Brain Lesion Analysis- ASHA 2007

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					                                                                                 How Does the Brain of an Individual with Aphasia Hear?
                                                                       Jennifer Mozeiko, Stephanie Nagle, Jennifer Paulovicks, Carl A. Coelho & Frank Musiek
                                                                                                                University of Connecticut, Storrs, CT

                            INTRODUCTION                                                          METHODS                                                                                                                             RESULTS

• Assessment of aphasia tends to involve behavioral testing requiring a                   Electrophysiological Recording                                                     Ear Effect                                                             Electrode Effect
patient to understand verbally presented instructions. Lesions resulting
in aphasia however, frequently involve areas associated with auditory                                                                                                 P2                                                                       P2
perception and processing.                                                        •Participants were requested verbally or by modeling           MP
                                                                                                                                                                                                                   right                                                                                      2=Cz
                                                                                  to sit quietly and to relax while listening to tones but                      N1
                                                                                                                                                                                                                    ear                  N1
                                                                                                                                                                                                                                                                                                              4=C3- contralateral to site of lesion
•The identification of specific auditory processing deficits which are            were given no other verbal instruction.                                              P2
distinct from verbal comprehension impairments may facilitate language                                                                                                                                                                                                                                        6=C4- ipsilateral to site of lesion
                                                                                                                                                              N1                                                                                    Poor morphology
rehabilitation for individuals with aphasia.                                      •Electrophysiological recordings were obtained using                                                                              ear

•Electrophysiologic testing does not require a behavioral response and            tonal stimuli presented through insert earphones.
yields more objective evaluation findings.                                        Electrodes were placed at C3, C4, and Cz and
                                                                                  referenced to the nape of the neck.
  • The late auditory evoked potentials (LAEPs) have been used to                                                                                                                                                                                P2
    evaluate auditory processing abilities in individuals with auditory           •Tones were presented at 60 dB SL                                                 No recognizable waves
                                                                                                                                                                                                                                                                                                                 5=C4- ipsilateral to site of lesion
    lesions (Musiek et al., 1992), aphasia (Selinger et al., 1989; Becker                                                                                                                                                                                                                                        1=Cz
    and Reinvang, 2007), and subcortical pathology (Bamiou et al.,                •Waveforms were online filtered from 1 to 30 Hz.               RB                                                               right                                                                                          3=C3- contralateral to site of lesion
                                                                                                                                                                                                                   ear                   N1
    2006). These potentials have been shown to be sensitive and
    specific to lesions of the central auditory nervous system (Musiek et         •Late potentials including the P300 were elicited
    al., 1992).                                                                   using a passive oddball paradigm in order to avoid                                    P2
•The binaural interaction component (BIC) is thought to be an inhibitory          any possibility of verbal confusion. 500 Hz tones
response to binaural stimulation, theorized to facilitate hearing in noise.       were used as the frequent stimuli and 2000 Hz tones
Difficulty hearing in noise is a common complaint among those with                were used as the target oddball stimuli. All tones
aphasia.                                                                          were 40 msec in duration, with a 10-20-10 rise-
                                                                                  plateau-fall time.
  • The BIC is characterized by an increase in waveform amplitude with                                                                                                                                                                 Ear effect for MP and RB- ear contralateral
    binaural stimulation compared to monaural stimulation                                                                                         CH                                                             right
                                                                                                                                                                                                                  ear                  to site of lesion shows smaller amplitudes.
  • The BIC has been demonstrated in normal hearing individuals in all                                                                                                                                                                              No ear effect for CH.
    the auditory evoked potentials from the earliest potentials (ABR) to                                                                                                                                                              Electrode effect for MP and RP- electrodes
    the late potentials (N100, P200, P300) (McPherson and Starr, 1993).                                                                                                                                           left
                                                                                                    RESULTS                                                    N1                                                 ear                   ipsilateral to site of lesion shows smaller
                                                                                                                                                                                                                                         amplitudes. No electrode effect for CH.
                                   PURPOSE                                         Auditory Processing In Individuals with Aphasia
    1.        To evaluate auditory processing abilities in individuals with      Two of the three participants demonstrated an
              aphasia.                                                            electrode effect for N1 and P2 waveforms. This                                                                                                 DISCUSSION
    2.        To investigate the possibility of BIC abnormalities in              means that the electrode over the damaged
              individuals with aphasia.                                           hemisphere of the brain showed reduced amplitude,          •Previous studies have documented electrode effects in the auditory middle latency response (Musiek 1999) but aside from Hough
                                                                                  regardless of the ear being stimulated. The same two       and colleagues (2003) who also found a variable ear effect, there has been little data examining electrode or ear effects with this
                                                                                  participants also showed an ear effect for N1 and P2.      population. The paucity of data on LAEPs in the aphasic population makes it difficult to interpret these findings.
                                                                                  This was demonstrated by decreased amplitudes at           •Within the existing literature, EP methodology varies widely. Differences in electrode placement, presentation of the stimuli and
                              PARTICIPANTS                                        all electrodes during the stimulation of one ear.          method of eliciting the P300 are a few of many variables that make comparison difficult. In future studies, age and hearing
  Table 1: Participants                                                                                                                      matched control subjects will be included in order to better characterize the LAEPs and BICs of individuals with aphasia. If it is
   Participants              Age            Western Aphasia      Boston Naming                                                               determined that poor LAEPs characterize this population, auditory training in conjunction with language therapy may prove to be a
                                            Battery              Test
                                                                                          The Binaural Interaction Component                 more effective course of treatment.
                                                                                 BIC values ranged from –.22 (no BIC) to 12.24 across
   MP                        62             43                   9
                                                                                   the 3 aphasic subjects.
   RB                        67             38.9                 0                                                                                                                                                              REFERENCES
   CH                        23             91.2                 59                      The Late Auditory Evoked Potentials
                                                                                                                                              Bamiou, D.E., Musiek F.E., Stow, I., Stevens J, Cipolotti, L, Brown M.M. & Luxon, L.M. (2006). Auditory temporal processing deficits in patients with insular stroke. Neurology, 67(4), 614-20.
                                                                                 No consistent trends were observed in terms of aphasia       Becker, F. & Reinvang, I. (2007). Successful syllable detection in aphasia despite processing impairments as revealed by event-related potentials. Behavioral and Brain Functions, 3, 6.
  All participants were native English-speaking males with chronic                                                                            Hough, M.S., Downs, R.C., Cranford, J.L. & Givens, G.D., (2003). Measures of auditory processing in aphasia: Behavioral and electrophysical analysis. Aphasiology, 17(2), 159-172.
                                                                                    test scores and corresponding LAEPs. Increased
  aphasia, secondary to left CVA. Each underwent otoscopy, pure-tone                                                                          McPherson, D.L. & Starr, A. (1993). Binaural interaction in auditory evoked potentials:brainstem, middle-and long-latency components. Hearing Research, 66(1), 91-8.
                                                                                   BIC and amplitudes of all LAEPs were observed for          Musiek, F.E., Baran, J.A., and Pinheiro, M.L. (1992). P300 Results in Patients with Lesions of the Auditory Areas of the Cerebrum. Journal of the American, Academy of Audiology, 3(1), 5-15.
  audiometry, and otoacoustic emissions evaluations. All demonstrated                                                                         Selinger, M, Prescott, T.E., & Shucard, D.W. (1989). Auditory event-related potential probes and behavioral measures of aphasia. Brain and Language, 36 (3), 377, 390.
                                                                                                   the youngest subject.
  normal outer and middle ear function at the time of testing.

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