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Neuron viewed with an electron microscope

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Neuron All neurons are electrically excitable, maintaining voltage gradients across their membranes by means of metabolically driven ion pumps, which combine with ion channels embedded in the membrane to generate intracellular-versus-extracellular concentration differences of ions such as sodium, potassium, chloride, and calcium. Changes in the cross-membrane voltage can alter the function of voltage-dependent ion channels. If the voltage changes by a large enough amount, an all-or-none electrochemical pulse called an action potential is generated, which travels rapidly along the cell's axon, and activates synaptic connections with other cells when it arrives. Neurons do not undergo cell division. In most cases, neurons are generated by special types of stem cells. Overview[edit] A neuron is a specialized type of cell found in the bodies of all eumetozoans. Many neurons fit the foregoing schema in every respect, but there are also exceptions to most parts of it. Anatomy and histology[edit]

neurotransmitters and neuromodulators The soft warm living substance of the brain and nervous system stands in stark contrast to the rigid metal and plastic hardware of a modern day computer, but at the fundamental level there are clear similarities between these two apparently disparate organizational systems and, of course, one is a product of the other. Not only are the nerve cell units (neurons) self-repairing and self-wiring under the grand design built into our genes, but they can also promote, amplify, block, inhibit, or attenuate the micro-electric signals which are passed to them, and through them. In this way they give rise to signalling patterns of myriad complexity between networks of cerebral neurons, and this provides the physical substrate of mind. These key processes of signalling by one group, or family, of neurons to another is achieved largely by the secretion of tiny quantities of potent chemical substances by neuronal fibre terminals. In this way, the nerve impulses are passed on from cell to cell. 1.

The Death Delusion « Kensho By Bard Canning “Afraid of dying? Don’t be. It’s said that Albert Einstein once commented that the most fundamental question we can ever ask ourselves is whether or not the universe we live in is friendly or hostile. Surely death is the greatest threat that we all face. I do not agree. Before outlining my hypothesis, I should make it clear that the aim of my writing is the excavation and study of the truth. To put it simply: I do not believe in death. I do not think that we are immortal, far from it. It has been my experience that once the spectre of death is stripped of its shadowy mask it becomes much easier to contend with as a concept. The Alpha and the Omega “Death, in itself, is nothing; but we fear, To be we know not what, we know not where.” John Dryden Everyone eventually reaches the point in their lives where they become fully aware of the inevitability of their own death. “Sapiens” is Latin for “being wise” or “knowing”; coupled with the human genus it forms “Homo Sapiens”. T.S.

Brain Atlas - Introduction The central nervous system (CNS) consists of the brain and the spinal cord, immersed in the cerebrospinal fluid (CSF). Weighing about 3 pounds (1.4 kilograms), the brain consists of three main structures: the cerebrum, the cerebellum and the brainstem. Cerebrum - divided into two hemispheres (left and right), each consists of four lobes (frontal, parietal, occipital and temporal). The outer layer of the brain is known as the cerebral cortex or the ‘grey matter’. It covers the nuclei deep within the cerebral hemisphere e.g. the basal ganglia; the structure called the thalamus, and the ‘white matter’, which consists mostly of myelinated axons. – closely packed neuron cell bodies form the grey matter of the brain. Cerebellum – responsible for psychomotor function, the cerebellum co-ordinates sensory input from the inner ear and the muscles to provide accurate control of position and movement. Basal Ganglia Thalamus and Hypothalamus Ventricles Limbic System Reticular Activating System Neurons Glia

List all the essential neurotransmitters Acetylcholine - synthesized from Choline, Lecithin, and panthothenic acid (B5), or Diethylaminoethanol (DMAE) - Arousal and orgasm - voluntary muscular control and proper tone - enhance energy and stamina - memory - long-term planning - mental focus Dopamine - synthesized from amino acid Levodopa - Alertness - Motivation - motor control - immune function - Ego hardening, confidence, optimism - Sexual Desire - Fat gain and loss - lean muscle gain - Bone density - ability to sleep soundly - Inhibits prolactin - thinking, planning, and problem solving - Aggression - Increase psychic and creative ability - Reduction of compulsivety - Salience and paranoia - Processing of pain - Increase sociability Serotonin (5-HT) - Synthesized from amino acid L-tryptophan with co-factor Niacin (B3), through the intermediate 5-hydroxytryptophan (5-HTP) Norepinephrine - Synthesized from Dopamine with co-factor of vitamin C through the intermediate DOPAC. Vasopressin - Yan Niemczycki

You Are Not So Smart UCSB scientists discover how the brain encodes memories at a cellular level (Santa Barbara, Calif.) –– Scientists at UC Santa Barbara have made a major discovery in how the brain encodes memories. The finding, published in the December 24 issue of the journal Neuron, could eventually lead to the development of new drugs to aid memory. The team of scientists is the first to uncover a central process in encoding memories that occurs at the level of the synapse, where neurons connect with each other. "When we learn new things, when we store memories, there are a number of things that have to happen," said senior author Kenneth S. "One of the most important processes is that the synapses –– which cement those memories into place –– have to be strengthened," said Kosik. This is a neuron. (Photo Credit: Sourav Banerjee) Part of strengthening a synapse involves making new proteins. The production of new proteins can only occur when the RNA that will make the required proteins is turned on. When the signal comes in, the wrapping protein degrades or gets fragmented.

