Injury to the cerebral hemispheres and cognitive function Flashcards
What is the first thing a neurologist wants to know in relation to brain lesions?
WHERE is the lesion?
- Clinical examination + observation
- Rudimentary understanding of neuroanatomy
What are the 6 layers of the grey matter laminar organisation in the cortex??
- I - molecular
- II - external granular
- III - external pyramidal
- IV - internal granular
- V - internal pyramidal
- VI - multiform
What are the differences of function between the left and right cerebral hemispheres?
- Left - verbal info, language, arithmetic, linear reasoning
- Right - spatial, nonverbal, number estimation, holistic problem solving
Variable between individuals, not easily studied.
What lobes does the Sylvian fissure separate?
Temporal and frontal
What are the 3 subregions of the frontal lobe?
- Motor, premotor, supplementary motor areas
- Inferior frontal cortex
- Prefrontal cortex (dorsolateral, ventromedial, orbital)
Describe the importance of the primary motor cortex? How is the premotor area different?
Primary motor cortex does voluntary motor activity of LIMBS and somatotopic organisation.
The premotor area does voluntary motor activity of the trunk.
What is the role of the supplementary motor area?
Complex and bimanual movements
Where are the inferior frontal regions?
Left inferior frontal gyrus - Broca’s area (44 + 45)
Describe the importance of the inferior frontal regions.
Critical for speech output
What is Broca’s aphasia?
Lesion of Broca’s area in the inferior frontal regions - severely reduced verbal output, halting and effortful, fully preserved comprehension however.
Short stuttering sentences, gramatically inaccurate.
What is the importance of the dorsolateral area of the prefrontal regions?
Self-monitoring, planning and problem-solving (‘executive function’)
What is the importance of the polar and orbitofrontal regions (of the prefrontal regions)?
Personality and social behaviour
What is the parietal lobe important for?
Sensations of touch, smell, taste
Multimodal integration
What can nondominant parietal lesions lead to?
Hemispatial neglect eg. coming in and only shaving one side of the face
V1 (striate cortex) is a the top of cortical processing in the occipital lobe. What will damage to V1 cause?
Cortical blindness or hemianopia
What are V2 and V3 (extrastriate) in the occipital lobe for? What can damage lead to?
Important for colour and motion.
Lesions can lead to acquired colour-blindness - achromatopsia, akinetopsia (inability to see movement)
What is the superior temporal gyrus important for?
Hearing - primary auditory cortex
What lies adjacent to the primary auditory cortex? What can damage to this area lead to?
Wernicke’s area - for language comprehension.
Damage -> Wernicke’s aphasia, fluent but nonsensical speech often containing word-like sounds, poor speech comprehension.
What connects Broca’s area and Wernicke’s area?
The arcuate fasciculus
What is amnestic syndrome? Which area of the brain does it affect?
The limbic system (fornix, hippocampus, mamillary) - it is the inability to store new information in the context of full awareness. Patients continuously repeat the same statements or questions.
What type of brain injury develops over seconds?
Haemorrhage - present with hypertension, results in impaired conscious level.
What type of brain injury develops over minutes?
Infarct, higher for people with vascular disease - peripheral or CHD.
Describe impacts of infection on the brain
Damage is diffuse, limited to white matter, frontal and temporal.
Fever, tachycardia, confusion
Eg. herpes encephalitis, develops over hours
How long does inflammation take and who is it typical in?
Develops over hours to days, in young patients with multiple lesions
What is neoplasia?
Formation of new or abnormal growth, develops over days to weeks, may be over primary or secondary.
Common among glial cells.
Can be due to primary or secondary brain tumours.
Alzehimer’s is the most common neurodegenerative disease, they are often age related. Where else in the brain does neurodegenration affect?
- Nigrostriatal neurons (Parkinson’s)
- Anterior horn cells (MNS)
- Focal cortical regions (“Pick’s”)
