Language and the Brain Flashcards
1
Q
what is language?
A
- A System by which sounds, symbols, and gestures are used for communication
- Sensory Process: Auditory (speech), Visual (sign, reading), tactile (tadoma)
- Motor Processes: Produces speech, writing, signs, gestures
- Subsystems of Language: Lexicon, semantics, phonology, morphology, syntax, pragmatics
2
Q
language vs. speech/sign
A
-
Language is the abstract representation of the form-meaning mapping through which symbols are converted into meaningful constructions and messages
- Abstract rules for putting together symbols to convey complex meanings about states and events in the world
- The rules must be understood and acquired by all speakers of the language
- Speech or sign is the use of a physical medium to transmit and receive the symbols of language
- Brain areas might be identified for perception or production of speech, or for the abstract representation of grammar
3
Q
Broca’s and Wernicke’s areas
A
- Broca’s: BA 44, 45, 46
- Subcortical structures: basal ganglia, thalamus and medial subcallosal fasciculus (nerve bundle under the callosum connecting SMA to anterior cingulate)
- Wernicke’s: BA 22, 41, 42
- Middle temporal, angular gyrus and subcortical structures (basal ganglia & thalamus)
4
Q
__________ areas are adjacent to Broca’s area
A
motor
5
Q
example of Broca’s aphasia speech
A
“Yes … ah … Monday … er … Dad and Peter (his name) and Dad … er …. Hospital … and ah …. Wednesday … Wednesday, 9 o’clock … and oh … Thursday … 10 o’clock … ah Doctors … two … an doctors … and er … teeth … yah!”
6
Q
characteristics of Broca’s aphasia speech
A
- Effortful articulation: Slowness in planning, execution & sequencing of speech
- Anomia (inability to access words) & paraphasias (sound or meaning substitutions)
- Semantic: table for bed
- Phonological: school for stool
- “Telegraphic” speech: Dominated by high content nouns, verbs & adjectives, absence of functors (articles, aux verbs, prepositions, morphological affixes)
- Agrammatism– sometimes evident: comprehension deficit related to failure to access syntactic organization of utterances or sentences
7
Q
Broca’s aphasia - production and comprehension deficit
A
- Agrammatism:
- The dog was licked by the cat. Who did was licking?
- The cow that chased the donkey was bitten by the dog. Who bit whom?
- Broca’s aphasia often associated with inability to answer these questions accurately
- Comprehension is not fully represented
- Suggests this is not just a production deficit
8
Q
Broca’s aphasia - idiomatic language
A
Idiomatic Language:
- Broca’s aphasics often use overlearned idiomatic phrases (“that’s the way the cookie crumbles”) in substitution for productive language
- Such aspects of language are thought to be strongly represented in Right hemisphere analogue of Broca’s area
9
Q
impairments associated with Broca’s aphasia
A
- Dysarthria (neuromuscular speech impairment)
- Verbal apraxia (inability to articulate w/o motor impairment)
- Buccofacial/Oral apraxia (Inability to move oral features in the absence of paresis
- Right hemiparesis or hemiplegia (motor impairment on right half of body), right hemisensory defect (inability to perceive stimulation on right side)
10
Q
characteristics of Wernike’s aphasia speech
A
- Speech is fluent (or rapid at least) but often meaningless
- Word salad, jargon, paraphasias
- Contains many functors, but often used inappropriately in long strings with few content words
- Characterized by:
- Limited comprehension of spoken or written language
- “Empty” but fluent speech, depth of meaning is absent
- Poor repetition
- Paraphasias
- Neologisms and jargon (“word-salad”)
- Associated signs: Right hemisensory deficits, right hemianopia (cortical blindness)
11
Q
example of Wernicke’s aphasia speech
A
“I feel very well. My hearing, writing been doing well. Things that I couldn’t hear from. In other words, I used to be able to work cigarettes I didn’t know how to be any able to.”
12
Q
Wernicke-Geschwind Model of Aphasia
A
Proposed circuit involving:
- Striate (Visual) Cortex
- Broca’s area
- Wernicke’s area
- Arcuate Fasciculus (tract connecting Wernicke’s and Broca’s Areas)
- Angular gyrus
13
Q
Wernicke-Geschwind Model of Auditory Processsing
A
Simple repetition task:
- Speech input - auditory cortex
- Meaning of utterance is processed in Wernicke’s area
- Sent to Broca’s area via the arcuate fasciculus
- Processed in Broca’s area for speech production
- Sent to Motor cortex for speech production
14
Q
Wernicke-Geschwind Model of Reading and Written Language
A
- Written input - visual cortex
- Converted into sound representation in Angular Gyrus
- Meaning of utterance is processed in Wernicke’s area
- Sent to Broca’s area via the arcuate fasciculus
- Processed in Broca’s area for speech production
- Sent to Motor cortex for speech production
15
Q
Wernicke-Geshwind model
Role of Arcuate Fasciculus
A
- Conduction Aphasia
- Lesion of fibers composing arcuate fasciculus
- Comparison with Broca’s aphasia, Wernicke’s aphasia: Comprehension good, speech fluent
- Difficulty repeating words
- Symptoms:
- Repetition task: Substitutes/omits words, paraphasic errors,
- cannot reproduce: functions, nonsense words, polysyllabic words
- Generally taken to support W-G model, since Broca’s and Wernicke’s areas are intact
19
Q
split brain studies
A
- Roger Sperry studied split-brained monkeys in 1950s
- Severed axons in the corpus callosum
- No major deficits at first sight
- With proper experiments, discovered that animals behaved as if they had 2 brains
- Language Processing in Split-Brain Humans
- Gazzaniga: Present stimuli to one hemisphere
- Two hemispheres initiated conflicting behaviors
24
Q
global aphasia
A
- Combination of Broca’s and Wernicke’s
- Typically associated with occlusion of main stem of middle cerebral artery (thus, impeding flow in both anterior and posterior branches)
27
Q
Reading and Writing:
Agraphia, Dysgraphia, Alexia, Dyslexia
A
- Anterior supramarginal gyrus; Posterior angular gyrus
- Alexia with agraphia (angular gyrus)
