PSYC 211 Introduction to Behavioral Neuroscience Lecture Notes PDF
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McGill University
Jonathan Britt
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These are lecture notes for Introduction to Behavioral Neuroscience, PSYC 211, covering course introductions, consciousness, syllabus, the professor, and important course information. This document also includes office hours and course textbook recommendations.
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Introduction to Behavioral Neuroscience PSYC 211 Lecture 1 of 24 – Consciousness (no associated reading) Professor Jonathan Britt Questions? Concerns? Please write to [email protected]...
Introduction to Behavioral Neuroscience PSYC 211 Lecture 1 of 24 – Consciousness (no associated reading) Professor Jonathan Britt Questions? Concerns? Please write to [email protected] 1 What is this course about? This course is an introduction to how the brain works. We cover topics that are fairly well understood by neuroscientists, such as what the brain is made of what neural activity is how neurons sense the world around us, signal to each other, adapt over time, and ultimately control muscles and glands neurological disorders We also discuss topics that neuroscientists don’t understand very well, such as emotions mental illness language learning hunger sleep sex differences 2 Your Prof – Jonathan Britt Office Hours (starting Sept 19) Thursdays from 10-11am Stewart Biology room N8/9 Associate Professor & McGill University, Montreal, QC Canada Research Chair Department of Psychology - Behavioural Neuroscience Research Fellow National Institute on Drug Abuse, Baltimore, MD Post-doctoral Fellow University of California at San Francisco, CA Ph.D. in Neurobiology University of Chicago, IL Research Assistant Oregon Health & Science University, Portland, OR B.A. Colorado College, Colorado Springs, CO I have a lab in Stewart Bio. My research Montreal explores the neural underpinnings of Portland motivation and reinforcement learning, San Francisco examines dopaminergic signaling and Chicago Baltimore neural processing in the basal ganglia, Colorado Springs combines optical imaging and targeted neural manipulations in studies of mouse learning and decision-making. 3 Syllabus Information These prerequisites are recommended but not critical: Introductory psychology (PSYC 100) or equivalent Introductory biology (BIOL 111, 112, 115) or equivalent Class attendance is helpful but not mandatory. All lectures are recorded (video and audio) and posted along with PowerPoint files on MyCourses. The recommended textbook is Discovering Behavioral Neuroscience 5th edition. You can purchase online access through MyCourses for $75. The textbook can be very helpful, but it is not essential to do well in this class. All exam questions come from my lectures. The textbook is good for clarifying misunderstandings, learning more about the field, and getting a different take on the material. (There is no need to buy the MindTap add-on. I do not incorporate MindTap assignments, nor do I give credit for MindTap quizzes.) 4 Exam Schedule and Grading Class grades are based on: 10% - Two homework quizzes (on MyCourses) that you can take as many times as you want (until December 9th). Only your highest grade is recorded. These are basically graded practice tests, and you should aim to get 100% on both. Each one is worth 5%. 25% - Midterm 1, in-class Monday 30th September, 4:05-5:25 PM. Covers lectures 1-8. 25% - Midterm 2, in-class Monday 11th November, 4:05-5:25 PM. Covers lectures 9-17. 40% - Final Exam, date in December will be determined by the university. Covers all lectures (cumulative) but emphasizes post midterm 2 material. You can also earn up to 2% extra credit (added to your final grade) if you participate in the psychology department study participant program. More information is on MyCourses. 5 What is Required Only the Final Exam (or Deferred Exam) is mandatory to get a grade in this class. The midterms and quizzes are technically optional, but they can only improve your overall class grade because I drop any mark that is lower than your final exam grade (and add the corresponding weight to the final exam). For example, If you only take the final exam or get your best score is on the final exam, then your class grade will be your final exam grade (+ any extra credit). If you miss midterm 1 or do worse on it than on the final exam, your class grade will be: 10% quizzes, 25% midterm 2, 65% final exam (+ any extra credit). If you don’t complete either quiz or do worse on them than on the Final Exam, your class grade will be: 25% midterm 1, 25% midterm 2, 50% final exam (+ any extra credit). We will try to accommodate requests for a midterm 1 make-up exam by (hopefully) offering a similar test during class time the following week: Monday, October 7th. I cannot guarantee that we will be able to accommodate make-up exam requests for midterm 1, but if you do miss that exam, please send a make-up exam request to the class account [email protected] before the end of Tuesday, October 1st. There will not be any make-up exam opportunities for Midterm 2. No exceptions. 