Biology of Mind Chapter 2 PDF

Chapter 2 The Biology of Mind MR. CARLO “MACHO” MAGPAROC Instructor 1 Surveying the Chapter: Overview What We Have in Mind ▪ Building blocks of the mind: neurons and how they communicate (neurotransmitters) ▪ Systems that build the mind: fun...

Chapter 2 The Biology of Mind MR. CARLO “MACHO” MAGPAROC Instructor 1 Surveying the Chapter: Overview What We Have in Mind ▪ Building blocks of the mind: neurons and how they communicate (neurotransmitters) ▪ Systems that build the mind: functions of the parts of the nervous system ▪ Supporting player: the slower-communicating endocrine system (hormones) ▪ Star of the show: the brain and its structures 2 Searching for the self by studying the body Phrenology Phrenology (developed by Franz Gall in the early 1800’s): the study of bumps on the skull and their relationship to mental abilities and character traits ▪ Phrenology yielded one big idea--that the brain might have different areas that do different things (localization of function). 3 Today’s search for the biology of the self: biological ▪ Biological psychology psychology includes neuroscience, behavior genetics, neuropsychology, and evolutionary psychology. ▪ All of these subspecialties explore different aspects of: how the nature of mind and behavior is rooted in our biological heritage. ▪ Our study of the biology of the mind begins with the “atoms” of the mind: neurons. 4 Neurons and Neuronal Communication: The Structure of a Neuron There are billions of neurons (nerve cells) throughout the body. 5  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. 6  When does the cell send the action potential?... when it reaches a threshold How neurons communicate ▪ When the (with each other): The signal is The neuron threshold is receives transmitted reached, the The action to another signals from action potential potential other cell. starts moving. travels down However, the neurons; ▪ Like a gun, it the axon some are message either fires or it from the cell must find a telling it to doesn’t; more body to the fire and some way to cross stimulation does terminal a gap are telling it nothing. branches. not to fire. between ▪ This is known as cells. This the gap is also “all-or-none” called the response. synapse. The threshold is reached when excitatory (“Fire!”) signals outweigh the inhibitory (“Don’t fire!”) signals by a certain amount. 7  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.” 8  Neurotransmitters Neurotransmitters are chemicals used to send a signal across the synaptic gap. 9  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. 10 Neural Communication: Seeing all the Steps Together 11  Roles of Different Neurotransmitters Some Neurotransmitters and Their Functions Neurotransmitter Function Problems Caused by Imbalances Serotonin Affects mood, hunger, Undersupply linked to depression; some sleep, and arousal antidepressant drugs raise serotonin levels Dopamine Influences movement, Oversupply linked to schizophrenia; learning, attention, and undersupply linked to tremors and emotion decreased mobility in Parkinson’s disease and ADHD Acetylcholine Enables muscle action, ACh-producing neurons deteriorate as (ACh) learning, and memory Alzheimer’s disease progresses Norepinephrine Helps control alertness Undersupply can depress mood and and arousal cause ADHD-like attention problems GABA A major inhibitory Undersupply linked to seizures, (gamma-aminobut neurotransmitter tremors, and insomnia yric acid Glutamate A major excitatory Oversupply can overstimulate the brain, neurotransmitter; producing migraines or seizures; this is involved in memory why some people avoid MSG (monosodium glutamate) in food 12  Serotonin Dopamine pathways pathways Networks of neurons that Networks of neurons that communicate with serotonin communicate with dopamine are help regulate mood. involved in focusing attention and controlling movement. 13 Hearing the message How Neurotransmitters Activate Receptors When the key fits, the site is opened. 14  Keys that almost fit: Agonist and Antagonist Molecules An agonist molecule fills An antagonist molecule the receptor site and fills the lock so that the activates it, acting like the neurotransmitter cannot neurotransmitter. get in and activate the receptor site. 15  The Inner and Outer Parts of the Nervous System The The central peripheral nervous nervous system system [PNS] [CNS] consists of consists of ‘the rest’ of the brain the nervous and spinal system. cord. The PNS The CNS gathers and makes sends decisions information for the to and from body. the rest of 16 More Parts of the Nervous System 17 The Autonomic Nervous System: The sympathetic NS arouses (fight-or-flight) The parasympathetic NS calms (rest and digest) 18 The Body’s “Slow but Sure” Endocrine Message System ▪ The endocrine system sends molecules as messages, just like the nervous system, but it sends them through the bloodstream instead of across synapses. ▪ These molecules, called hormones, are produced in various glands The endocrine system refers to a set of around the body. glands that produce chemical messengers 19 called hormones.  