S3C4 (2.0) Flashcards
What is the role of the vestibular system?
Balance and spatial orientation
What does the vestibular system consist of?
Otolith organs - uttricle and saccule
Semicircular canal
What is the role of the otolith organs?
Detect changes in gravity (e.g., head position) and generate electric impulses transmitted by the vestibular nerve
What are maculae?
Thickenings in the wall of the utricle and saccule, which consist of supporting cells, vestibular hair cells, an otolithic membrane, and otoliths (particles of calcium carbonate)
What does the utricle sense?
Senses motions in the horizontal plane
What does the saccule sense?
Sense motions in the sagittal plane (vertical)
What does the semicircular sense?
Sense rotary movements at their ampullas
Where do the hair cells of the vestibular organ synapse?
Each hair cell makes an excitatory synapse with the end of a sensatory axon from the vestibular nerve, branch of the vestibulocochlear nerve (CN VIII)
Where are the cell bodies of the vestibular nerve axons?
Scarpas ganglion
What are the membranous sacs withing the bone (vestibular system) filled with?
Endolymph - collectively called the membranous labyrinth
What is the chemical composition of endolymph?
High in K+ and low in Na+.
What is between the bony walls (the osseous labyrinth) and the membranous labyrinth?
Perilymph
What is the chemical composition of perilymph?
Low in K+ and high in Na
What is the role of the tight junctions that seal the apical surfaces of the vestibular hair cells?
Ensuring that endolymph selectively bathes the hair cell bundle while remaining separate from the perilymph surrounding the basal portion of the hair cell
What does movements of the stereocilia towards the kinocilium cause?
The vestibular organs opens mechanically gated transduction channels located at the tips of the stereocilia.
This causes depolarisation of the hair cell, causing neurotransmitter release onto (and excitation of) the vestibular nerve fibres.
What does the biphasic nature of the receptor potential mean?
Some transduction channels are open in the absence of stimulation, with the result that hair cells tonically release neurotransmitter, thereby generating considerable spontaneous activity in vestibular nerve fibres
What is the role of the stroila?
Divide the hair cells into two populations with opposing polarities in the utricle and saccule
What is the otolithic membrane?
A fibrous structure in which crystals of calcium carbonate called otoliths are embedded
What happens when the head tilts?
Gravity causes the membrane to shift relative to the sensory epithelium.
The shearing motion between the otolithic membrane and macula displaces the hair bundles
This displacement of the hair bundles generates a receptor potential in the hair cells.
Where are the hair bundles in the otolith organs?
Embedded in the lower, gelatinous surface of the membrane.
What signalling pattern from the otoliths would indicate an absolute head position?
Sustained
What signalling pattern from the otoliths would indicate an linear acceleration of the head?
Transient
What happens when the head turns in the plane of one of the semicircular canals?
The inertia of the endolymph produces a force across the cupula, distending it away from the direction of head movement and causing a displacement of the hair bundles within the crista.
What are the consonant features?
Manner
Voicing
Place
What is manner?
Manner - the way sound is said
fricatives (hissing noise)
Plosives (exploding from the lips e.g. pp)
Nasals (use the nose to produce resonance e.g. Mm)
What is voicing?
(b-p, d-t, g-k, z-s)
Duration (voice onset time)
Intensity
What is place? (speech)
(b-d-g, p-t-k)
Frequency
Intensity
What are formants?
chunks of energy clustered in certain frequency areas. In the case of vowels, the first two formants combined create a characteristic vowel which enables differentiation between subtly different sounds
What does successful language require?
Attention Speech perception Speech production Language: vocab, grammar, syntax Auditory memory Auditory feedback Social skills and pragmatics
What language skills can you expect at 2 months old?
Pre-verbal
Crying
Gestures
Coos and gurgles
What language skills can you expect at 6-10 months old?
Babbling
Can distinguish sounds and reproduce them
Communicates by sounds and intonations
Able to express pleasure and displeasure.
What language skills can you expect at 6-12 months old?
Begin by detecting very small differences between speech sounds - phonemes
As they get older they learn to ignore other non specific sounds
contrast different vowel phonemes
recognise consonants
What language skills can you expect at 1 year old?
On word stage - morphemes Understand 50 words say 5 one word to describe actions semantics develops before word
What language skills can you expect at 18 months old?
Two word phrases 20-50 words Naming Demanding Questioning
What language skills can you expect at 2.5 years old?
Simple sentences Lacks tenses Errors in syntax Recognition of rhyme and intonation 200-300 words
What language skills can you expect between 2.5-5 years old?
improvements in phonemes
Development of pronunciation - articulation
What language skills can you expect between 6-10 years old?
Master syllable stress to distinguish between similar words
What did Piaget argue?
Thought comes before language.
What did Skinner think was important for language development?
Environment
What did Vgotsky say can enable a child to advance?
Social support from adults and especially from more competent peers
What % of profoundly deaf children are born into hearing families?
90%
What is the impact of a deaf child being born into hearing families?
Delayed Theory of Mind development
What was the bat-Chava meta analysis?
Deaf children of deaf parents had higher self esteem than deaf children of hearing parents
Self-esteem higher among deaf people using sign language
What are the 4 developmental pathways? (Glickman and Harvey)
Culturally hearing
Culturally marginal
Culturally Deaf
Bicultural
What happens at the level of the medulla? (cochlear)
The axons innervate the dorsal cochlear nucleus and ventral cochlear nucleus ipsilateral to the cochlea where the axons originated.
Where do the axons from the ventral cochlear nucleus project?
The superior olive (superior olivary nucleus) on both sides of the brain stem.
Where do the axons of the olivary neurons ascend?
Ascend in the lateral lemniscus and innervate the inferior colliculus of the midbrain.
Where do all ascending auditory pathways converge?
Inferior colliculus
Where do the neurons in the inferior colliculus send out axons?
The medial geniculate nucleus (MGN) of the thalamus, which in turn projects to auditory cortex