Biopsychology Outline Overview Hardware Software Domains of Interest Lecture 4 Biopsychology Neurons Bases for Normal and Abnormal Function The Synapse Neurotransmitters Examples Mapping Brain Function Neuroimaging techniques CAT MRI EEG PET fMRI Lateralization Overview Biopsychology is about how biological factors understood very broadly can affect and influence human mind and human behavior This can include Health Psychology How stress affects people Drugs how they affect both normal functioning and health Hereditary Genetic Psychology Neuroanatomy and Physiology how the brain works and how the brain affects information processing and mental illness health Basic Functions of Neural Tissue o Receive Information o Integrate Information Neurons receive information from other neurons some neurons receive information for the external environment these are called sensory neurons Neurons combine information from a variety of sources neurons take in input from all the neurons that they are connected to each cell in the body can be in contact with 1000 100 000 other cells so the average neuron can be taking in input from 50 60 000 different sources so the neuron takes that information and integrates it together o Transmit Information After the neuron integrates information it will pass along that information to everything that it is connected to other neurons or to muscles neurons that pass information to muscles are called motor neurons 1 A Single Nerve Cell through the dendrites processed in the some and transmitted down the axon Nerve cells receive integrate process and transmit information information comes in Three primary components Dendrites branches see left receive information Soma middle cell body integrates processes information Axon connects neurons transmitting information Axon may or may not be covered in a fatty substance called a Myelin sheath that insulates the axon it prevents cross connections and speed transmission down the axon Long fiber that outputs information Axons can be of various lengths in the human system up to seven feet long At the end of the axon are terminal buttons which are involved in the connection between one cell and the next What Happens When a Neuron Fires The cell membrane is selectively permeable it selectively allows things in some things can get in while other things cannot A neural cell is selectively permeable to positive ions of sodium Salt Because the cell will not let the positive sodium ions in they build up on the outside These ions attract negative ions inside the cell This creates an electrical potential across the membrane so the cell is like a little battery the typical charge on a neuron is about 1 200th of the charge on a flashlight battery 2 When the cell fires a small segment of the cell membrane at the soma at the When the cell is at rest there is a build up of charge on either side is referred to as the cell membrane being polarized the inside of the cell tends to have a higher negative charge than the outside The magnitude of the polarization is called the resting potential very beginning of the axon depolarizes This lets the positively charged sodium atoms into the cell The charge on the cell was negative now it becomes either neutral or slightly positive When this happens it triggers the same reaction depolarization in the next segment of the cell membrane which triggers depolarization in the next segment So this change in charge is moving down the axon this shift in charge is called the action potential The rate of the action potential is constant for any given cell it may vary among different cells but for any single cell it is always the same The rate ranges between 2 10 m s and 120 m s 260mph This is fast relative to the speed at which we operate in the world however relative to other ways of processing information computers for example it is extremely slow When neurons fire they fire in an all or none manner when they take in information they do so in a graded manor When it transmits information it cannot fire more weakly or more strongly like a light with no dimmer switch When it takes in information the level of activity in the cell fluctuates like a light on a dimmer switch the level depends on the amount of the neurotransmitter and tells the cell to increase or decrease activation by x amount If the level of activation reaches a threshold the cell fires until this happens the neuron does not communicate any information It takes in a lot of information and makes 1 decision Example This is like an election you take in information from many different sources in this case voters and make one yes or no decision How do you transmit intensity You transmit intensity by the rate of the fire not the intensity of the fire the more intense the stimulus the more rapidly the cell fires however you cannot fire continuously because every time you fire you have to reboot the system Neurotransmitters are chemicals that carry information from one cell to the next across the synapse When the signal gets to the end of the axon to the terminal button it needs to transmit information to the next neuron in line However none of the neurons are physically connected there is a gap called the synaptic cleft the junction of the two cells is the synapse At the terminal button there are little sacs that contain neurotransmitters There are many different neurotransmitters they are proteins and each has a particular physical shape and each has a receptor site at the receiving neuron that is shaped to fit the neurotransmitter like a key in a lock The synapses are flooded with neurotransmitters from all the neurons in the area Whether a cell fires or doesn t fire can have consequences to the next cell down the line not firing has equal consequence to firing emotional processing and for behavior at the level that we actually experience What goes on in the synapse has enormous consequences for informational and Examples Drugs Alcohol scramble processing at the synapse There are relationships between mental illness and various neurotransmitters 3 Endorphins were one of the first neurotransmitters to be examined A Synapse and Neurotransmitter Example This kind of very simple processing however out of a whole system of these stupid units you build a system that operates in a very complex intelligent way this is the bases for human behavior Neural net take in input from a lot of sources give out input to a lot of sources net because it is a system
View Full Document
Unlocking...