produce hormones such as Adrenal Glands adrenaline/epinephrine, noradrenaline/norepinephrine, and cortisol. Adrenal Glands 1. The sympathetic “fight or flight” nervous system responds to stress by sending a message to adrenal glands to Pancreas release the hormones listed above. 2. Effect: increased heart rate, blood pressure, and blood sugar. These20 The Pituitary Gland ▪ The pituitary gland is the “master gland” of the endocrine system. ▪ It is controlled through the nervous system by the nearby brain area--the Pituitary gland hypothalamus. ▪ The pituitary gland produces hormones that regulate other glands such as the thyroid. ▪ It also produces growth hormone (especially during sleep) and oxytocin, the “bonding” 21 Investigating the Strategies for finding out what is different about the Brain and Mind: mind when part of the brain isn’t working normally: ▪case studies of accidents (e.g. Phineas Gage) ▪case studies of split-brain How did we move beyond patients (corpus callosum phrenology and get inside the cut to stop seizures) skull and under the “bumps”? ▪lesioning brain parts in ▪by finding what happens when animals to find out what part of the brain is damaged or happens otherwise unable to work ▪chemically numbing, properly magnetically deactivating, ▪by looking at the structure and or electrically stimulating activity of the brain: CAT, MRI, parts of the brain 22 Studying cases of brain damage When a stroke or injury damages part of the brain, we have a chance to see the impact on the mind. 23 Intentional brain damage: Lesions (surgical destruction of brain tissue) ▪ performed on animals ▪ has yielded some insights, especially about less complex brain structures ▪ no longer necessary, as we now can chemically or magnetically deactivate brain areas to get similar information 24 Split-Brain Patients ▪ “Split” = surgery in which the connection between the brain hemispheres is cut in order to end severe full-brain seizures ▪ Study of split-brain patients has yielded insights discussed at the end of the chapter 25 We can stimulate parts of the brain to see what happens ▪ Parts of the brain, and even neurons, can be stimulated electrically, chemically, or magnetically. ▪ This can result in behaviors such as giggling, head turning, or simulated vivid recall. ▪ Researchers can see which neurons or neural networks fire in conjunction with certain mental experiences, and even specific concepts. 26  EEG: PET: positron emission electroencephalogram tomography An EEG The PET scan allows us to see (electroencephalogram) is what part of the brain is active a recording of the by tracing where a radioactive electrical waves sweeping form of glucose goes while the across the brain’s surface. brain performs a given task. It is useful in studying seizures and sleep. 27  MRI: magnetic fMRI: functional MRI resonance imaging MRI (magnetic resonance imaging) Functional MRI reveals makes images from signals produced by brain activity and brain tissue after magnets align the spin function rather than of atoms. structures. Functional MRI The arrows below show ventricular compares successive enlargement in a schizophrenic patient MRI images taken a (right). split second apart, and shows changes in the level of oxygen in bloodflow in the brain. 28 Areas of the brain and their functions The limbic The brainstem The cortex (the (border) and cerebellum: outer covering): system: coordinates manages integrates the body emotions, and information connects thought to body 29  The Brainstem: Pons and Medulla ▪ The medulla controls the most basic functions such as heartbeat and breathing. ▪ Someone with total brain damage above the medulla could still breathe independently, but someone with damage in this area could not. ▪ The pons helps coordinate automatic and unconscious movements. 30 The Thalamus (“Inner Chamber”) ▪ The thalamus is the “sensory switchboard” or “router.” ▪ All sensory messages, except smell, are routed through the thalamus on the way to the cortex (higher, outer brain). ▪ The thalamus also sends messages from the cortex to the medulla and 31  Reticular (“Netlike”) Formation ▪ The reticular formation is a nerve network in the brainstem. ▪ It enables alertness, (arousal) from coma to wide awake (as demonstrated in the cat experiments). ▪ It also filters incoming sensory information. 32  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. 33 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. 34 ▪ helps process emotions,  The Amygdala ▪ Electrical stimulation of a cat’s amygdala provokes aggressive reactions. ▪ If you move the electrode very slightly and cage the cat with a mouse, the cat will cower in terror. 35  The Hypothalamus: ▪ lies below (“hypo”) the thalamus. 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. 