Week 4 Lecture 9: Localisation Flashcards
What are the names of the sulci in the cerebral cortex that you can see from a lateral view of the brain?
- central sulcus - divides frontal from parietal lobes
- lateral sulcus - divides frontal and parietal from temporal lobes
- frontal sulci - superior and inferior
- temporal sulci - superior and inferior
The frontal lobe is divided into how many gyri?
3 - superior, middle and inferior
The temporal lobe is divided into how many gyri?
3 - superior, middle, inferior
What does the parieto-occipital sulcus divide?
divides the parietal from the occipital lobe
where is the calcarine sulcus?
middle of the medial view of the occipital lobe
Where is the cingulate sulcus?
c-shaped sulcus coursing through the frontal, parietal and nearly occipital lobes - runs parallel with the corpus callosum
Where is the collateral sulcus?
- runs on the inferior surface of the temporal and occipital lobes
- demarks the position of the parahippocampal gyrus
What is the uncus?
- part of the temporal bone
- where the parahippocampal gyrus hooks back on itself to form a medially projected bump (uncus)
What system is the limbic lobe apart of?
limbic system
What is the limbic system responsible for?
emotion and memory
What 2 gyri form the limbic lobe?
- cingulate
- parahippocampal
What is herniation?
parts of the brain shifting compartments caused by e.g tumour, hydrocephalous, haemorrhage
What is uncal herniation?
- herniation at the uncus
- if the uncus herniates past the tentorium cerebelli, it would herniate into the midbrain and cause compression of the brainstem
What are brodmann’s areas?
- cortical map dividing the cortex into 46 areas
- based on cellular organisation of cerebral cortex (cell types in different areas)
What are the two types of primary projection areas?
- sensory - specific sensory pathways terminate here, perceived sensation
- motor - specific motor pathways originate here
Which cortical area corresponds to the general sensation (somaesthetic) modality?
post-central gyrus
Which cortical area corresponds to the visual modality?
either side of the calcarine sulcus (striate cortex) and occipital pole
Which cortical area corresponds to the auditory modality?
heschl’s gyrus (superior temporal gyrus)
Which cortical area corresponds to the olfactory modality?
uncus
What does gustatory mean?
taste
Which cortical area corresponds to the gustatory modality?
inferior post-central gyrus
where is the primary motor cortex?
pre-central gyrus
What is the function of association areas? (a.k.a secondary sensory areas)
- receive input from primary sensory area
- involved in interpretation/understanding from the primary area
- surround the primary areas
- information is sent from primary projection areas to secondary areas which give the information meaning
Which cortical area corresponds to the general sensation modality?
superior parietal lobe
Which cortical area corresponds to the visual modality?
pre-striate area
Which cortical area corresponds to the auditory modality?
lateral fissure/ superior temporal gyri
Which cortical area corresponds to the pre motor area?
anterior to pre-central sulcus on lateral surface
anterior to primary motor cortex
Which cortical area corresponds to the supplementary motor area?
anterior to pre-central sulcus on medial surface
anterior to primary motor cortex
Which cortical area corresponds to the frontal eye field?
- anterior to pre motor
- in frontal lobe
What is the function of the primary motor cortex?
- controls voluntary contractions of specific muscles
- sends information from the primary motor cortex, through the brainstem, through specific tracts in the spinal cord to effector muscles
- descending motor fibres
Which brodmanns area is the primary motor cortex?
BA 4
What are the 3 motor areas associated with the primary motor cortex?
- Supplementary motor and pre motor
- Frontal eye
- Brocas area
What is the function of the pre motor area?
organise a complex activity and send it to the pre-central gyrus to execute the movement
What does the frontal eye field control?
controls voluntary scanning movements of the eyes
What are the functions of Broca’s area?
