Fundamental deficits of auditory perception in Wernicke's aphasia.
OBJECTIVE
This work investigates the nature of the comprehension impairment in Wernicke's aphasia (WA), by examining the relationship between deficits in auditory processing of fundamental, non-verbal acoustic stimuli and auditory comprehension. WA, a condition resulting in severely disrupted auditory comprehension, primarily occurs following a cerebrovascular accident (CVA) to the left temporo-parietal cortex. Whilst damage to posterior superior temporal areas is associated with auditory linguistic comprehension impairments, functional-imaging indicates that these areas may not be specific to speech processing but part of a network for generic auditory analysis.


METHODS
We examined analysis of basic acoustic stimuli in WA participants (n = 10) using auditory stimuli reflective of theories of cortical auditory processing and of speech cues. Auditory spectral, temporal and spectro-temporal analysis was assessed using pure-tone frequency discrimination, frequency modulation (FM) detection and the detection of dynamic modulation (DM) in "moving ripple" stimuli. All tasks used criterion-free, adaptive measures of threshold to ensure reliable results at the individual level.


RESULTS
Participants with WA showed normal frequency discrimination but significant impairments in FM and DM detection, relative to age- and hearing-matched controls at the group level (n = 10). At the individual level, there was considerable variation in performance, and thresholds for both FM and DM detection correlated significantly with auditory comprehension abilities in the WA participants.


CONCLUSIONS
These results demonstrate the co-occurrence of a deficit in fundamental auditory processing of temporal and spectro-temporal non-verbal stimuli in WA, which may have a causal contribution to the auditory language comprehension impairment. Results are discussed in the context of traditional neuropsychology and current models of cortical auditory processing.
Neuroscience and Aphasia Research Unit, University of Manchester, UK; Psychology and Clinical Language Sciences, University of Reading, UK. h.v.robson@reading.ac.uk
Holly
H
Robson
Manon
M
Grube
Matthew A
MA
Lambon Ralph
Timothy D
TD
Griffiths
Karen
K
Sage
D000161:Acoustic Stimulation; D000368:Aged; D000369:Aged, 80 and over; D001041:Aphasia, Wernicke / Q000175:diagnosis / Q000523:psychology*; D001301:Audiometry, Pure-Tone; D001303:Auditory Cortex / Q000502:physiology; D001307:Auditory Perception / Q000502:physiology*; D003072:Cognition Disorders / Q000523:psychology*; D032882:Comprehension / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006320:Hearing Tests; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010897:Pitch Discrimination; D011597:Psychomotor Performance / Q000502:physiology; D015203:Reproducibility of Results