6 Extra Credit Opportunity Earn up to 2% extra credit (added to your final grade) for participating in a 2-hour study through the Department of Psychology Extra Credit Study Participant Program. You can find a step-by-step tutorial explaining how to participate on MyCourses. If you have questions after watching that tutorial, please write to the coordinator of this program at [email protected] You course TAs and I are not involved in this program in any way. The administrators of it simply inform us who should get this extra credit at the end of the semester. 7 Teaching Assistants The TAs: Madeleine Morris, In-Hyun Baek, Naima Mansuri, Caitlyn Antal, Caroline Rajda They will help you to understand the course material by… 1. Leading formal review conferences 2. Answering your emailed questions 3. Answering questions posted on the MyCourses Discussion Board 4. Meeting with you one-on-one or in small groups. Email [email protected] to setup a meeting. 5. Going over exams with you after the fact. Please address all questions pertaining to all aspects of this course to [email protected] 8 TA Led Review Conferences Date Day Topic Time & Location Always 6:00 -8:00 pm Sept 12 Thursday Neurons & Receptors Sept 19 Thursday Neurotransmitters & Drugs MCMED 504 Sept 26 Thursday Pre-Midterm 1 Oct 10 Thursday Vision & Hearing MCMED 504 Oct 29 Tuesday Hunger & Sex MDHAR G-10 Nov 7 Thursday Pre-Midterm 2 Nov 19 Tuesday Language & Emotions MDHAR G-10 Nov 26 Tuesday Neurological Disorders MCMED 504 Dec 5 Thursday Pre-Final Exam TAs do not typically record these sessions, but they do post their PowerPoint presentations on MyCourses. 9 Today’s Topic: Consciousness & Free Will The Questions: What is consciousness? Do we have free will? Research method: Ask people with brain damage how they perceive the world (what is their subjective experience). Results: Brain damage can significantly disrupt a person’s conscious awareness of their surroundings and their own body without them even noticing. Take home point: We still do not know how consciousness works or what it is. The concept of free will remains a hot topic and is unsettled. 10 What is consciousness? Where can we find it? Let’s define consciousness as the state or quality of awareness – awareness of thoughts, perceptions, memories, and feelings. The state of awareness creates a subjective experience. If a being is capable of having a subjective experience, then there is something that it is like to be that being. What is it like to be a rock, or house plant, or ant? What is it like to be a calculator, computer, or AI robot? 11 Medical Fad in the 1940s and 50s - Lobotomy The frontal lobotomy used to be a popular treatment for psychosis, depression, anxiety, etc. The Nobel Prize was awarded for this procedure in 1949. By the 1950s, over 20,000 lobotomies had performed in the US alone. The popularity of this procedure waned in the mid 1950s following the discovery of partially effective antipsychotic medications. 12 A DIFFERENT MEDICAL PROCEDURE The split-brain operation An outdated surgical approach for treating seizure disorder (epilepsy). It involves cutting the corpus callosum: the bundle of nerve fibers that connect the left and right sides of the cerebral cortex. This surgery is generally effective, but it has unacceptable side effects (unlike the frontal lobotomy?!?). 13 14 Brain Anatomy – Cerebral Hemispheres Our cerebral hemispheres are critical for our ability to consciously process sensory information (sights, sounds, touch, etc.). Our cerebral hemispheres are also critical for our ability to consciously (purposefully) move our body in space (e.g., hand and leg movements). Each cerebral hemisphere is responsible for one half of the body, but the nerve fibers mostly crisscross: The left brain is largely responsible for the right side of the body. The right brain is largely responsible for the left side of the body. For example, damage to the left cerebral hemisphere will selectively disrupt movements and sensory processing on the right half of the body. 15 Brain Anatomy – Retinal Axons How the left/right distinction applies to vision: When you look at something (a fixation point), everything you see to the left of that spot is processed by the right brain, and everything you see to the right of that spot is processed by the left brain. 