I. Phrenology- 1st Neuroscience
1. Sir Francis Gall: invented phrenology, a popular but ill-fated theory that claimed bumps on the head could reveal our mental abilities and our character traits; phrenology, however, did correctly focus attention on the idea that various brain regions have particular functions; popular 1819-1820 in Britain(Victorian Period); Moral and intellectual faculties are innate; brain is the source of all mental activity; key word: organs, bump; ex: A prominent protrusion in the forehead at the position means “benevolence”
2. Phrenology Parlors: abused the science for commercial purposes; thousands consulted phrenologists’ advice for everything from hiring employees to finding marriage partner
II. Neurons
1. Parts of Neuron: neuron is a nerve cell; the basic building block of the nervous system; dendrite, nucleus, soma/cell body, axon, myelin sheath, nodes of Ranvier, semi-permeable membrane, axon terminals, synapse/synaptic cleft or gap; information travels from the sensory neurons(aka afferent) to the interneurons(neurons in the brain and spinal cord that serve as an intermediary b/w sensory and motor neurons, carry info around the brain for processing) then finally to the motor neurons(carry the info from the CNS to the appropriate muscles to carry out behaviors, body movements; aka efferent); stimulus to receptor to(sensory neuron) coordinator(brain or spinal cord) to(motor neuron) to effector(muscles or glands) to response(movement)
2. Neural Response: the electrical and chemical transmission of info from one neuron to another by releasing chemical neurotransmitters into the synapse; communication within a neuron is electrical and communication b/w neurons is chemical
3. Change of the neuron: inside the neuron, the ions are mostly neg. changed and outside the neuron, the ions are mostly pos. changes, the neuron is said to be polarized; when a neuron fires(neuron impulse), the charge switches; sodium and potassium
4. Dendrites: bushy, branching extensions of a neuron that receive messages
5. Nucleus: contains the cell's DNA and is responsible for protein production and packaging
6. Soma/cell body: the cell’s life, support center
7. Axon: passes messages away from the cell body to other neurons, muscles, or glands; axons speak, dendrites listen
8. Myelin sheath: a layer of fatter tissue segmentally encasing the fibers of many neurons that insulates axons and helps speed neural impulses
9. Nodes of Ranvier: The myelin does not enclose the axon in one entire sheath, but has gaps at intervals called the nodes of Ranvier. The precise function of these nodes is unknown but the nodes are major sites of sodium channels and may serve to prevent the decay of nerve impulses by effectively amplifying them.
10. Semi-permeable membrane: This allows certain particles to pass through it but restricts others. In relation to the transmission of nerve impulses, this membrane selectively restricts the passage of charged particles (ions). The membrane contains special "gates" or "ion channels" that, when they are open, selectively let positively charged ions pass through. The two principle gates are the sodium and potassium channels.
11. Axon Terminals: forms junctions with other cells
12. Synapse: gap b/w axon and dendrites; They transmit information between neurons, filter out low frequency impulses
13. Action potential: a neural impulse; a brief electrical charge that travels down an axon. The action potential is generated by the movement of pos. charged atoms in and out of channels in the axon’s membrane, act as valves to ensure that impulses pass across them in one direction only, and act as junctions allowing impulses to be divided up along many neurons or merge into one.
14. Stages: resting potential (positive-outside/negative-inside), threshold (the level of stimulation required to trigger a neural impulse), Absolute Refractory period (reloading), and repolarization (pumps out pos. and in
