speech and cortical asymmetry Flashcards
what are gyri?
rounded ridges (surface of the cerebral cortex)
what are sulci?
grooves in the cerebral cortex
what is found in the precentral gyrus?
primary motor cortex
what do focal lesions in the precentral gyrus cause?
cause paralysis or weakness in particular muscle groups
what does the central sulcus separate?
parietal and frontal lobe
what does the post-central gyrus contain?
primary somatosensory cortex
what does the lateral sulcus separate?
separates parietal, frontal lobe from temporal lobe.
what is broca’s area?
part of the left frontal lobe, just above the lateral sulcus, which controls spoken speech
what did Brodmann do?
• Brodmann noticed subtle differences in neuron type and density in various parts of the cortex and divided them into over 50 areas.
what is brodmann area 4?
primary motor cortex
what is brodmann areas 1, 2, 3?
somatosensory
what is brodmann areas 17, 18, 19?
visual cortex
what is brodmann areas 41 and 42?
auditory cortex
what is the association cortex?
cerebral cortex outside the primary areas: areas whose function is obscure
what controls language vocalisation?
Broca’s area - specialized cortical areas in left hemisphere only just above the lateral sulcus
Insula
what is the insula?
hidden region of the cortex in the lateral sulcus which is also active during speech production
what is the opercular cortex?
cortex on upper and lower lips of lateral fissure
which hemisphere is the opercular cortex thicker on?
the left
what is the opercular cortex involved with?
language production
what is wernicke’s area?
a cortical area at the proximal end of the superior temporal gyrus in the temporal lobe
what is wernicke’s area adjacent to?
primary auditory cortex
what does wernicke’s area control?
language perception
what are symptoms of Broca’s aphasia?
Halting speech Repetitive Disordered grammar Disordered syntax Disordered work order Sense behind words
what are symptoms of Wernicke’s aphasia?
Fluent speech No repetition Good syntax Grammar ok Meaningless Inappropriate words
what is aphasia?
inability to understand or produce speech as a result of brain damage
what is expressive aphasia?
use single words (find it difficult to link words in grammatical sentences)
what is receptive aphasia?
speak fluently but in an almost meaningless way
what joins broca’s and wernicke’s areas?
arcuate fasciculus
what is arcuate fasciculus?
bundle of cortico-cortical association fibres
what does damage to arcuate fasciculus cause?
conduction aphasia – patients show impaired ability to repeat back heard or written words.
o Patients also have difficulty reading aloud
what is speech output characterised by?
word-finding difficulties
explain the wernicke-geschwind model
word concepts formed in Wernicke’s –> stored in buffer memory –> Broca’s area via arcuate fasciculus
converted into motor programs –> motor cortex of the mouth, lips and tongue
when we speak, how do we hear our own voice?
sound produces patterns of neuronal activity in the auditory cortex which are decoded into perceived words/fractions of words in Wernicke’s area
why are our perceived words compared with the output in buffer region?
to see if our physical speech sounds like what we wanted to say
what blood vessel supplies Broca’s and Wernicke’s areas?
branches of the middle cerebral artery
what do strokes affecting the middle cerebral artery affect?
both the Broca and Wernicke areas: producing global/total aphasia.
what scans can be used to show which area of the brain is active during vocalisation/hearing words?
fMRI/PET scans
which side of the brain is normally active during listening to speech?
the left
how many people have left-hemisphere language specialisation?
70-95%
what are right hemisphere regions corresponding to Broca’s and Wernicke’s areas involved with?
tasks requiring non-semantic speech recognition and generation – intonation rhythm and emphasis
non-language communication skills - understanding body language, gesture and emotional content of speech
what do lesions of the right hemisphere regions cause?
produce robotic, monotonous speech known as aprosodia
what do lesions in area 44 cause?
tend to change patient’s speech to a dull monotone.
what do lesions in area 22 cause?
listening errors (can’t tell whether it’s a question, struggles with sarcasm).
what do the left prefrontal lobes do?
allows you to focus attention on particular objects/problems, gives you analytical and logical skills (in particular use of language and mathematics)
what do the right frontal lobes do?
maintain overall awareness even if you are focusing on something else. Allows you to switch your attention and concentrate on new inputs
