Lecture 9 Flashcards
(39 cards)
What is learning?
the process by which experiences change our NS
Changes associated with learning are referred to as?
memories
What are memories?
changes in the circuits that participate in perceiving, performing, thinking and planning
Explain the Hebb Synapse
The persistence or repetition of a reverberatory (something that keeps coming back) activity (or “trace”) tends to induce lasting cellular changes that add to its stability
- a connection between 2 neurons (anatomical connection) takes place only if bother neurons are firing at the same time
= Simultaneous activation
Explain the Hebb Rule
How and when will the brain change to represent a memory?
- if a synapse becomes repeatedly active at about the same time the post synaptic neutron fires, changes will take place in the structure or chemistry of the synapse that will strengthen it
E.g.
puff of air to the eye –> neuron of somatosensory system –> synapse P –> blink
1000 Hz tone –> neuron in auditory system –> synaps T –> blink
puff of air + tone –> eye blink; test: tone –> eye blink??
- during conditioning tone and blink neurons are active at the same time (not sequential; happening simultaneously)
What type of learning is involved with habituation and sensitization?
Repetition learning
- not associative
Is Hebb’s law specific to associative learning?
Yes
- associating two things at a time
What is non-associative learning?
repeat stimulation/lack of stimulation (not associating S-S or S-R)
- all about amount of usage
Explain topographical maps
- change with the use of afferent (input) pathways
- details vary between individuals
- E.g. increased use of fingers –> enlarged image of fingers
- intense disuse of a hand produces enlargement of cortical areas neighbouring the hand (e.g. face)
- evidence that these maps change with experience
–> repeated stimulation of one synapse
What is synaptic enhancement?
Pre-synaptic action potentials leave an after-effect that alters the release of neurotransmitters in response to subsequent action potentials
- If the after-effect increases the amount of neurotransmitters released by successive action potentials = synaptic enhancement
What is synaptic depression?
Pre-synaptic action potentials leave an after-effect that alters the release of neurotransmitters in response to subsequent action potentials
- if the after-effect educes the release of neurotransmitters by subsequent action potentials = synaptic depression
Explain facilitation
1 pre-synaptic action potential in a burst of stimulation
- 1 second duration of enhancement
Explain augmentation
A few hundred action potentials in a burst of stimulation
- 10 second duration of enhancement
Explain potentiation
A few thousand action potentials in a burst of stimulation
- 5 minute duration of enhancement
Explain what tetanus is
Form of synaptic potentiation that was first described at a neuromuscular junction
- because of this, potentiation follows a sustained, high frequency burst of action potentials = post-titanic potentiation
What triggers short term synaptic enhancement?
buildup of intracellular calcium inside the pre-synaptic terminal during action potential activity
Complex biological functions of calcium
In neurons - allow release of neurotransmitters (ion goes in and allows docking of synaptic vesicle, fusing –> release of neurotransmitters)
Repetition - calcium buildup –> more neurotransmitters released at stimulation
- only pre-synaptic
- short lasting
- general change (not specific to particular neutron/neurotransmitter)
Associative learning utilizes?
longterm potentiation
- long term changes in synaptic strength
What is longterm potentiation?
neuronal activity can lead to long term after effects that alter the release of neurotransmitters, the anatomy and the sensitivity of post synaptic sermonical on a time scale of hours or days
What are some characteristics of LTP?
- lasts longer
- hours, days; in the brain forever - requires the activation of special receptors
- mediated by pre- and post-synaptic changes
- some changes are anatomical
- hetero-synaptic
- changes specific to synapses are active at the same time - associative
- 2 events happening at the same time
Schizophrenia patients have problems with which learning system?
associative
Effects of induced LTP
Enhancement of response
- form of selectivity induced by simultaneous stiulation
What is the role of glutamate?
principal excitatory neurotransmitter of the brain and spinal cord (very abundant)
What receptors are stimulated by glutamate?
NMDA and AMPA receptors