SN7
SHORT NOTE
5M
★ High-yield
Enumerate the functional areas of the cerebral cortex with the effects of their lesions.
Functional Areas of the Cerebral Cortex
| Area | Brodmann | Function | Effect of lesion |
|---|---|---|---|
| Primary motor | 4 | Voluntary skilled movement | Contralateral spastic paralysis |
| Premotor / supplementary | 6 | Planning and sequencing of movement | Apraxia |
| Primary sensory | 3, 1, 2 | Touch, pain, temperature, proprioception | Contralateral sensory loss |
| Sensory association | 5, 7 | Stereognosis, body image | Astereognosis, neglect |
| Primary visual | 17 | Vision | Homonymous hemianopia |
| Visual association | 18, 19 | Interpretation | Visual agnosia |
| Primary auditory | 41, 42 | Hearing | Difficulty localising sound |
| Broca | 44, 45 | Motor speech | Expressive aphasia |
| Wernicke | 22 | Comprehension | Receptive aphasia |
| Angular gyrus | 39 | Reading and writing | Alexia, agraphia |
| Prefrontal | 9–12 | Judgement, planning, personality, working memory | Disinhibition, apathy, loss of judgement |
Cerebral Dominance
- 95% of right-handers and 70% of left-handers are left hemisphere dominant for language
- Dominant hemisphere — language, calculation, analysis, logic
- Non-dominant hemisphere — spatial relations, music, facial recognition, emotional tone of speech
- Determined clinically by the Wada test or functional MRI before neurosurgery
Syndromes of Cortical Lesions
| Lesion | Syndrome |
|---|---|
| Dominant parietal | Gerstmann syndrome — agraphia, acalculia, finger agnosia, left–right disorientation |
| Non-dominant parietal | Contralateral neglect, dressing and constructional apraxia |
| Frontal lobe | Personality change, disinhibition, primitive reflexes, incontinence |
| Temporal lobe | Memory impairment, complex partial seizures, Klüver–Bucy syndrome |
| Occipital | Cortical blindness with intact pupillary reflexes |
Applied Aspects
- The classical case of Phineas Gage — frontal lobe injury transformed his personality while leaving intelligence and memory intact; the foundation of frontal lobe physiology
- Plasticity — cortical maps reorganise after injury and with practice; the basis of rehabilitation after stroke, and greatest in childhood
- Localisation guides diagnosis — the pattern of deficit predicts the site of the lesion before any imaging is done
One book of nineteen in the KAVACH series · mbbsadda.in
All questions in Autonomic Nervous System & Integrative Physiology
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- Q4Describe the cardiovascular, respiratory and metabolic changes that occur during exercise. Add a note on the effects of training. ★
- Q5Classify memory and describe the mechanism of its formation. Describe the areas concerned with speech and the types of aphasia. ★
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- SN2Define fever. Describe its mechanism, phases and effects. ★
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- SN5Describe heat stroke and differentiate it from heat exhaustion. Add a note on acclimatisation to heat. ★
- SN6Write a short note on denervation hypersensitivity.
- SN7Enumerate the functional areas of the cerebral cortex with the effects of their lesions. ★