Neurobiol of Learning & Memory Flashcards

Question

Neuron death : ***see diag. slide 15-16

Answer 1

Competition/ target neurons / connections ( pruning)

Answer 2

Change in response to experiences - neurons grow more dendrites! - Animals in enriched environments > greater dendritic branching/ improved learning skills.

Answer 3

Use it or lose it!

Answer 4

Our cortex changes to accommodate motor activity that we need / use: ***see diagrams. slide 19

Answer 5

CBT > reorganisation of our “neural circuits"

Answer 6

Synapses change in response to experiences * Synaptic Plasticity = LT changes in how our synapses work * Long Term Potentiation * Long Term Depression ((Kalat module: Neurochemistry of learning

Answer 7

Much of what learned about neuroplasticity: comes from the sea slug - extensive studies re neuroplasticity : associated with sensitisation /habituation : gill withdrawal reflex Similar & Few and large neurons - so easy to study!

Answer 8

Like a muscle: use more > stronger!!! - "Fire togther: wire together " - +++ Exposure: EPSP larger > act.pot > synapse strengthened !!!! * 2 sens. signals : gap of time re act.pot for both within about 50ms > LINKAGE + STRENGTHENING ( ASSOCIATION !!! ) * see diagrams slides 24-26

Answer 9

Neurons fire at different frequencies (Hz) -When neurons fire they release NT into synapse -Frequency means the number of synaptic excitations per second Low frequency = 1-5 Hz / HIGH frequency = 50-100 Hz #Differences in firing frequencies : alter communication between synapses

Answer 10

Long Term Potentiation (LTP) * Brief high frequency electrical stimulation of an excitatory pathway >to long-lasting enhancement in strength of the stimulated synapses Long Term Depression (LTD) * Brief LOW frequency electrical stimulation of an excitatory pathway > to a long-lasting WEAKENING of the strength of the stimulated synapses * LTP and LTD rely on the function of #GLUTAMATE receptors

Answer 11

Glutamate - Ionotropic & metabotropic receptors - Ionotropic let in calcium (Ca++) or sodium (Na+) - Ionotropic - NMDA (N-methyl-D-aspartate) - Ionotropic: AMPA (a-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid) - Ionotropic: Kainate receptors - Metabotropic (mGluR1 - mGluR7) - linked to 2nd MESSENGER systems - NMDA receptors are unique - usually “plugged” with Magnesium (Mg++) ...Only when the dendrite becomes depolarised does the Magnesium leave the NMDA receptor (if glutamate is bound) so that positive ions can come into the cell

Answer 12

Cells that "fire together wire together" * High frequency stimulation is not enough to cause LTP * EPSP in one part of the neuron requires an ACT. POT to occur at SAME time in order to produce HUGE DEpolarisations * > propogation (ie more positive to the dendrites from the axon hillock of the firing neuron) * Synapses that co-operate to produce this action potential are wired together and can induce firing later on - independently!

Answer 13

Bidirectional regulation of synaptic strength (up or down) * LTP *LTD * Synapses that are active when cell is weakly depolarised (i.e., only small EPSP...not action potential) will become weaker.

Answer 14

Bidirectional regulation of the AMPA Receptor * affects how strongly or weakly inputs are received * affects future signalling/firing of the neuron in question - How does this relate to memory? Animal models (Morris water maze): show NMDA receptor antagonists cause animals to ‘fail to remember’. (Antagonists directed at Calcium entry to cell or that block PKC/CaMKII have similar effects) ####NMDA receptors : needed for acquisition or consolidation of memories

Answer 15

What about ‘maintenance’ of memories? - occur by changes in intracellular messengers - (upregulation) > physical change in the neuron - Synthesis of new proteins/ neuronal circuits (dendritic branching) - Disassembly of existing circuits (dendritic pruning) LTP - strengthens connections that our brains require to remember LTD - prunes unwanted connections to correct incorrectly learnt pathways or to ‘unlearn’ a behaviour (extinction). (NB: increase in phosphatases helps us to forget ‘unimportant’ information - you DONT need to remember everything!) Memories * begin as ELECTRICAL signals * temporarily remain by changes in second messenger systems ( become long-term when synaptic proteins/structures are modified)

Answer 16

- Aplysia : studying N-P of habituation/sensitisation - simple nervous systems/ remain similar between individual slugs - LTP has 3 properties of specificity (active synapses become stronger) >>> 1. co-operativity (synapses that are active together, wire together) 2. associativity (weak inputs paired with strong inputs: become strengthened). 3. Hebb’s theory : only synapses that are active within "50 ms" of an action potential produce LTP.

