NEUROSCI 101 Lecture Notes - Lecture 4: Neurotransmitter Receptor, Neuromuscular Junction, Signal Generator
17 views5 pages
Ch. 13 Neural Basis of Memory
Pre Lecture Questions:
● Each neuron synthesizes and releases only one neurotransmitter
○ F, neurons can release multiple types of NTs
● Dopamine can trigger either an IPSP/EPSP depending on what receptor its binding to
○ T for multiple neurotransmitters
● If you blocked Ca2+ at the end of the axon, more neurotransmitters would be released
○ F, need Ca uptake for vesicles to release NTs into the synapse since the
depolarization of the neuron cell will open the Ca2+ gates and stimulate the
release of NTs from vesicles
● Glutamate is the neurotransmitter used in the peripheral nervous system at every
neuromuscular junction.
○ F, acetylcholine (ACh)
● If I discovered a drug that rapidly stimulated an EPSP in a postsynaptic cell, what type of
receptor is it likely bound to?
○ ionotropic receptor, which leads to direct opening of ion channels but is shorter
acting, explaining the rapid stimulation
●Three Steps in Stimulating a LTP:
○ record the EPSP with a recording electrode to record the baseline
○ give a pulse burst, a high frequency stimulation with an electrode
○ give the same pulse at the time of the pre-tetanus
What NTs/receptors are involved in LTP?
●NT: Glutamate
●Receptors: AMPA, NMDA
● AMPA
○excitatory ionotropic postsynaptic receptor
○ Glutamate binds to the receptor, Na+ flows in, depolarizes the cell
○ strictly chemically gated, glutamate binds to receptor, Na+ influx causes EPSP
● NMDA
○ Mg2+ ion sits in the channel, blocking the channel opening from Ca2+ to come in
○ thus, postsynaptic dendrite is NOT depolarized
○ depolarization of postsynaptic cell leads to Mg coming off, Ca coming in when
receptors bind to AMPA in other areas
○Glutamate binds to the receptor, Ca2+ flows in, depolarizes the cell
○ chemically and voltage gated
■ after depolarization of the postsynaptic membrane via AMPA receptor
activation, Mg is removed and NMDA allow Ca to enter in response to Glu
● When depolarization occurs after AMPA/NMDA stimulation, more AMPA receptors are
activated. Release of retrograde signal generator, which enhances more Glu release
and thus more vesicles to release their contents simultaneously.
● After tetanus, same axn pot will produce a larger postsynaptic polarization
find more resources at oneclass.com
find more resources at oneclass.com
● Multiple tetnuses over time to enhance learning: genetic alteration > therefore Increased
protein synthesis leads to building more synapses
● post - no of receptors
● pre - no of NTs
● long term - changes in protein synthesizers that alter gene structure and synaptic
connections
● consistent w/ Hebb’s Law
Is LTP the mechanism of learning and memory formation?
● consistent w/ conditions necessary for memory
●correlational observations - time course of LTP similar for memory formation
●somatic interventions - pharmacological treatments that block LTP impair learning
●behavioral interventions - training an animal in a memory task can induce LTP
Does hippocampus have special role in spatial navigation?
● behavioral studies show that lesions to the hippocampus disrupt navigation that is
directed by relational cues, but not stimulus response learning
● hippocampus has “place cells” that fire only when the animal is in the same location as
determined by the relational cues
○ explains why rats that go back to the same location in memory will retrieve
memories that happened in that location
● hippocampus required for relational learning, but not stimulus-response learning
○ ex. rats swimming in a pool to find hidden platform (hippocampal learning with
regards to spatial recognition)
■ relational learning - start animal in different location on each trial, requires
multiple cues to know where you are in space
● control rat gets better, hippocampal lesioned rat constant time
■ stimulus-response learning - start animal in same location on each trial
● both control and lesioned rats learn just as quickly
●DON’T NEED HIPPOCAMPUS TO DO STIMULUS RESPONSE
LEARNING
● hippocampal place cells only fire when the animal is in a particular spatial location
defined by relational cues in the environment
○ but if we move the cues around in the environment, locations in which place cells
would fire change
● John O’Keefe, May-Brit and Edvard Moser won Nobel Prize in 2014 for discovering
place cells in the hippocampus
Systems Neuroscience of Memory
1. HM, lasting legacy
2. taxonomy of memory
3. hippocampus (medial temporal lobe) not important to all types of memory
4. memory is transferred from hippocampus to neocortex for storage
Cognitive Neuroscience/Psych Definitions:
find more resources at oneclass.com
find more resources at oneclass.com