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Biomedical subjects

I Peretz

Publications and source records attributed to I Peretz.

At least 37 records · Page 2Linked to original sources

Atypical hemispheric specialization in intellectual deficiency.

In order to determine the relation between hemispheric specialization for language and intellectual deficiency, two groups of lower-IQ subjects were compared to normal-IQ controls on word-dichotic listening tasks. Two conditions in which stimuli differed by their level of phonological complexity were used. Normal controls showed the expected right-ear advantage in both conditions. Moreover, they showed a greater magnitude of ear difference on the condition requiring higher-order phonological processing. In the mentally deficient group, almost half the subjects exhibited a left-ear advantage and they showed no difference between the two conditions in terms of the magnitude of ear difference. These results point to the presence of atypical hemispheric specialization in mentally deficient subjects.

Adolescent↗

Left ear advantage in pitch perception of complex tones without energy at the fundamental frequency.

Normal right-handed subjects were required to make pitch comparisons of complex tones in which the fundamental frequency was either present or absent. In both conditions, tones were presented monaurally. An increase in left-ear superiority was observed in the response time measurements when the fundamental was absent. These findings support the notion that the right hemisphere possesses a special mechanism for pitch computation.

Adult↗

Examination of the working memory components in normal aging and in dementia of the Alzheimer type.

The verbal and attentional components of working memory were examined in patients with Alzheimer's disease, normal elderlies, and young controls. Patients with Alzheimer's disease, showed a reduced span but were sensitive to word length. This is indicative of a functional rehearsal procedure. However, the effect of phonological similarity on immediate recall was smaller in patients with Alzheimer's disease and these patients showed a depressed performance in tasks of phonological analysis. There was also a significant decrement in a task that assessed the attentional component of working memory. Examination of individual patterns of performance showed that the phonological deficiency was severe in a subgroup of patients while the attentional deficit was more general.

Adolescent↗

Perceiving the tonal ending of tune excerpts: the roles of pre-existing representation and musical expertise.

In this study, sensitivity to tonal relations was assessed by using real melodies instead of traditional scales or chords. Two groups of listeners-one trained, one untrained-rated the goodness of fit of each of the 12 tones of the chromatic scale as the final note of familiar and unfamiliar tune excerpts. The unfamiliar excerpts were the mirror forms in pitch and time of the familiar tunes. The results showed that musicians and nonmusicians exhibited responses that were governed by tonal relations with both familiar and unfamiliar tunes. These findings were corroborated by multiple-regression analysis, which revealed that the pattern of ratings reflected knowledge of the musical structure, beyond the contribution of surface features such as note frequency or pitch proximity between the two last tones.

Adolescent↗

[Musical excerpts: indices relating to familiarity, age of acquisition and verbal associations].

The objective of the present study was to establish estimates of familiarity, of age of acquisition, and of verbal associations in relation to 144 musical excerpts drawn from the repertoire of tunes that is expected to be shared by all French-speaking Québec university students. The excerpts were synthesized monophonic lines (which can be found in Appendix B) that were tape recorded. A first group of 60 university students were required to indicate their degree of familiarity (on a 5-point scale) with each excerpt and the age period at which they learned the excerpt. A second group of 60 students indicated whether the original tune was vocal or instrumental as well as the first words that came to mind. In each group, half the subjects were presented with the 144 excerpts in a different order. Overall, the material was found to be highly familiar and to have been mostly learned between the ages of 5 and 15. Most of the excerpts were easily categorized as vocal or instrumental with the exception of 26 excerpts, which were accordingly classified as ambiguous. Finally, 57% of the excerpts elicited verbal responses. There was a high level of agreement in some of the verbal responses provided, referred to as dominant responses. In contrast, 21 excerpts gave rise to very little verbal recall, hence specifying a subset of "purely" musical material. All indices of familiarity, of acquisition age, and of verbal responses (specifying the overall rate of verbal responding, the content of the dominant response as well as its frequency of occurrence) are provided for each excerpt in Appendix A. Finally, the most interesting aspect of the present study was revealed by the analysis of the errors in verbal recall. Subjects tended to fill in missing elements by words that fitted the meaning of song lyrics as well as the temporal structure of the music. For instance, instead of providing "MON BEAU SAPIN", subjects would provide "mon grand sapin". The use of such a procedure is consistent with the notion that music serves as a memory aid which facilitates the communication of news and ideas.

Adult↗

Functional dissociations following bilateral lesions of auditory cortex.

