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Introduction to Neuroscience I, 1h of lectures by Nathan Woodling and Anthony Chung-Ming Ng for lecture 10 in the free on-line course "Human Behavioral Biology"

Neuroscience is another way to understand animal behavior. This brain-centered science has limitations, but it offers powerful insights.

"The chief function of the body is to carry the brain around." -- Thomas Edison

The nervous system consists of the central nervous system (CNS, brian & spinal cord) and the peripheral nervous system (all motor & sensory nerves outside the spinal cord including the nerves controlling heartbeat, digestion, etc.)

Compartmentalization of the brain: Different parts of the brain are specialized for different functions: different parts, different functions, different sizes.

The last 3m is an excellent video in a video: "The Synaptic Cleft" by The Glue-Tang Clan. You might want to watch that part even if you skip the details.

The rest of this gets detailed, but I typed in the notes so I might as well share them!

10. Introduction to Neuroscience I

Parts of the brain

brain stem: interface/regulation between spinal cord and brain
cerebellum: helps control motor movement and learning of motor skills by trial and failure corrections

4 lobes of the cortex (outer layer):
occipital lobe: in the back or posterior part of the skull; receives visual information
parietal lobe: senses touch information (larger parts of the brain control more sensitive body parts such as the touch-sensitive fingertips)
temporal lobe: behind temples, receives auditory information, and memory formation
frontal lobe: at the front or anterior part of the skull: plans actions and controls movements; the part of the frontal lobe controling each body part is arranged roughly in accord with the arrangement of the body itself (knee above foot)

limbic system: below the cortex and above brain stem; it controls things associated with emotion, learning, and memory; it includes the hippocampus ("seahorse": important for memory and forming new memories; discovered when surgery to allay H.M.'s siezures caused him to lose the ability to form new memories but he could remember things from childhood) & amygdala (almond-shaped in front of the hippocampus; involved in fear & anxiety such as smelling sweat from sky divers)

Brain systems associated with hormones:
hypothalamus (near center of the brain): 4f's: flight, fight, feeding behavior, reproductive behavior
pituitary gland (underneath hypothalamus)

spinal cord specialized: motor nerves send out signals, sensory nerves receive information

Santiago Ramón y Cajal (1852-1934): father of modern neuroscience & nobel laureate (1906): did the anatomical work showing the brain consisted of branching structures of cells

Heinrich Wilhelm Gottfried von Waldeyer-Hartz (1836-1921) popularized the neuron theory that the mush of the nervous system consists of separate cells called neurons

Cell types in the brain:
Most (∼90%) cells in the nervous system are glia (defined as everything but neurons): they are the glue of the nervous system
astrocytes (star-shaped): provide nutrients to neurons and help regulate how they fire
oligodendrocytes and Schwann cells wrap around the axons to help with neuron firing
microglia: the brain's immune cells
neurons: computational units of the brain; binary signaling: either on or off (resting potential); ∼100 billion neurons in the average brain each with about 10,000 connections (synapses) to other neurons, so ∼1 quadrillon synapses in your brain: ∼400 billion stars in the Milky Way, so ∼2000 times more synapses than stars in the Milky Way

pre-synaptic neuron: neuron sending the signal
post-synaptic neuron: neuron receiving the signal
Parts of a neuron:
* soma: cell body
* dendrite: branched projections receiving information from other neurons
* nucleus: like all other cells has the DNA
* axon hillock: sums up signals received and decides whether to fire or not
* axon: "wire" to send information out to the next neuron
* terminal: the end of the axon that passes the signal to the next neuron; it stores neurotransmitter in spherical vesicles
* In the rest state or highly polarized state, the neuron pumps +ions out of the cell, so - charge inside the neuron

synapse: junction between pre-synaptic & post-synaptic neuron: neurotransmitters emitted from the terminal to receptors on the dendrite which open channels to pump ions (+ or -: excitatory or inhibitory)

Functioning of the synapse:
* if enough +ions enter the neuron locally it enters a depolarized state
* If enough +charge makes it to the axon hillock to exceed a threshold (the action potential), then the axon hillock opens more channels to let more +ions in which feeds forward down the axon resulting in a release of neurotransmitter from the synaptic vesicles in the axon terminal
* In addition to firing, the neurotransmitter or the state of charge could induce a genomic effect by activating transcription factors which may increase or decrease the responsiveness of the neuron

neurotransmitters occur in the axon terminal, they release in event of the action potential, and it induces a change of charge in the dendrite of the post-synaptic neuron. There are many types of neurotransmitters some excitatory some inhibitory. Neuroscience currently thinks there are a few hundred neurotransmitters. Used neurotransmitter must clear out to allow further signaling. One process is called reuptake: recycling of used neurotransmitter back into the pre-synaptic neuron. Another is degrading: break them down which can then be detected in the blood, urine or cerebrospinal fluid.

Some common neurotransmitters:
* dopamine: associated with the reward system (pleasure), but it has many, many other functions (due to compartmentalization of the brain)
* epinephrine = adreniline: fight or flight response
* serotonin: regulation of sleep, appetite & mood
* Acetylcholine
* GABA (gamma-Aminobutyric acid): the chief inhibitory neurotransmitter in the mammalian central nervous system
* glutamate: the chief excitatory neurotransmitter in the vertebrate nervous system

neuropharmacology: external manipulation of synaptic events
Mescaline, LSD, Psilocybin are halucinogens that interfere with the serotonin receptors: There are many ways to manipulate events at the synapse

Parkinson's disease: inadequate dopamine in the part of the brain controlling motor movement
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