Neurobiology aspect of memory
Things not covered in class from textbook, won’t be on the test
95% will be from what we covered from class.
No lecture afterwards
What is electricity? It is the flow of electrons from negatively charged place to positively charged
place. Electrons function as a wave and particle at the same time.
Neurons generate electricity by using charged atoms.
Opening and closing channels depends on the property of the protein channel.
Resting potential is -65mV
Outside have more sodium (more than the total potassium), inside has more potassium and
negatively charged large proteins.
Sodium-potassium pump results and maintains in the resting membrane potential. Transfers 3
sodium ions to the outside with 2 potassium ions to the inside. Working against the membrane
potential, therefore uses ATP (provides energy by phosphorylation of protons).
When electricity arrives, sodium channels open when the cell gets more positive (depolarized).
Electricity doesn’t travel easily in wet biological environments, therefore it is not passive. The
membrane doesn’t conduct electricity, therefore myelination occurs for insulation. Also the
message keeps getting recreated along the way.
Sodium goes inside the cell because the inside is more negative and also along the
concentration gradient of sodium.
42:35:00 Action potential.
Sodium channel closes when a large enough positive charge has been achieved around +40mV.
At +40mv another channel opens, the potassium channel, 2 forces will work again, the diffusion
and electric forces, causing the inside to become more negative.
The initial depolarization (small rising phase) is caused by the passive flow of electricity.
All-or-none rule: constant amplitude and width of action potential once triggered. This is due to
the property of the channels.
The AP travels by opening and closing of the channels.
Action potential regenerates at the node of Ranvier, and is passively conducted under the
myelin sheath, the message decays because electrons pump into “objects” and don’t go
through, electrons will travel very fast, but not all electrons will.
Best of both worlds: fast and regeneration.
The post-synaptic neuron can either be depolarized or hyperpolarized.
Possibilities at synapse: EPSP, IPSP, spatial and temporal summation. Inhibition can lead to excitation. How? A neuron can inhibit the action of another inhibitory
Learning a memory is nothing