Cortical Asymmetry Flashcards
where is the Broca’s area
- left frontal lobe just above the lateral sulcus
where is the primary motor cortex
- Primary motor cortex is located inside the precentral gyrus
What did Broadmann do
- Broadmann using a stain for neuronal cell bodies showed that there were subtle differences in neurone type and density in different parts of the cortex
- He divided the cortex into 50 anatomically different areas, this was the start of the science of cytoarchitectonics
what Brodmann area is the primary motor cortex
area 4
what Brodmann area is the visual cortex
area 17 18,19
what are the Brodmann area of the somatosensory cortex
the somatosensory (touch) cortex includes areas 1,2 & 3.
what are the brodmann area of the auditory cortex
areas 41 and 42
what is the association cortex
- this is the large part of the cortex that is outside of specific areas and tend not to have any function
what hemisphere is language controlled by
left
what does Brocas area do
- language vocalisation, it is controlled by specialised cortical areas in the left hemispheres
What brodmann area is Broca’s area
44 & 45. (the areas are sometimes known as pars opercularis and pars triangularis of the frontal lobe)
what is the fold underneath Brocas area called
Insula
what is the role of the insula
- modern MRI have shown that the insula is active during speech production therefore it may be part of the speech production cortex
what is the opercular Cortex
- This is the cortex on the upper and lower lips of the laterl fissure, this cortex is thicker in the left hemisphere this is thought to correlate with language production
where is Wernickes area
it is adjacent to the primary auditory cortex which is also on the temporal lobe
what does Wernickes area do
- does language perception
- it has shown that the area that is involved in speech recognition
where is speech heard
- it is heard on the auditory cortex on both the left and right sides of the brain
what type of aphasia does damage to Brocas result in
expressive aphasia
what type of aphasia does damage to Wernickes area result in
receptive Aphasia
describe expressive aphasia
- Halting speech
- Repetitive
- Disordered grammar
- Disordered syntax
- Disordered word order
- Sense behind words
- Patients with expressive aphasia use single words: they find it difficult to link words together into grammatical sentences
describe receptive aphasia
- Fluent speech
- No repetition
- Good syntax
- Grammar ok
- Meaningless
- Inappropriate words
- Patients with receptive aphasia speak fluently but in an almost meaningless way
what is the tract that connects Borcas and Wernickes area
Broca & Wernicke’s areas are joined by a bundle of cortico-cortical association fibres called the arcuate fasciculus
what does damage to the arcuate fascicles result in
Damage to arcuate fasciculus produces conduction aphasia.
describe conduction aphasia
- Patients with Conduction Aphasia show an impaired ability to repeat back heard or written words.
- Speech output is characterized by word-finding difficulties
- also have difficulty reading aloud but they may have good comprehension
describe how The Wernicke Geschwind model works
- hear a noise - this is coded in the auditory cortex
- When we wish to speak the word concepts are formed in Wernicke’s area, stored in some kind of buffer memory and then sent via the arcuate fasciculus to Broca’s area.
- Here they are converted into motor programs which are then sent to the motor cortex of the mouth, lips and tongue.
- When we speak we hear our own voice. The sounds produce patterns of neuronal activity in the auditory cortex.
- These patterns are decoded into perceived words or fractions of words in Wernicke’s area.
= The input signals (perceived words) are compared with the output in the buffer to see if our physical speech sounds matched what we wanted to say.
what happens when you are deaf
Without this feedback (The Wernicke Geschwind model) of your own heard speech learning to speak is difficult this is why deaf children find speech more difficult to learn
what is the blood supply to the Broca and Wernickes area
Both broca and Wernicke’s areas are supplied by branches of the middle cerebral artery
what will a stroke to the proximal part of the middle cerebral artery do
- will affect both broca and Wernicke areas producing global or total aphasia
can the Borcas area be on the right or left side of the brain
both
- it is estimated that between 70% to 95% of humans have a left-hemisphere language specialization.
- 5% to 30% of humans have anomalous patterns of specialization.
- These might include: (a) having a right-hemisphere language specialization or (b) having bilateral specialization.
what is the right hemisphere involved of in speech
- They are involved in rhythm, volume, intonation and emphasis of speech
what does intonation mean
- Intontion – same words but different out tonight – going out tonight and going out to night
what does a lesion of the right hemisphere region in Brocas equivalent do
- lesion of these right hemisphere regions in brocas equvialnet may produce robotic, monotonous speech. This is known as aprosodia.
what does a lesion of the right hemisphere region in wernickes equivalent do
- If you have a lesion in werkinces area on the right hand side then you cannot tell if someone changes emphasis
what is Aspordia
a robotic monotonous speech
What does the left prefrontal lobe do
- enable you to focus your attention on particular objects or problems, and block out distracting inputs.
- They facilitates analytical and logical skills, in particular use of language and mathematics to solve problem
what does the right prefrontal lobe do
- maintain broad overall vigilance on all sensory inputs so that if something important occurs you can switch your attention and concentrate on the new inputs.
- The right hemisphere is important for survival as it can override the left hemisphere and make you pay attention to the immediate environment.
