Structure and Function of the Brain Flashcards
Describe the cerebral cortex
The cerebral cortex is arranged into regions with specified functions:
- Brodmann’s areas. Brodmann’s classification is based on cytoarchitectural/histological structure of the cortex
What is the result of cortical lesions?
- Can result in focal or widespread deficits:
- Motor and sensory cortical lesions result in CONTRALATERAL symptoms due to decussation.
- Cognition, language and memory can all be affected.
- Lesions can be due to stroke, tumours or trauma
What are the main functions of the right hemisphere?
- Left motor functions
- Left sensory functions
- Left stereognosis
- Left body image
- Left visual fields
- Bilateral audio
- Spatial perception
- Facial recognition
What are the main functions of the left hemisphere?
- Right motor functions
- Right sensory functions
- Right stereognosis
- Right body image
- Right visual fields
- Bilateral audio
- Speech
- Writing
- Language
What do association cortical regions do?
Allow for interpretation of received information
What symptoms can occur with loss of an associated area/connections between areas cause?
Agnosia - loss of ability to recognise objects, shapes, smells or sounds
Astereognosis - loss of tactile ability to recognise objects by texture, shape, size and weight (but can describe them)
Prosopagnosia - inability to recognise faces
Synaesthesia - stimulation of one sensory/cognitive pathway leads to automatic experiences in a second sensory/cognitive pathway
What is a nucleus in the CNS?
Collection of neuronal cell bodies at a point of synapse that share a similar function and projections
NB: The thalamus represents a large collection of nuclei
What is the definition of the blood brain barrier?
It is a highly selective semipermeable membrane border that separates circulating blood from the brain and extracellular fluid in the CNS
What is the structure of the blood brain barrier?
It is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane
What characteristics allow the blood brain barrier to protect the brain?
- Tight junctions (physical barrier)
- Transport (mediate influx/efflux of compounds)
- Metabolic/Enzymatic (high concentration of specialised enzyme systems including nucleotidases and peptidases)
- Immunological (perivascular macrophages - mast cells reinforced by microglial cells)
What are the functions of the blood brain barrier?
- Maintains brain homeostasis and optimal conditions for neuronal function
- Protects brain against surging fluctuations in plasma ion concentrations
- Restricts entrance of potentially harmful macromolecules (such as albumin, prothrombin, bilirubin, plasminogen)
- Allows selective transport of essential nutrients into the brain
