PSY106 Fall 2024 Lecture Notes PDF

WEEK 7, NOV 11TH – 17TH One in-person lecture with new content (Wed) Read Week 7 Readings on Canvas Submit your Writing Assignment by Friday at 11:59pm Optional: attend a Zoom review session led by Dr. Scudder: Thurs 2-3pm (link on Canvas) Optional: Participate in Week 7 Disc...

WEEK 7, NOV 11TH – 17TH One in-person lecture with new content (Wed) Read Week 7 Readings on Canvas Submit your Writing Assignment by Friday at 11:59pm Optional: attend a Zoom review session led by Dr. Scudder: Thurs 2-3pm (link on Canvas) Optional: Participate in Week 7 Discussion by Sunday at 11:59pm Optional: Attend a tutoring session No quiz this week Exam 2 will be held on Nov 18th – check out the page on Canvas for more information on how to prepare!  TUTORING SESSIONS (WEEK 7 & 8) Structured Review Sessions (sign-up required): Thurs 11/14 11-12pm (Psych East 3834): Leia & Xi Thurs 11/14 4-5pm (Psych East 3834): Uma & Sukari Thurs 11/14 5-6pm (Psych East 3834): Grace & Joey Fri 11/15 1-2pm (Psych East 2822): Leia & Xi Fri 11/15 2-3pm (Psych East 2822): Uma & Sukari Fri 11/15 3-4pm (Psych East 2822): Grace & Joey Drop-in Sessions: Tues 11/12 5-6pm (Library 4575): Uma & Xi Wed 11/13 5-6pm (Psych East 2824): Sukari & Joey Thurs 11/14 12-1pm (Transfer Student Center): Leia & Joey The Thursday and Friday Fri 11/15 11-12pm (ONDAS Student Center): Sukari & Xi drop-ins will feature a Fri 11/15 3-5pm (Psych East 2824) (cheat sheet party): Uma bonus problem set that & Leia, Grace & Uma you can work on! Sun 11/17 6-7pm (Zoom): Grace & Sukari Mon 11/18 10-12pm (Psych East 2824) Today’s Topics: 11A: Olfactory Pathways 11B: Planning Movement 11C: Executing Movement 11D: Learning to Move DR. SCUDDER PSY106 INTRODUCTION TO BIOPSYCHOLOGY FALL 2024 LECTURE 11A: OLFACTORY PATHWAYS DR. SCUDDER PSY106 GOALS OF THIS SECTION Describe the brain circuits that enable conscious perception of smells and emotional responses to smells Discuss the existence of pheromones and their behavioral importance  GLOMERULI Olfactory bulb Olfactory nerve Olfactory epithelium Exposed to the environment and therefore can be damaged Open Neuroscience Initiative ANOSMIA: LOSS OF SENSE OF SMELL Very few individuals are anosmic from birth, but many more can permanently lose sense of smell from injuries and illnesses Poses many problems: smell can allow us to assess safety of situations or food products Also linked to high rates of depression – tight link between olfactory system and emotion Covid can induce a transient anosmia – have you experienced this? OLFACTORY PATHWAYS Orbitofrontal cortex The olfactory bulb neurons (mitral cells) primarily send their axons (olfactory tract) to an area called piriform cortex, which can trigger emotional responses to smells Piriform cortex also sends information to the thalamus, which relays it to other areas in the frontal Piriform cortex is found on the ventral lobe, generating conscious (bottom) surface of the brain and is perception of the smell very closely intertwined with emotional regions like the amygdala Wilson, 2012 OLFACTORY PATHWAYS Olfactory receptor Axons in the olfactory tract carry neurons (olfactory epithelium) information from the olfactory bulb directly Olfactory nerve to olfactory cortex, also known as piriform cortex Mitral cells in the Doesn’t need thalamus to get to cortex! olfactory bulb Emotional response: information from Olfactory tract olfactory cortex goes to limbic areas like the amygdala (more in Unit 3) Olfactory cortex (piriform cortex) Conscious perception: from olfactory cortex to thalamus (different nucleus from LGN) and other areas of frontal cortex Thalamus Emotion regions (limbic system) Frontal cortex PHEROMONES Organisms can secrete compounds called pheromones that influence the behavior of other organisms In mammals, pheromones are typically detected by the vomeronasal organ, though humans generally do not have this Pheromones can stimulate aggression, defensive behaviors, and influence mating decisions Humans seem sensitive to some pheromones through our olfactory system, but much of the data is inconclusive MARIJUANA AND THE SENSE OF SMELL THC is the psychoactive component of marijuana (the chemical that makes you feel high when you ingest/inhale marijuana products) THC affects neurons by binding to receptors called cannabinoid receptors throughout the brain The olfactory bulbs have lots of cannabinoid receptors (in rodents, at least), and THC appears to enhance olfactory processing – it boosts the sense of smell This seems to stimulate the appetite, causing the animal to seek out and ingest more food Scientific American: “Why Marijuana Gives People the Munchies” MYSTERY #3 A group of friends go out for dinner, then head back to their apartment to responsibly use