CNS - Brain Maturation and Ageing

Question 1

What does brain maturation involve?

Answer 1

Mitosis and apoptosis of neurones, development and pruning of synapses, increased myelination, strengthening of connectivity

Question 2

What is a sensitive period?

Answer 2

A period in time when the brain is more susceptible to developmental learning

Question 3

What is a critical period?

Answer 3

A period of time during which is the only time a behaviour can be learned - if an animal doesn’t learn during this period it never will (e.g eyepatch used during critical period for binocular vision)

Question 4

What brain development occurs during adolescence?

Answer 4

Significant brain development - non-linear and region specific
significant synaptic pruning, reduction and refinement of grey matter, increased myelination and enhanced connectivity

Question 5

What is the neurological basis for risk taking behaviour in adolescent humans?

Answer 5

Sensory and motor cortex are fully developed by sexual maturity but pre-frontal and frontal cortex are not fully developed (impulse control and consideration of others)

Question 6

Name two types of memory (not short and long term)

Answer 6

Declarative and procedural memory

Question 7

What is declarative memory?

Answer 7

specific facts which may result from a single experience i.e. knowing THAT something is the case

Question 8

What is procedural memory?

Answer 8

motor skills resulting from repetitive training i.e. knowing HOW to do something

Question 9

What are the features of short term memory?

Answer 9

Seconds to hours in duration
Electrical memory trace only
Limited storage capacity (7-10 chunks of info at a time)
Must be rehearsed to be consolidated as LTM
If not rehearsed, easily forgotten

Question 10

What are the features of long term memory?

Answer 10

Days to years in duration
Physical memory trace - growth of new dendrites, new synapses etc
Apparently infinite capacity
Constantly refined in light of new STMs
Can take longer to retrieve information from LTM
Forgetting often just transient

Question 11

How do you form a memory?

Answer 11

Attention is paid to a sensory experience
This results in transient changes in activity of existing synapses
If STM is rehearsed –> LTM
Physical changes including growth of dendrites, forming of new synapses

Question 12

Why does more learning enable more learning?

Answer 12

Animals with greater learning potential have longer more branched dendrites so more potential for synaptic connections

Question 13

What are the two forms of Non-associative learning?

Answer 13

Hibituation - natural response to a stimulus reduces over time
Sensitisation - natural response to a stimulus increases over time
Depends on the context/emotional sate of the animal as to which is used

Question 14

What are the two forms of Associative learning?

Answer 14

Operant conditioning - animal learns to associate a behaviour with an outcome e.g begging
Classical Conditioning - animal learns to associate two stimuli that produce a desirable behaviour e.g clicker training

Question 15

What is classical conditioning?

Answer 15

Pairs a conditioned stimulus (something the animal wouldn’t normally react to e.g. a verbal phrase) with an unconditioned stimulus (something the animal would normally react to e.g. a treat)
Motivation is key - incentive learning

Question 16

Name and explain 3 causes of apparent loss of learning

Answer 16

Constantly presenting the animal with the conditioned stimulus without the unconditioned - eventually the animal stops responding
Context - for accurate retrieval of learning, the conditions must be the same as those present during learning e.g. puppy in room with other dogs vs quiet room with just the owner
Conflicting information during testing e.g. dog recall (shouting vs being sweet)

Question 17

What is CDS?

Answer 17

Cognitive Dysfunction Syndrome is a degenerative disease affecting brain tissue, which is common in older animals. It’s recognised by changes in behaviour but loss of learning and memory starts occuring long before visible behaviour changes

Question 18

Neuropathology of CDS?

Answer 18

Brain atrophy - widening of sulci, narrowing of gyri, dilation of ventricles and decreased neuronal density
Senile plaques - protein plaques (esp. beta- amyloid) around neurones. often in pre-frontal and temporal cortex, hippocampus and blood vessels
Oxidative damage - free radicals damage proteins, lipids, nucleotides, neurones
Neurofibrillary tangles - phosphorylation of the tau protein causes disintegration of neuronal microtubules, and unbound tau forms clumps

Question 19

Clinical signs of CDS?

Answer 19

DISHA
Disorientation
Interaction and social behaviour changes
Sleep-wake cycle alterations
House soiling
Activity level changes