13- Learning & Memory Flashcards
Lashley
Equipotentiality and Mass Action
Equipotentiality- all parts of the cortex contribute equally to complex behaviour such as learning and any part can substitute for any other part of the cortex
Mass action- the cortex works as a whole, more cortex is better
(based on rats)
Thompson’s search for the engram in the cerebellum
Lateral Interpositus Nucleus (LIP)
- nucleus of the cerebellum identified as essential for learning
-After stopping LIP fxn, rabbit learns at rate of one with no previous practice
=LIP necessary for learning and retention
Hebb
Short term and long term memory
-Consolidate: info enters ST memory until brain has time to consolidate it into LT memory
Baddeley
Working memory
-delayed response task (requires responding to something that you saw or heard a short while before- prefrontal cortex stores image of stimulus)
Anterograde vs Retrograde Amnesia
Anterograde- unable to remember events after brain damage
Retrograde- unable to remember before brain damage (for a few years)
*damage to Hippocampus (medial temporal lobe)
- impairment to episodic memories, declarative memories
-better with implicit than explicit, - ## intact procedural memory (basal ganglia)
Hippocampus in memory
- declarative, and episodic memory, as well as spatial memories and mapping the environment
- cannot consolidate ST to LT memory
- doesn’t matter where learning occurred
Memory tasks for animals
Delayed matching-to-sample task
-animal sees objecft and after delay, gets a choice btw 2 objects from which he must chose the one that resembles the sample
Delayed nonmatching-to-sample task
-same procedure but animal must chose the diferent object
Radial maze
-8+ arms some of which have a bit of food or reinforcer at the end
Morris water maze task
-test of spatial memory where rat must swim through murky water to find rest platform just below the surface
(hippocampal damage = can only find when starting from same place and when platform is in same place)
Korsakoff’s Syndrome
brain damage by prolonged thiamine (vit B1) deficiency (needed to metabolize glucose = decrease of brain neurons, especially dorsaomedial thalamus- main input to prefrontal cortex)
-severe alcoholics
-symptoms = apathy, confusion, memory loss, confabulation (guessing to fill in memory gaps, learn better by rehersal)
Alzeimer’s Disease
- better procedural than declarative
- varies from day to day = malfunctioning neurons
- damaged structures cluster into plaques = hippocampal and cortical atrophy
=serious memory loss, confusion, depression, restlessness, hallucinations, delusions, sleeplessness, loss of appetite
-increase wt age
Amyloid-B (protein that cuts neurons in individuals wt early onset, caused by genes)
Tau protein (part of intracellular support structure of neurons= tangles
-Treat: drugs that stimulate acetylcholine receptors and prolong its release
increase antioxidants and curcumin
Parietal lobe damage & memory
difficulty associating one piece of info wt another in remembering
Semantic dementia
loss of semantic memory, damage to anterior and inferior temporal lobe
Prefrontal cortex & memory
- Anterior cingulate cortex
- Onbitofrontal prefrontal cortex
- ventromedial prefrontal cortex
-decision making, learning about rewards and punishment
Hebbian Synapse
one that increases in effectiveness b/c of simultaneous activity in the presynaptic and postsynaptic neurons
*associative learning
Aplysia
marine mollusk
Habituation - decrease response to a stimulus that is presented repeatedly and accompanied by no change in other stimuli
(Aplysia- depends on change in synapse btw sensory and motor neuron)
Sensitization- increase response to mild stimuli after exposure to more intense stimuli
Strong sitmulation on skin = facilitating interneuron- releases serotonin (5-HT) onto presyn terminals of sensory neurons= block K+ channels into membrane = takes longer to repolarize at later Action Potentials
=Presyn neuron releases NT longer
=sensory neuron synthesizes new proteins to produce longer sensation
LTP Long-term-Potentiation
1+ axons connected to a dendrite bombard it with a breif and rapid series of stimuli (some synapses potentiated for minutes, days or weeks)
- depends on glutamate receptors:
- AMPA receptor (also responds to drug AMPA)
- NMDA receptor (also responds to drug NMDA)
- Ionotropic receptors (channel for ions to enter postsyn cell)
-GLutamate stimulates alot
-AMPA opens Na+ channels
-NMDA depends on degree of polarization across membrane (blocked by magnesium ions)
-Na+ enters through AMPA = depolarization = displace magnesium ions = Na and Ca enter at NMDA
=activates CaMkII protein to migrate to synapse
