Chapter 14: Human Communication Flashcards
Aphasia
Disturbance in the comprehension or production of language
- caused by brain damage
- Broca’s aphasia - Wernicke’s aphasia
Broca’s Area
Important in language production
- left frontal lobe
Wernicke’s area
Important in language comprehension
- left temporal gyrus
Left Hemisphere in language
Controls comprehension and production
Right hemisphere in language
Controls activities like reading maps, perceiving spatial relations, recognizing complex geometrical forms, organizing a narrative, the expressions and recognition of emotion in the tone of voice and prosody
Split-Brain Operation
Brain surgery that is occasionally performed to treat a form of epilepsy
- Surgeon cuts corpus callosum, which connects two hemispheres of brain
Factors in language production
Occipital, temporal, and parietal lobes of brain are involved in perceptions of current and past events
- involves brain mechanisms in posterior part of cerebral hemispheres - Largely responsible for having something to say and ability to tell story about it
Factors in Language Comprehension
- Recognizing words may be auditory or visual
- Comprehension involves recognition of word using Wernicke’s area in the left temporal lobe in auditory association cortex
- Must also understand the meanings of words and memories associated with them
- Comprehension of figurative aspects of language involves right hemisphere
- Metaphors (right superior temporal cortex), proverbs, moral stories
Bilingualism
Ability to communicate fluently in two languages
Bilingualism Brain Structures
- Common and language-specific areas found in the frontal and posterior temporal/parietal cortexes
- Language- specific areas found in some subcortical structures
- Density of grey matter and increased density in left parietal cortex of bilingual compared to monolingual individuals
Prosody
Rhythmic, emphatic, and melodic aspects of speech - important means of communication of emotion
- Function of the right hemisphere - likely related to musical skills, expression and recognition of emotions
Prosody: Broca’s area
Can cause deficits in prosody
Prosody: Wernicke’s area
Prosody is unaffected
Recognition of People’s Voices
- Regions of right hemispheres are involved in recognizing specific voices
- Phonagnosia
Phonagnosia
Caused by damage to parietal lobe or anterior superior temporal cortex
Broca’s aphasia
Caused by damage to frontal lobes: produces agrammatism, anomia, articulation difficulties
- Can comprehend language better than produce it - Difficulty in using function words - Reliance on context words - Can also be caused by lesions of the basal ganglia
Agrammatism
Difficulty in comprehending or properly employing grammatical devices
Anomia
Difficulty in finding (remembering) the appropriate word to describe subject, action, or attribute
Function words
Preposition, article, or other word that conveys little meaning of sentence but is important in specifying its grammatical structure
Content Words
Noun, verb, adjective, adverb that conveys meaning
Broca’s Aphasia Physiology
- Includes damage to underlying subcortical white matter, bundles of axons
- Motor memories- of the sequences of muscular movements that are needed to articulate words
- Basal ganglia involvement- especia;;y head of caudate nucleus
- Broca’s area has projections to primary motor cortex
Speech Production in Broca’s Area
Contains motor memories
- Memories of sequences of muscular movements that are needed to articulate words - Damage to inferior caudal left frontal lobe disrupts ability to articulate words, this region is likely candidate for talking
Speech Production: Articulation Difficulties
- Individuals with Broca’s aphasia also have difficulty in articulation
- Broca’s patients recognize that pronunciation is incorrect and try to correct it
- Pronunciation of words caused activation of left anterior insula
Wernicke’s Aphasia
Receptive aphasia caused by damage to Wernicke’s area in the left hemisphere and the posterior language area
- Afflicted individuals seem unaware of deficits - Poor language comprehension and production of meaningless speech - People use few content words and words strung together don’t make sense
Wernicke’s Aphasia Abilities Disrupted
- Recognition of speaking words
- Comprehension of meaning of words
- Ability of convert thoughts into words
Pure Word Deafness
Ability to hear, speak, and usually to read and write without being able to comprehend meaning of speech
- Can recognize emotion by intonation of speech, but can’t understand what is being said
- Speech deficit is restricted only to recognition of spoken words
Wernicke Speech Sounds
Location of memories of sequences of sounds that constitute words
- Auditory association cortex of superior temporal gyrus recognized sounds of words
- Left Hemisphere: rapidly changing complex sounds - Right Hemisphere: more slowly changing components, like melody
Mirror Neurons
Neurons activated when we either perform an action or see action performed by someone else
- Speech: temporal and frontal cortical language areas were activated
Posterior Language Area
Wernicke’s aphasia
- Lateral fissure, near junction of temporal, occipital, and parietal lobes
- Place for interchanging info between auditory representation of words and meaning of words and meaning of words, stored as memories in rest of sensory associations cortex
Transcortical Sensory Aphasia
Caused by damage to the posterior language area
- patients can’t understand the meanings of words but can repeat them
Anomia Aphasia
Fluent and grammatical and good comprehension, but they have difficulty finding appropriate words
- Posterior lesions - Circumlocution
Circumlocution
Strategy by which people with anomia find alternative wats to say something when they are unable to think of most appropriate word
Conduction Aphasia
- Fluent and meaningful speech with good comprehension, but very poor repetition
- Caused by damage to arcuate fascículus
- Second pathway, between the posterior language area and Broca’s area, is indirect and is based on the meaning of words, not on the sounds they make
Arcuate Fasciculus
Suggests direct connection between Wernicke’s area and Broca’s area
[…] connects Broca’s area with […]
