Musical Processing in Aphasia, ASHA Convention 2016
Musical processing in Aphasia
Sadhvi Saxena, Yasmeen Faroqi-Shah, L. Robert Slevc, Madeline Pifer, & Tara Pinto
University of Maryland, College Park
Friday, November 18, 2016, 9:30 AM - 10:00 AM, Session Number: 5624
Introduction
Persons with aphasia (PWA) demonstrate difficulties with auditory processing across language
domains, including phonetic, semantic and syntactic contrasts. Less is known about their ability to
process non-linguistic stimuli such as music. Existing research on processing musical structure in PWA
has been equivocal. Some studies have found difficulties in processing harmonic structure and chord
sequences of Western music (Patel et al., 2008; Sammler et al., 2011), while two case studies found
preserved musical processing (Peretz, 1993, Slevc et al., 2016).
A better understanding of musical processing in aphasia is relevant for several reasons. First,
there are claims about the neuro-rehabilitative effects of listening to music and musical instrumental
training for neurologically based disorders (Francois et al., 2015). Investigating processing of musical
structure in PWA will enable better prediction of the therapeutic benefit associated with musical
engagement. Secondly, it informs the theoretical debate about the extent to which musical and
linguistic processing rely on the same neural and cognitive resources, given that language and Western
music both have hierarchical “syntactic” structure (Patel, 2003). While psycholinguistic and
neuroimaging studies support sharing of neural and cognitive substrates (e.g., LaCroix et al., 2015),
findings in persons with brain damage have been equivocal (Peretz, 2006).
This study investigated three questions, 1) whether musical structure processing is
compromised in persons with aphasia, 2) whether there is a relationship between processing of musical
and linguistic structure, and 3) if prior musical experience is associated with structural processing of
music and language.
Methods
c individuals with aphasia (14 female, Mean (SD) age=60 (10.1) years) and 20 age and education
matched right-handed neurotypical adults (13 female, Mean (SD) age=60 (8.2) years) participated in this
study. All were primary speakers of English with at least a high school education. All participants with
aphasia had suffered a single left hemisphere cerebrovascular accident. Participants provided self-report
on extent of musical experience (Ollen, 2006). The aphasia severity range of PWA was 30.8 to 100
(Aphasia Quotient from the Western Aphasia Battery-Revised, Kertesz, 2006), and included persons with
anomic (N=13), Broca’s (N=8), conduction (N=2) and Wernicke’s (N=1) aphasia. Musical expertise was
measured by the Ollen Musical Sophistication index (OMSI, Ollen 2006), which is a self-report
questionnaire on engagement in various music-related activities (playing instruments, attending
concerts, composing music, etc.)
Four computer-based tasks of sensitivity to structure in music and language were administered
in a counterbalanced order. All participants responded with their left hand to accommodate for left
hemiparesis in PWA. Two comparable acceptability judgment tasks were developed as explicit measures
of sensitivity: goodness judgments of sentences that sometimes contained morphosyntactic violations
(Sentence Judgment) and judging chord sequences that sometimes included out-of-key chords (Chord
Judgment). These tasks were considered explicit because participants typically made judgments after
listening to the entire sentence/chord sequence. Accuracy of acceptability judgments was the key
measure, and hence A-prime, a measure of signal detection, was computed (Zhang & Meuller, 2005).
Two implicit measures of syntactic and musical structure were used, Word Monitoring, where
target words to be monitored sometimes followed morphosyntactic violations, and Harmonic Priming,
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Musical Processing in Aphasia, ASHA Convention 2016
where participants made timbre judgments (trumpet or voice) on the final chords of sequences that
ended on harmonically expected (tonic) or less expected (subdominant) chords. The task demands of
word monitoring were comparable to that of harmonic priming. The premise of these implicit tasks is
that participants speed to detect the target word or timbre is affected if it immediately follows an
unexpected element such as a morphosyntactic violation or subdominant chord. Hence the priming
effect, calculated as the response time difference between unexpected and expected conditions, is the
key dependent measure of automatic processing of syntax. This difference was transformed to a
standardized (z) score to enable comparisons between control and PWA while disregarding the overall
slower responses of PWA.
Results and Discussion
Both PWA and control groups performed above chance on the explicit judgment tasks (A’ >.5).
However, PWA were significantly worse than healthy controls in sensitivity to the Sentence Judgement
(PWA A’ Mean(SD) = .77(.15) vs. control A’ Mean(SD) = .96(.03); F(1,41) = 27, p <.001). In contrast,
groups did not differ on the Chord judgment task (PWA A’ Mean(SD) = .7(.19) vs. control A’ Mean(SD) =
.77(.13); F(1,41) = 1.9, p >.05). Both groups showed implicit automatic processing of linguistic and
musical syntax in Word monitoring and Harmonic Priming respectively, with showing different response
speed to unexpected versus expected stimuli. There were no significant group differences for either
language (Word monitoring effect for PWA Mean(SD) = 114(206.3) vs. control Mean(SD) = 101.5(35.4);
F(1,41) = .08, p >.05) or music (Harmonic Priming effect PWA Mean(SD) = 9.7(340) vs. control Mean(SD)
= -35.8(86.3); F(1,41) = .34, p >.05). For PWA, prior musical expertise (as measured by OMSI and years of
musical practice) correlated significantly with a variety of language measures including Sentence
Judgment, Word Monitoring effect, WAB-AQ (all Spearman rs>.7, all p-values<.01).
To summarize, PWA performed worse than the control group only in explicit Sentence
Judgment, and were comparable to the control group in automatic syntactic processing (Word
monitoring) and musical processing (Chord Judgment and Harmonic Priming). And there was an
association between language abilities in PWA (both syntactic processing and overall aphasia severity)
and prior musical expertise. These results are partially consistent with the only other group comparison
of PWA and healthy adults on explicit and implicit linguistic and musical syntactic tasks (Patel et al.,
2008). While both studies found explicit linguistic syntactic judgment to be impaired, Patel et al. also
found impaired PWA performance on the remaining three tasks. Overall, our findings show preserved
musical processing in PWA, and lend support to the idea that prior musical experience affords a
cognitive reserve for language deficits in post-stroke aphasia.
References
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Musical Processing in Aphasia, ASHA Convention 2016
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