Silvia - Anatomy Of Lang Part 1 Flashcards
Brain lateralisation overview
Sensory input and motor control (motor and somatosensory cortex) contra lateral e.g. left hemi gets touch from right side. Left hemi gets visual input from right visual field in both eyes. Quickest route for visual via optic nerve from retina to direct hemi, longer to take cc
Left hemi dom for lang, handedness , split brain
For most right handed, left hemi has language. Right hemi dom in some left handed people (30%) but some use both, may be bc world for right so learn. In split brain, objects to lvf goes to right so can’t say it. In normal, info presented to rvf remembered more for longer words as they take longer to go to the right hemi
Contralateral hearing
In dichroic listening task, speech processed in left hemi (right ear), music is right hemi (left ear). If good at music, more grey matter in right as tune eat , other mammals the same
Bantu
Speak using clicks, these activate l hemi for them as its language but in English activates right as just sound. Same w Chinese/tonal langs
Brain structured
Temporal lobe the main one. Brocas area in the inferior frontal lobe, close to motor so may have damage to mouth movements- have trouble w speech production but comprehension fine. Wernickes in auditory/ temporal frontal , has understanding of language
Processing pathways called lang networks
All the areas (frontal, temporal, auditory, visual) connected by white matter pathways. Info from occipital to frontal in 70ms. Stroke means lose functions. In left hemi have dorsal and ventral streams. Ventral: info enters via auditory, passes to front along temporal (has semantic meaning) dorsal: angular gyrus linked to brocas and motor (production) two routes interact
Ventral / speech perception
Speech arrives at auditory, left hemi extracts sound identity e.g. phonemes. Has fine grained analysis esp for words in isolation and have no context to rely on. Has wernickes areas - damage means no meaningful speech and auditory damage so no feedback. Meaning in the temp lobe
Dorsal route
When learning language, have sound repetition with no meaning (doesn’t engage ventral) . I’d mess up phoneme have dorsal damage, if close meaning have ventral damage
Brain development and experience
Some is genetically determined, handedness is partially hereditary, animals also show. Can develop in the womb but don’t know evolutionary benefits. Sensory input can shape development via plasticity. White matter increases as you get older but grey matter peaks at 10-12 then shrinks diff across diff lobes. Ind expereince like skills, neglect and a typical like blind
Neglect and blind
Neglect- bucharest early intervention project. Young kids in orphanage, foster or normal. Those in orphanages weren’t neglected but didnt have one to one input and interaction. White matter and grey matter lowest in orphans, then foster then family. For blind, the sensory cortex can be used for other things like learning brain and echolocation
Reading and writing background
Didn’t evolve especially for writing, no spec brain area but use existing ones. We did evolve to speak e.g. baby communication. Writing is recent in evolution, relies on spoken lang. 5m adults functionally illiterate-may be due to teaching methods e.g. can read but no comprehension.
Reading background brain area and lexicon+ from stroke patients
Reading has a network of areas to transform visual into meaning. We can read a word in many forms and extract typical features e.g. font/sideways. Means we have a storage for visual word forms
Serial vs global recognition
When learning to read, do it letter by letter but when later on, more global- evidence from Cambridge is that we can understand words as long as first and last letter correct.eye tracking - people jump words that are predictable. In right hemi, delay for longer words as processing bits
The triangle model
Has semantics, phonology and orthography (predicts how fast ppl recognise words), sometimes dual route, each is connected separately not flow. Phonology is sounds , orthography is letters, semantic is the meaning
Dorsal vs ventral routes linked to the triangle model
Dorsal is for repeating sounds, happens when reading non words, don’t acess the meaning (phonology to orthography only) , with motor for speaking.ventral is for understanding, has meaning (semantics), in temp, used for reading words silently. If reading out loud, use both
Visual word from area background
In the fusiform gyrus in the left hemi, the right hemi is for face recognition . Responds more to words than consonant strings, more to upper and lower case equality e.g. CHAIR not cHaIr, real words even if sound the same as non word e.g. taxi over taksi. Things presented in both visual fields processed in left mainly. - da,aged in terry as couldn’t recognise words. Key reading area
Visual word for area studies - dehaene and cohen 2011
Compared expert readers, ex literates (learnt in adulthood) and illiterate, matched for culture, measured how many words they could read in a minute in scanner. More visual area from literate and least from illiterate but for faces, houses, tools it was the opposite (most activity in illiterate), for nonsense words-literate highest. Means visual area becomes specialised for word recognition. Not word specific as also for object naming, auditory and blind have it for braille (modality indepdent)
Why the visual area may exist
Whendoing auditory word repetition, transfer sounds into motor so activate orthographic form, automatic links are made so sounds activate the area. Terry has damage between auditory form and visual area so has deficit saying what’s written ?
Developmental dyslexia
Difficulty reading, no spoken issues, genetic, phonology impairment (can’t separate word into sounds e.g. can’t say cat w out first sound, rhyming. Only reading impaired not speaking as doing need to break up word into sounds. Deficit w non word repetition. Can’t make orthography into phonology. Have deactivation in reading network, overactivation in L inferior frontal gyrus, diff grey and white vol. some reach good reading due to strategies, right hemi assumes functions (overactive Broca’s area), comorbid so hard to tell brain diffs
Acquired dyslexia from stroke
Fine visual lexicon and comp but can’t pronounce unfamiliar words, misread as familiar. Stm for speech sounds and manipulation of sounds (phonological bugger) damaged/ impaired graphemeeto phoneme conversion. When told to tick items w same sound won’t tick quay and key. Need early intervention for phonological
