Injury to the cerebral hemispheres and cognitive function

Question 1

What is the first thing a neurologist wants to know in relation to brain lesions?

Answer 1

WHERE is the lesion?

• Clinical examination + observation
• Rudimentary understanding of neuroanatomy

Question 2

What are the 6 layers of the grey matter laminar organisation in the cortex??

Answer 2

• I - molecular
• II - external granular
• III - external pyramidal
• IV - internal granular
• V - internal pyramidal
• VI - multiform

Question 3

What are the differences of function between the left and right cerebral hemispheres?

Answer 3

• Left - verbal info, language, arithmetic, linear reasoning
• Right - spatial, nonverbal, number estimation, holistic problem solving

Variable between individuals, not easily studied.

Question 4

What lobes does the Sylvian fissure separate?

Answer 4

Temporal and frontal

Question 5

What are the 3 subregions of the frontal lobe?

Answer 5

1. Motor, premotor, supplementary motor areas
2. Inferior frontal cortex
3. Prefrontal cortex (dorsolateral, ventromedial, orbital)

Question 6

Describe the importance of the primary motor cortex? How is the premotor area different?

Answer 6

Primary motor cortex does voluntary motor activity of LIMBS and somatotopic organisation.

The premotor area does voluntary motor activity of the trunk.

Question 7

What is the role of the supplementary motor area?

Answer 7

Complex and bimanual movements

Question 8

Where are the inferior frontal regions?

Answer 8

Left inferior frontal gyrus - Broca’s area (44 + 45)

Question 9

Describe the importance of the inferior frontal regions.

Answer 9

Critical for speech output

Question 10

What is Broca’s aphasia?

Answer 10

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.

Question 11

What is the importance of the dorsolateral area of the prefrontal regions?

Answer 11

Self-monitoring, planning and problem-solving (‘executive function’)

Question 12

What is the importance of the polar and orbitofrontal regions (of the prefrontal regions)?

Answer 12

Personality and social behaviour

Question 13

What is the parietal lobe important for?

Answer 13

Sensations of touch, smell, taste

Multimodal integration

Question 14

What can nondominant parietal lesions lead to?

Answer 14

Hemispatial neglect eg. coming in and only shaving one side of the face

Question 15

V1 (striate cortex) is a the top of cortical processing in the occipital lobe. What will damage to V1 cause?

Answer 15

Cortical blindness or hemianopia

Question 16

What are V2 and V3 (extrastriate) in the occipital lobe for? What can damage lead to?

Answer 16

Important for colour and motion.

Lesions can lead to acquired colour-blindness - achromatopsia, akinetopsia (inability to see movement)

Question 17

What is the superior temporal gyrus important for?

Answer 17

Hearing - primary auditory cortex

Question 18

What lies adjacent to the primary auditory cortex? What can damage to this area lead to?

Answer 18

Wernicke’s area - for language comprehension.

Damage -> Wernicke’s aphasia, fluent but nonsensical speech often containing word-like sounds, poor speech comprehension.

Question 19

What connects Broca’s area and Wernicke’s area?

Answer 19

The arcuate fasciculus

Question 20

What is amnestic syndrome? Which area of the brain does it affect?

Answer 20

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.

Question 21

What type of brain injury develops over seconds?

Answer 21

Haemorrhage - present with hypertension, results in impaired conscious level.

Question 22

What type of brain injury develops over minutes?

Answer 22

Infarct, higher for people with vascular disease - peripheral or CHD.

Question 23

Describe impacts of infection on the brain

Answer 23

Damage is diffuse, limited to white matter, frontal and temporal.

Fever, tachycardia, confusion

Eg. herpes encephalitis, develops over hours

Question 24

How long does inflammation take and who is it typical in?

Answer 24

Develops over hours to days, in young patients with multiple lesions

Question 25

What is neoplasia?

Answer 25

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.

Question 26

Alzehimer’s is the most common neurodegenerative disease, they are often age related. Where else in the brain does neurodegenration affect?

Answer 26

• Nigrostriatal neurons (Parkinson’s)
• Anterior horn cells (MNS)
• Focal cortical regions (“Pick’s”)