Action potential is when the neuron fires this is

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Action potential is when the neuron fires; this is when the inside briefly becomes more positive and outside becomes more negative; - During an action potential, the charge reverses due to the movement of the ions; this brief reversal in charge moves down the axon in a wave - How is the strength of a stimulus conveyed? How many cells are firing; strong fire more, weak fire less Frequency of firing; quickly is strong, slow is weak Myelinated Axons: Saltatory Conduction - Signal ‘jumps’ from one node of Ranvier (area of polarity reversal) to the next; speeds up conduction Information Transmission Between Neurons - Terminal Buttons: synapses one the outside of a neuron; can be between 1000 and 10000 of these on each neuron - Chemical Messengers: neurotransmitters; pass on information from one neuron to the next - Synaptic Transmission: 1. Synthesis and storage of neurotransmitter molecules in synaptic vesicles 2. Release of neurotransmitter molecules into synaptic cleft 3. Binding of neurotransmitters at receptor sites on postsynaptic membrane 4. Inactivation (by enzymes) or removal (drifting away) of neurotransmitters 5. Reuptake or neurotransmitters sponged up by the presynaptic neuron - Binding can have two results: Excitatory Signal: make the receiving cell more likely to fire; become less negative relative to outside—closer to reaching threshold Inhibitory Signal: makes it less likely to fire; becomes more negative relative to outside—farther from reaching threshold Major Neurotransmitters - GABA: gamma-aminobutyric acid; the principle inhibitory NT (STOP) - Glutamate: the principle excitatory NT (GO) - Dopamine(DA): voluntary movement, reward circuits, cognitive processes; too little can result in Parkinson’s disease (treated with L-dopa), too much can result in Schizophrenia; related to drug craving and addiction; cocaine increases activity in dopamine circuits - Serotonin(5-HT): sleep, appetite, mood; some antidepressants like Prozac prevent reuptake of serotonin, for treating depression; called selective serotonin reuptake inhibitors (SSRIs)
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- Norepinephrine(NE): sympathetic NS response, learning and memory, wakefulness, emotion; closely related to adrenaline - Endorphins (endogenous morphine): pain killers bind to our natural endorphin receptor sites and mimic endorphins, producing analgesia (pain relief) - Acetylcholine (Ach): memory, attention, arousal, muscle activation; low levels of Ach in Alzheimer’s disease; drug treatments increase Ach activity in brain; Nicotine mimics Ach, Curare blocks Ach Brain Sectioning Neurogenesis Research Methods in Brain Research - Lesioning: destroying a part of the brain and examining effects Deliberate lesions (animals, necessary brain surgeries) Experiments of nature (strokes, tumours, traumatic brain injuries, etc.) - Electrical Stimulation of Brain(ESB): stimulating a brain structure by sending a weak electrical current through an electrode; ex) Dr. Wilder Penfield Ex) ESB in animals using implanted electrodes Can stimulate (or record from) individual cells - Electroencephalography(EEG):
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