16 Cutting The Corpus Callosum The corpus callosum is a bundle of fibers that interconnects the two cerebral hemispheres. It enables the two hemispheres to share information so that each side knows what the other side is perceiving and doing. If the corpus callosum is cut, the two cerebral hemispheres cannot directly talk to each other. However, they can still send information downwards (to the brainstem and spinal cord) to control muscles. These lower brain areas process information beneath conscious awareness, and they help coordinate movements by integrating the information they receive from the two cerebral hemispheres. It is impressive how well the brain stem and spinal cord can coordinate bilateral movements when the two cerebral hemispheres lose the ability to talk to each other. 17 Brief History of the Split-Brain Surgery 26 patients received split-brain surgery in Rochester NY around 1940. The doctor claimed the surgery was a success (i.e., reduced frequency and intensity of seizures with minimal side effects). An independent group of scientists soon re-examined these patients with a host of neurological and psychological tests (IQ, memory, motor skills, general interviews, etc.). They concluded: 1. the patients’ improvements were short-lived and/or exaggerated 2. cutting the corpus callosum did not do very much (good or bad) Over the next decade Roger Sperry at Caltech (California) became confident the corpus callosum was important for something. His lab cut the corpus callosum of cats and monkeys, where they could be confident the surgeries were clean and complete. They argued that it caused cognitive peculiarities. When a neurosurgeon at Caltech decided to do the split-brain procedure on a new patient in 1962, he invited Sperry’s group to conduct pre- and post-operative examinations. 18 Split Brain Patients - Interesting Dilemmas In general, when the split-brain patients were recovering from their surgery, they reported that they felt fine, no different than before. Nothing was weird, nothing was out of the ordinary. Often the frequency and/or severity of their seizures were reduced. The surgeries were a success. However, some of these patients began to say that their left hand sometimes had a mind of its own. Their left hand sometimes actively worked against what the person was consciously trying to accomplish. One patient reported that one time his left hand suddenly started to attack his wife, and he had to use his right hand to protect her, to thwart his left hand. It seemed that the left hand of split-brain patients was controlled by processes outside their conscious awareness. What was happening in their right cerebral hemisphere, which controls the left hand? The right hand, controlled by the left brain, never acted out of the ordinary. Its actions were always consistent with the person’s conscious intentions. Does this mean that consciousness is located in the left cerebral hemisphere? 19 Split Brain Patients - Vicki In the first months after her surgery, shopping for groceries was infuriating. Standing in the supermarket aisle, Vicki would look at an item on the shelf and know that she wanted to place it in her trolley — but she couldn't. “I'd reach with my right hand for the thing I wanted, but the left hand would come in and they'd kind of fight,” she says. “Almost like repelling magnets.” Picking out food for the week was a two-, sometimes three-hour ordeal. Getting dressed posed a similar challenge: Vicki couldn't reconcile what she wanted to put on with what her hands were doing. Sometimes she ended up wearing three outfits at once. “I'd have to dump all the clothes on the bed, catch my breath and start again.” After about a year, Vicki's difficulties abated. Conflicts with her left hand became rare. For the most part she was herself: slicing vegetables, tying her shoelaces, playing cards, even waterskiing. 20 Studies on Split Brain Patients Touch When a split-brain patient closes their eyes and touches a familiar but unidentified object with their left hand, they cannot identify the object out loud. Vision When a split-brain patient sees an image only in their left peripheral vision, which is processed on the right side of the brain, they cannot verbalize what they see. Split brain patients cannot say out loud something that only the right brain sees. Split brain patients appear to be unconscious of – cannot verbalize – any stimuli directed exclusively to their right brain. Split brain patients were largely unaware and unbothered by their deficits in perception. With practice on any given task, they could smoothly choreograph the movements of their body. One hemisphere seemed to take the lead in controlling behaviour in a situation dependent manner, and well-practiced bimanual skills were well coordinated by subcortical structures. 