Transcript neurons
The Biology of Mind. Consciousness and the Two-Track Mind. Neuroscience and Behavior Biological psychology is the scientific study of the biological bases of behavior and mental processes. This area of research is also called biopsychology. Both terms emphasize the idea of a biological approach to the study of psychological processes. Biological psychology is one of the scientific disciplines that makes important contributions to neuroscience—the scientific study of the nervous system. As neuroscientists, biopsychologists bring their expertise in behavior and behavioral research to this scientific endeavor. Some of the other scientific disciplines that contribute to neuroscience include physiology, pharmacology, biology, and neurology. Neurons Communication throughout the nervous system takes place via neurons—cells that are highly specialized to receive and transmit information from one part of the body to another. Glial cells Along with neurons, the human nervous system is made up of other types of specialized cells, called glial cells between neurons and blood vessels in the brain. Glia and Blood-Brain Barrier Basic types of neurons There are three basic types of neurons, each communicating different kinds of information: Sensory neurons convey information about the environment, such as light or sound, from specialized receptor cells in the sense organs to the brain. Sensory neurons also carry information from the skin and internal organs to the brain. Motor neurons communicate information to the muscles and glands of the body. blinking your eyes activates thousands of motor neurons. Interneurons communicate information between neurons. By far, most of the neurons in the human nervous system are interneurons, and many interneurons connect to other interneurons. Characteristics of the Neuron • Most neurons have three basic components: a cell body, dendrites, and an axon. The cell body contains the nucleus, which provides energy for the neuron to carry out its functions. The cell body also contains genetic material and other structures that are found in virtually all the cells in the body Components of the neuron The cell body contains the nucleus, which provides energy for the neuron to carry out its functions. The cell body also contains genetic material and other structures that are found in virtually all the cells in the body. Extending out from the cell body are many short, branching fibers, called dendrites. Dendrites receive messages from other neurons or specialized cells. The axon is a single, elongated tube that extends from the cell body in most, though not all, neurons. Axons carry information from the neuron to other cells in the body, including other neurons, glands, and muscles. The axons of many, though not all, neurons are surrounded by the myelin sheath. The myelin sheath is a white, fatty covering anufactured by special glial cells. The Neuron Soma Dendrites Myelin Sheath Axon Axon Terminals Function of ion gate Action Potentials Communication Between Neurons In the brain, as in the rest of the nervous system, information is transmitted by electrical impulses that speed from one neuron to the next. The Synapse The point of communication between two neurons is called the synapse. The transmission of information between two neurons occurs in one of two ways: electrically or chemically. Chemical Signals One neuron will transmit info to another neuron or to a muscle or gland cell by releasing chemicals called neurotransmitters. The site of this chemical interplay is known as the synapse. An axon terminal (synaptic knob) will abut another cell, a neuron, muscle fiber, or gland cell. This is the site of transduction – the conversion of an electrical signal into a chemical signal. Synaptic Transmission An AP reaches the axon terminal of the presynaptic cell and causes V-gated Ca2+ channels to open. Ca2+ rushes in, binds to regulatory proteins & initiates NT exocytosis. NTs diffuse across the synaptic cleft and then bind to receptors on the postsynaptic membrane and initiate some sort of response on the postsynaptic cell. Important Neurotransmitters Acetylcholine -learning, memory, muscle contractions Dopamine – movement, thought processes, rewarding sensations Serotonin - emotional states, sleep Norepinephrine - physical arousal, learning, memory GABA - Inhibition of brain activity Endorphins Pain perception Positive emotions Central & peripheral nervous system The central nervous system includes the brain and the spinal cord. Bundles of neuron axons that carry information in the peripheral nervous system. Reflex a simple, automatic, inborn response to a sensory stimulus Brain Sensory neuron (incoming information) Interneuron Motor neuron (outgoing information) Muscle Skin receptors Spinal cord Neural Networks Neurons in the brain connect with one another to form networks Inputs Outputs The brain learns by modifying certain connections in response to feedback interconnected neural cells with experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results computer simulations of neural networks show analogous learning Specialized Cortical Regions revealed with PET scan Brain scan images Brain scan images have become so commonplace in news articles and popular magazines that it’s easy to forget just how revolutionary brain imaging technology has been to the field of neuroscience Looking at Brain-Scan Images The ‘Split Brain’ studies Surgery for epilepsy : cut the corpus callosum Roger Sperry, 1960’s Special apparatus picture input to just one side of brain screen blocks objects on table from view Verbal left hemisphere Nonverbal right hemisphere The ‘Split Brain’ studies Picture to right brain can’t name the object “What “Using “What yourdid left did hand, see?” Pick you up you what see?” you saw.” left hand can identify by touch Picture to left brain can name the object left hand cannot identify by touch ?? I saw an Verbal Verbal apple. leftleft hemisphere hemisphere Nonverbal right hemisphere