Lecture 21 Flashcards
Laterization
Moat language issues, left side
Left hemisphere dominant for 90%
Right dominance is seen in 4% of Right handed folk and 27% of left
Is usually like a mirror image
Prosody
rhythm, tone and emphasis in speech
Usually a function of the right hemisphere so left hemisphere injuries do not do anything to it
Recognition of voices
Recognition of a voice is independent of understanding words and meaning
Phonagnosia - is a disorder where people cannot recognize voices. Localized damage to the right superior temporal cortex
Metaphores
Also use right hemisphere
Aphasia
Disturbance in understanding, repeating or producing meaningful speech
Cannot be caused by sensory or motor deficits nor by lack of motivation
Must be isolated, such that the person must be capable of recognizing when others are attempting to communicate. Must be somewhat aware of what is happening around them.
Sensory association cortex aphasias
Posterior Sensory Receptive Wernicke's Fluent
Frontal lobe damage causes issues with speaking and the following aphasias
Anterior Motor Expressive Bocca's Non-fluent
3 questions for aphasias
Is the speech fluent?
If so, frontal lobe is ok
Can you comprehend the spoken messages
Can te person repeat phrases
Word comprehension
Posterior language area
When you hear or write the word dog, do you understand what the word means?
Different areas code for the words and semantic meanings of things.
This is all joined up by the posterior language area
This is located at the junction of the temporal, occipital and parietal lobes, around the posterior end of the lateral fissure. It is crucial for language comprehension (seen, heard or spoken).
Damage to this causes transcortical sensory aphasia
Transcortical Sensory Aphasia
Failure to comprehend the meaning of the word and an inability to express thoughts with meaningful speech
Word perception and speaking are fine but NO understanding of the meaning of speech
Can repeat words
Read and write (without understanding)
ALSO do not know you have it
Conduction aphasia
Damage to the arcuate fasciculate and surrounding tissue
Usually this forms a link between Wernicke’s and broca’s areas
Can understand speech and communicate. Cannot repeat words they hear
Especially nonsense words
Find this hard on the STM as this requires rehearsal and moving things around the cortex
Wernicke’s area
Involved in analysis of speech sounds and the recognition of spoken words. Is a region of the auditory association cortex on the left lobe.
Being able to hear is one thing (primary auditory cortex)
Recognizing words another (Wernicke’s area)
Comprehending them is yet another (posterior language area)
There is an over lap between the last two
Pure Word Deafness
Disorder of auditory word recognition. Cannot understand or repeat spoken info.
I can hear you but I cannot understand what you are saying
Can be caused by damage to Wernicke’s area or auditory input to this region
Can hear fine Interpret non-speech sounds Read and write Read lips Speak intelligently but they cannot recognize their own words. Over time, their speech becomes awkward. Often like when a deaf person speaks.
Wernicke’s Aphasia
Damage to Wernicke’s area and posterior language area
So you have features of transcortical sensory aphasia and pure word deafness
Poor language comprehension
Meaningless, many function words
Has prosody and sounds natural just meaningless
Receptive aphasia or fluent aphasia as people have no issue coming up with nonsense to say, just that words have no meaning to them
Difference between Wernicke’s Aphasia and Transcortical Sensory Aphasia
Transcortical can repeat words; they can recognize spoken words
Wernicke’s cannot repeat words because they cannot recognize them
Both associated with damage around Wernicke’s area. You cannot differentiate between then with a brain scan.
Pure Alexia
Damage to the visual word-form area (VWFA on the fusiform gyrus of the left hemisphere. Not right which is FFA.
People with pure alexia or pure word blindness cannot read, as they just can’t read what they write
This can be caused also by a stroke which incorporates the primary visual field on the left hemisphere and the corpus callosum. In this case information from the LVF will cross over to the RH and cannot go back to the left VWFA area. So this person cannot process words even though they have an intact VWFA.
Dyslexia
Means faulty reading. people with this have difficulty reading
Reading
Reading involves direct recognition and sounding it out letter by letter (2 processes)
Whole word reading
Recognizing a whole word
Phonetic reading
Reading by decoding the phonetic significance of letter strings; sound reading
Whole word reading
Requires VWFA
We get better at this with practice so can easily see English words apart but not so Arabic or mandarin
Surface dyslexia
Inability to recognize whole words
Can only read phonetically
Irregularly spelled words cause an issue
Pair pare pear
Phonological dyslexia
Cannot sound out words
Can read familiar words but not new ones or nonwords
Very hard in Japanese cos have symbols for whole words and letter so in this language could have an inability to read one distinct part of a sentence.
Developmental dyslexia
Mostly phonological, genetic
Have great difficulty learning to read and some never become fluent readers even if otherwise intelligent
Have issues with grammar and spelling and cannot distinguish the order of sound sequences
No idea about neural basis
Less common in words without irregular pronunciations (like English/French is harder than Japanese/Italian)
Direct Dyslexia
Can read out loud
Cannot extract meaning of words
Usually seen with larger deficits like transcortical sensory aphasia
Is a block between visual center and language comprehension region
Edges, corners and reading
We see edges and corners
Brain good at this
Is the basis for pattern recognition in words and reading