21 The Localization of Language in the Brain Researchers already knew (from studying people with brain damage) that most human language ability – comprehension of language and ability to talk and write – is generally located in the left cerebral hemisphere. The right hemisphere of the cerebral cortex has very limited language abilities (in 90% of people). However, Sperry discovered that the mute right cerebral cortex of some split-brain patients could understand simple phrases. The right brain seemed to retain a bit of a “dictionary” and could understand simple numbers, letters, and short statements. He also found split-brain patients could use their left hand (controlled by their mute right brain) to indicate answers to simple questions. 22 The Neuroscientist V. S. Ramachandran What is the personality of the right brain in split brain patients? Link to full video: https://www.youtube.com/watch?v=af0Sbwxj8WE 23 Split Brain Patient Experiments 24 Split Brain Patient Joe Why did your left hand do that? Link to full video: https://www.youtube.com/watch?v=ZMLzP1VCANo 25 Split Brain Consciousness When split-brain patients were asked to explain in words why they performed an action that had been initiated by their right hemisphere, they sometimes made up a post hoc answer. For example, when the command ‘laugh' was directed to the right hemisphere of one patient, he laughed. When asked why he was laughing, he said “you guys come up and test me every month – what a way to make a living!” Another example: When a patient’s right brain was instructed to walk, he walked out of the room. When asked why he did that, he immediately responded “to get a Coke.” It seemed that the left brain was constantly generating explanations for actions that were instigated by the right brain. Gazzaniga developed the Interpreter Theory to explain these phenomena and more importantly why people — including split-brain patients — have a unified sense of self and mental life. He was fascinated by the fact that split brain patients never reported feeling anything less than whole. Their hemispheres didn't miss each other. 26 Gazzaniga’s Interpreter Theory Gazzaniga’s Interpreter Theory says that behaviour is fully controlled by unconscious processes, and that the function of our left-brain consciousness is simply to create narratives with the information it has in an attempt to make sense of the world. Accordingly, consciousness doesn’t directly influence behaviour, at least not in real time (i.e., not in the current moment). Rather, it weaves disparate points of information into a story that has meaning (after the fact). The underlying premise is that free will is an illusion; our conscious mind does not directly control our behaviour, despite our intuition. Consciousness is just storytelling, and since storytelling relies on language, consciousness is only located in the left cerebral hemisphere of the human brain. The previous textbook I used included language ability in the definition of consciousness: Consciousness Involves awareness of — and ability to tell others about — our thoughts, perceptions, memories, and feelings 27 How did we get here? Before the scientific revolution, experiments and mathematical formalizations were rare and underappreciated. People relied more on intuition than math (e.g., it certainly doesn’t feel like the earth is moving). Faith in math and science grew immensely during the scientific revolution, starting with Copernicus in the mid 1500s and culminating in Newton’s ideas of universal gravity and the laws of motion (F=ma) in the late 1600s. At this time, people started to suspect that the world was deterministic, that in accordance with the laws of physics there might be an unbroken chain of cause and effect stretching back to the origin of the universe, and humans can only witness, not interfere, with this chain of events. 28 Our intuitions cannot be trusted In the middle of the scientific revolution, Rene Descartes started questioning everything, doubting everything (a philosophical approach sometimes referred to as Cartesian doubt or hyperbolic skepticism). If our intuitions and perceptions are misleading us, if the earth is actually spinning and hurtling through space, what can we trust? After doubting everything, even existence itself, Descartes famously drew a line in the sand and stated, “I think, therefore I am.” Perhaps this famous phrase is best understood as a double negative: An evil demon cannot trick someone into thinking they exist if they don’t exist. But what is thinking? What are thoughts and ideas? You can’t touch them or hold them. You can’t find them by cutting open the head. They are immaterial. For Descartes, the act of thinking proved that an immaterial world exists. 