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Results for “Pitch Discrimination”

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At least 433 records · Page 24Linked to original sources
PubMed1986

Hippocampal lesions disrupt classical conditioning of cross-modality reversal learning of the rabbit nictitating membrane response.

The role of the hippocampus and subiculum in classical conditioning of tone-light discrimination reversal learning of the rabbit nictitating membrane response was investigated using aspiration lesions of both limbic structures. Only two of seven animals with hippocampal-subicular damage successfully reached reversal criteria within 21 days of conditioning, although all hippocampectomized animals learned the initial discrimination at rates equivalent to those of two control groups. Thus, previously reported deficits in two-tone reversal learning seen after similar lesions are not due to increased within-modality generalization to the conditioned stimuli (CS) serving as the CS+ and CS-.

Animals↗
PubMed1982

Evoked potentials in the dentate gyrus reflect the retention of past sensory events.

Averaged sensory evoked potentials were recorded from the outer molecular layer of the dentate gyrus (OM AEP) in freely moving rats trained to criterion performance in a two-tone differential discrimination paradigm. OM AEPs showed consistent fluctuations in amplitude based on the acquired significance of the tone through their association with reward (CS+) or non-reward (CS-). However, the relationship between tone significance and OM AEP configuration was dependent upon the sequence of trials preceding the evoked potential, irrespective of whether the potential was evoked by a CS+ or CS-. Specifically, when the preceding sequence contained an increased number of CS- trials, the amplitude of the initial negative component (N1) of the OM AEP was increased, while that of the slower (N2) component was reduced; conversely, when the preceding sequence contained an increased number of CS+ trials, the amplitude of N1 was reduced, while that of N2 was increased. The results suggest that the transmission of sensory information into the dentate gyrus is biased by prior experience.

Animals↗
PubMed1989

Discriminability, loudness, and masking in the rat (Rattus norvegicus): a confirmation and extension.

In Experiment 1, rats discriminated between two sound pressure levels (SPL) of a pure tone: standard (STD) SPLs of 84 and 74 dB and comparison (CO) SPLs 4, 14, and 24 dB below STD were tested in quiet and 60 dB noise at 4 and 12.5 kHz (24 conditions). The decibel difference between STD and CO accounted for only 43.52% of the variance in the signal detection measure of sensitivity, d', across conditions, whereas the loudness difference (LD = STD0.35 - CO0.35) accounted for 89.82% of the variance in d'. These results confirm and extend previous observations that: (a) equal decibel differences are not equally discriminable; (b) loudness for the rat increases as a power function of SPL with an exponent of 0.35: and (c) masked loudness is a linear function of loudness in quiet. In Experiment 2, the assumptions of normal distribution and equal variance implicit in the use of the d' measure were examined. Receiver operating characteristic curves that were well approximated by straight lines of unit slope in normal-normal coordinates were obtained and thereby validated the use of d' in Experiment 1.

Animals↗
PubMed2003

The effect of training on frequency discrimination: generalization to untrained frequencies and to the untrained ear.

While there is growing evidence that frequency discrimination improves with practice, there are, however, limited and inclusive reports regarding the generalization of learning to untrained conditions. The goals of the present study were therefore (1) to measure the effect of multi-session training on difference limen frequency (DLF) thresholds and evaluate the relative contribution of procedural and stimulus learning by comparison to a control (untrained) group; (2) to evaluate the extent of generalization of the trained frequency to two untrained frequencies known to be temporally coded; and (3) to estimate the generalization of the trained frequency to the untrained ear, for both trained and untrained frequencies. Two groups of subjects were included: a trained group (n = 5) and a control group (n = 5). For the trained group, DLF thresholds for 1 kHz (trained frequency) and 1.1 and 2.0 kHz (untrained frequencies) were obtained using a two-interval, two-alternative forced choice paradigm before and after an eight-session training. The control group was tested using the same stimuli only twice, with a 3-week interval between testing. Results showed that (1) multi-session training improves frequency discrimination in normal hearing young adults; (2) adding a control group to the study allowed estimation of the effect of limited exposure to the stimuli and task in naïve listeners and evaluation of the magnitude of procedural learning; (3) learning was generalized across frequencies that are coded by similar mechanisms; (4) generalization of learning occurred in the untrained ear for trained and untrained frequencies. These results have important clinical and theoretical implications regarding the processes underlying perceptual learning and the effectiveness of auditory habilitation strategies.

Acoustic Stimulation↗
PubMedDate not supplied

[Internal inhibition in rats after destruction of amygdaloid complex nuclei].

In experiments on male albino rats bilateral lesions of the basolateral amygdala (BLA) impaired extinction and differentiation of the food-procuring conditioned reflexes where as bilateral corticomedial (CMA) lesions had no effect on them. The BLA damage caused a significant impairment of the aversive stimuli discrimination but had no effect on the extinction of the conditioned avoidance reflex in a shuttle-box. The CMA lesions in both hemispheres led to attenuation of aversive stimuli discrimination and delay of avoidance extinction. The data obtained testify to the BLA dominant role in internal inhibition of the alimentary conditioned reflexes and the CMA dominant role in internal inhibition of avoidance conditioning and furthermore to the importance of BLA in the evaluation of the emotional significance and biological validity of the stimuli (reward or punishment).

Amygdala↗
PubMed1978

Strength of the pitches associated with ripple noise.

A discrimination procedure was used to measure the pitch strength of the repetition pitches associated with comb-filtered or ripple noise. Pitch strength was measured as a function of overall ripple noise level, the repetition pitch of the noise, and as a function of the center frequency of 1/3-octave bandpass filtered noise. In addition, other experiments were conducted to help determine which parameters should be used in measuring pitch strength when the discrimination procedure is employed. Pitch strength was strongest for pitches of approximately 500 Hz. The stimuli had essentially no pitch strength for pitches below 50 and above 2000 Hz. The strongest pitches were obtained when 1/3-octave filters were placed in a frequency region cented at four times the repetition pitch. Filtering at other center frequencies resulted in a large decrease in pitch strength. These results are consistent with assumptions concerning the dominant region for pitch perception of complex stimuli. The results are also discussed in terms of processing information from reflected sound sources.

Auditory Threshold↗
PubMed1999

Culture-general and culture-specific factors in the discrimination of melodies.

We examined effects of a culture-general factor, pattern redundancy (number of repeated tones), on the discrimination of 5-tone melodies that differed in their adherence to Western tonal conventions. Experiment 1 evaluated the ability of 9-month-old infants to differentiate "standard" melodies from subtly altered "comparison" melodies. Greater redundancy of the standard melodies was associated with enhanced infant performance, but musical conventionality had no effect. Experiment 2 evaluated comparable abilities in 5-year-old children and musically untrained adults. Children's performance was enhanced by the redundancy of standard melodies, but the effect was greater in conventional than in unconventional contexts. The redundancy of standard melodies facilitated adults' performance in conventional but not in unconventional contexts. Thus, increasing musical exposure seems to attenuate the effects of culture-general factors such as pattern redundancy while amplifying the influence of culture-specific factors.

Adult↗