Aphasias

Aphasia

• Aphasia – “a disorder of language, including a defect or loss of expressive (production) or receptive (comprehension) aspects of written or spoken language as a result of brain damage.” (Harley, 2001)

• Affects more than 1 million Americans, with 80,000 new cases acquired each year

3 main types of aphasia

• Broca’s aphasia: – agrammatic, non-fluent

• Wernicke’s aphasia:– anomic, fluent (usually retrieve real words that are

semantically empty. Patients are generally unaware that they’re ill)

• Conduction aphasia:– can’t repeat what they hear

• Dementia (not aphasia, but still affects language): usually fluent and grammatical, just nonsensical

Tests for Aphasia

• From the Boston Diagnostic Aphasia Test

• Patients are shown pictures and asked to describe them

• Both of these samples show non-fluent, agrammatic aphasics

Paul Broca “founding father of physical anthropology”

• French surgeon who was intrigued with brain size and its relationship to age, sex, intelligence, race, and environment

• Belonged to an anthropological society whose members examined human skulls and conducted research on the brains of deceased medical patients

“Tan” • Admitted to nursing home at 31 years old, since

he couldn’t speak

• Had been in a nursing home for 21 years when Broca was introduced to him

• Seemed to comprehend speech, but could only respond with gestures and the syllable “tan” – (although able to swear when provoked!)

• When Tan died, Broca performed an autopsy and found a frontal lobe lesion in the 3rd frontal gyrus of the left hemisphere (Broca’s area)

Comparison of speech from aphasics

• Broca’s aphasia: Yes…ah…Monday…er…Dad and Peter H…(his own name)…and Dad…er…hospital…and ah…Wednesday…Wednesday, nine o’clock. Ah doctors…two…an doctors…and er…teeth…yah.

(explaining that he came to the hospital for dental surgery)

Non-fluent aphasia

• Disruption in grammatical processes in general. Comprehension problems detectable when context can’t provide correct syntactic interpretation

• Speech is almost entirely nouns and fillers. Very few verbs, and fewer inflectional affixes (-s, -ed, …)

• Caused by damage to Broca’s area or Parkinson’s disease (damages basal ganglia, complex neural centers buried inside frontal lobes)

Wernicke’s Aphasia

• Fluent, nonsensical speech• Severe comprehension

problems• Grammar is (mostly) intact• Most patients are unaware of

their language problems (agnosia)

Comparison of speech from aphasics

• Wernicke’s aphasia: Well, this is…mother is away here working her work out here to get her better, but when she’s looking, the two boys looking in the other part. One their small tile into her time here. She’s working another time because she’s getting, too…

(describing scene of children stealing cookies while mother’s back is turned)

Anomia

• Inability to retrieve names (nouns) , caused by damage to the angular gyrus (slightly behind Wernicke’s area)

• HW – suffered a stroke, highly intelligent but could not retrieve nouns from mental dictionary. “First of all this is falling down, just about, and is gonna fall down and they’re both getting something to eat…but the trouble is this is gonna let go and they’re both gonna fall down…”

• Often name related objects or distort sounds of correct words: (phonolgical/semantic neighbors)– table “chair”, elbow “knee”, clip “plick”, butter “tubber”, ceiling

“leasing, ankle “ankley, no mankle, no kankle”, comb “close, saw it, cit it, cut, the comb, the came”

Pure Word Deafness

• Can read, speak, recognize non-linguistic sounds (music, slamming doors, animal cries)

• Cannot recognize spoken words, repeat back speech

• Hearing is otherwise normal– Impaired in phoneme recognition/differentiation

(/pa/ from /ba/, /ga/ from /ka/ - so no categorical perception)

– patients report that they are hearing what you’re saying, but that it just “doesn’t compute”

• damage to auditory nerve, corpus collosum

Anomia and Herpes Simplex Encephalitis • Patients could name nonliving things but not living things. HSE

caused impaired visual object recognition and also impairment at naming or describing visual objects (Sartori and Job, 1988, Silvery and Gainotti, 1988, Warrington and Shallice, 1984)

– Some relevant symptoms of HSE:• Psychiatric symptoms (71%)• Seizures (67%)• Focal weakness (33%)• Memory loss (24%)• Other findings include the following:

– Altered mental status – Photophobia – Movement disorders

• So There DOES seem to be a connection between specific anomias and the kind of general brain damage that a patient is suffering (from www.emedicine.com)

Aphasics and swearing

• Most aphasics can swear!– No syntax required– Since this is emotional vocabulary, likely stored in

the right brain – Connections with subcortical brain structures which

mediate arousal (including amygdala-mediated learning)

Loss of language vs. loss of intelligence

• Can you still perform higher-level cognitive functions if language abilities are damaged? – A few case studies

• Patient with semantic dementia (damage to temporal lobe) – couldn’t remember what to buy in grocery store, but she figured out that, if she took used boxes, empty containers, she could match those up with what she needed to buy and cope with her difficulties

• Catholic monk, “Brother John” had paroxysmal aphasia (due to epilepsy). During “spells”, he would become globally aphasic. Lecours and Joanette (1980) recounted a spell in which he was taking a train trip from Italy to Switzerland. Despite his loss of speech production, comprehension, and reading, Brother John was able to get off the train at the appropriate spot, find his hotel, find another hotel when the first one was full, order supper in a restaurant, and wait until his language skills returned

Other language impairments

Consonants vs. Vowels• Two Italian patients: AS produced errors on vowels,

but IFA produced errors on consonants

Complaints of the elderly: • Older adults – most frequent complaint is that they

can’t find words. They make pauses, do circumlocution, ‘empty speech’ – where pronouns don’t have a clear referent, make substitution errors. Proper nouns are more difficult to retrieve than common nouns

Language and emotion – alexithymia & depression

• alexithymia – difficulty identifying and describing emotional states. Lack of emotional-expressive words in speech production, probably due to lack of right-hemisphere information available to speaking – the right hemisphere organizes lexicon according to contextual, affective,

idiosyncratic, or personalized principles. It has been proposed that an “affect lexicon” (emotional lexicon) is a resident of the right hemisphere. (Bowers et al, 1993)

– Measurably present in patients with bulimia nervosa (de Groot, Rodin, & Olmstead, 1995)

• Depression affects the rate of speech. It is generally hypophonic (not much intonation) and slower. Increased pauses, decreases in volume at the end of sentences – patients with depression perform differently on acoustic-perceptual tests