Lecture on September 24th: Introduction to Neurophysiology

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Psychology & Brain Sciences
Lori Astheimer Best

Behavioral Neuroscience, Lecture on September 24th Introduction to Neurophysiology Neural communication in the brain, > between neurons, chemical. >> happens at synapses. > within neurons, electrical. >> neural electrical impulse- changes in the relative charge of the inside the cell versus the outside of the cell. >>> how does this happen? By changing the distribution of ions along the membrane. All about ions, An ion is an electrically charged atom or molecule > sometimes have unequal number of protons and electrons. Two major types, Anion, extra electrons (negative - Cl-) Cation, extra protons (positive - Na+, K+) > Anion vs. Cation defends on chemical properties of atom. Electrical currents in neuronal membranes are caused by the movement of electrically charged atoms (ion) in and out of the cell - through ion channels. > Ion channels are made of proteins that span the membrane (transmembrane proteins) have an opening that allows ions to flow through them. > Some neurotransmitters bind to receptor sites on the outside surface of ion channels and cause them to open or close. The neuron at rest: > Unequal distribution of charges, more anions inside the cell and more cations outside of the cell. > You can the cell has an electrical gradient, a membrane potential (there is a potential for these ions to move), and the neuron is polarized (there is a difference) - in this case it would be negatively polarized since there is more negative cells in the membrane. Measuring the resting potential > Reference electrode - outside of the cell > Recording electrode - inside the cell > Oscilloscope - lets us visualize the cell > Usually the resting voltage of neurons is around -60 to -70volts. Graded changes in potential, > Can be artificially applied with an electrical stimulator. >> Another set of electrodes and the simulator pumps ions into the cell. Depolarization vs. Hyperpolarization > Depolarization, membrane potential becomes more positive. >> closer to zero. > Adding more positive charge inside the cell. > Excitatory. VS. > Hyperpolarization, charge inside cell becomes even more negative compared to outside. >> further from zero. > Inhibitory. The effects of hyperpolarizing and depolarizing stimuli on a neuron, > after pumping negative ions in, there is a greater change at the sight of injection but the effects fade across the neuron. (Hyperpolarizing) > if we add a few positive ions there is minimal changes. If we add more positive ions there are drastic spike chan
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