Answer 17

LTP : produced by upregulation of CaMKinase II & Protein Kinase C - upregulate AMPA "glutamate" receptors - LTD; phosphatases, >DEactivate glutamate receptors -Activation of AMPA receptors: >opening NMDA glutamate receptors.....Treatment with NMDA receptor "antagonists" >reduce rodent memory -Memories : "electrical signals" > temporarily stored : in "2nd messenger systems" > stored LT by changes in the neurons.

Answer 18

WM tempstorage of information so our actions are ongoing (so you don’t forget what you were doing half-way through something!). ST retention also means that you can use this to ‘manipulate’ information – (e.g., do a simple maths equation ‘in your head’) -WM: PFC of the frontal lobe - tested using a "delayed response task" -Subject receives a stimulus (light over one lever (out of 10)) ...Light goes off, ....delay period (longer the delay, better the working memory) - Subject asked to press lever that light was over Card game: memory / or in animal models: T-maze

Answer 19

The hippocampus : involved in several types of memory H.M. had his hippocampus removed (medial temporal lobe,) - Intellect /language OK!! - Suffered amnesia (loss of memory) - Anterograde amnesia (cannot form NEW memories) - Retrograde amnesia (cannot remember recent memories before surgery) - Cannot learn new facts (declarative) - bad at explicit memory (aware) - Can learn new motor skills (procedural) - ok with implicit memory (unaware) ****H.M.’s condition suggested :hippocampus was more important for some memories than others.

Answer 20

The hippocampus : Two of the main memory types are: 1. Declarative (explicit) memory - many of ours are episodic (single events) “object recognition” tests - require animals to show which object is familiar and which is novel (rodents) “Delayed matching-to-sample task” which is familiar (primates) “Delayed nonmatching-to-sample task” which is new (primates) 2. Spatial memory - memories of things in space “radial arm maze” - rodents (rats learn to enter each arm once for food reward) “Morris water maze” - finding the platform submersed in milky solution ***Animals with hippocampal damage have trouble with all of these tasks

Answer 21

* Neurodegeneration - selective death of Acetylcholine (ACh) cells * Slowly progressing Dementia * Memory loss * Change in personality * Apraxia - loss of ability to co-ordinate movements * Aphasia - loss of ability to articulate ideas and comprehend written/spoken word * Agnosia - cannot interpret sensory stimuli

Answer 22

Patients with Alzheimer’s Disease: Reduced Acetylcholine (ACh) Acetylcholine ... prevalent in brain regions involved in memory * Hippocampus, cortex and movement * Striatum - Acetylcholine binds to two (cholinergic) receptor subtypes Nicotinic Muscarinic *The muscarinic antagonist atropine can "disrupt memory processing". *Atropine has also been shown to "inhibit the process of neurogenesis" * Acetylcholine is involved in "proliferation and differentiation of neural stem cells"!

Answer 23

Working (temporary) memory involves the prefrontal cortex and is tested using a delayed response task * Amnesia is the loss of memory - anterograde amnesia is the loss of new memories (or inability to form new memories) after brain damage, retrograde amnesia is the loss of memories that have formed recently before brain damage * The hippocampus is most important for declarative and spatial memory * Declarative memory can be tested by object recognition and spatial memory can be tested in radial arm maze or Morris water maze * Alzheimer’s Disease is slow degeneration of neurons, with dementia and memory loss * Patients with Alzheimer’s Disease have reduced Acetylcholine (ACh) * Acetylcholine binds to muscarinic and nicotinic receptors * Atropine is a muscarinic receptor antagonist that can disrupt memory processing and neurogenesis * Neurogenesis is the development of new neurons

Neurobiol of Learning & Memory Flashcards

(49 cards)