用户:Grotton JXz Donbrako/Psychology/Chapter 3

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Neuroanatomy

• Neuroanatomy refers to the study of the parts and function of neurons.
• Neurons are individual nerve cells that make up your central nervous system.
• Every neuron is made up of discrete parts.

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• 神 经 元 玉 照.jpg

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• Dendrites: Rootlike parts of the cell that stretch out from the cell body.
  • Dendrites grow to make synaptic connections with other neurons.
• Cell Body: Contains the nucleus and other parts of the cell needed to keep it living (mitochondria, nucleus, Golgi apparatus, ribosomes, etc.).
• Axon': Wire-like structure ending in the terminal buttons that extends from the cell body.
• Myelin Sheath: A fatty covering around the axon of some neuron.
• Terminal Buttons: The branched end of the axon that contains neurotransmitters.
• Neurotransmitters: Chemicals contained in terminal buttons that enable neurons to communicate. Neurotransmitters fit into receptor sites on the dendrites of neurons like a key fits into a lock.
• Nodes of Ranvier: The small gaps between the myelin sheath are the Nodes of Ranvier. These gaps are where neural transmission takes place on myelinated neurons.
• Synapse: This is the gap between the terminal button and the dendrite.
  • Synapse.jpg

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How a Neuron Fires

• Neural firing is an electrochemical process. Electricity travels within the cell from the dendrites to the terminal buttons.
• Neurotransmitters travel between cells in the synapses of neurons.
• Electricity does not jump across the synapse; neurotransmitters travel across.

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• Neuron has a slightly negative charge (-70mV).
• Neurotransmitters from one neuron land on the dendrites of another neuron.
  • The neurotransmitters fit into receptor sites.
• If the threshold is reached, the neuron becomes permeable to positive ions and they rush down the neuron causing it to fire.

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• All-or-nothing Principle: Neurons either fire or don't; this principle is called the all-or-nothing principle.
• A neuron is similar to a gun in that, you cannot shoot the gun just a little. （Boolean型变量啊嗯）

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• Neurotransmitters are chemicals held in the terminal buttons that travel across the synapse to the dendrite of another neuron.
  • Some neurons are excitatory, some are inhibitory.
• Excitatory neurotransmitters make the next neuron fire.
  • Glutamate is an excitatory neurotransmitter.
• Inhibitory neurotransmitters prevent the next neuron firing.
  • GABA(gamma-Aminobutyric acid) is an inhibitory neurotransmitter.
• Acetylcholine is involved in movement, memory function, and muscle contraction (particularly in the heart).
• Dopamine is involved in movement, alertness, attention, reward, and imbalances are associated with Parkinson’s and Alzheimer's disease.
• Endorphins are involved in pain control. They are the body's natural painkillers.
• Serotonin is involved in mood, sleep, pain, sensitivity, and arousal.
• Norepinephrine/Noradrenaline is involved in alertness/arousal.

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Neurons (afferent, inter, efferent)

• Afferent/Sensory Neurons take information from our senses to the spinal cord.
• Interneuron, found in the spinal cord, relays signals between (afferent) sensory neurons, and (efferent) motor neurons; involved in the process of sensory-motor integration.
• Efferent Neurons are conducting cells that carry information from the central nervous system (the brain and spinal cord) to muscles and organs throughout the body.

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• A subset of movements are controlled by direct transmission from afferent to efferent cells at the level of the spinal cord.
• Reflexes: Quick and involuntary responses to environmental stimuli.

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Nervous System

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• The CNS (Central Nervous System) is composed of the brain and spinal cord.
• The PNS (Peripheral Nervous System) consists of all the other nerves in your body other than those in the brain and spinal cord.
  • ↓The PNS的Motor Neurons is divided into two categories: the somatic and the autonomic. PNS还有Sensory Neurons，效果如其名。
• The somatic nervous system controls our voluntary muscle movements. The motor cortex of the brain sends impulses to the somatic nervous system, which controls the muscles that allow us to move.
• The autonomic nervous system is responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
• (automatic)The sympathetic nervous system mobilizes our body to respond the stress. It is involuntary.
  • This part of our nervous system carries messages to organs, glands, and muscles. The sympathetic nervous system controls heart rate, blood pressures, respiration, and slows non-vital functions such as digestion and reproductive organs.
  • Also called the Fight or Flight System.
• The parasympathetic nervous system is responsible for slowing down our body after a stress response.
• The parasympathetic nervous system puts on the brakes to slow down the body’s autonomic nervous system.
• Often referred to as the Rest and Digest System.

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Brain Study

• Ways we can study the brain: Accidents, Lesions, Electroencephalogram, Computerized Axial Tomography, Magnetic Resonance Imaging, Positron Emissions Tomography, Functional Magnetic Resonance Imaging.

