Neural Activity in Mechanoreceptive Cutaneous Afferents: Stimulus-Response Relations, Weber Functions, and Information Transmission

Werner, Gerhard; Mountcastle, Vernon B.

doi:10.1152/jn.1965.28.2.359

Cited by 456 publications

(195 citation statements)

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“…As might be expected, responses of gustatory afferents increase as the concentration (intensity) of the tastant increases [62]. Furthermore, the difference in firing rates (measured in rats) evoked by two tastants that are just discriminable (i.e., are one 'just noticeable difference' apart, as measured in humans) is constant across the range of concentrations, as Werner and Mountcastle have found to be the case in tactile intensity discrimination [21]. Note, however, that sensation magnitude cannot be inferred from discriminability [63][64][65].…”

Section: Peripheral Code Of Perceived Intensity In Other Sensory Modamentioning

confidence: 60%

Tactile intensity and population codes

Bensmaı̈a

2008

Behavioural Brain Research

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An important question in neuroscience is how different aspects of a stimulus are encoded at different stages of neural processing. In this review, I discuss studies investigating the peripheral neural code for perceived intensity in touch. One of the recurrent themes in this line of research is that information about stimulus intensity is encoded in the activity of populations of neurons. Not only is information integrated across afferents of given type, but information is also combined across submodalities to yield a unified percept of stimulus intensity. The convergence of information stemming from multiple submodalities is particularly interesting in light of the fact that tactile these are generally thought to be parallel sensory channels with distinct sensory functions and little cross-channel interactions. I discuss implications of a recently proposed model of intensity coding for psychophysical functions and for the coding of intensity in cortex. I also briefly review the peripheral coding of intensity in other sensory modalities. Perceived intensity and integration within and across submodalitiesIntensity is a basic perceptual dimension in the sense that any two stimuli can be compared along the intensive continuum as long as they impinge upon the same sensory sheet (the retina, the cochlea, the olfactory epithelium, etc.). For instance, the brightness of two objects or the loudness of two sounds can be readily compared (see [1], e.g.). Our experience with tactile stimuli -perceiving a puff of air, a light tap or a strong nudge -suggests that tactile intensity is a unitary percept; however, this belief may not be as straightforward as one might initially suppose. Indeed, the skin is innervated by a variety of receptors, several of which subserve the sense of "discriminative touch," within which perceived (tactile) intensity is subsumed. The retina comprises four types of photoreceptors, so the presence of multiple receptor types is not what separates the sense of touch from its visual counterpart. The important distinction is that input from the four photoreceptors has long been known to converge, even within the retina itself, whereas input from low-threshold mechanoreceptive afferents is thought to remain segregated through at least the first cortical processing stage [2]. In fact, the four populations of low-threshold mechanoreceptive afferents are commonly thought to form the inputs to four distinct sensory channels in touch [3]. However, when contacting everyday objects, all four mechanoreceptive channels are more often than not activated. The study of the perception of intensity allows us to investigate how information stemming from these four channels is combined to yield a unitary percept of stimulus intensity.Address: Krieger 338, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, Phone: (410) Fax: (410) 516-8648, Email: sliman@jhu.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our cust...

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Section: Peripheral Code Of Perceived Intensity In Other Sensory Modamentioning

confidence: 60%

Tactile intensity and population codes

Bensmaı̈a

2008

Behavioural Brain Research

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“…Information can be carried in spike rate (Werner and Mountcastle, 1965;Tolhurst, 1989), spike timing , spike correlations across neurons Singer, 1992, 1996;De Charms and Merzenich, 1996;Gawne et al, 1996;Roelfsema et al, 1997), or a combination of these. Recently, a great deal of attention has been focused on correlated firing: that the probability of one cell spiking is related to whether other nearby cells fire (Mastronarde, 1983;Ts'o and Gilbert, 1988;Engel et al, 1990;Gawne and Richmond, 1993;Zohary et al, 1994;Kreiter and Singer, 1996;De Oliveira et al, 1997;Lebedev et al, 2000;Maldonado et al, 2000;Bair et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

The Role of Correlations in Direction and Contrast Coding in the Primary Visual Cortex