Anterior segment connected Broca’s area with inferior parietal cortex
[…] connects Wernicke’s area with […]
Posterior segment connects Wernicke’s area with inferior parietal cortex
Conduction Aphasia
The arcuate fascículos is responsible for a phonological loop
Conduction Aphasia Deaf Individuals
Use of narrative devices such as facial expressions or movements of heads, eyes, and body, inferior frontal cortex and superior temporal cortex of right hemisphere were activated in edition to expected language regions of left hemisphere
Sign Language
- Expressed by movements of the hands; most common form of ASL
- Left hemisphere plays more important role (as it does in spoken language)
- Role of mirror neurons
Stuttering
- Characterized by pauses, prolongation of sounds or repetitions of sounds, syllables or words that disrupts normal flow of speech
- Influenced by genetic factors
- Abnormal auditory feedback
- Caused by abnormalities in neural mechanisms involved in planning and initiating speech
Speech Production and Comprehension: Brain Mechanisms
Excessive activation of Broca’s area and insula (regions involved in articulation), supplementary motor area, and vermis of cerebellum, as well as absence of activation in auditory regions of temporal lobe
Delayed auditory feedback
Procedure in which person wearing headphones tries to speak normally while hearing their own voice, which is delayed, usually by 50-200 msec
Stuttering Physiology
Axons in white matter connect ventral premotor cortex with regions of superior temperal cortex and inferior parietal cortex that are involved in integrating planning of speech with auditory feedback from one’s own voice
Reading and Writing
- Brain damage can also produce reading and writing disorders
- Aphasia usually accompanied by parallel reading and writing deficits
Reading and Writing: Wernicke’s aphasia
Much difficulty reading and writing
Reading and Writing: Broca’s aphasia
Comprehend what they read, but poor reading aloud
Reading and Writing: Conduction aphasia
Generally have some difficulty reading (make semantic paraphasias)
Reading and Writing: Transcortical sensory aphasia
Read aloud accurately but might not comprehend
Pure Alexia
Loss of ability to read without loss of ability to write
- Lesions in visual cortex of left occipital lobe and posterior end of corpus callosum
Pure Alexia Symptoms
- Perceptual disorder characterized by loss of ability to read without loss of the ability to write; produced by brain damage
- Can recognize words spelled aloud
- Visual information prevented from reaching visual association cortex
- Patients have difficulty with visual, not auditory, input
Reading: Role of the Brain
Reading involves two processes
- Whole-word reading - Phonetic reading
Study of dyslexias provided info about brain mechs involved in reading
- Acquired dyslexia - Developmental dyslexia
Whole-Word Reading
Reading by recognizing word as a whole
“Sight reading”
Phonetic Reading
Reading by decoding phonetic significance of letter strings
“Sound reading”
Dyslexia
Faulty reading
Acquired Dyslexia
Damage to brains of people who know how to read
- Surface dyslexia
- Direct dyslexia
- Phonological dyslexia
Developmental Dyslexia
Difficulties when children are learning to read
- Reading difficulty in person of normal intelligence and perceptual ability
- Involves more than deficits in reading
- Phonological impairments
- Difficulty in writing
- Have difficulty blending or rearranging sounds of words that they hear
Surface dyslexia
Reading disorder in which a person can read words phonetically but has difficulty reading irregularly spelled words by whole-word method
- deficit in whole-word reading
Direct dyslexia
Language disorder caused by brain damage in which person can read words aloud without understanding them
- deficit in understanding written words
Phonological dyslexia
Reading disorder in which person can read familiar words but has difficulty reading unfamiliar words or pronounceable nonwords
- deficit in sounding words out
Visual Word-Form Area (VWFA)
Region of fusiforme gyrus on base of temporal lobe that plays critical role in whole-word recognition
- Surrounds junction of inferior parietal lobe and superior temporal lobe
VWFA plays a central role in […]
VWFA plays a central role in both phonological and whole-word reading
VWFA: part of […] must be involved in perceiving written words
VWFA: part of visual association cortex must be involved in perceiving written words
Damage to VWFA produces […]
Damage to VWFA produces surface dyslexia and impaired whole-word reading
- VWFA can recognize word even if it closely resembles another one
Plasticity in VWFA
- Written language is a recent invention
- Brain plasticity allowed development of language and writing systems across many cultures
- Fluency and literacy can develop quickly
- Importance of constancy in visual system, such as ways lines meet at vertices
Understanding of Reading
- Reading skill is positively associated with activation of VWFA
- Decreased activation in left temporoparietal cortex and in VWFA for dyslexics
- Hyperactivation of left inferior frontal cortex and Broca’s area
Role of Brain in Understanding of Writing
- Dysgraphia is a writing disturbance, common with dyslexia
- Many brain regions involved
- Motor aspects involve the dorsal parietal cortex and premotor cortex
- Brain damage can disrupt ability to form letters or impair ability to spell
Skills Used in Writing
- Audition
- Vision
- Memorization
- Motor memory
Audition
Sound recognition —> say—> read—>write
Motor memory
Left cortex are uniquely involved in motor memory for typing
- Dystexia
Dystexia
Deficits in motor memory for texting on cell phone
- Stroke affecting junction between left parietal and occipital lobes
Neural Basis of Writing
Brain damage can impair writing
- Phonological dysgraphia - Orthographic dysgraphia - Memory deficits
Direct dysgraphia is similar to direct dyslexia
Phonological Dysgraphia
Writing disorder in which person cannot sound out words and write them phonetically
- Damage to Broca’s area, ventral pre central gyrus, and insula
Orthographic Dysgraphia
Writing disorder in which person can spell regularly spelled words but not irregularly spelled ones