some legal recreational substances. Soon after, the smell of wings wafts into the room and they suddenly feel extremely hungry – they decide to order WingStop, even though they just ate. Why would they feel this way? The THC in the marijuana they consumed activated cannabinoid receptors on neurons in their olfactory bulbs, heightening their sensitivity to smell and stimulating their appetites INTRODUCTION TO BIOPSYCHOLOGY FALL 2024 LECTURE 11B: PLANNING MOVEMENT DR. SCUDDER PSY106 GOALS OF THIS SECTION Introduce the main components of various motor systems in the mammalian nervous system Describe the regions involved in decision-making and motor planning WHY HAVE SENSES? The “purpose” of all of these sensory systems is to guide behavior in a way that optimizes survival and reproduction Vision: find food, avoid predators, find safe hiding spots, assess mates Audition: hear and avoid predators, communicate with other members of the species Gustation: assess nutritional content of food, motivate us to eat “good” foods Olfaction: find and assess safety of food, avoid predators, find compatible mates Somatosensation: awareness of immediate surroundings, react to things touching us, avoid painful and dangerous stimuli, awareness and control of limbs These all have one clear thing in common – all of the senses provide us with some information that is used to guide or change our actions MOTOR CONTROL: PLANNING ACTION Once sensory information from our environment has been gathered, various parts of the brain engage in decision-making No time to get into details in this course, but various parts of prefrontal cortex and parietal cortex do most of this When a decision has been reached, the brain must put a plan together and execute it Multiple brain regions enable the planning, execution, and refinement of movement We will largely focus on the pathways that are used for voluntary (or “volitional” movement) – intentionally moving parts of your body to accomplish a goal KEY BRAIN REGIONS Prefrontal cortex: decision- making and high-level planning Premotor & supplementary motor cortex (also called “secondary motor areas”), and the basal ganglia: formulates a specific plan Primary motor cortex: organizes movement of specific body parts and sends commands Spinal cord and muscles: Association cortex = prefrontal executes plan by moving specific + parts of parietal cortex parts of body MOTOR HIERARCHY: COMPANY ANALOGY Highest level: CEO Other executives Managers Workers ASSOCIATION CORTEX: THE CEO Refers to large regions of cortex in the parietal lobe and the frontal lobe The decision to act and the overall goal are encoded by neurons in these regions Decision-making is an extremely active area of neuroscience research, but hard to study – how do you ask a mouse what its “plan” is? Do mice even plan? ASSOCIATION CORTEX Parietal cortex (specifically an area called “posterior parietal cortex”) can gather multimodal sensory input from many cortical areas (visual cortex, auditory cortex, somatosensory cortex, etc) This region can then send information to the frontal lobe (PFC and secondary motor areas) to help initiate actions Posterior parietal cortex and prefrontal cortex collaborate to decide on a high-level goal SECONDARY MOTOR AREAS Supplementary and Pre- motor areas (SMA and PMA – sometimes just called “secondary motor areas”) help plan the actions that need to be executed Directly excite neurons in primary motor cortex (M1) to tell them what to do once plan is formulated SECONDARY MOTOR AREAS Some neurons in these areas seem to be active when the subject is observing someone else do a particular action (mirror neurons) Might allow for learning of skills via observation Also lots of activity when you’re thinking about doing a particular action What happens when primary motor cortex receives a plan from secondary motor areas? INTRODUCTION TO BIOPSYCHOLOGY FALL 2024 LECTURE 11C: EXECUTING MOVEMENT DR. SCUDDER PSY106 GOALS OF THIS SECTION Describe the organization of primary motor cortex Explain how commands are sent down to the spinal cord and to specific muscle groups Describe the roles of the cerebellum and the basal ganglia Describe the pathology underlying Parkinson’s Disease and the current approaches to treating it PUTTING PLANS INTO ACTION Supplementary and Pre-motor areas help plan the specific actions that need to be executed Directly excite neurons in primary motor cortex (M1) to tell them what to do once plan is formulated Primary motor cortex is a strip of cortex just rostral to the central sulcus PRIMARY MOTOR CORTEX (M1) Contains a map of the body, with certain regions very over- represented (places that need more careful motor control) Directly sends axons down to the spinal cord to control muscle groups Stimulation produces