Introduction to Feedforward Neural Networks - Introduction Neural networks are a very popular data mining and image processing tool. Their origin stems from the attempt to model the human thought process as a an algorithm which can be efficiently run on a computer. The human brain consists of neurons that send activation signals to each other (figure on the left) thereby creating intelligent thoughts. Because the breadth of neural networks is very large, this project focuses on feed-forward neural networks, perhaps the most common type. Algorithm Description Artificial neural networks (the ones that run on a computer as opposed to a brain) can be thought of as a model which approximates a function of multiple continuous inputs and outputs. Computing Output We will first see how to compute the output of an already learned neural network which means that the entire network (topology, activation functions, weights, and biases) is known at this point. We will now see how to compute the output of a single neuron N_i.

10 Brilliant Social Psychology Studies | PsyBlog Ten of the most influential social psychology experiments. “I have been primarily interested in how and why ordinary people do unusual things, things that seem alien to their natures.Why do good people sometimes act evil?Why do smart people sometimes do dumb or irrational things?” –Philip Zimbardo Like eminent social psychologist Professor Philip Zimbardo (author of The Lucifer Effect: Understanding How Good People Turn Evil), I’m also obsessed with why we do dumb or irrational things. The answer quite often is because of other people – something social psychologists have comprehensively shown. Over the past few months I’ve been describing 10 of the most influential social psychology experiments. Each one tells a unique, insightful story relevant to all our lives, every day. 1. The ‘halo effect’ is a classic social psychology experiment. » Read on about the halo effect -» 2. » Read on about cognitive dissonance -» 3. » Read on about Sherif’s Robbers Cave experiment -» 4. 5. 6. 7. 8. 9. 10.

The Learning Brain Gets Bigger--Then Smaller With age and enough experience, we all become connoisseurs of a sort. After years of hearing a favorite song, you might notice a subtle effect that’s lost on greener ears. Perhaps you’re a keen judge of character after a long stint working in sales. Whatever your hard-learned skill is, your ability to hear, see, feel, or taste with more nuance than a less practiced friend is written in your brain. One classical line of work has tackled these questions by mapping out changes in brain organization following intense and prolonged sensory experience. But don’t adopt that slogan quite yet. If you were to look at the side of someone’s brain, focusing on the thin sliver of auditory cortex, it would seem fairly uniform, with only a few blood vessels to provide some bearing. One of the great neuroscience findings of the past several decades is that the ‘state lines’ of the auditory map (as well as many other sensory maps) are redrawn after training. So what does change? Are you a scientist?

Feedforward Neural Networks 2.5.1 Feedforward Neural Networks Feedforward neural networks (FF networks) are the most popular and most widely used models in many practical applications. They are known by many different names, such as "multi-layer perceptrons." Figure 2.5 illustrates a one-hidden-layer FF network with inputs and output . , also called the neuron function. Figure 2.5. Mathematically the functionality of a hidden neuron is described by where the weights { } are symbolized with the arrows feeding into the neuron. The network output is formed by another weighted summation of the outputs of the neurons in the hidden layer. The neurons in the hidden layer of the network in Figure 2.5 are similar in structure to those of the perceptron, with the exception that their activation functions can be any differential function. where n is the number of inputs and nh is the number of neurons in the hidden layer. } are the parameters of the network model that are represented collectively by the parameter vector . In[1]:=

The Ten Most Revealing Psych Experiments Psychology is the study of the human mind and mental processes in relation to human behaviors - human nature. Due to its subject matter, psychology is not considered a 'hard' science, even though psychologists do experiment and publish their findings in respected journals. Some of the experiments psychologists have conducted over the years reveal things about the way we humans think and behave that we might not want to embrace, but which can at least help keep us humble. That's something. 1. 'Lord of the Flies': Social Identity Theory The Robbers Cave Experiment is a classic social psychology experiment conducted with two groups of 11-year old boys at a state park in Oklahoma, and demonstrates just how easily an exclusive group identity is adopted and how quickly the group can degenerate into prejudice and antagonism toward outsiders. Researcher Muzafer Sherif actually conducted a series of 3 experiments. 2. 3. 4. 5. 6. 7. 8. 9. 10. Turns out that it's all about framing.

Meditation found to increase brain size Kris Snibbe/Harvard News Office Sara Lazar (center) talks to research assistant Michael Treadway and technologist Shruthi Chakrapami about the results of experiments showing that meditation can increase brain size. People who meditate grow bigger brains than those who don’t. Researchers at Harvard, Yale, and the Massachusetts Institute of Technology have found the first evidence that meditation can alter the physical structure of our brains. Brain scans they conducted reveal that experienced meditators boasted increased thickness in parts of the brain that deal with attention and processing sensory input. In one area of gray matter, the thickening turns out to be more pronounced in older than in younger people. “Our data suggest that meditation practice can promote cortical plasticity in adults in areas important for cognitive and emotional processing and well-being,” says Sara Lazar, leader of the study and a psychologist at Harvard Medical School. Controlling random thoughts - The Anatomy of Movement Susan Schwerin, PhD | March 5, 2013 Almost all of behavior involves motor function, from talking to gesturing to walking. But even a simple movement like reaching out to pick up a glass of water can be a complex motor task to study. Figure 1a: Principal cortical domains of the motor system. The primary motor cortex (M1) lies along the precentral gyrus, and generates the signals that control the execution of movement. The primary motor cortex, or M1, is one of the principal brain areas involved in motor function. Figure 1b: The motor homunculus in primary motor cortex. A figurative representation of the body map encoded in primary motor cortex. Other regions of the cortex involved in motor function are called the secondary motor cortices. Neurons in M1, SMA and premotor cortex give rise to the fibers of the corticospinal tract. The spinal cord is comprised of both white and gray matter. Figure 2: Cortical control of skeletal muscles.

Image by Thomas Deerinck / Mark Ellisman by kaspervandenberg Dec 23