Frequency discrimination in the auditory system: Place or periodicity mechanisms?
01 May 1970-Vol. 58, Iss: 5, pp 723-730
TL;DR: A modification of the structure of an optimum sinusoidal frequency discrimination system is conjectured that seems to be, at least qualitatively, consistent with the available evidence.
Abstract: The pattern of all-or-none firings in many sensory nerves can usefully be modeled as a set of sample functions from non-stationary random processes whose parameters are determined by the sensory stimulus. Given such a description, one can compare the parameter estimation, discrimination, or detection performance of a human observer (as measured behaviorally) with the computed limiting performance of an ideal observer operating on the same neural input. Such a comparison is carried out in detail for the discrimination in frequency of an auditory sinusoidal tone burst. The results suggest that the human listener behaves as if he ignored (at least for this class of sounds) the periodicity information in the auditory nerve pattern (resulting from the phase-locking of the firings to the stimulus), but made full effective use of the place information (resulting primarily, although not entirely, from the mechanical tuning of the inner ear). On the other hand, it is known that the auditory system can discriminate certain more complicated stimuli on the basis of periodicity information if that is the only cue available. A modification of the structure of an optimum sinusoidal frequency discrimination system is conjectured that seems to be, at least qualitatively, consistent with the available evidence.
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TL;DR: This work reviews the striking progress in the study of the links between neural activity and perception, giving particular emphasis to the kinds of neural events that underlie the perceptual judgments of conscious observers.
Abstract: The newly defined field of cognitive neuroscience attempts to draw together the study of all brain mechanisms that underlie our mental life. Historically, the major sensory pathways have provided the most trustworthy insights into how the brain supports cognitive functions such as perception, attention, and shortterm memory. The links between neural activity and perception, in particular, have been studied revealingly in recent decades. Here we review the striking progress in this area, giving particular emphasis to the kinds of neural events that underlie the perceptual judgments of conscious observers.
794 citations
Cites background from "Frequency discrimination in the aud..."
...It quickly became clear that the quality of signals available by pooling over the population of neurons would be easily sufficient to explain the known behavioral performance (Siebert 1970)....
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TL;DR: A simple calculation is described which combines rate, place, and temporal information to provide a good representation of the vowels' spectra, including a clear indication of at least the first two formant frequencies.
Abstract: This paper is concerned with the representation of the spectra of synthesized steady‐state vowels in the temporal aspects of the discharges of auditory‐nerve fibers. The results are based on a study of the responses of large numbers of single auditory‐nerve fibers in anesthetized cats. By presenting the same set of stimuli to all the fibers encountered in each cat, we can directly estimate the population response to those stimuli. Period histograms of the responses of each unit to the vowels were constructed. The temporal response of a fiber to each harmonic component of the stimulus is taken to be the amplitude of the corresponding component in the Fourier transform of the unit’s period histogram. At low sound levels, the temporal response to each stimulus component is maximal among units with CFs near the frequency of the component (i.e., near its place). Responses to formant components are larger than responses to other stimulus components. As sound level is increased, the responses to the formants, pa...
551 citations
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...( Sicbert, 1970; Goldstein, 1972; Litt_lefield, 1973; Johnson, 1974)...
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TL;DR: A model in which spikes are generated by a Poisson process whose rate is the product of a drive that is sensory in origin and a gain summarizing stimulus-independent modulatory influences on excitability provides an accurate account of response distributions of visual neurons in macaque lateral geniculate nucleus and cortical areas V1, V2 and MT.
Abstract: Responses of sensory neurons differ across repeated measurements. This variability is usually treated as stochasticity arising within neurons or neural circuits. However, some portion of the variability arises from fluctuations in excitability due to factors that are not purely sensory, such as arousal, attention and adaptation. To isolate these fluctuations, we developed a model in which spikes are generated by a Poisson process whose rate is the product of a drive that is sensory in origin and a gain summarizing stimulus-independent modulatory influences on excitability. This model provides an accurate account of response distributions of visual neurons in macaque lateral geniculate nucleus and cortical areas V1, V2 and MT, revealing that variability originates in large part from excitability fluctuations that are correlated over time and between neurons, and that increase in strength along the visual pathway. The model provides a parsimonious explanation for observed systematic dependencies of response variability and covariability on firing rate.
