discriminate pairs of ICMS pulse trains that differed in amplitude. In both the detection and discrimination experiments, ICMS parameters-amplitude, pulse width, pulse train duration, and pulse train frequency-spanned the range that is detectable and has been typically deemed safe (12-14). Results from the present experiments will inform the design of future studies involving ICMS as well as the development of sensory encoding algorithms for neuroprostheses. ResultsWe trained two monkeys to perform two variants of a twoalternative forced-choice (2AFC) task: a detection task and a discrimination task. In both tasks, the animal was seated in front of a computer monitor that conveyed information about the trial...

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Section: Discussionmentioning

confidence: 99%

Behavioral assessment of sensitivity to intracortical microstimulation of primate somatosensory cortex

Kim

Callier

Tabot

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

128

132

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“…In the words of Georgeson and Meese (2006), "The jury's still out." Other significant contributions to this ongoing debate may be found in García-Pérez and Alcalá-Quintana (2007), Gorea and Sagi (2001), Katkov, Tsodyks, and Sagi (2006a,b), Klein (2006), Kontsevich, Chen, and Tyler (2002) and Solomon (2007b). Green (1983) was the first to articulate the suspicion that dipper functions were not necessarily indicative of any simple mapping between stimulus and a single sensory response, however noisy that response might be.…”

Section: One-mechanism Explanations Of the Handlementioning

confidence: 99%

The history of dipper functions

Solomon

2009

Attention, Perception & Psychophysics

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Dipper-shaped curves often accurately depict the relationship between a baseline or "pedestal" magnitude and a just-noticeable difference in it. This tutorial traces the 45-year history of the dipper function in auditory and visual psychophysics, focusing on when they happen, and why. Popular theories for both positive and negative masking (i.e. the "handle" and "dip," respectively) are described. Sometimes, but not always, negative masking disappears with an appropriate re-description of stimulus magnitude.

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“…Furthermore, if p > (q + 1), as it can be (Meese et al, 2006), then the second stage imposes expansion (not compression) on the signal. Exactly how the second stage should be interpreted is presently unclear, as several components might contribute to its form including: static nonlinearities (Legge&Foley,1980),dynamic contrast gain control (Heeger, 1992;Foley, 1994), stimulus uncertainty (Pelli, 1985;McIlhagga, 2004;Petrov, Verghese & McKee, 2006), multiplicative noise (Kontsevich, Chen & Tyler, 2002;McIlhagga & Peterson, 2006) and local light adaptation (Kingdom & Whittle, 1996;McIlhagga & Peterson, 2006). At present we treat it as a mathematical convenience.…”

Section: Introductionmentioning

confidence: 99%

Binocular interaction: contrast matching and contrast discrimination are predicted by the same model

Baker¹,

Meese²,

Georgeson³

2007

Spatial Vis

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How do signals from the 2 eyes combine and interact? Our recent work has challenged earlier schemes in which monocular contrast signals are subject to square-law transduction followed by summation across eyes and binocular gain control. Much more successful was a new 'two-stage' modelinwhichtheinitialtransducerwasalmostlinearandcontrastgaincontroloccurredbothpreand post binocular summation. Here we extend that work by: (i) exploring the two-dimensional stimulus space (defined by left-and right-eye contrasts) more thoroughly, and (ii) performing contrast discrimination and contrast matching tasks for the same stimuli. Twenty-five base-stimuli made from 1 c/deg patches of horizontal grating, were defined by the factorial combination of 5 contrasts for the left eye (0.3-32%) with five contrasts for the right eye (0.3-32%). Other than in contrast,thegratingsinthetwoeyeswereidentical.Ina2IFCdiscriminationtask,thebase-stimuli weremasks(pedestals),wherethecontrastincrementwaspresentedtooneeyeonly.Inamatching task,thebase-stimuliwerestandardstowhichobserversmatchedthecontrastofeitheramonocular orbinoculartestgrating.Inthemodel,discriminationdependsonthelocalgradientoftheobserver's internalcontrast-responsefunction,whilematchingequatesthemagnitude(ratherthangradient)of responsetothetestandstandard.Withallmodelparametersfixedbypreviouswork,thetwo-stage model successfully predicted both the discrimination and the matching data and was much more successful than linear or quadratic binocular summation models. These results show that performance measures and perception (contrast discrimination and contrast matching) can be understoodinthesametheoreticalframeworkforbinocularcontrastvision.

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Separating the effects of response nonlinearity and internal noise psychophysically

Cited by 73 publications

References 47 publications

Behavioral assessment of sensitivity to intracortical microstimulation of primate somatosensory cortex

Behavioral assessment of sensitivity to intracortical microstimulation of primate somatosensory cortex

The history of dipper functions

Binocular interaction: contrast matching and contrast discrimination are predicted by the same model

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