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DISORDERS OF AUDITORY PROCESSING 1 DAY 20 – OCT 14, 2013 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Harry Howard Tulane University.

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Presentation on theme: "DISORDERS OF AUDITORY PROCESSING 1 DAY 20 – OCT 14, 2013 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Harry Howard Tulane University."— Presentation transcript:

1 DISORDERS OF AUDITORY PROCESSING 1 DAY 20 – OCT 14, 2013 Brain & Language LING NSCI Harry Howard Tulane University

2 Course organization The syllabus, these slides and my recordings are available at If you want to learn more about EEG and neurolinguistics, you are welcome to participate in my lab. This is also a good way to get started on an honor's thesis. The grades are posted to Blackboard. 10/14/13Brain & Language - Harry Howard - Tulane University 2

3 REVIEW 10/14/13Brain & Language - Harry Howard - Tulane University 3

4 An alternative: the TRACE II model 10/14/13Brain & Language - Harry Howard - Tulane University 4

5 DISORDERS OF AUDITORY PROCESSING Ingram §8 10/14/13Brain & Language - Harry Howard - Tulane University 5

6 10/14/13Brain & Language - Harry Howard - Tulane University 6 Reasons for delay in development of models of auditory processing Neuroanatomical differences between the visual and auditory systems the auditory system has a neuroanatomical redundancy built into it: it transmits information about sound in all parts of space to both hemispheres, rather than to one result: disorders of auditory processing are quite rare dichotic listening tasks are less informative than visual-half field presentation diagnostic difficulty caused by the close relationship between speech comprehension and auditory processing Terminological confusions relating to auditory processing disorders “verbal processing” can conflated with “auditory processing” Technical factors that have made auditory stimuli more difficult to study than visual stimuli

7 The central auditory pathway Note that the subcortical pathway is rather complex. 10/14/13Brain & Language - Harry Howard - Tulane University 7

8 Another version 10/14/13Brain & Language - Harry Howard - Tulane University 8

9 A1, A2, A3 A1 = core A2 = belt A3 = parabelt 10/14/13Brain & Language - Harry Howard - Tulane University 9

10 A1 Tonotopic mapping of organ of Corti (in the cochlea) to area A1 10/14/13Brain & Language - Harry Howard - Tulane University 10

11 Temporal lobe 10/14/13Brain & Language - Harry Howard - Tulane University 11

12 Linguistic model, Fig. 2.1 p /14/13Brain & Language - Harry Howard - Tulane University 12 Discourse model Syntax Sentence prosody Morphology Word prosody Segmental phonology perception Segmental phonology perception Acoustic phonetics Feature extraction Segmental phonology production Segmental phonology production Articulatory phonetics Speech motor control INPUT Sentence level Word level

13 10/14/13Brain & Language - Harry Howard - Tulane University 13 The Broca-Wernicke-Lichtheim model (of the LH)

14 10/14/13Brain & Language - Harry Howard - Tulane University 14 Disorders of cortical auditory processing Cortical deafness Auditory agnosia Speech agnosia or pure word deafness Phonagnosia Phonological retrieval disorder

15 10/14/13Brain & Language - Harry Howard - Tulane University 15 Cortical deafness Wernicke and Friedlander (1883) described a patient who was unable to hear any sounds, but had no apparent damage to the hearing apparatus and labeled the disorder cortical deafness. One review of the literature, reported “only 12 cases of significant deafness due to purely cerebral pathology” (Graham, Greenwood & Lecky, 1980:43) Identifying cases of cortical deafness has proved to be difficult for several reasons: patients rarely suffer bilateral lesions in the critical region of auditory cortex in the lateral temporal lobes; some patients believed to suffer from cortical deafness may, in fact, suffer from auditory inattention or neglect; cortical deafness is often transient, resolving to a less severe, or more specific, auditory processing disorder such as pure word deafness or auditory agnosia.

16 Agnosia VisionAudition Can not recognize objects in general visual agnosiaauditory agnosia Can not recognize linguistic objects alexia (word blindness) speech agnosia (pure word deafness) Can not recognize human objects prosopagnosia (face blindness) phonagnosia 10/14/13Brain & Language - Harry Howard - Tulane University 16 An impairment in which a patient fails to recognize a stimulus in a sensory modality, although perception in the modality is unimpaired. By “perception”, we mean the subcortical processing of the modality.

17 10/14/13Brain & Language - Harry Howard - Tulane University 17 Auditory agnosia It is best defined as an inability to recognize sounds independent of any deficit in processing spoken language. at times, it has been replaced by a more general definition referring to a deficit involving any type of auditory stimuli. It dates back to Freud (1891), but the first case of ‘pure’ auditory agnosia appears to have been reported only thirty years ago (Spreen et al., 1965). They presented a patient who was severely impaired at identifying a variety of sounds such as coughing, whistling and a baby crying, but showed no evidence of impaired speech comprehension.

18 Speech agnosia Pure word deafness, auditory-verbal agnosia Kussmaul (1877) coined the term “pure word deafness” to refer to an inability to comprehend spoken words despite intact hearing, speech production and reading ability. One patient complained that speech sounded “like a great noise all the time... like a gramophone, boom, boom, boom, jumbled together like foreign folks speaking in the distance”. Another said: “I can hear you talking but I can’t translate it”. Examiner: What did you eat for breakfast? Patient: Breakfast, breakfast, it sounds familiar but it doesn’t speak to me. (Obler & Gjerlow 1999:45) The experience of speech appears to undergo a qualitative change, and some word deaf patients cannot judge the length of a word. However, some patients appear able to extract information about the speaker from their voice despite being unable to comprehend the spoken message … i.e., sex, age, region of origin, or affective information. 10/14/13Brain & Language - Harry Howard - Tulane University 18

19 10/14/13Brain & Language - Harry Howard - Tulane University 19 Phonagnosia An impairment in the ability to recognize familiar voices, while being unimpaired on other auditory abilities. (Van Lancker and Canter 1982) Subjects were asked to identify which of four names or faces matched a particular famous voice. >> Just as prosopagnosia reflects an impairment in the ability to recognize familiar faces. Subsequent research produced evidence for a double dissociation between memory for familiar voices and the ability to discriminate between unfamiliar voices: One group of patients performed normally on the discrimination task but was impaired on the memory task, whereas another group of patients performed normally on the memory task, but was impaired on the discrimination task. >> Prosopagnosia has a similar double dissociation.

20 Summary Non-speech sounds VoicesSpeechCause Cortical deafness ✖✖✖ bilateral lesions to A1 Auditory agnosia ✖✔✔ damage to feature detectors in A2 & A3 Pure word deafness ✔✔✖ damage to phonetic feature detectors or speech motor loop Phonagnosia ✔✖✔ damage to inferior and lateral parietal regions of the RH 10/14/13Brain & Language - Harry Howard - Tulane University 20

21 10/14/13Brain & Language - Harry Howard - Tulane University 21 Optic aphasia A patient CANNOT name an object presented visually, but the patient CAN … name the object from a verbal description, describe the function of the object, or sort pictures of objects into categories, so it is not visual agnosia. Cause: impairment of pathway from visual object perception to semantic representation the object’s semantic representation can be activated only enough for basic tasks, such as sorting, but not enough for naming.

22 NEXT TIME Finish Ingram §8. ☞ Go over questions at end of chapter. 10/14/13Brain & Language - Harry Howard - Tulane University 22


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