Core auditory processing deficits in primary progressive aphasia

Abstract

The extent to which deficits in non-verbal auditory processing contribute to the clinical phenotype of primary progressive aphasia (PPA) is unclear. Grube et al. reveal impairments in processing the timing of brief sequences of non-linguistic stimuli, particularly in the non-fluent variant, indicative of a core central auditory impairment in PPA.

Music Perception in Dementia

“…Our findings provide further evidence that LPA and PNFA have associated phenotypes of nonverbal auditory impairment [32,64,[87][88][89]. The musical phenotype was more severe in the PNFA group here; the involvement of pitch pattern analysis in this syndrome is in line with previous work [32] and suggests a putative mechanism linking generic mechanisms of dynamic auditory encoding with speech production via the dorsal auditory cortical pathway, extending over a range of timescales relevant to processing of individual and sequential speech sounds [9,77,[90][91][92], Marked involvement of musical perceptual mechanisms might be anticipated from the severe and focal involvement of auditory association areas in the progressive aphasias [9,11].…”

“…The extent to which musical deficits reflect music-specific processes might then depend on the nature of the interaction between auditory working memory and the relevant musical characteristic, as suggested by previous work [48][49][50]. This factor may partly explain the lack of evidence here for specific deficits of temporal pattern processing from music, which we anticipated particularly in the PNFA group [64]. While in principle this could also reflect the small study cohort or failure to sample relevant temporal windows (as temporal characteristics of music are less constrained than pitch variations), temporal analysis of musical sequences may be more intimately reliant on auditory working memory capacity than pitch analysis; moreover, the linkage between temporal analysis and working memory mechanisms may have a neuroanatomical substrate (including insular cortex) that is targeted in PNFA [93].…”

“…In the healthy brain perceptual analysis of rhythm and metre engages cortico-subcortical circuitry jointly involved in preparing motor output [58][59][60][61]. While evidence in AD is not conclusive [19,36,62,63], impairments of temporal pattern processing have been described in PNFA associated with involvement of peri-Sylvian cortex [64]: this may be attributable both to loss of dynamic precision mediated by the dominant hemisphere and the high temporal resolution required for accurate processing of speech signals [65,66].…”

Cholinergic depletion and basal forebrain volume in primary progressive aphasia

“…A.1) along with a volumetric MRI scan. For MRI volumetric comparisons, we included an additional set of 24 healthy controls (67.3 ± 8.83 years), scanned on the same scanner, as well as 17 additional PPA patients (4 LV, 6 NFV and 7 SV) (Table 1) (Grube et al, 2016) and 77 additional controls (64.6 ± 5.86 years) who were scanned on a different scanner (see MRI acquisition and analysis).…”

“…In addition to the initial sample of 11 PPA and 10 control subjects, this extended sample contained 24 additional controls who had undergone a volumetric research MRI on the same scanner using the same sequence as mentioned above as well as 17 additional PPA (4 LV, 6 NFV and 7 SV) (Grube et al, 2016) and 77 additional controls who had undergone a T 1 -weighted structural MRI on a 3T Philips Intera system and an eight-channel head coil (coronal inversion recovery prepared 3D gradient-echo images; TI 900 ms, TE = 4.6 ms, voxel size (0.98 × 0.98 × 1.2) mm 3 ).…”