3. Epilepsy and Neuroplasticity

Question 1

What is epilepsy?

Answer 1

• chronic medical condition produced by temporal changes in the electrical function of the brain
• causes seizures which affects awareness, movement or sensation

Question 2

Who is mainly affected by epilepsy?

Answer 2

• children and the elderly
• binomial distribution

Question 3

Why is epilepsy idiopathic?

Answer 3

• no single cause
• often not clear why it is being experienced

Question 4

What do the symptoms of epilepsy depend on?

Answer 4

• the type of epilepsy
• the area of the brain effected (lots of specialisation)

Question 5

What are the subtypes of epilepsy?

Answer 5

• partial epilepsy: simple partial seizures and complex partial seizures
• generalised epilepsy: grand mal seizures and petit mal seizures

Question 6

What are simple partial seizures?

Answer 6

• localised to specific areas of the brain
• localised effects that are usually sensory and/or motor

Question 7

What are complex partial seizures?

Answer 7

• localised to specific areas of the brain
• ‘complex’ as their effects are complex and diverse
• also referred to as temporal lobe epilepsy

Question 8

What is aura in terms of partial seizures?

Answer 8

symptoms preceding the partial seizure
- abnormal sensations e.g sense of fear, strange tastes etc

Question 9

What are petit mal (absence) seizures?

Answer 9

• can involve entire brain: generalised at low level
• person is briefly ‘absent’
• more common in children: often disappear with age

Question 10

What are grand mal seizures?

Answer 10

• can involve entire brain: generalised
• patient may lose consciousness, fall to the ground, rigidly extend all limbs then have jerks in all extremities

Question 11

What’s happening to a brain during a seizure?

Answer 11

• EEG detects synchronised activity of many neurons (field potentials)
• diagnosis based on EEG measures plus neuropsychological symptoms

Question 12

What can induce seizures in animal models?

Answer 12

• infusion of excitatory agents

Question 13

What is the pharmacological treatment for seizures?

Answer 13

• drugs that target GABA or NA+ channels
• seek to dampen down the excessive neural firing e.g increasing the release of the inhibitory neurotransmitter GABA

Question 14

What is neuroplasticity?

Answer 14

• changes to brain structure, connectivity and function over time in response to changing environment (internal or external)

Question 15

What are the 3 key principles to neuroplasticity?

Answer 15

1. neurodegeneration
2. neural regeneration
3. neural reorganisation

Question 16

What is neurodegeneration?

Answer 16

• connections in the brain die with age (not the neurons)
• this optimises the network

Question 17

Why does neurodegeneration occur in the context of brain disease?

Answer 17

• disruption to the homeostatic environment within and surrounding the neuron

Question 18

Why does neuronal death occur?

Answer 18

1. disruption of normal neurotransmitter function
2. loss of fuel supply
3. attack from infections, toxins or own immune systems
4. faulty genetic signalling
5. physical injury

Question 19

What are the two types of neuronal death?

Answer 19

1. necrosis: death due to cellular ill health (unmanaged), leads to bits of cell floating around
2. apoptosis: the cellular self destruct option (adaptive), programmed cell death

Question 20

Which nervous system is neural regeneration affective in and which is it not?

Answer 20

• capacity for it in the PNS
• more complex in CNS

Question 21

What does regeneration depend on?

Answer 21

• tissue environment

Question 22

What is neural reorganisation?

Answer 22

• reorganises maps in the brain

Question 23

What happens in response to loss of peripheral input?

Answer 23

• reorganisation involves intact/connected areas expanding to take over tissue that receives no input
• this is based on the changes in connectivity, strengthening of previous partially overlapping connections and some new connections