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Results for “Pitch Discrimination”

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PubMed2000

ERP development in the rat in the course of learning two-tone discrimination task.

To clarify some neurophysiological aspects of learning, we investigated the relationship between the course of learning and development of ERP and investigated developmental processes of ERPs. Nine male Sprague-Dawley rats were trained for a two-tone discrimination task and rat P3 and N1 component were longitudinally recorded. Both rat P3 and N1 gradually increased with learning only for target tones. An improvement in the proportion of correct responses preceded the increase in ERPs, and the increase in P3 and N1 proceeded almost simultaneously. These findings suggest that multiple kinds of information processing were acquired with learning the two-tone discrimination task. ERP development could be utilized as an index of establishment of learning.

Acoustic Stimulation↗
PubMed2000

The selectivity of the occipitotemporal M170 for faces.

Evidence from fMRI, ERPs and intracranial recordings suggests the existence of face-specific mechanisms in the primate occipitotemporal cortex. The present study used a 64-channel MEG system to monitor neural activity while normal subjects viewed a sequence of grayscale photographs of a variety of unfamiliar faces and non-face stimuli. In 14 of 15 subjects, face stimuli evoked a larger response than non-face stimuli at a latency of 160 ms after stimulus onset at bilateral occipitotemporal sensors. Inverted face stimuli elicited responses that were no different in amplitude but 13 ms later in latency than upright faces. The profile of this M170 response across stimulus conditions is largely consistent with prior results using scalp and subdural ERPs.

Acoustic Stimulation↗
PubMed2004

Formant discrimination in noise for isolated vowels.

Formant discrimination for isolated vowels presented in noise was investigated for normal-hearing listeners. Discrimination thresholds for F1 and F2, for the seven American English vowels /i, I, epsilon, ae, [symbol see text], a, u/, were measured under two types of noise, long-term speech-shaped noise (LTSS) and multitalker babble, and also under quiet listening conditions. Signal-to-noise ratios (SNR) varied from -4 to +4 dB in steps of 2 dB. All three factors, formant frequency, signal-to-noise ratio, and noise type, had significant effects on vowel formant discrimination. Significant interactions among the three factors showed that threshold-frequency functions depended on SNR and noise type. The thresholds at the lowest levels of SNR were highly elevated by a factor of about 3 compared to those in quiet. The masking functions (threshold vs SNR) were well described by a negative exponential over F1 and F2 for both LTSS and babble noise. Speech-shaped noise was a slightly more effective masker than multitalker babble, presumably reflecting small benefits (1.5 dB) due to the temporal variation of the babble.

Acoustic Stimulation↗
PubMed1977

Orientation and lever responding in auditory discriminations in squirrel monkeys.

Head orientation during auditory discriminations was studies in squirrel monkeys using a two-lever trial-by-trial procedure. Animals were studied using auditory discriminations based on the position of the sound and on the spectral content differences between a pure tone and a noise. After the percentage of correct responses reached asymptote, head orientation was measured using videotape recordings. Orientation occurred on virtually every trial and was under the control of the position of the sound under all conditions. Lever responding was controlled by the same parameters of the sound under some conditions, and by different parameters in others. Orientation and lever responding were correlated (a level response could be predicted from the direction of orientation) when both responses were under the control of the same parameters of the sound. The two responses were uncorrelated when they were controlled by different parameters of the sound. Orientation and lever responding were not functionally related.

Animals↗
PubMed2000

Influence of sensitivity on response bias in taste and audition.

A detection theoretic analysis was employed to examine sensitivity and response bias in two modalities. In Experiment 1, 6 tasters made same-different judgments about the concentration of either sucrose or quinine in pairs of tonic water samples. The beverages were colored, but color was not predictive of the concentration of the sweet or bitter ingredient. When same-different ratings were collapsed to approximate the outcome of a categorical decision, tasters with poorer sensitivity appear to have adopted more extreme response criteria than did tasters with greater sensitivity, irrespective of taste quality, color, or whether pairs of solutions comprised the same or different colors. In Experiment 2, 3 individuals discriminated pairs of 1000-Hz sinusoids differing in amplitude. Six amplitude differences were tested. Rating-scale versions of two paradigms: The single-interval yes-no task and the two-interval same-different task were used to measure sensitivity and bias. There was a preponderance of "same" responses in the same-different task. Estimates of bias obtained from collapsed ratings in both tasks were unaffected by sensitivity, but a consideration of the range over which sets of criteria were spread suggested a general tendency toward more conservative response biases as sensitivity declined.

Adult↗
PubMedDate not supplied

[Neuronal activity of the caudate nucleus in the cat upon presentation of positive and negative conditioned stimuli].

Spike activity in the cat caudate nucleus was studied during accomplishment of a positive instrumental defensive reflex, as well as during formation of inhibitory--differentiation and extinction--conditioned reflexes. Most of the neurones which exhibited plastic reorganizations, were localized in the dorsal segment of the caudate nucleus. With a well stabilized conditioned reflex, spike reactions of the inhibitory sign prevailed. In response to inhibitory stimuli, bioelectrical activity set in neurones, whose spike discharges were suppressed during realization of the conditioned reflex, as well as a change of the sign of evoked spike reactions in some cells reacting to the positive stimulus.

Animals↗
PubMed1993

Auditory perception of fractal contours.

A series of experiments examined auditory contour formation, investigating listeners' sensitivities to a family of random fractals known as fractional Brownian noises. Experiments 1A and 1B looked at identification of contours when 3 different noises were portrayed using variations in the pitch, duration, or loudness of successive notes of a sequence. Listeners could categorize pitch and loudness encodings, but not duration mappings. Experiment 2 looked at the effect of simultaneous presentation of pitch and loudness information, finding that these dimensions combined additively to increase identification of the noise distributions. Experiment 3 looked at discrimination of pitch contours as a function of changing fractal dimension. Discrimination curves approximated an inverted U shape, a finding that is not understandable in terms of sensitivity to differences in fractal dimension per se, nor in terms of "tuned" perceptual sensitivity to statistical regularities of the environment.

Acoustic Stimulation↗
PubMed2005

An autocorrelation model with place dependence to account for the effect of harmonic number on fundamental frequency discrimination.

Fundamental frequency (f0) difference limens (DLs) were measured as a function of f0 for sine- and random-phase harmonic complexes, bandpass filtered with 3-dB cutoff frequencies of 2.5 and 3.5 kHz (low region) or 5 and 7 kHz (high region), and presented at an average 15 dB sensation level (approximately 48 dB SPL) per component in a wideband background noise. Fundamental frequencies ranged from 50 to 300 Hz and 100 to 600 Hz in the low and high spectral regions, respectively. In each spectral region, f0 DLs improved dramatically with increasing f0 as approximately the tenth harmonic appeared in the passband. Generally, f0 DLs for complexes with similar harmonic numbers were similar in the two spectral regions. The dependence of f0 discrimination on harmonic number presents a significant challenge to autocorrelation (AC) models of pitch, in which predictions generally depend more on spectral region than harmonic number. A modification involving a "lag window"is proposed and tested, restricting the AC representation to a limited range of lags relative to each channel's characteristic frequency. This modified unitary pitch model was able to account for the dependence of f0 DLs on harmonic number, although this correct behavior was not based on peripheral harmonic resolvability.

Acoustic Stimulation↗