Behavioral and neural correlates of perceived and imagined musical timbre

The generality of findings implicating secondary auditory areas in auditory imagery was tested by using a timbre imagery task with fMRI. Another aim was to test whether activity in supplementary motor area (SMA) seen in prior studies might have been related to subvocalization. Participants with moderate musical background were scanned while making similarity judgments about the timbre of heard or imagined musical instrument sounds. The critical control condition was a visual imagery task. The pattern of judgments in perceived and imagined conditions was similar, suggesting that perception and imagery access similar cognitive representations of timbre. As expected, judgments of heard timbres, relative to the visual imagery control, activated primary and secondary auditory areas with some right-sided asymmetry. Timbre imagery also activated secondary auditory areas relative to the visual imagery control, although less strongly, in accord with previous data. Significant overlap was observed in these regions between perceptual and imagery conditions. Because the visual control task resulted in deactivation of auditory areas relative to a silent baseline, we interpret the timbre imagery effect as a reversal of that deactivation. Despite the lack of an obvious subvocalization component to timbre imagery, some activity in SMA was observed, suggesting that SMA may have a more general role in imagery beyond any motor component.

Effects of training and melodic features on mode perception

The two modes most widely used in Western music today convey opposite moods—a distinction that nonmusicians and even young children are able to make. However, the current studies provide evidence that, despite a strong link between mode and affect, mode perception is problematic. Nonmusicians found mode discrimination to be harder than discrimination of other melodic features, and they were not able to accurately classify major and minor melodies with these labels. Although nonmusicians were able to classify major and minor melodies using affective labels, they performed at chance in mode discrimination. Training, in the form of short lessons given to nonmusicians and the natural musical experience of musicians, improved performance, but not to ceiling levels. Tunes with high note density were classified as major, and tunes with low note density as minor, even though these features were actually unrelated in the experimental material. Although these findings provide support for the importance of mode in the perception of emotion, they clearly indicate that these mode perceptions are inaccurate, even in trained individuals, without the assistance of affective labeling.

Aging and memory for music: A review

People of all ages enjoy listening to music, yet most research in musical development has concentrated on infancy through childhood. Our recent research program examined various aspects of music cognition in younger (ages 18 through 30) and older adults (ages 60 through 80) with varying amounts of musical experience. The studies investigated the independent and combined influences of age and experience on a wide assortment of long and short-term memory tasks. Results showed that some musical tasks reflect the same age-related declines as seen in nonmusical tasks, and musical training does not reduce these age-related declines. In other tasks, experience differences were larger than age differences; in some cases, age differences were nonexistent. The analysis considers how aging and experience may affect different aspects of cognition, and the paper concludes by pointing out the many musical activities that even nonmusical seniors are well equipped to succeed at and enjoy.

Absolute pitch and planum temporale

An increased leftward asymmetry of the planum temporale (PT) in absolute-pitch (AP) musicians has been previously reported, with speculation that early exposure to music influences the degree of PT asymmetry. To test this hypothesis and to determine whether a larger left PT or a smaller right PT actually accounts for the increased overall PT asymmetry in AP musicians, anatomical magnetic resonance images were taken from a right-handed group of 27 AP musicians, 27 nonmusicians, and 22 non-AP musicians. A significantly greater leftward PT asymmetry and a significantly smaller right absolute PT size for the AP musicians compared to the two control groups was found, while the left PT was only marginally larger in the AP group. The absolute size of the right PT and not the left PT was a better predictor of music group membership, possibly indicating “pruning” of the right PT rather than expansion of the left underlying the increased PT asymmetry in AP musicians. Although early exposure to music may be a prerequisite for acquiring AP, the increased PT asymmetry in AP musicians may be determined in utero, implicating possible genetic influences on PT asymmetry. This may explain why the increased PT asymmetry of AP musicians was not seen in the group of early beginning non-AP musicians.

Prediction accuracy of young and middle-aged adults in memory for familiar and unfamiliar texts

This study investigated the influence of age, familiarity, and level of exposure on the metamemorial skill of prediction accuracy on a future test. Young (17 to 23 years old) and middle-aged adults (35 to 50 years old) were asked to predict their memory for text material. Participants made predictions on a familiar text and an unfamiliar text, at three different levels of exposure to each. The middle-aged adults were superior to the younger adults at predicting performance. This finding indicates that metamemory may increase from youth to middle age. Other findings include superior prediction accuracy for unfamiliar compared to familiar material, a result conflicting with previous findings, and an interaction between level of exposure and familiarity that appears to modify the main effects of those variables.

