Anatomy and neurobiology of memory: L12

Question 1

role of amygdala in memory

Answer 1

1. supporting memory for emotionally arousing experiences
   - fear conditioning
   - representations of emotional experiences

Question 2

lesions of amygdala result in

Answer 2

• loss of conditioned fear and impairment of new fear learning
• reduced memory for emotionally laden events

Question 3

what 3 regions of the extra-temporal brain are particularly involved in memory?

Answer 3

• papez’s circuit
• frontal lobes
• diencephalon

Question 4

what did James Papez propose in 1937

Answer 4

a specific brain circuit was devoted to emotional experience and expression
(Papez circuit + amygdala = limbic system)

Question 5

what does papez’s circuit comprise of?

Answer 5

maxillary bodies, fornix, anterior thalamic nuclei (ATN), cingulate gyrus and the hippocampus

Question 6

what is the efferent pathway?

Answer 6

outgoing, leaves the hippocampus -> fornix -> maxillary bodies. An efferent projection is then sent to the anterior -> cingulate cortex

Question 7

what do lesions to papez’s circuit result in?

Answer 7

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

Question 8

frontal lobes are involved in (1)

Answer 8

• memory processing

- motor programming and function

Question 9

1. central sulcus location

2. primary motor cortex location

Answer 9

1. line dividing frontal and occipital lobes

2. front side of the central sulcus = most posterior component of the frontal lobes

Question 10

define homunculus

Answer 10

how the neuronal structure of the primary motor cortex and the primary somatosensory cortex are laid out

Question 11

frontal lobes are involved in (2)

Answer 11

• cognitive control processes e.g. problem solving, planning, monitoring and self-correction

Question 12

1. pre motor area

2. prefrontal area

Answer 12

1. planning motor functions

2. executive cognitive processes

Question 13

what are the frontal lobes involved in regarding memory? (Simons & Spiers)

Answer 13

• developing and implementing strategies for appropriate memory encoding and retrieval

Question 14

Damage to DLPF (area in frontal lobes) results in

Answer 14

misrepresentation of the chronological order of memories

Question 15

Damage to prefrontal cortex can experience

Answer 15

confabulation = production of statements involving bizarre distortions of memory

Question 16

Frontal lobe memory involvement

Answer 16

connections go directly back and forwards to the perirhinal cortex and the hippocampus via the fornix

Question 17

define diencephalon

- comprises?

Answer 17

• interbrain = thalamus and hypothalamus

Question 18

what is the thalamus?

Answer 18

• cortical connections of thalamus send reciprocal projections to different parts of the brain

Question 19

damage to particular area of thalamus results in?

Answer 19

severing the connection to its corresponding section of the brain

Question 20

Thalamus and memory

Van der Werf study results

Answer 20

• anterior and medical lesions more likely to cause memory deficits than posterior or lateral lesions
• dense amnesic syndrome associated with mammillo-thalamic tract damage

Question 21

what did cases with medio dorsal nucleus (MDN) and/or internal medullary lamina (IML) damage but spares MTT show?

Answer 21

specific retrieval difficulties (preserved recognition)

Question 22

damage to thalamus:

• dorsal medial
• intralaminar/ midline

Answer 22

• dorsal medial, midline and intralaminar nuclei of the thalamus = role in memory
• deficits in selecting the appropriate information to be retrieved ‘active retrieval’
• deficits seen in semantic memory, memory retrieval

Question 23

axon hillock threshold needs to reach what for an AP to fire

Answer 23

55mV

Question 24

• resting membrane potential is?

- undershoot is

Answer 24

-70mV

under -70 mV

Question 25

whats an excitatory post synaptic potential?

Answer 25

when a neurotransmitter crosses the synaptic cleft and produces an excitatory change in the dendrite (= increasing the voltage)

Question 26

what is synaptic plasticity?

- whats long-term potentiation?

Answer 26

• the biochemistry of synapses change to alter the effect on post-synaptic neuron
• 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 27

what’s Hebb’s rule?

Answer 27

• when an axon of cell A excited cell B & repeatedly or persistently takes part in firing it
• growth process or metabolic changes occurs in one or both cells

Question 28

Long-term potential (LTP)

Answer 28

• the effect of cell A sending a message to cell B
• baseline EPSP measured for single electric stimulus
• 100 electrical stimuli delivered rapidly
• increased EPSP for subsequent single electrical stimulus = LTP

Question 29

LTP causes synaptic change

Answer 29

• additional receptors are inserted in the post synaptic membrane = more receptors for neurotransmitters to lock into

Question 30

LTP: what changes occur in synapses?

Answer 30

• increased sensitivity of receptors to glutamate
• increased amount of glutamate released by the pre-synaptic terminal button
• protein synthesis in post-synaptic dendrites

Question 31

sites of long-term potentiation

Answer 31

• hippocampus
• entorhinal cortex
• prefrontal cortex
• motor cortex
• thalamus
• amygdala
• visual cortex

Question 32

other mechanisms of synaptic plasticity

Answer 32

• long term depression (low frequency stimulation = decreases synaptic strength)
• habituation ( repeated stimulation -= reduces strength of synaptic response)
• sensitisation (single noxious stimulus = exaggerated synaptic response)