Montani

Kohn²,

et al. 2007

J. Neurosci.

114

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The spiking activity of nearby cortical neurons is not independent. Numerous studies have explored the importance of this correlated responsivity for visual coding and perception, often by comparing the information conveyed by pairs of simultaneously recorded neurons with the sum of information provided by the respective individual cells. Pairwise responses typically provide slightly more information so that encoding is weakly synergistic. The simple comparison between pairwise and summed individual responses conflates several forms of correlation, however, making it impossible to judge the relative importance of synchronous spiking, basic tuning properties, and stimulus-independent and stimulus-dependent correlation. We have applied an information theoretic approach to this question, using the responses of pairs of neurons to drifting sinusoidal gratings of different directions and contrasts that have been recorded in the primary visual cortex of anesthetized macaque monkeys. Our approach allows us to break down the information provided by pairs of neurons into a number of components. This analysis reveals that, although synchrony is prevalent and informative, the additional information it provides frequently is offset by the redundancy arising from the similar tuning properties of the two cells. Thus coding is approximately independent with weak synergy or redundancy arising, depending on the similarity in tuning and the temporal precision of the analysis. We suggest that this would allow cortical circuits to enjoy the stability provided by having similarly tuned neurons without suffering the penalty of redundancy, because the associated information transmission deficit is compensated for by stimulus-dependent synchrony.

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“…Magnitude is an inherent property of all stimuli, and its subjective perceptual estimation, when assayed psychophysically, conforms to a power function whereby a constant percentage increase in the stimulus magnitude produces a constant percentage increase in the sensed effect (1). Neurophysiological recordings have shown that increasing stimulus magnitude is transduced by peripheral sense organs following the power law then ''represented'' by a linear increase in response strength across sensory system levels feeding ''primary'' cortical areas (2)(3)(4). In the auditory system, the magnitude and modulation of the sound-pressure envelope provide information that is essential for the perception of the distance separating an animal or human from other sound sources and convey critical information for vocal communication (5).…”

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confidence: 99%

Associative learning shapes the neural code for stimulus magnitude in primary auditory cortex

Polley

Heiser

Blake

et al. 2004

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

120

116

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Since the dawn of experimental psychology, researchers have sought an understanding of the fundamental relationship between the amplitude of sensory stimuli and the magnitudes of their perceptual representations. Contemporary theories support the view that magnitude is encoded by a linear increase in firing rate established in the primary afferent pathways. In the present study, we have investigated sound intensity coding in the rat primary auditory cortex (AI) and describe its plasticity by following paired stimulus reinforcement and instrumental conditioning paradigms. In trained animals, population-response strengths in AI became more strongly nonlinear with increasing stimulus intensity. Individual AI responses became selective to more restricted ranges of sound intensities and, as a population, represented a broader range of preferred sound levels. These experiments demonstrate that the representation of stimulus magnitude can be powerfully reshaped by associative learning processes and suggest that the code for sound intensity within AI can be derived from intensity-tuned neurons that change, rather than simply increase, their firing rates in proportion to increases in sound intensity.intensity ͉ plasticity ͉ Pavlovian ͉ sound ͉ perceptual learning A complete rendering of the neural code for a stimulus event must portray not only how the stimulus engages the receptor sheet over space and time but also how stimulus magnitude impacts the spatiotemporal patterns of neural responses in central sensory structures. Magnitude is an inherent property of all stimuli, and its subjective perceptual estimation, when assayed psychophysically, conforms to a power function whereby a constant percentage increase in the stimulus magnitude produces a constant percentage increase in the sensed effect (1). Neurophysiological recordings have shown that increasing stimulus magnitude is transduced by peripheral sense organs following the power law then ''represented'' by a linear increase in response strength across sensory system levels feeding ''primary'' cortical areas (2-4). In the auditory system, the magnitude and modulation of the sound-pressure envelope provide information that is essential for the perception of the distance separating an animal or human from other sound sources and convey critical information for vocal communication (5). Although the psychophysical thresholds for human loudness discrimination (1, 6) and putative neural codes for loudness based on firing rate or spatial patterns of excitation have been described in the eighth nerve, auditory midbrain and primary auditory cortex (AI) (7-13), very little is known about how, or if, loudness discrimination thresholds can be altered by training or how the effects of such perceptual learning would affect the hypothesized ''neural codes'' for loudness.In the present study, we demonstrate that training animals to associate changes in sound intensity with reward induced largescale plasticity in the neuronal response representation of sound intensity in the AI. Ra...

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Neural Activity in Mechanoreceptive Cutaneous Afferents: Stimulus-Response Relations, Weber Functions, and Information Transmission

Cited by 456 publications

References 0 publications

Tactile intensity and population codes

Tactile intensity and population codes

The Role of Correlations in Direction and Contrast Coding in the Primary Visual Cortex

Associative learning shapes the neural code for stimulus magnitude in primary auditory cortex

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