We present two patients with bilateral lesions of the superior temporal cortex who manifested a number of functional dissociations in the auditory domain. The perception of speech and environmental sounds were preserved; yet, the perception of tunes, prosody and voice was impaired. As the processing of melodic but not rhythmic variations in musical sequences was selectively disturbed, the deficit cannot be attributed to a general impairment in auditory memory or sequential processing. These findings suggest that melody processing is not mediated by a general-purpose auditory architecture but by specialized cortical subsystems residing within the lesioned areas. Current taxonomies of auditory agnosia and models of normal music cognition are evaluated in light of the functional dissociations manifested by these patients.

Adult↗

Boundaries of separability between melody and rhythm in music discrimination: a neuropsychological perspective.

The detailed study of a patient who suffered from a severe amelodia without arhythmia as a consequence of bilateral temporal lobe damage revealed that the processing of melodic information is at least partially separable from the processing of rhythmic information. This dissociation was replicated across different sets of material, was supported by the presence of a reversed association, and was maintained in conditions that promote integration in the normal brain. These results argue against the view that melody and rhythm are treated as a unified dimension throughout processing. At the same time, they support the view that integration takes place after early separation of the two dimensions.

Adult↗

The role of contour and intervals in the recognition of melody parts: evidence from cerebral asymmetries in musicians.

The left hemisphere (LH) has been shown to be involved in tasks requiring interval-based procedures, and the right hemisphere (RH) in task allowing a contour-based approach in melody recognition. Support for this distinction was obtained by studying contour properties at the level of whole melodies and interval characteristics at the level of individual tones. The purpose of the present study was to extend the validity of this two-component model at the level of melody parts. It was predicted that both the LH interval-based procedure and the RH contour-based approach contribute to melody part recognition, but that their respective efficiency will depend on the structure of the parts used as recognition probes. To address this question along the lines of prior work Bever and Chiarello, Science 185, 537-539, 1974), a probe recognition task was presented monaurally to right-handed musicians. The recognition probes that corresponded to one of the melody parts were found to be far more accurately and quickly recognized than the probes that bridged across the contour-defined boundary. On the latter, subjects performed initially at about chance level. They improved, however, after some exposure to the task, that is on the second half of the test material in Experiment 1 and on the second half of Experiment 2, and displayed the predicted interaction between laterality and probe type. Subjects recognized the probes that coincided with a part delineated by contour boundaries in the left ear (or the RH) more easily; whereas they recognized more easily the probes which crossed contour boundaries in the right ear (or the LH). These findings justify the consideration of contour as an important grouping factor in pitch sequences and emphasize the usefulness of laterality effects.

Adult↗

Contribution of articulatory rehearsal to short-term memory: evidence from a case of selective disruption.

We describe a brain-damaged patient with disturbed articulatory rehearsal in whom all predictions derived from a working memory model were fulfilled. The patient showed a reduced verbal span, no word-length effect on immediate recall in both the visual or the auditory modalities, no phonological similarity effect in the visual modality, and no effect of articulatory suppression. A slowed overt articulation rate provided independent evidence for disrupted articulatory rehearsal. The other components of working memory, the visuospatial scratch-pad, phonological storage system, and central executive, were functional. The selectivity of the deficit can be taken as evidence for the specific role of articulatory rehearsal in working memory.

Aphasia↗

Processing of local and global musical information by unilateral brain-damaged patients.

Melody processing in unilaterally brain-damaged patients was investigated by manipulating the availability of contour and metre for discrimination in melodies varying, respectively, on the pitch dimension and the temporal dimension. On the pitch dimension, right brain-damaged patients, in contrast to left brain-damaged patients and normal controls, were found to be little affected by the availability of contour as a discrimination cue. However, both brain-damaged groups were impaired on tasks requiring consideration of pitch interval structure. These findings are consistent with hierarchical contribution of the cerebral hemispheres, with the right hemisphere being primary in representing the melody in terms of its global contour and the left hemisphere by filling in the intervallic structure. On the temporal dimension, only the discrimination of durational values (the rhythm) was found to be impaired by a lesion in either hemisphere, which spared, however, the metric interpretation of the musical sequences. These latter results are discussed in the light of current models of temporal processing. Finally, evidence of double dissociation between the processing of the pitch dimension and the processing of rhythm was obtained, providing further support for the need to fractionate musical perceptual abilities in order to arrive at a theory as to how the two hemispheres cohere to produce a musical interpretation of the auditory input.

Adult↗

Dichotic perception and laterality in neonates.

