3 Localizationists Franz Gall (early 1800s) Paul Broca (1850s): a neurologist----“articulate speech” located in the posterior-inferior frontal lobeKarl Wernicke (1874): a German neuropsychiatrist published work on “sensory aphasia” –lesions in the posterior temporal lobe
4 Anti-localizationists Marie Jean-Pierre Florens (colleague of Gall!) was the firstJohn Hughlings Jackson (NHNSND) a British neurologist—early 1900sHenry Head—British neurologist sEquipotentialistsLead to theories of cerebral dominance
5 Language and Cerebral Dominance Left hemisphere dominance for sph/lang was Broca---early thoughts were that left and right halves of the brain were mirror images on one anotherSymmetry notion lasted until Goodglass and Kaplan, Penfield and Roberts (1950s)!!Confusion about function: right handed people were left hemisphere dominant
6 Therefore, Left handed people must be right hemisphere dominant????? Only a theory based upon case studiesMaybe from an effort to “equalize” theories---make things “symmetrical”Think of theories of phonation---honest!(neurochronaxic theory!)
7 50s researchers noticedBoth left and right handed people had similar problems after brain injuryWe learned from the early sodium amytal studies that a small # of people are right hemisphere dominantMost adults are left hemisphere dominant for sph/languageThe question is: how are we born?Think cerebral plasticity……
8 Implications of cerebral plasticity Younger injuries have greater opportunity to improveOlder patients recover less language function than younger patientsThe older the patient at the time of injury the more severe the persistent consequences of the injury
9 ConnectionistsThese theories focus on function of areas surrounding the injury; in the case of language impairmentThe periSylvian region of the left frontal lobe is sometimes called the anterior language zoneImportant for planning and executing language: speech, writing, and maybe gesturesThe periSylvian region in the left temporal lobes is the posterior language zoneFor comprehending and formulating linguistic messages with accurate syntax and semantic structures
11 Anterior Language Zone Posterior frontal lobe, just anterior to the motor stripHolds the location of Broca’s area: the motor speech planning siteBroca’s area: responsible for planning & organizing speech movements for the primary motor cortexInjury here produces Broca’s aphasia
12 Posterior Language Zone Located in the posterior superior left temporal lobea.k.a. Wernicke’s areaSometimes called the auditory association cortexImportant for storage and retrieval of mental representations for words, word meanings, grammatical and linguistic rules
13 Remember the connectionists? Wernicke’s gets most of its input from the primary auditory cortex (Heschl’s Gyrus)Function of the primary auditory cortex is perception and discrimination of auditory stimuliIf a tree falls in the woods and there is no one there to hear it……….
14 More connectionistsWernicke’s and Broca’s are connected by a large bundle of nerve fibers (a fasciculus)Runs between the mid temporal lobe and the frontal lobe via the parietal lobeThe arcuate fasciculus is the primary route by which linguistic messages formulated in Wernicke’s are transmitted forward to Broca’s area
15 The angular gyrusAt the junction of the temporal, parietal and occipital lobesImportant for processes in reading and writingDamage to the angular gyrus causes:Alexia: reading impairmentAgraphia: writing impairment
16 Language Functions Comprehension of speech Spontaneous speech RepetitionOral ReadingWritingGestural responses to spoken commands
17 “Fluency”Important to understanding the connectionist model because connectionist aphasia syndromes are divided into “fluent” and “non-fluent” types.Relationship between: speech fluency, paraphasia, repetition and language comprehension.
18 Fluent (aphasic patients) have normal or near normal speech rates and use a variety of different grammatical constructions; function words and grammatical inflections are present, and usually syntactically appropriate. Intonation patterns are present and usually appropriate. Nonfluent (aphasic patients) have slow and labored speech. The variety of grammatical constructions is often restricted and intonation may be reduced or absent; function words and grammatical affixes may be omitted, and patients may rely a lot on nouns (Howard & Hatfield, 1987, p. 147).
