Stimulus Control of Behaviour

Question 1

hippocampal functions

Answer 1

• rapidly binds multiple sensory inputs, contextual cues together (without reinforcement); these cues define particular moment in time; forms links between storage sites
• associated with forming new memories and memory arrangements (places and objects)
• directs gradual strengthening of connections

Question 2

glutamate and seizures

Answer 2

• open channels that are permeable to Na+; some influx of Na+ into postsynpatic membrane will cause it to become slightly depolarized
• pyramidal cell of middle layer of hippocampus have dendritic spines
• temporal lobe or medical temporal lobe seizures originate in hippocampal/amygdala area; associated with alterations to hippocampal structures and other networks
• after a seizure, hippocampal neurons that are part of mossy fibers form new synaptic connections

Question 3

ACh and memory

Answer 3

• ACh acts on nicotinic and muscarinic receptors in CNS
• cholinergic neurons are essential for
  1. new memory formation in hippocampus
  2. AMPA + NMDA receptors = ionotropic + activated by glutamate
• cortical ACh release increases during memory acquisition but NOT during recall of a rewarded operant B or during consolidation

Question 4

functions of ACh

Answer 4

1. implicated in aging-related dementia of hippocampus-dependent learning
2. cholinergic neurons densely innervate the hippocampus
3. mediate formation of episodic/semnatic memory

Question 5

AD development

Answer 5

• causes decrease in number of cholinergic neurons
• causes decrease in level of choline acetyltransferase (enzyme necessary for synthesizing ACh in basal forebrain)
• alterations in function of muscarinic/nicotinic ACh recept have been associated with AD
• elevation of ACh levels via blockade of acetylcholinesterase (enzyme that breaks down ACh): method to treat AD
• NOTE: anticholinergic meds (often used for gastrointestinal disorders) can cause dementia; suggests role of cholinergic neurons in memory

Question 6

longterm potentiation

Answer 6

lasting increase in neural excitability observed in postsynaptic neuron
VERY IMPORTANT REFER TO PAGE 45 OF NOTEBOOK + SLIDES 26 to 29

Question 7

AMPA receptors

Answer 7

• activated in postsynaptic neuron by glutamate release from presynpatic neuron
• allows Na+ to enter postsynaptic cell and initiate depolarization
• linked to induction of longterm potentiation (LTP)

Question 8

NMDA

Answer 8

• induction of LTP linked to NMDA receptor activation
• NMDA receptor activation requires depolarization of post-synaptic neuron
• activated in post synaptic neuron by glutamate release from presynpatic neuron
• NMDA receptor function requires action potential to dislodge Mg2+

Question 9

lesioning hippocampus

Answer 9

• eliminates contextual conditioning
• does not affect ability to learn that some discrete new cue predicts fear UR; fear depends on basolateral amygdala

Question 10

hippocampus and memories

Answer 10

• medial temporal lobes (MTL) = formation of episodic/semantic memories
• hippocampus NOT necessary for short term memory
• long term storage of episodic memories involve brain regions engaged in:
  1. perception
  2. processing
  3. analysis of learned material
• no sustained hippocampal activity during working memory process

Question 11

episodic memory

Answer 11

• past experiences identified by time and place
• consciously retrieved; recall episodes
• hippocampus essential for:
  1. formation and retrieval
  2. form links (visual - auditory)

Question 12

semantic memory

Answer 12

• memory for knowledge of fats independent of personal experience (hippocampus is less important)

Question 13

consolidation

Answer 13

• gradual process of forming lasting links/connections
• constitute long term memory
• concussion can interrupt recent events still in processes of consolidation

Question 14

“cells that fire together, wire together”
- Hebb

Answer 14

• memory results from altered synpase connections
• memories = stored in multiple brain regions
• when one neuron excites another, the connection = strengthened
• firing neuron then becomes more likely to cause the other to fire
  Eric Kandel
• supports Hebb’s theory
• memory results from physical changes in connections between neurons

Question 15

“cells that fire together, wire together” process

Answer 15

1. when presynpatic neuron is given brief electrical pulse, there is a slight probability that he postsynaptic neurons will fire
2. applying intense and frequent pulses to the presynpatic neuron leads to a greater probability that postsynaptic neuron will fire
3. when a single brief pulse = applied subsequently, it produces greatest probability that the post synaptic neuron will fire

Question 16

inducing LTP

Answer 16

1. enhance amount of NT
2. enhancing responsiveness of postsynaptic cell (mainly due to this)
   glutamate role
   - most excitatory synpases in brain use this as NT
   - engages NMDA + AMPA

Question 17

HM

Answer 17

• his seizures originated in temproal lobes - doctors removed parts of his MTL and hippocampus
• lost ability to remember new information for more than a few minutes
• lost ability to transfer new info to longterm memory; consolidation capacity = LOST, could not encode new episodes (common in AD)
• anterograde amnesia

Question 18

amnesia

Answer 18

• deficit in longterm memory; individuals lose ability to retrieved vast quantities of info
• types: anterograde and retrograde

Question 19

implicit memory

Answer 19

• memory expressed through responses/actions/reactions
• unconscious, automatic
• HM retained implicit memory

Question 20

explicit memory

Answer 20

• consciously retrieved
• requires longterm memory recall
• HM could recall many life events from when he was younger post surgery
• details faded as he aged
• same pattern found in some patients with MTL damage