M Ashcraft PYSCH 1105 CHAPTER 2 BIOLOGY OF THE MIND INTRODUCTION o Psychological and biological processes and inherently intertwined o Phrenology A popular but ill fated theory that bumps on the head could predict character traits and mental abilities Corrected focused the idea that certain brain regions have certain functions o Recent discoveries made by biologists Body is composed of cells Among these cells are nerve cells that conduct electrical current and send signals to each other through the tiny gaps between them Specific regions have specific functions within the brain We use these regions to integrate information and conduct our experience of sight pain etc Our adaptive brain is wired through experience Biological scientists scientists that study the link between psychcology and biology Tissues are composed of specialized cells that make up our individual NUERAL INTEGRATION o Nuerons Basic building blocks of the nervous system Types Motor efferent neurons carry information from the CNS to the rest of the Sensory neurons carry information to the central nervous system body Interneuron located in the CNS intergrate the information responsible for the nervous systems complexity most abundant Components Dendrite receiving extensions attached to the soma Myelin Sheath a layer of fatty tissue that surrounds the axon and provided Soma cell body Axon conduct signal away from the cell body electrical insulation o Degeneration results in multiple sclerosis Transmission Triggered by chemicals from neighboring neurons or from our senses Action Potential o A brief electrical charge that travels down an axon o Generated by the movement of positively charged ions travelling in and out of channels on the axon Threshold Each neuron receives excitatory and inhibitory signals from many neurons When the excitatory signals minus the inhibitory signals exceed a minimum intensity threshold the neuron fires an action potential Generate signals like batteries through chemical signals Converts chemistry to electricity through the interaction of ions o Resting potential negative charge inside positive charge outside Charge maintained by selectively permeable membrane of the axon At the axon hillock the gates open allowing positive ions to rush in depolarizing o This activates gates further down on the axon generating an action o During the refractory period the cell pumps the sodium ions back potential outside Integration o Make decisions based on impulse from excitatory and inhibitory impulses If exceed a certain level threshold an AP will result o Action potential Properties M Ashcraft All or none A strong stimulus can trigger more neurons to fire and to fire more often but it does not affect the action potentials strength or speed Intensity of an action potential remains the same throughout the length of the axon o Nueral Communication Synapse Causes a pause in transmission A gap between the axon tip of the sending neuron and the dendrite or soma of the receiving Nuerotransmitters When the signal reaches the axon tip it stimulates the release of chemicals from the axon These chemicals are called neurotransmitters Travel across the cleft and bind to specific receptor sites on the receiving neuron This causes gates to open on the receiving cell that can inhibit or excite a neuron Influence ability to create an AP Reuptake the remaining neurotransmitters are reabsorbed Prevents overstimulation Neurotransmitter Acetylcholine Ach Function Neuromuscular junction learning and memory Dopamine Influences learning movement attention and emotion Serotonin Effects mood hunger sleep and arousal Norepinephrine GABA Glutamate Control of alertness and arousal Major Inhibitory Major excitatory memory functions Disease Alzheimer s Ach producing neurons deteriorate if receptors are blocked then brief anesthesia results Excess dopamine receptor activity is linked to schizophrenia Starved of dopamine the brain produces the tremors and decreased mobility of Parkinson s disease Undersupply linked to depression Prozac and some other antidepressant drugs raise serotonin levels Undersupply can suppress mood Undersupply linked to seizures tremors and insomnia Oversupply can overstimulate brain produc ing migraines or seizures which is why some people avoid MSG monosodium glu tamate in food Candance Pert and Soloman Snyder o Discovered through opiate study that we have endorphins linked to pain control and o Which are enhanced through exercise runner s high and acupuncture Drugs and chemicals influence o Do not flood the brain with opiates because the brain will stop making endorphins o Many chemicals amplify or inhibit the effect of neurotransmitters lock and key pleasure mechanism Agonist a chemical similar enough to the neurotransmitter to use its receptor and mimic its effects Ex opiates from drugs fill the receptors of endorphins M Ashcraft NERVOUS SYSTEM Kinds of Neurons Antagonists block a nuerotransmitter s functioning Ex botulism binds to Ach receptors paralysis o Sensory rely from receptors the brain bipolar o Motor from CNS to target multipolar o Internueron intergrating center unipolar Central Nervous System CNS o The brain and the spinal cord Peripheral Nervous System PNS o Glands muscles and sensory receptors o 2 sections Somatic and Motor Somatic enables movement of our skeletal muscles Automatic controls glands and visceral organs functions like control of HB and digestion Sympathetic Nervous System o Arouses and expends energy o o Directs energy from digestion to skeletal muscles and Flight or fight response vasodilates in skin Increases heart rate o Parasympathetic Nerous System o Resting and Digesting Nerves THE BRAIN Electrocardiogram EEG o Bundles of axons that enable the CNS and PNS connection o An amplified recording of electrical activity across the brain surface measured by electrodes placed on the scalp Neuroimaging Techniques o PET scan positron emission tomography A visual of brain activity that detects a radioactive form of glucose while the brain performs a task Shows the chemical consumption of certain regions of the brain o MRI magnetic resonance imaging Uses magnetic and radio waves to produce computer generated images that distinguish amongst different types of brain tissue Rapidly images the brain while it is still active the head is put in a strong mag netic field which aligns the spinning atoms of brain molecules Then a radio wave pulse momentarily disorients the atoms When the
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