Fundamental deficits of auditory perception in Wernicke's aphasia

Cortex. Jul-Aug 2013;49(7):1808-22. doi: 10.1016/j.cortex.2012.11.012. Epub 2012 Dec 10.

Abstract

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.

Conclusion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Aged
  • Aged, 80 and over
  • Aphasia, Wernicke / diagnosis
  • Aphasia, Wernicke / psychology*
  • Audiometry, Pure-Tone
  • Auditory Cortex / physiology
  • Auditory Perception / physiology*
  • Cognition Disorders / psychology*
  • Comprehension / physiology
  • Female
  • Functional Laterality / physiology
  • Hearing Tests
  • Humans
  • Image Processing, Computer-Assisted
  • Language Tests
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neuropsychological Tests
  • Pitch Discrimination
  • Psychomotor Performance / physiology
  • Reproducibility of Results