Lecture 2

Question 1

What is the Limbic system composed of?

Answer 1

Papez’s circuit + amygdala

Question 2

What does the role of the amygdala in memory include?

Answer 2

Key role: supporting memory for emotionally arousing experiences.
In addition:
- enhances storage of memory of emotionally arousing experiences
- classical (fear) conditioning
- facilitates the rich representation of emotional experiences

Question 3

What results from lesions to the amygdala?

Answer 3

• Loss of the ability to develop and/or remember fear

- Reduced memory for emotionally laden events

Question 4

What does Papez’s circuit consist of?

Answer 4

Mamillary bodies + Fornix + Thalamic Nuclei (ATN) + Cingulate Gyrus + Hippocampus

Question 5

What results from lesions to Papez’s circuit?

Answer 5

• Declarative memory impairment (poor relational memory/encoding)
  
  • most reliable when hippocampus or ATN are lesioned

Question 6

What are the components of the diencephalon?

Answer 6

Thalamus & Hypothalamus

Question 7

What are lesions to the thalamus similar to, and why?

Answer 7

Lesions to the thalamus are similar to lesions to the Frontal Lobes, because it is a very richly connected network with the Frontal Lobes.

Question 8

What are the three main nuclei of the thalamus in memory?

Answer 8

• Dorsal medial nuclei
• Intralaminar nuclei
• Midline nuclei

Question 9

What results from damage to the DMN?

Answer 9

Deficits in selecting the correct memories.

Question 10

What results from damage to the intralaminar/midline nuclei?

Answer 10

Deficits in semantic memory and semantic memory retrieval.

Question 11

What are two of the key functions of the Frontal Lobes?

Answer 11

• Motor programming

- Cognitive control processes

Question 12

What is the role of the Frontal Lobes in memory?

Answer 12

The FLs are responsible for creating organised memories and facilitating the organised retrieval of memories.

Question 13

What results from lesions to the frontal lobes (in terms of memory)?

Answer 13

• Impairment in remembering contextual details such as when events occurred, and their chronological order
• Confabulation: creation of memories with a kernel of truth but elaborate with false/unfeasible detail.

Question 14

What are the extra temporal connections to the medial temporal lobes?

Answer 14

1. Papez’s circuit
2. Frontal Lobes
3. Diencephalon

Question 15

Summarise the effect of a lesion to Papez’s circuit.

Answer 15

Impaired declarative memory: impaired relational memory/encoding.

Question 16

Summarise the effect of lesions on the frontal lobes.

Answer 16

• Difficulty in recalling contextual details of events
• Confabulation
• Impaired ability to organise the encoding, retrieval and maintenance of memories.

Question 17

Summarise the effect of lesions on the DMN, intralaminar and midline nuclei. (Thalamus)

Answer 17

• Impaired memory due to reduced mental flexibility and inappropriate selection of information retrieval.
• Impaired semantic memory and semantic memory retrieval.

Question 18

List 7 features of a neuron.

Answer 18

Cell body, nucleus, dendrite, axon, nodes of Ranvier, myelin sheath (Schwann cells), axon terminals/buttons.

Question 19

In an action potential, how does depolarisation occur?

Answer 19

The opening of ion channels allows the diffusion of cations (Na+, K+) into the intracellular fluid and anions (Cl-) into the extracellular fluid.

Question 20

Describe, roughly, activity at a synapse.

Answer 20

Vesicles in the presynaptic neuron contain neurotransmitters which must be released; they will dock at the presynaptic membrane leading Ca+ ion to be expelled and the vesicles to release the NTs into the synaptic cleft, where they either bind to receptors in the post synaptic membrane, are swept away, or the presynaptic neuron will reuptake them.

Question 21

What is synaptic plasticity?

Answer 21

The changing of the biochemistry of synapses that alter the effect on the post synaptic neuron.

Question 22

What cognitive activity involves synaptic plasticity?

Answer 22

Learning

Question 23

Describe Long Term Potentiation.

Answer 23

A long term increase in the excitability of a neuron to a particular synaptic input caused by repeated high frequency activity of that input.

Question 24

Describe Long Term Depression.

Answer 24

A long term decrease in the excitability of a neuron to a particular synaptic input caused by consistently low frequency activity of that input.

Question 25

Describe habituation.

Answer 25

Post synaptic neurons will reduce their firing as a result of a specific synaptic input if that input is being delivered at a constant neither high frequency nor low frequency rate.

Question 26

Describe sensitisation.

Answer 26

Post synaptic neurons will become sensitised to specific ‘noxious stimuli’ if it is presented infrequently enough.

Question 27

Describe Hebb’s Rule.

Answer 27

When an axon of cell A… excites cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells so that A’s efficiency as one of the cells firing B is increased.

Question 28

How does long term potentiation cause synaptic changes?

Answer 28

• Extra glutamate (excitatory NT) to be installed in cell B
• Change is permanent
• Increased sensitivity to glutamate
• Increased glutamate release
• Increased protein synthesis in post synaptic density.

Question 29

Where does LTP generally occur?

Answer 29

Hippocampus, entorhinal cortex, PFC, MC, Thalamus, Hypothalamus, PVC.