29 Mind-Body Dualism The apparent contradiction between the deterministic laws of physics and our subjective experience of free will led Descartes to develop the philosophy known as mind-body dualism: While the body may be a mechanical device and the world deterministic, the mind (or soul) is something else, something immaterial that exists outside the body. But, if the movement of all atoms can be well explained by the physical laws of nature, how can our immaterial souls control our material bodies? This paradox is known as the Cartesian impasse. Is free will an illusion? Do we have control over our own thoughts and actions? 30 The evolution of thought Neural networks evolved to sense the internal and external world and to coordinate movements of the organism. In addition to automatic responses (e.g., pull your hand back if it feels too hot), neural networks give rise to thoughts (e.g., my hand is burning hot). Thoughts do not produce preordained, automatic behavioural responses. Thoughts and ideas exist as patterns of brain activity that are independent of any sensory input or motor output. They are their own things. There is no physical law that says ideas have to exist, yet they do exist. Neural network activity generates ideas, the most important being that things have meaning, that things happen for a reason. We theorize and create stories about the meaning of things. Yet, when we look at the laws of physics, we don’t find any meaning. We only find equations that faithfully describe the interactions of all physical matter. 31 Is the world deterministic? In a deterministic world, all events, including human actions, are ultimately determined by causes that are independent (external) of free will. In a deterministic world, everything is preordained, following a path determined by the laws of physics. There is no inherent meaning in a deterministic world. Stuff just happens. Yet, we know it doesn’t make sense to say, “the molecule made me to do it.” Molecules don’t have any inherent meaning to them. They just are. Sure, we may understand the physical cause and effect of a molecule moving around, but what that movement means to an organism, what it represents, is entirely different. Our brains construct a world of ideas on top of the laws of nature, a world in which things have meaning. The world of ideas represents a distinct layer of our reality, a layer that harnesses (directs, constrains) the physical laws of nature, controlling how the world will play out. 32 Thoughts have influence and power Thinking is not just calculating. It is a creative act, which gives rise to abstract ideas that direct and constrain how the organism will act in the future. Thinking is an act of creation that involves theorizing, not only about what we are and how the world is, but how these things ought to be, how they might otherwise be. It is by imagining future possibilities and theorizing about cause and effect that we develop the idea that things happen for a reason, that things have meaning. Self-awareness grows out of the realization that our thoughts do influence the future. I believe that by envisioning a potential future, neural networks take control over the future. They construct the future. *I encourage you to read Kevin Mitchell’s blog if you’re interested in this topic, 33 as he often posts thought-provoking ideas on the philosophy of mind. Important Outstanding Questions A few important outstanding questions related to the brain: 1. How is it we feel things? What are feelings and why do they feel so personal? What is consciousness, how does it work, and what has it? 2. What is thinking and how does it work? Do we have free will because we think, or is thinking just the calculation of predetermined answers? 3. What is mental illness and how should we treat it? It is difficult for us to understand mental illness – a disturbance in how someone feels or thinks – when we don’t really understand the neural basis of feeling and thinking. 34 We Have Learned a Lot About the Brain We do know a lot about the brain, however. We know what the brain is made of and how things works at the cellular level. We know how neurons communicate with each other. We understand how sensory stimuli is transduced and initially processed. We also know the function of the last few cells in the motor system pathway. However, once we get a few cells deep into the network, we don’t really understand what is happening or how information is processed. This leaves us with a very limited understanding of the neural bases of cognition, emotion, consciousness, decision making, etc. 35 Jill Bolte Taylor What consciousness is like without language The video excerpt shown in class is linked to on MyCourses Link to full Ted Talk: https://www.ted.com/talks/jill_bolte_taylor_s_powerful_stroke_of_insight 36 Another Ted Talk, if you are interested… Here is another interesting video if you’re in the mood (not mandatory): Anil Seth’s Ted Talk - How your brain hallucinates your conscious reality 37