Transcript the brain
Chapter 2 The Biology of Behavior PowerPoint® Presentation by Jim Foley Homework this Weekend Read pp.56-58 Complete questions on p.58 MONDAY BE ON TIME!! We’re doing a fun experiment. Searching for the biology of “self” Is our identity in the heart? In the brain? In the whole body? Biological Psychologists explore the associations between body, mind, and behavior. 3 Overview: What We Have in Mind Building blocks of mind: Neurons and how they communicate (neurotransmitters) Systems that build the mind: Functions of Parts of the Nervous system Supporting player: the slower-communicating Endocrine system (hormones) Tools for examining the brain and its activities More primitive and advanced brain structures Neural and Hormonal Systems Neurons and Neuronal Communication: The Structure of a Neuron There are billions of neurons (nerve cells) throughout the body. Action potential: a neural impulse that travels down an axon like a wave Just as “the wave” can flow to the right in a stadium even though the people only move up and down, a wave moves down an axon although it is only made up of ion exchanges moving in and out. When does the cell send the action potential? When it reaches a threshold. How neurons communicate (with each other): The neuron receives signals from other neurons; some are telling it to fire and some are telling it not to fire. • When the threshold is reached, the action potential starts moving. • Like a gun, it either fires or it doesn’t; more stimulation does nothing. • This is known as the “all-ornone” response. The threshold is reached when excitatory (“Fire!”) signals outweigh the inhibitory (“Don’t fire!”) signals by a certain amount. The action potential travels down the axon from the cell body to the terminal branches . The signal is transmitted to another cell. However, the message must find a way to cross a gap between cells. This gap is also called the synapse. The Synapse The synapse is a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The synapse is also known as the “synaptic junction” or “synaptic gap.” Neural Communication: Between Neurons WILEY VIDEO © 2012 John Wiley & Sons, Inc. All rights reserved. Watchin g Live ANIMATION Neurotrans -mitters Neurotransmitters Neurotransmitters are chemicals used to send a signal across the synaptic gap. Reuptake: Recycling Neurotransmitters [NTs] Reuptake: After the neurotransmitters stimulate the receptors on the receiving neuron, the chemicals are taken back up into the sending neuron to be used again. Neural Communication: Between Neurons © 2012 John Wiley & Sons, Inc. All rights reserved. Neural Communication: Seeing all the Steps Together Roles of Different Neurotransmitters Some Neurotransmitters and Their Functions Neurotransmitter Function Problems Caused by Imbalances Serotonin Affects mood, hunger, sleep, and arousal Dopamine Influences movement, learning, attention, and emotion Undersupply linked to depression; some antidepressant drugs raise serotonin levels Oversupply linked to schizophrenia; undersupply linked to tremors and decreased mobility in Parkinson’s disease and ADHD Norepinephrine Enables muscle action, learning, and memory Helps control alertness and arousal ACh-producing neurons deteriorate as Alzheimer’s disease progresses Undersupply can depress mood and cause ADHD-like attention problems GABA gammaaminobutyric acid A major inhibitory neurotransmitter Glutamate A major excitatory neurotransmitter; involved in memory Undersupply linked to seizures, tremors, and insomnia Oversupply can overstimulate the brain, producing migraines or seizures; this is why some people avoid MSG (monosodium glutamate) in food Acetylcholine (ACh) Serotonin pathways Networks of neurons that communicate with serotonin help regulate mood. Dopamine pathways Networks of neurons that communicate with dopamine are involved in focusing attention and controlling movement. Divisions of the Nervous System The Inner and Outer Parts of the Nervous System The Central Nervous System (CNS), the brain and spinal cord, is the body’s decisionmaker. The Peripheral Nervous System (PNS), gathers information from the body and sends CNS decisions out to the body. Types of Neurons _____________ Sensory Neurons _____________ carry messages IN from the body’s tissues and sensory receptors to the CNS for processing. Motor neurons ____________ carry instructions OUT from the Interneurons CNS out to the _____________ (in the brain body’s tissues. and spinal cord) process information between the sensory input and motor output. The Peripheral Nervous System The Autonomic Nervous System: The sympathetic arouses NS _________ (fight-or-flight) The parasympathetic calms NS ________ (rest and digest) Neural Networks These complex webs of interconnected neurons form with experience. Neurons that fire together, wire together Remember: “__________________________________.” Interneurons in the Spine Decisions without ______________ made ___________ the brain Your spine’s interneurons trigger your hand to pull away from a fire