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Flashcards in Week 4 Lecture Deck (43)
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1
Q

Define plasticity

A

The capacity of the nervous system to change in response to environmental stimuli - this capacity underlines experience-dependent modifications of brain functions.

2
Q

What are the 3 adaptive responses in which brain plasticity can change?

A
  1. at genetic/molecular
  2. neurophysiological
  3. functional
3
Q

What does our ability to learn to change our brain plasticity depend on?

A

Depends on the plasticity of the circuits in the brain - the ability for the neutrons to make lasting changes in the efficiency of their syntactic transmission

4
Q

Who developed the association and networking of neutrons, and what did he infer?

A

Donald Hebb. “if two neutrons are active at the same time, the connection between them is strengthened”

5
Q

What is the Hebbian rule?

A

When an axon of cell A is near enough to excite cell B and repeatedly or persistently firing in it, some growth processes or metabolic changes take place in one or both cells such that A’s efficiency as one of the cells firing B is increased

6
Q

What is Hebb’s law often paraphrased as?

A

“Neurons that fire together wire together”

7
Q

What sis Thimothy Bliss and Terje Lom describe about plasticity?

A

The described long-term potentiation in the hippocampus , a form of plasticity with wide implications for understanding and memory

8
Q

What are the 3 pathways in the hippocampus?

A

1 .perforant path

  1. mossy fibre pathway
  2. Schaffer’s collaterals pathway
9
Q

What are patterns of synaptic activity in the CNS producing a long-lasting increase in synaptic strength called?

A

long-term potentiation

10
Q

What are patterns of synaptic activity in the CNS producing a long-lasting decrease in synaptic strength called?

A

long-term depression

11
Q

Describe a non-associative LTP

A

Two stimulating electrodes (1 and 2) each activate separate Schaffer collaterals fibres, thus providing a test and control synaptic pathways.

only pathway 1 is stimulated with high frequency

12
Q

Describe the recording of a non-associative LTP

A

synaptic responses recorded in a CA1 neutron in response to stimulation of synaptic pathways 1 or 2 minutes before and one hour after a high frequency train of stimuli

13
Q

In a non-associative LTP, what does the magnitude of the change vary upon?

A

How many trains of stimulation are applied

14
Q

What is one difference between an associative LTP?

A

The same weak stimulus to pathway 2 is activated together with a strong stimulation of pathway 1, and both sets of synapses are strengthened (both inputs are stimulated and both synaps are strengthened).

15
Q

What is the molecular basis of associative LTP?

A

The channel opens only when glutamate is bound to NMDA receptors and the postsynaptic cell is depolarised to stop the block of the NMDA channel.

16
Q

Where has the NMDA receptors been “mutated” (inhibited) to show the effects of NMDA on spatial memory?

A

In the Morris water test with rodents. Blocking the NMDA receptors (preventing LTP) altered the rodents spatial memory, making it more difficult.

17
Q

What are some of the most widely used organisms for studying the cellular foundations of learning and memory?

A

rodents, honey bees, birds and the sea slug Aplysia Californica

18
Q

What causes then gill withdrawal reface in the Aplysia sea slug?

A

stimulation of the siphon

19
Q

What happens after repeated stimulation of the sensory neuron in the sea slug Aplysia?

A

Less neurotransmitter are released by the sensory neuron (the gill doesn’t withdraw)- habituation of the reflex it is a presynaptic phenomenon.

20
Q

What happens if a stimulation of the siphon is also given with the stimulation on the tail or head before touching the siphon to the Aplysia?

A

The siphon gill response is sensitised.

21
Q

What do Clark’s nutcracker show about functional plasticity?

A

Retrieves hidden seeds in winter
good spatial memory
largest hippocampus ration

22
Q

What does the Florida scrub jay show about functional plasticity?

A

Stores food but less dependent on it
weaker spatial memory
smaller hippocampus ratio

23
Q

Describe filial imprinting on animals?

A

IN the first week of their life, infant rats develop a lifelong preference to odours associated with their mothers nipples

24
Q

Describe a critical period

A

If it is absolutely essential for an experience to occur within a particular interval to allow normal development , the interval is called a critical period.

25
Q

Describe a sensitive period

A

When the effect of an experience has a great effect on development during a period but the development is not exclusive to that period and can occur outside of it, it is called a sensitive period

26
Q

If there is no visual experience in early development, what is the effect of this?

A

The synapses are lost, and thus many functional connections in the brain are lost (“use it or lose it”).

27
Q

If one eye is not functional in the critical period, what can this mean for the individual?

A

Monocular vision can be lost forever.

28
Q

If someone has been playing violin their whole life, what will happen with their fifth finger is stimulated?

A

More neurons will fire than those of non-musicians

29
Q

In musicians, what is different in their brain than others?

A

The size of the Omega sign

30
Q

What did Paul Broca discover?

A

That ADULT patients with lesions in the left frontal lobe display aphasia

31
Q

What did Jules Cotard discover?

A

Observed children with left frontal lesions who developed near normal adult language functions.

32
Q

What are three things that Woods and Teuber discover about damage to the left or right hemisphere?

A
  1. language survives after early left hemisphere injury
  2. much of the survival depends on the appropriation of a potential language zone in the right hemisphere
  3. the shift of the language has a price (some visuospatial orientation is impaired)
33
Q

What is found in relation to cortical reorganisation in the cortex, without visual input?

A

There is an expansion of auditory and somatosensory cortices

34
Q

About 50% of amputees experience what?

A

Severe, chronic pain in their phantom limbs.

35
Q

What did Dr. Ramachandram find?

A

That parts of the phantom arm “invaded” other parts of the body (the hand on the shoulder etc).

36
Q

What are the three ways that plasticity is made possible?

A
  1. alteration of the synaptic strength
  2. formation of new connections and
  3. by adding new neurons
37
Q

Describe an example of neurogenesis in bird song learning

A

Before the start of the mating season, the number and size of cells in the HVC increases dramatically.

38
Q

Where does adult neurogenesis occur in the brain?

A

In the dentate gyrus of the hippocampus

39
Q

What are two ways that drugs alter neurogenesis?

A
  1. ecstasy (MDMA) exposure decreases the survival of neuronal precursor in the dentate gyrus.
  2. alcohol increases the risks of MDMA in neurogenesis and also long-term memory
40
Q

How does depression affect the hippocampus?

A

Decreases hippocampal volume by around 20%.

41
Q

What does antidepressant medication do for neurogenesis?

A

enhances plasticity and hippocampal neurogenesis but does not have immediate therapeutic affects

42
Q

What is an activity which promotes neurogenesis?

A

Aerobic exercise.

43
Q

Brains which are in richer, more stimulating environments have what affect on neurogenesis?

A

Have increased number of synapses and larger dendritic arbours.Can lead to the formation of neurons and reverses loss go neurons.