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 36food pellets. Review of Brain Structures 37  The Cerebral Cortex The lobes consist of: ▪ outer grey “bark” structure that is wrinkled in order to create more surface area for 20+ billion neurons. ▪ inner white stuff—axons linking parts of the brain. ▪ 180+ billion glial cells, which feed and protect neurons and assist neural transmission. 300 billion synaptic connections The brain has left and right 38 hemispheres The Lobes of the Cerebral Cortex: Preview ▪ Frontal Lobes involved in speaking and muscle movements and in making plans and judgments ▪ Parietal Lobes include the sensory cortex include the visual areas; ▪ Occipital Lobes they receive visual information from the opposite visual field ▪ Temporal Lobes include the auditory processing areas 39  Functions of the Brain: The Motor and Sensory Strips Output: Motor Input: Sensory cortex (Left cortex (Left hemisphere hemisphere section controls section receives the body’s right input from the side) body’s right side) 🡨 Axons 🡨Axons receiving motor sending signals FROM sensory the cortex information 40 TO the cortex  Sensory Functions of the Cortex ▪ The sensory strip deals with information from touch stimuli. ▪ The occipital lobe deals with visual information. ▪ Auditory information is sent to the temporal lobe. 41 The Visual Cortex This fMRI scan shows increased activity in the visual cortex when a person looks at a photograph. 42 Association function of the cortex More complex animals have more cortical space devoted to integrating/associating information 43  Association Areas: Frontal Lobes ▪ The frontal lobes are active in “executive functions” such as judgment, planning, and inhibition of impulses. ▪ The frontal lobes are also active in the use of working memory and the processing of new memories. 44 Phineas Gage (1823-1860) Case study: In a work accident, a metal rod shot up through Phineas Gage’s skull, destroying his eye and part of his frontal lobes. After healing, he was able to function in many ways, but his personality changed; he was rude, odd, irritable, and unpredictable. Possible explanation: Damage to the frontal lobes could result in loss of the ability to suppress impulses and to modulate emotions. 45 Parietal Lobe Association Areas This part of the brain has many functions in the association areas behind the sensory strip: ▪managing input from multiple senses ▪performing spatial and mathematical reasoning ▪monitoring the sensation of movement 46 Temporal Lobe Association Areas Some abilities managed by association areas in this “by the temples” lobe: ▪recognizing specific faces ▪managing sensory input related to sound, which helps the47 Whole-brain Association Activity Whole-brain association activity involves complex activities which require communication among association areas across the brain such as: ▪memory ▪language ▪attention ▪meditation and spirituality ▪consciousness 48 Specialization and Integration Five steps in reading a word aloud: 49 Plasticity: The Brain is Flexible If the brain is damaged, especially in the general association areas of the cortex: ▪the brain does not repair damaged neurons, BUT it can restore some functions ▪it can form new connections, reassign This 6-year-old had a existing networks, and hemispherectomy to end insert new neurons, some life-threatening seizures; her grown from stem cells remaining hemisphere compensated for the damage. 50  Our Two Hemispheres Lateralization (“going to one side”) The two hemispheres serve some different functions. How do we know about these differences? ▪Brain damage studies revealed many functions of the left hemisphere. ▪Brain scans and split brain studies show more about the functions of the two hemispheres, and how they coordinate with each other. 51 The intact but lateralized brain Right-Left Hemisphere Differences Left Hemisphere Right Hemisphere Thoughts and logic Feelings and intuition Details such as “trees” Big picture such as “forest” Language: words and Language: tone, inflection, definitions context Linear and literal Inferences and associations Calculation Perception Pieces and details Wholes, including the self 52  Split- Brain Studies To end severe whole-brain seizures, some people have had surgery to cut the corpus callosum, a band of axons Researchers have studied the connecting the impact of this surgery on hemispheres. patients’ functioning. 53  Split visual field Each hemisphere does not perceive what each EYE sees. Instead, it perceives the half of the view in front of you that goes with the half of the body that is controlled by that hemisphere. 54 Divided Awareness in the Split Brain Try to explain the following result: 55 The divided brain in action ▪ Talent: people are able to follow two instructions and draw two different shapes simultaneously ▪ Drawback: people can be frustrated that the right and left sides do different things 56 End. Thank you. 57