522 citations
TL;DR: It is shown that efficient information transmission is achieved by a transformation of the initial three colour mechanisms into an achromatic and two opponent chromatic channels, providing a logical rationale reconciling opponent type processing as an optimal necessary step after the initialThree colour mechanisms.
Abstract: This paper presents a systematic analysis of the role of opponent type processing in colour vision and the relation between opponent type colour transformations and the initial three colour mechanisms. It is shown that efficient information transmission is achieved by a transformation of the initial three colour mechanisms into an achromatic and two opponent chromatic channels. The derivation of the transformation is dependent solely on criteria from information theory. Thus it provides a logical rationale reconciling opponent type processing as an optimal necessary step after the initial three colour mechanisms, unifying respectively the Hering and Young-Helmholtz approaches to colour vision. The effects of chromatic adaptation on the spectral response of the achromatic and two chromatic channels are discussed from the point of view of information theory. It is argued that adaptation serves as a dynamic readjustment of these responses, necessary to meet criteria of efficient colour information transmission. The results are confronted with empirical observations to test the principles of the theory and the relation to other theories is discussed. Within the same framework the issue of trichromacy is discussed. It is argued that a broad class of typical colour spectra can effectively be represented by three significant degrees of freedom that make up a trichromatic system.
508 citations
TL;DR: An analytically tractable framework is presented to describe mechanical and neural processing in the early stages of the auditory system, and algorithms are developed to assess the integrity of the acoustic spectrum at all processing stages.
Abstract: An analytically tractable framework is presented to describe mechanical and neural processing in the early stages of the auditory system. Algorithms are developed to assess the integrity of the acoustic spectrum at all processing stages. The algorithms employ wavelet representations, multiresolution processing, and the method of convex projections to construct a close replica of the input stimulus. Reconstructions using natural speech sounds demonstrate minimal loss of information along the auditory pathway. Close inspection of the final auditory patterns reveals spectral enhancements and noise suppression that have close perceptual correlates. The functional significance of the various auditory processing stages is discussed in light of the model, together with their potential applications in automatic speech recognition and low bit-rate data compression. >
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TL;DR: It is found that the presence of a second tone diminishes the responses to the first tone if appropriate stimulus parameters are chosen and all fibers tested showed this two‐tone inhibition.
Abstract: Spike discharges from single fibers in the auditory nerve of anesthetized cats were recorded with micro‐electrodes. Rates of discharge were measured as functions of the frequencies and levels of either single tones or two tones presented simultaneously. We found that the presence of a second tone diminishes the responses to the first tone if appropriate stimulus parameters are chosen. All fibers tested showed this two‐tone inhibition. Response areas and inhibitory areas were defined from isorate contours. The general characteristics of the inhibitory areas are found to be similar for a population of over 300 fibers.
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TL;DR: In this paper, the first and second effects of pitch shift were investigated for a spectrum consisting of three Fourier components and the ambiguity of pitch was measured in two more or less independent ways.
Abstract: The residue is defined as the joint perception of a number of Fourier components. Depending on circumstances outside the scope of this paper, it has a pronounced pitch. The consequences of this phenomenon for the theory of hearing are briefly reviewed in the light of past experiments. Special attention is then called to what are termed the first and second effects of pitch shift. The first effect is found when equidistantly shifting the entire Fourier spectrum. The second effect shows itself primarily in a slight drop in pitch when increasing the frequency spacing of the Fourier components. Presented are rather extensive measurements of these effects for a spectrum consisting of three components. Their inherent connection is shown along with their mathematical relationship. As an important experimental finding, the ambiguity of pitch is presented, measured in two more‐or‐less independent ways. All these phenomena strongly point towards a pitch‐extracting mechanism different from and subsequent to the basilar membrane and operating in the time domain.
403 citations