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Prosody processing after stroke: evidence from a classification and an imitation tasks
Poster Session C, Saturday, September 13, 11:00 am - 12:30 pm, Field House
This poster is part of the Sandbox Series.
Giada Antonicelli1,2, Karen Arellano1,2, Nerea Gorostiola1,2, Pia Hembach3, Simona Mancini1,4; 1Basque Center on Cognition Brain and Language (BCBL), Donostia-San Sebastián, Spain, 2University of the Basque Country (UPV/EHU), Bilbao, Spain, 3RWTH Aachen University, Aachen, Germany, 4Ikerbasque, Basque Foundation for Science, Bilbao, Spain
Prosody comprehension is a complex process that requires to perceive sound, extract relevant acoustic features and integrate them into a coherent percept to be compared with stored intonation representations. Superior temporal areas, basal ganglia, and frontal regions are crucial interconnected hubs for intonation processing. While temporal areas are the locus of acoustic perception and semantic representations, the role of other implicated regions is less clear, as is hemispheric lateralization. Prosody comprehension impairments have been observed after brain damage to either hemisphere, although the right temporal cortex seems to be especially sensitive to slow spectral modulations involved in prosody. To contribute evidence to such debate, we recruited 16 stroke survivors (days post-stroke = 34.81±9.24), presenting with either a right-hemisphere (N=7, involving frontal areas, basal ganglia, thalamus and temporal and parietal regions) or a left hemisphere lesion (N=9, involving frontal areas, basal ganglia and thalamus). They were tested on a prosody classification task with two conditions, sentences and sequences of monosyllables. Their responses were compared to those of 15 healthy controls. To better characterize possible prosody classification deficits, we also analyzed responses from an imitation task on the same stimuli, in which participants mimicked the intonation they heard. Classification performance was measured based on response accuracy (correct, incorrect), while imitation quality was operationalized as the acoustic distance from the target, determined via both human rating and dynamic time warping. Crawford’s tests revealed that seven stroke survivors had average accuracy below three standard deviations from the controls’ mean in both conditions, accompanied by significantly poorer imitation performance. Of these, three of them had a lesion in left frontal regions, one in the left thalamus, one in the left basal ganglia, one in left fronto-parietal and one in right frontal regions. Seven brain-damaged participants showed anomalous responses only in the imitation task. Out of those, five had right hemisphere lesions (one temporal, one parietal, two frontal, one in the basal ganglia), while two had damage in the left basal ganglia and the thalamus, respectively. One stroke survivor with a small right thalamus lesion was not different from controls. These results suggest that left frontal lesions were associated with reduced performance in both prosody classification and imitation, while right frontal regions only in one out of three cases. As for condition effects, all basal ganglia lesions were linked to deficits in the monosyllabic condition, while poor performance in the sentence condition was evident in individuals with frontal, temporal and parietal lesions, regardless of hemisphere. Our observations support left frontal regions as a ‘control panel’ of prosody processing that integrates percepts during comprehension and plans intonation modulations during production. In line with existing findings, basal ganglia might support lower-level motor representations, such as the ones involved in rhythm perception/generation. In our results, they were particularly linked to the monosyllabic condition, characterized by a more rhythmic profile compared to the sentence condition. Future work should include a wider sample of participants and lesions and explore the relationship between prosody comprehension/imitation and meaningful prosody generation.
Topic Areas: Disorders: Acquired, Prosody