Groups of 4-day-old neonates were tested for dichotic discrimination and ear differences with the High-Amplitude-Sucking procedure. In the first experiment, dichotic speech discrimination was attested by comparison with a control group. Furthermore, among those subjects who showed a substantial recovery of sucking response at least after one of the two syllable changes, it was observed that significantly more subjects manifested a stronger reaction to a right-ear change than to a left-ear change. In the second experiment, 4-day-old neonates were tested on syllable and music timbre discrimination. The significant Stimulus Type x Ear interaction observed suggests perceptual asymmetries indicative of very precocious brain specialization.

Arousal↗

Analytic processing in the classification of melodies as same or different.

Two groups of non-musicians were required to classify pairs of melodies as "same" or "different". The experimental group was instructed to respond as fast as possible, while the control group did not receive such a speed requirement. Contrary to the control subjects, the experimental subjects exhibited a right-ear advantage in accuracy for "different" responses. Thus, time pressure was instrumental in inducing subjects to rely mainly on left-hemisphere processing. The fact that "different" responses were both faster than "same" ones and quicker than melody offset indicates the use of a self-terminating search process. The features searched for were, in all likelihood, local. Indeed, contrary to control subjects, experimental subjects performed equally well with (1) melodies differing in both contour and local pitches and with (2) melodies differing in local pitches only.

Adolescent↗

Shifting ear differences in melody recognition through strategy inducement.

In a previous study, the pattern of ear superiority displayed by nonmusicians in a task where dichotically presented target melodies have to be recognized among four probes was found to be correlated with subjects' descriptions of their operating modes: those who reported focusing on critical local differences in pitch tended to show right ear advantage (REA) and the others LEA. The purpose of the present study was to examine if laterality patterns can be affected by treatments designed to induce particular strategies. Treatments supposed to orient toward analytic processing, advising attention to critical notes, with (Experiment 2) or without (Experiment 1) the additional task of reporting their location, produced the expected shift toward REA. To the contrary, treatments supposed to orient toward holistic processing, advising attention to overall contour or requesting aesthetic judgments (Experiment 1), failed to produce the expected shift toward LEA. The result can be attributed either to a basic difference in susceptibility to strategic control between the different operating modes or, more simply, to ineffectiveness of the present holistically oriented treatments.

Adolescent↗

Shifting ear differences in melody comparison through transposition.

Nonmusicians were required to classify pairs of melodies as "same" or "different". When they were instructed to compare melodies played at the same pitch level as fast as possible, a REA was elicited. In contrast, a tendency in favor of the left ear came out when, all other things being equal, melodies were transposed, i.e. played at a different pitch level. Transposition was thus instrumental in leading subjects to rely more on right-hemisphere processing. Independent evidence for a change in the processing mode that was adopted with these two types of material was provided by the response times. The results indicated the use of a self-terminating process of analytic search only with the untransposed melodies. Results are discussed in terms of the notion that the preferential use of local or global properties in melodies determines the intervention of the left or the right cerebral hemisphere, respectively.

Adolescent↗

[Hemispheric asymmetry in amusia].

The search of hemispheric dominance for music has been for long the main aim of the study of amusias. Musical abilities were first localized in the left hemisphere, then in the right one. In the light of the available data, these two diverging conceptions do not appear paradoxical anymore. Indeed, brain injury on either side can provoke musical deficits. However, the nature of the deficit seems to depend on the particular hemisphere damaged. Right-sided lesions appear to disturb the melodic aspects of musical sequences while left-sided lesions seem to deteriorate the rhythmic aspects. Although the clinical literature involves insightful suggestions on how the musical abilities are organized, especially with respect to linguistic functions, these indications are not sufficient to provide a clear picture of the nature of the functional differences for music between hemispheres. Research is not systematic. Commentaries and suggestions are proposed to guide future investigations.

Aphasia↗

Task determinants of ear differences in melody processing.

In Experiment 1 nonmusicians were presented with dichotic melodies, which differed either on all pitches or by a single note, followed by a set of four binaural melodies. They were asked to recognize among the alternatives only one member of the dichotic pair in the "single-focus" task, and both dichotic melodies in the "double-focus" task. These different attention requirements led to a LEA in the first task which contrasted with the REA observed in the other task when melodies differed by all pitches. A possible confounding (fusion of the common pitches) prevents comparison of the tasks for melodies differing by a single pitch. The role of the extent of melody differences was further investigated in a second experiment by changing melodies on one, two, or three notes. No effect of material was observed on ear asymmetries. Task demands appeared as the most critical determinant of ear differences and are discussed in terms of their particular influence on the adoption of an analytic or holistic processing mode. Male subjects were found to be more responsive than females to analytic processing suggestions.

Adult↗