19 Connectionist Aphasia Syndromes FluentDamage posterior to the Rolandic FissureSph flows smoothly and effortlesslyFluent aphasic spkrs. Usually manipulate rate, intonation, and stressNon FluentDamage anterior to the Rolandic FissureSph is halting and made with great effortRate is slower than normal, intonation is limited, stress is missing (diminished)
20 Paraphasias“errors in speaking produced by speakers with aphasia” (Brookshire)2 forms: literal and verbal paraphasiaLiteral paraphasia: phonologic (phonemic) errors----”tootbrust” for toothbrushVerbal paraphasia: semantic errors (usually related to the term) as in “knife” for forkSports talk: “play was admiral; defense had pronouns”NOTE: literal paraphasia vs. apraxia
21 RepetitionVariations in speech repetition and language comprehension are indicators of several fluent aphasia “syndromes”
24 Broca’s aphasia Expressive, motor or anterior aphasia Because of proximity to the motor strip (face, hand and arm) and because descending pyramidal fiber tracts run alongside Broca’s area: pts with Broca’s display right-sided hemiplegia or hemiparesis
25 Broca’s areaLower part of the premotor cortex; just anterior to the primary motor cortexPremotor cortex: plans skilled voluntary movements for the motor cortex in both hemispheresBroca’s area is adjacent to motor cortex of the face; thus it is the speech motor planner
26 Speech style Slower rate, laborious movement, halting Long pauses between words; sometimes even within wordsLacking intonationMisarticulations are common; some consonants and vowels are distortedShort phrases usually missing functor words I.e., conjunctions, prepositions and articles
27 Speech style: Broca’sMissing functor words causes the description of agrammatic; sometimes called telegraphicNext slide is from from a patient describing a picture from the Boston Diagnostic Aphasia Examination (BDAE). The “Cookie Theft.”
29 Broca’s aphasia: Writing Pts. Write as they speak: slowly and laboriouslyStrings of content words sprinkled with misspellings, distortions/omissions of letters.Poor form, maybe due to hemiplegia (forced to use non-dominant hand)Usually print; not cursive; slanted writing
31 Broca’s: comprehension Comprehension is better than speech or writeAlthough Broca’s pts tend to be slow readers (careful testing will probably show both reading and listening impairments)Repair strategy is usually preserved, e.g., they make attempts to correct errors in sph or writing
32 Broca’s comprehension Tend to be good tx candidates because they are usually cooperative;error awareness sometimes leads to emotional labilityUsually remember goals from day to day
33 Wernicke’s aphasiaAlso has other names: sensory aphasia, receptive aphasia and posterior aphasiaSalient feature: impaired comprehension of spoken and printed verbal materialsIf severe, pt may be unable to comprehend simple spoken or written materialMild/moderate: get the basic idea but tend to miss the details
34 Wernicke’sOften don’t associate sound (or sight) of words and their meaningsDifficulty with semantic distinctions e.g., know difference between small vs. tiny, good vs. wonderful, etc.Often display problems with short term retention and recall for verbal materialTend to do poorly on digit recall, recall lists, etc
35 Wernicke’sPerformance tends to deteriorate when instructions are longer, more verbal
36 Wernicke’s: speechUnlike Broca’s, Wernicke’s patients’ speech is usually smooth, even well formed grammaticallySpeech seems less effortful; sometimes even long, syntactically correct utterances with proper prosodyMay see some delay when there is difficulty with word recall
37 Speech sounds good, eh? Not. Speech is usually typified with verbal paraphasias (sometimes literal paraphasias, too)Ferbus lalo! NeologismsStrings of neologisms: jargonEssentially, Wernicke’s aphasics produce “empty speech” it lacks meaningUsually filled with “stuff” or “things” or pronounsEven circumlocute!
40 LogorrheaSome Wernicke’s patients will talk copiously until you MUST interrupt themDue to circumlocution and poor self monitoring skills
41 Wernicke’s: writingYup, it resembles their speech: writing is better in that the letters are well formed, they write with ease and it is legibleMost will use cursiveHandwriting is mechanically normal but ----it lacks contentParaphasias in speech usually show up in writing, tooYeah, logorrhea happens in writing, too.
42 Wernicke’s candidacyPatients are usually alert, attentive and likely to stay on the task at handMild forms usually know their errorsModerate forms rarely notice errors nor attempt to repair errorsCan’t stay on task in testing and tx proceduresConversational speech is tangential
43 Auditory comprehension problems complicate all communication trials Pragmatics/turn taking is usually preserved
44 ConcommitantsWernicke’s patients are not usually hemiplegic (unless there is involvement of the motor strip-- “global aphasia”)Lesions deep in the temporal lobe may destroy portions of the visual cortexCauses contralateral visual field loss