Identification of speeded and slowed familiar melodies by younger, middle-aged, and older musicians and nonmusicians

There is a range of tempos within which listeners can identify familiar tunes (around 0.8 to 6.0 notes/s). Faster and slower tunes are difficult to identify. The authors assessed fast and slow melody-identification thresholds for 80 listeners ages 17–79 years with expertise varying from musically untrained to professional. On fast-to-slow (FS) trials the tune started at a very fast tempo and slowed until the listener identified it. Slow-to-fast (SF) trials started slow and accelerated. Tunes either retained their natural rhythms or were stylized isochronous versions. Increased expertise led to better performance for both FS and SF thresholds (r = .45). Performance declined uniformly across the 62-year age range in the FS condition (r = .27). SF performance was unaffected by age. Although early encoding processes may slow with age, expertise has a greater effect. Musical expertise involves perceptual learning with melodies at a wide range of tempos.

Perception of mode, rhythm, and contour in unfamiliar melodies: Effects of age and experience

We explored the ability of older (60-80 years old) and younger (18-23 years old) musicians and nonmusicians to judge the similarity of transposed melodies varying on rhythm, mode, and/or contour (Experiment 1) and to discriminate among melodies differing only in rhythm, mode, or contour (Experiment 2). Similarity ratings did not vary greatly among groups, with tunes differing only by mode being rated as most similar. In the same/different discrimination task, musicians performed better than nonmusicians, but we found no age differences. We also found that discrimination of major from minor tunes was difficult for everyone, even for musicians. Mode is apparently a subtle dimension in music, despite its deliberate use in composition and despite people's ability to label minor as "sad" and major as "happy."

The effects of aging and musical experience on the representation of tonal hierarchies

Two experiments explored the representation of the tonal hierarchy in Western music among older (aged 60 to 80) and younger (aged 15 to 22) musicians and nonmusicians. A probe tone technique was used: 4 notes from the major triad were presented, followed by 1 note chosen from the 12 notes of the chromatic scale. Whereas musicians had a better sense of the tonal hierarchy than nonmusicians, older adults were no worse than younger adults in differentiating the notes according to musical principles. However, older adults were more prone than younger adults to classify the notes by frequency proximity (pitch height) when proximity was made more salient, as were nonmusicians compared with musicians. With notes having ambiguous pitch height, pitch height effects disappeared among older adults but not nonmusicians. Older adults seem to have internalized tonal structure, but they sometimes fail to inhibit less musically relevant information.

Recognition of familiar and unfamiliar music in normal aging and Alzheimer's disease

We tested normal young and elderly adults and elderly Alzheimer’s disease (AD) patients on recognition memory for tunes. In Experiment 1, AD patients and age-matched controls received a study list and an old/new recognition test of highly familiar, traditional tunes, followed by a study list and test of novel tunes. The controls performed better than did the AD patients. The controls showed the “mirror effect” of increased hits and reduced false alarms for traditional versus novel tunes, whereas the patients false-alarmed as often to traditional tunes as to novel tunes. Experiment 2 compared young adults and healthy elderly persons using a similar design. Performance was lower in the elderly group, but both younger and older subjects showed the mirror effect. Experiment 3 produced confusion between preexperimental familiarity and intraexperimental familiarity by mixing traditional and novel tunes in the study lists and tests. Here, the subjects in both age groups resembled the patients of Experiment 1 in failing to show the mirror effect. Older subjects again performed more poorly, and they differed qualitatively from younger subjects in setting stricter criteria for more nameable tunes. Distinguishing different sources of global familiarity is a factor in tune recognition, and the data suggest that this type of source monitoring is impaired in AD and involves different strategies in younger and older adults.

Aging and experience in the recognition of musical transpositions

The authors examined the effects of age, musical experience, and characteristics of musical stimuli on a melodic short-term memory task in which participants had to recognize whether a tune was an exact transposition of another tune recently presented. Participants were musicians and nonmusicians between ages 18 and 30 or 60 and 80. In 4 experiments, the authors found that age and experience affected different aspects of the task, with experience becoming more influential when interference was provided during the task. Age and experience interacted only weakly, and neither age nor experience influenced the superiority of tonal over atonal materials. Recognition memory for the sequences did not reflect the same pattern of results as the transposition task. The implications of these results for theories of aging, experience, and music cognition are discussed.