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Accident

• Accidents give clues about brain function.
• Famous case（典中典） (1848) of a railroad worker, Phineas Gage who was hit by a piece of rebar in the front of his head. Having sustained damaged to his frontal lobe, and having become highly emotional and impulsive after.
  • Doctors concluded that the frontal lobe was somehow regulating emotion.
• 扩展文章：真实的不死男：铁棍刺穿头颅却谈笑风生，死后被掘尸研究（文/快哉风）

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Lesions

• Lesion is the removal or destruction of the brain.
• A famous（？） example is doctors who lesioned mentally ill patients who had no other treatment options. Lesions give clues about function.
• Researchers discovered that lesioning a part of the frontal lobe would make the patients calm and relieve some serious mental conditions.
• 扩展文章：“科学”曾这样为恶：游戏《光之镇》的幕后故事（作者：phxfed）
  • （本文部分涉前脑叶白质切断术配图可能引起读者不适，请爱眼人士谨慎阅读）

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Electroencephalogram/EEG

• EEG detects current given off by the electrochemical reactions going on in the brain.
• Neurons use an electrochemical process to send signals.
• Researchers can examine what type of waves the brain produces during different stages of consciousness and use this information to generalize about brain function.
• Widely used in sleep research.
• 脑电图示意图.jpg

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Computerized Axial Tomography

• CAT or CT scan is a sophisticated X-ray.
• A CAT scan uses X-ray cameras that rotate around the brain and combine all the pictures into a detailed three-dimensional picture of the brain’s structure.

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Magnetic Resonance Imaging

• The MRI is similar to a CAT scan.
• MRI determines the structure; it gives a more detailed image than CAT.
• An MRI uses magnetic fields to measure the density and location of brain material.
• Does not expose patients to X-rays like a CAT scan.
• 磁共振成像示意图.jpg

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Positron Emissions Tomography

• A PET scan lets researchers see what areas of the brain are most active during certain tasks. It will determine brain function.
• In PET scans of the brain, a radioactive atom is applied to glucose (blood sugar葡 萄 糖).
• If one area of the brain is using more glucose during some activity, (e.g., problem solving, listening, reading, eye movement, etc.), it is a good indication that that area is associated with that mental state or that behavior.
• 正电子成像术示意图.jpg

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Functional Magnetic Resonance Imaging (fMRI)

• fMRI combines elements of MRI and PET scans. （融 合 降 临）
• An fMRI scan can show details of brain structure with information about blood flow to the brain, function.
• Best of both words approach – you can measure structure and function.

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Brain Terminology

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Hindbrain

• The hindbrain consists of structures in the top part of the spinal cord.
• The hindbrain controls basic biological functions that keep us alive (respiration, heart rate, blood pressure).
• Important structures within the hindbrain are the Medulla, Pons, and Cerebellum.
  • The Medulla, also known as the Medulla Oblongata, located above the spinal cord, is involved in control of blood pressure, heart rate, and breathing.
  • Pons, located just above the medulla and toward the front, connects the hindbrain with the midbrain and forebrain. It is also involved in the control of facial expressions.
  • The cerebellum (located on the bottom rear) coordinates some habitual muscle movements such as tracking a target with our eyes.
    • Cerebellum means little brain, named this probably because it looks like a miniature brain.

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Forebrain

• Areas of interest to us in the forebrain that make up the limbic system:
  • The thalamus, located on top of the brain stem, is responsible for receiving sensory signals coming from the spinal ford and sending them to the right areas of the forebrain.
    • Kind of like an air traffic control person, who directs where the incoming planes should land.
  • The hypothalamus, a small structure below the thalamus, controls body temperature, sexual arousal, hunger, thirst, and biological rhythms (wake/sleep patterns).

• • The hippocampus, looks like two arms surrounding the thalamus, is vital to our memory.
    • Memories are processed through the hippocampus and then sent to other locations in the cerebral cortex for permanent storage.
    • Research shows that memories or information must pass through this area first in order to be encoded.
    • Individuals with brain damage of the hippocampus are unable to retain new information. If the hippocampus is damaged, old information may also be lost.
  • The amygdala（挨着海马体的那俩） is very important to certain emotions like fear and aggression.
• The thalamus, hypothalamus, amygdala, and hippocampus (all the brain parts we just covered) are grouped together and are called the limbic system.
• 相关实验：“Mice made to kill”（耶鲁大学）。（scientists-used-light-to-turn-mice-into-stone-cold-killers(washingtonpost)）

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Celebral Cortex

• Cerebral cortex: Gray, wrinkled stuff that is densely packed with neurons.
• The surface of the cerebral cortex is wrinkled. The big wrinkles are called Fissures.
• Fissures increase the availability of surface area. The more wrinkles, the more surface area contained within the skull.

• The cerebral cortex is divided into two hemispheres: left and right.
  • The left hemisphere gets sensory messages and controls the motor function of the right half of the body.
  • The right hemisphere gets sensory messages and controls the motor function of the left half of the body.
  • This is called contralateral control.
• Hemispheric specialization refers to the different and specific functions performed by the two hemispheres of the brain.
  • It is possible that the left hemisphere may be more active during logic and sequential tasks and the right during spatial and creative.
  • But this is still under investigation.

• Split brain patients, patients whose corpus callosum has been cut to treat epilepsy, cannot orally report information only presented to the right hemisphere, since the spoken language centers of the brain are usually located in the left hemisphere.

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Genetics/Genetic Disorders=

（待补充）

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