before you can say OUCH! Sensory neuron This is an example of a ________________. reflex action Motor neuron The brain finds out about the reflex ____ after it happens. The Endocrine System The endocrine system: a set of glands that produce chemical messengers called hormones. The Body’s “Slow but Sure” Endocrine Message System The endocrine system sends messages just like the molecules as ________, nervous system, but it sends them Pituitary through the bloodstream instead of ____________________ gland across synapses. hormones These molecules, called _________, are produced in various glands around the body. The messages go to the brain and other tissues. pituitary gland is the “master gland” of the endocrine The _______________ system. It is controlled through the nervous system by the nearby brain area--the hypothalamus. The pituitary gland produces hormones that regulate other glands. Tools of Discovery and Brain Structures What We’ll See: How we learn about the brain: Scans and more The primitive, lifesustaining, inner parts of the brain: The _________ brainstem and limbic system ______ Higher Brain structure that help us think and act: Cerebral Cortex The _____________ Monitoring activity in the brain Tools to read electrical, metabolic, and magnetic activity in the brain: EEG: electroencephalogram PET: positron emission tomography MRI: magnetic resonance imaging fMRI: functional MRI EEG: electroencephalogram An EEG (electroencephalogram) is a recording of the __________ Electrical waves __________ sweeping across the brain’s surface. An EEG is useful in studying seizures and sleep. 28 PET: positron emission tomography The PET scan allows us to see what part of the brain is active by ________________________ tracing where a radioactive form of glucose goes while the brain performs a given task. MRI: magnetic resonance imaging MRI (magnetic resonance imaging) makes images _____________from signals produced by brain tissue after magnets align the spin of atoms. The arrows below show ventricular enlargement in a schizophrenic patient (right). fMRI: functional MRI Functional MRI reveals brain activity and function rather than structures. Functional MRI compares successive __________________ MRI images taken a split second apart, and shows changes in the level of oxygen in bloodflow in the brain. 30 The Brain: Less Complex Brain Structures Our tour of the brain begins with parts of the human brain found also in simpler animals; these parts generally deal with less complex functions: Brainstem (Pons and Medulla) Thalamus Reticular Formation Cerebellum Limbic System The Brainstem: Pons and Medulla The Base of the Brainstem: The Medulla The medulla controls the most heartbeat and basic functions such as __________ _____________ breathing _____________. Someone with total brain damage above the medulla could still breathe independently, but someone with damage in this area could not. The Thalamus The crossover The thalamus is the “sensory switchboard” or “________”: All sensory router messages, except smell, are routed through the thalamus on the way to the cortex (outer brain). over These messages cross _________ from one side of the body to the opposite side of the brain. Reticular (“net-like”) Formation The reticular formation is a nerve network in the brainstem. It enables alertness (arousal); stimulating this makes us wide awake. It also filters incoming sensory information and relays it to other brain areas. Cerebellum (“little brain”) The cerebellum helps coordinate voluntary _______________ _______________ movement such as playing a sport. The cerebellum has many other functions, including enabling nonverbal learning and memory. The Limbic (“Border”) System The limbic system coordinates: emotions such as fear and aggression. basic drives such as hunger and sex. the formation of episodic memories. The hippocampus (“seahorse”) processes conscious, episodic memories. works with the amygdala to form emotionally charged memories. The Amygdala (“almond”) consists of two lima bean- sized neural clusters. helps process emotions, especially fear and aggression. The Amygdala: Enabling two different responses to threat Electrical stimulation of one area of a cat’s amygdala provokes aggressive reactions. If you stimulate a different part of the amygdala and put the cat in a cage with a mouse, the cat will cower in terror. In what region would damage most likely: 1. Disrupt your ability to skip? 2. Disrupt your ability to hear and taste? 3. Perhaps leave you in a coma? 4. Cut off your breath and heartbeat? Cerebellum The Hypothalamus: lies below (“hypo”) the thalamus. regulates body temperature and ensures adequate food and water intake (homeostasis), and is involved in sex drive. directs the endocrine system via messages to the pituitary gland. Thalamus The Hypothalamus as a Reward Center Riddle: Why did the rat cross the grid? Why did the rat want to get to the other side? Pushing the pedal that stimulated the electrode placed in the hypothalamus was much more rewarding than food pellets.