Final Exam: Chapter 24 Memory Systems, Chapter 25 Molecular Mechanisms of Learning and Memory

Question 1

learning

Answer 1

• acquisition of new knowledge or skills

- molecular problem involving change in synaptic strength

Question 2

molecular vs systems problems

Answer 2

• molecular problem: what are molecular mechanisms whereby that storage occurs at each site?
• systems problem: where in the brain are various memories stored?

Question 3

memory

Answer 3

retention of learned information

Question 4

declarative memory

Answer 4

memory of facts
temporal lobe; diencephalon
conscious effort

Question 5

nondeclarative memory

Answer 5

implicit
direct experience
-procedural memory
-classical conditioning
-----skeletal musculature (cerebellum)
-----emotional responses (amygdala)

Question 6

non associative learning

Answer 6

-change in behavioral response that occurs over time in response to single type of stimulus (either habituation or sensitization)

Question 7

habituation

Answer 7

learning to ignore a stimulus that lacks meaning

Question 8

sensitization

Answer 8

intensifies your response to all stimuli, even those that previously evoked little or no reaction

Question 9

associative learning

Answer 9

• behavior altered by formation of associations between events
• –classical conditioning
• –instrumental conditioning

Question 10

classical conditioning

Answer 10

associating a stimulus that evokes measurable response with second stimulus that normally does not evoke this response
-the learned response to the conditioned stimulus=conditioned response

Question 11

instrumental conditioning

Answer 11

individual learns to associate a response (motor act) with meaningful stimulus (typically reward such as food)

Question 12

why do we study using invertebrate models?

Answer 12

(aplysia californica or drosophila melanogaster)

• in invertebrates, changes are presynaptic; vertebrates, changes=post synaptic
• small nervous system
• large neurons
• identifiable neurons (classified by size, location)
• identifiable circuits
• ability to learn
• simply genetics (small genomes, rapid life cycles)

Question 13

ex habituation in aplysia

Answer 13

repeated stimulus–>response weakens

1. Ca2+ channels open less often with repetition (worn out)
2. less opening –> reduced inward Ca2+ –> lower presynaptic Ca2+ –> less NT
3. less withdrawal of gill muscle
4. muscle habituation

Question 14

memory storage

Answer 14

sensory information

• ->working memory OR
• –>short term memory
• ——–>with time and consolidation, long term memory

Question 15

Hebb’s rule 1

Answer 15

-learning=synaptic strengthening
-pre and post synaptic coactivation
-when axon of cell A excites cell B and repeatedly and persistently takes part in firing it, some growth process/metabolic process takes place in one or both of the cells so that A’s efficiency, as one of the cells firing B, is increased
-or, when presynaptic axon is active and, at the same time, the post synaptic neuron is STRONGLY activated by other inputs, synapse=strengthened
…If activation of cell assembly persists for long enough, consolidation occurs by growth process
-neurons that fire together are wired together
-cell assembly held in working memory unless it undergoes this process

Question 16

cell assembly

Answer 16

• internal representation of object=all cortical cells activated by stimulus
• group of these simultaneously active neurons
• cells are reciprocally interconnected

Question 17

Hebb’s rule 2

Answer 17

• forgetting=synaptic weakening
• presynaptic activity does not cause post synaptic activity
• when pre synaptic axon is active and, at the same time, post synaptic neuron is WEAKLY activated by other inputs, synapse is weakened
• neurons that fire out of sync lose their link

Question 18

Morris water maze

Answer 18

• hippocampus necessary for spacial memory
• ->mice with bilateral hippocampal damage never figure out/remember location of platform
• place field evokes greatest response, place cells
• block NMDA receptor is blocking spatial memory

Question 19

Memory consolidation

Answer 19

• process by which some experiences (which are being held temporarily by transient modifications of neurons) are selected for permanent storage in long term memory
• changes short term memory to long term

Question 20

ex sensitization aplysia

Answer 20

-strong noxious stimulus–> strong response returns
STEPS
1. apply brief electrical shock to head of aplysia
2. 5-HT released presynaptically by L29 onto the sensory neuron
3. G protein coupled receptor activated
–>activates Adenyl cyclase
—–>production of cAMP from AMP
———>activates protein kinase A (PKA)
4. Protein kinase A attaches PO4 to K+ channels
–>channels close
5. decrease in K+ conductance, prolongs action potential
6. More Ca2+ entry
–>more NT release per AP
—–>gill withdrawal reflex restored

Question 21

long-term potentiation

Answer 21

-hippocampus (critical for memory formation)
-high freq electrical stimulation: tetanus
-induces LTP and subsequent test stimulation evokes EPSP much greater
-modification of stimulated synapses so that they are more effective
-Input specificity: only active inputs show synaptic plasticity
*however, tetanus not always required – just need synapses active at the same time post synaptic CA1 neuron depolarized (this is often caused by the tetanus though)
+ COOPERATIVITY: coactive synapses must cooperate enough to produce enough depolarization to cause LTP

Question 22

mechanisms behind LTP

Answer 22

-CA1 neurons have NMDA receptors
(review)
-only conduct Ca2+ when
1. glutamate binds and
2. post synaptic membrane depolarized enough to displace MG2+
AMPA: ligand gated; conducts Na
NMDA: ligand and voltage gated; conducts Na and Ca

Question 23

ex classical conditioning aplysia

Answer 23

US=strong shock of tail
R=withdrawal of gill
CS=gentle stimulation of siphon
-like during sensitization, 5-HT
-but also Ca2+ acts at same time
——-
-CS + US=greater activation of adenyl cyclase becase CS increases Ca2+
-increase in sensitivity to G protein activation
-learning: Ca2+ and 5-HT coincide, increase cAMP, increase protein kinase activity (PKA)

Question 24

Synaptic structural changes

Answer 24

-occur after LTP
-sprouting synapses increases responsive post synaptic surface, increases probability of AP triggering presynaptic glutamate release
PRESYNAPTIC CHANGES
-amount of NT released
-size of presynaptic terminal
-number of axon terminals (sprouting)
POST SYNAPTIC CHANGES
-Phosphorylation of AMPA receptor
-externalization of AMPA and NMDA receptors
-synthesis of new AMPA and NMDA receptors
-increase in size of post synaptic element
-changes in spine shape

Question 25

Long term depression (LTD)

Answer 25

1. Synaptic transmission occuring at same time as strong depolarization of post synaptic neuron causes LTP
2. synaptic transmission at the same time as weak/modest depolarization, LTD
   * *difference is in NMDA activation
   - with only weak depolarization, partial blockage of channels by Mg2+, not enough Ca2+ entering
   - with stronger depolarization, Mg2+ displaced, Ca2+ levels activate protein phosphatases (enzymes that take phosphate groups off proteins)
   - ->LTP is putting phosphate groups on, LTD is taking them off