- regulates pattern of breathing and vocalisation needed for normal speech
- inferior frontal gyrus
Which hemisphere is dominant?
left
Where is broca’s area located?
inferior frontal gyrus
What is the function of the primary somatosensory cortex?
receives sensory pathways for touch, temperature, vibration, pain, proprioception
Where is our primary somatosensory cortex?
post central gyrus - posterior to central sulcus
What type of fibres are our primary somatosensory cortex made of?
ascending sensory fibres
What is the lateral VPL and where does it receive input from?
- nuclei in the thalamus
- ventral posterolateral nucleus
- recieves input from leg
Where does the medial VPL recieve input from?
arm
What is the VPM and where does it receieve input from?
- ventral posteromedial nucleus
- recieves input from face
How is the pre-central and post-central gyrus organised?
- somatotopically
- lateral to medial: face–> arm –> trunk –> leg
- if information has come from face, it will be projected laterally in the post-central gyrus to reach the section that controls movement of the face area
What is meant by somatotopic organisation?
relating to the orderly and specific relation between particular body regions and corresponding motor areas of the brain the somatotopic arrangement within the thalamus.
Where are the association somatosensory areas located?
superior parietal lobe
What is the function of the association somatosensory areas?
interpretation, understanding and recognition of sensation
What would injury to the association somatosensory area cause?
either -hypoesthesia (diminished sensation), or -anaesthesia (absence of sensation) And -tactile agnosia
What is tactile agnosia?
the inability to recognise or identify an object by naming, matching to sample, or demonstrating its use
What is the function of the primary auditory cortex?
conscious perception of sound
Where does the primary auditory cortex recieve input from?
medial geniculate nucleus of the thalamus
How is the primary auditory cortex organised?
tonotopically:
- lower frequencies are projected more medially into the gyrus
- higher frequencies are projected more laterally
What is Wernicke’s area?
- surrounds primary auditory area
- auditory information is interpreted and given significance
- interpretation of written or spoken word
Explain the course of information in the primary visual cortex
- receives information from retina
- information stops at thalamus
- relay at lateral geniculate nucleus
Information from which sensory modalities stop at the thalamus?
all of them except smell
What is the function of the associated visual area?
interpretation of visual information (recognise faces, objects, trees)
A lesion in the association visual area would result in what?
prosopagnosia - inability to recognise faces
Where is the taste cortex located?
- extends from inferior margin of post central gyrus
- extends to insula (a strip of cortex that is stuck between the frontal, parietal and temporal lobes)
What is the main function of the general association cortex?
involved in more complex aspects of behavioural and intellectual functioning
What are the two general association cortexes and what our their functions?
- Pre frontal cortex:
- regulates moods and feelings
- involved in higher order cognitive functions
- conceptualisation, planning, judgement - Parieto-temporal cortex:
- integrates information from different modalities
- involved in memory
- vision, hearing, touch - gives these meaning
What are the two language areas and which hemisphere are they located in?
- wernicke’s area
- broca’s area
- in the dominant hemisphere (usually left)
What is the name given to the association fibres connecting Broca’s and Wernicke’s areas?
arcuate fasciculus
What is conduction aphasia?
- impaired repitition
- comprehension and fluency intact
- can understand information but can’t repeat it
How would conduction aphasia occur?
if there is injury to the arcuate fasciculus
What is Wernicke’s aphasia?
- sensory/fluent aphasia
- words come out fluently but don’t make sense
- inability to understand language
What is Broca’s aphasia?
- motor/non-fluent aphasia
- can understand language perfectly well but cannot articulate
- inability to correctly articulate speech
What is the difference between dysphasia and aphasia?
dysphasia = difficulty with speech aphasia = loss of ability to speak
What is the dominant hemisphere responsible for?
- linguistic functions
- numerical skills
What is the non-dominant hemisphere responsible for?
spatial awareness
What is agnosia?
- disorders of understanding
- awareness of sensation persists, but significance of this sensation is lost
What is apraxia?
inability to carry out purposive movements, although there is no paralysis