- Davidson study 2003 (continued)o Conclusions There are various methods for gaining scientific knowledge Experimental knowledge is crucial to a causal understanding Even carefully designed experiments yield results open to multiple interpretationso Important in the experimental process: How do we refine? Observe/ask Explore correlations Examine processes we can’t “see” Manipulate variables  experiment Examine results What are other explanations?Introduction to Biological Psychology: The Nervous System and Neurotransmitter Processes- Overview:o How does the nervous system operate?o Basic neuron structure & physiologyo How do neurotransmitters influence emotion, thought & behavior?o Specific neurotransmitters & their neuronal & psychological functionso How are neural messages integrated into communication systems?o How do different parts of the nervous system interact?- What is a neuron?o A building block of the nervous systemo Communication cells- they collect, integrate, & transmit electrochemical infoo Dendrites : collect info, they look like brancheso Cell body : makes sense of the info received by the dendriteso Axons : Transmit info at the synapseo Vesicles : release neurotransmitters across the synapseo Myelin sheath : made up of glial cells, brings nourishment & serves as protection for axons (like an electrical cord); the insulation allows for smooth transmission- Different types of neuronso Sensory/afferent neurons : pick up info from the environment from sensory organs & send it to the brain (e.g. touch, pain, heat)o Motor/efferent neurons : affect movement (signals from the spinal cord to muscles/the periphery) (e.g. walking sends information from taking a step to the brain, which sends signals to the muscles to contract to keep walking)o Interneurons : there are billions, way more than other types of neurons; they communicate between neurons- Myelin sheatho Made of glial cells, insulation for axons, speeds neural transmissiono There are gaps in the sheath which allow saltatory conductiono Saltatory conduction: when action potentials “jump” across the “nodes of ranvier”o Nodes of ranvier : the space between 2 myelin sheaths on an axon where depolarization & action potentials occur- Glial cells: protective; they can increase in number as the brain is used- Demyelinating diseaseo E.g. multiple sclerosiso When the myelin sheath deteriorateso This causes lesions/scarring in the brain, & nerve paino Transmission from one neuron to the next is slowedo There are problems w/coordination & smooth movements- Action potentials cause neuronal communicationo Depolarization or hyperpolarization is required for neurons to communicateo Changes in electrical potential lead to actiono Resting membrane potential :  At rest the neuron is more negative on the inside than on the outside (it is negatively charged) The neuron receives a signal The “gates” open in the cell membrane The potential changeso Depolarization  A neuron receives a signal The gates in the cell membrane open Sodium ions (Na+) rush in The inside becomes slightly more positive This causes action- *Action potentials are an “all or nothing” evento Hyperpolarization  Neurons are less likely to fire Sodium channels are less likely to allow sodium into the neuron This is known as resting potential The inside is more negative than the outside- Mirror neurons o They are found in the frontal and parietal lobeso They fire when you observe someone engaging in behavior (even though you yourself may not be engaging in the same behavior)o E.g. when you are watching soccer, the neurons are firing even though you aren’t playingo You recognize another person’s goals/intentionso Autism may be the result of mirror neuron dysfunction- Neurotransmitters & psychological functionso Agonist : facilitates neurotransmitters; it enhances the effects E.g. depression is the result of low levels of serotonin Serotonin is released, but not enough of it, more needs to be available Serotonin selective reuptake inhibitor (SSRI) can help; it slows the process of thereuptake of serotonin It is the most common antidepressant b/c there are few side effects MAO inhibitor is another type of antidepressant that inhibits the breakdown of serotonin in the terminal button (so there is more serotonin to be released)o Antagonist : inhibits neurotransmitter effects; blocks receptor cellso Research on Acethylcholine (Ach) A neurotransmitter that causes muscle contraction, regulates attention & sleep; also important for memory Shortage causes memory deficits Might be able to combat Alzheimer’s with it (unless the brain is already damaged) Joseph Martinez conducted an experiment on the causal relationship between Ach & memory- He injected mice with Scopolamine or a saline after letting them learn a maze, and observed if they remembered where the food was located- Operational IV: scopolamine; the control was a salineo Scopolamine blocks Ach; it is an antagonisto The corresponding agonist is physostygmine (which facilitates learning & enhances memory)- Operational DV: time to finding the food in the mazeo The theoretical DV was memory- Result: scopolamine inhibited the mice from remembering where the food was located, so they took longer to find it than the control group- Overview: onew way to organize & categorize neurotransmitterso Acetylcholine: affects motor control & mental processes Links smooth motor & muscle control/neurons Curare: Ach antagonist which causes temporary muscle paralysis & is deathly (b/c it stops the heart & lungs from functioning) Causes muscle contraction, regulates attention, memory & sleep A shortage causes memory deficits & sometimes delusions Excess causes spasmso Mononoamines (single amino acids) Involved in arousal & motivation Epinephrine (adrenaline, in the bloodstream) & norephinephrine (a stimulant), serotonin,