Effect of unilateral temporal-lobe excision on perception and imagery of songs

Auditory imagery for songs was studied in two groups of patients with left or right temporal-lobe excision for control of epilepsy, and a group of matched normal control subjects. Two tasks were used. In the perceptual task, subjects saw the text of a familiar song and simultaneously heard it sung. On each trial they judged if the second of two capitalized lyrics was higher or lower in pitch than the first. The imagery task was identical in all respects except that no song was presented, so that subjects had to generate an auditory image of the song. The results indicated that all subjects found the imagery task more difficult than the perceptual task, but patients with right temporal-lobe damage performed significantly worse on both tasks than either patients with left temporal-lobe lesions or normal control subjects. These results support the idea that imagery arises from activation of a neural substrate shared with perceptual mechanisms, and provides evidence for a right temporal- lobe specialization for this type of auditory imaginal processing.

Common parietal activation in musical mental transformations across pitch and time

We previously observed that mental manipulation of the pitch level or temporal organization of melodies results in functional activation in the human intraparietal sulcus (IPS), a region also associated with visuospatial transformation and numerical calculation. Two outstanding questions about these musical transformations are whether pitch and time depend on separate or common processing in IPS, and whether IPS recruitment in melodic tasks varies depending upon the degree of transformation required (as it does in mental rotation). In the present study we sought to answer these questions by applying functional magnetic resonance imaging while musicians performed closely matched mental transposition (pitch transformation) and melody reversal (temporal transformation) tasks. A voxel-wise conjunction analysis showed that in individual subjects, both tasks activated overlapping regions in bilateral IPS, suggesting that a common neural substrate subserves both types of mental transformation. Varying the magnitude of mental pitch transposition resulted in variation of IPS BOLD signal in correlation with the musical key-distance of the transposition, but not with the pitch distance, indicating that the cognitive metric relevant for this type of operation is an abstract one, well described by music-theoretic concepts. These findings support a general role for the IPS in systematically transforming auditory stimulus representations in a nonspatial context. (C) 2013 Elsevier Inc. All rights reserved.

Hearing in the mind's ear: A PET investigation of musical imagery and perception

Neuropsychological studies have suggested that imagery processes may be mediated by neuronal mechanisms similar to those used in perception. To test this hypothesis, and to explore the neural basis for song imagery, 12 normal subjects were scanned using the water bolus method to measure cerebral blood flow (CBF) during the performance of three tasks. In the control condition subjects saw pairs of words on each trial and judged which word was longer. In the perceptual condition subjects also viewed pairs of words, this time drawn from a familiar song; simultaneously they heard the corresponding song, and their task was to judge the change in pitch of the two cued words within the song. In the imagery condition, subjects performed precisely the same judgment as in the perceptual condition, but with no auditory input. Thus, to perform the imagery task correctly an internal auditory representation must be accessed. Paired-image subtraction of the resulting pattern of CBF, together with matched MRI for anatomical localization, revealed that both perceptual and imagery. tasks produced similar patterns of CBF changes, as compared to the control condition, in keeping with the hypothesis. More specifically, both perceiving and imagining songs are associated with bilateral neuronal activity in the secondary auditory cortices, suggesting that processes within these regions underlie the phenomenological impression of imagined sounds. Other CBF foci elicited in both tasks include areas in the left and right frontal lobes and in the left parietal lobe, as well as the supplementary motor area. This latter region implicates covert vocalization as one component of musical imagery. Direct comparison of imagery and perceptual tasks revealed CBF increases in the inferior frontal polar cortex and right thalamus. We speculate that this network of regions may be specifically associated with retrieval and/or generation of auditory information from memory.

Mental concerts: Musical imagery and auditory cortex

Most people intuitively understand what it means to “hear a tune in your head.” Converging evidence now indicates that auditory cortical areas can be recruited even in the absence of sound and that this corresponds to the phenomenological experience of imagining music. We discuss these findings as well as some methodological challenges. We also consider the role of core versus belt areas in musical imagery, the relation between auditory and motor systems during imagery of music performance, and practical implications of this research.