muscle contractions of specific muscle groups, sometimes complex gestures with a given body part Organization was uncovered by Wilder Penfield; also learned that movements happen on the opposite (contralateral) side of the body) PRIMARY MOTOR CORTEX There are multiple descending pathways from motor cortex Some of these stop off at brainstem nuclei We’ll just focus on the direct motor cortex -> spinal cord pathway (corticospinal tract) CORTICOSPINAL TRACTS This tract (pathway) fully decussates (crosses the midline) Right primary motor cortex controls left side of body, and vice versa This happens as the tract passes through the medulla Axons in this tract eventually contact lower motor neurons (or motoneurons) in the spinal cord, near the body part that is being controlled SPINAL CORD & MUSCLES The cell bodies of lower motor neurons are within the spinal cord, but the axons leave the spine and directly synapse onto muscles Cell bodies are in the central nervous system, but axons are in the peripheral nervous system When an action potential occurs in a motor neuron, it releases acetylcholine onto specific parts of the muscle – this synapse is called the neuromuscular junction (NMJ) Acetylcholine excites the muscle fibers, causing them to contract (mostly nicotinic receptors at this receptor) MOTOR CONTROL STEPS 1) Parietal cortex processes sensory information from the environment and works with prefrontal cortex to reach a decision about what action to take 2) Prefrontal cortex sends information about decision to secondary motor areas, which plan the specific actions that will be necessary to accomplish goal 3) Secondary motor areas send action plan to neurons in primary motor cortex, which is organized by body part 4) Neurons in primary motor cortex send axons down into the spinal cord, where they contact lower motor neurons on the opposite side (full decussation) 5) Motor neurons fire action potentials, resulting in the release of acetylcholine onto muscle fibers, exciting them and causing contractions  PUTTING IT TOGETHER Posterior parietal cortex “I’m feeling sleepy and I smell some freshly brewed coffee” Basal ganglia & Cerebellum ensure these “Let’s pick up the cup of Prefrontal cortex actions are smooth and coffee on my desk” well-timed “Get ready to use your Secondary motor cortex arm and hand muscles” “I will reach out my arm, Primary motor cortex put my hand around the cup, and tighten my grip” Motor neurons spike, Spinal Cord causing arm and hand muscles to contract BASAL GANGLIA Motor control is heavily influenced by a set of brain areas called the basal ganglia – think of them as high-level consultants to the CEO and executives of the company Set of interconnected brain regions beneath the cortex (subcortical) that closely communicate with cortex and thalamus This brain area helps motor cortex know the right time to start and stop specific movements, and also helps to inhibit inappropriate actions Don’t worry about the structures that compose the basal ganglia – I’m a big fan of this region, so you can ask me if you want more details Ch. 30 of FoN goes into detail as well BASAL GANGLIA Functions as a key integration system for monitoring both the outside world (senses) and internal states in order to reach a decision on whether or not to act Dopamine from the substantia nigra (nucleus in the midbrain) is essential here – the whole system stops functioning in its absence Parkinson’s Disease involves the selective death of dopaminergic neurons in the SN, leading to a severe loss of motor control – particularly the ability to initiate movement PARKINSON’S DISEASE Neurons within the substantia nigra die off (often for no known reason) These neurons provide all of the dopamine for the motor regions of the basal ganglia – cell death results in a progressive loss of dopaminergic innervation (dopamine release) Leads to extreme difficulty in initiating and controlling movements Dopamine neurons have visibly died off in this post- mortem tissue sample; surviving neurons appear unhealthy compared to a control sample PARKINSON’S DISEASE Dopamine is synthesized from the precursor “L-dopa” or “levodopa” L-dopa can be administered in pill form to provide extra resources for struggling dopamine neurons Neurons can now synthesize and release more dopamine Why not administer dopamine directly? It can’t cross the blood-brain barrier – levodopa can, though! DEEP BRAIN STIMULATION In very severe cases (when levodopa doesn’t work), a stimulating electrode can be implanted deep in the brain Usually implanted in or near the basal ganglia Tiny bursts of electricity can be sent to disrupt neurons there and restore normal function DEEP BRAIN STIMULATION Incredibly invasive surgery, but can be life-changing! MOTOR CONTROL LOOP Basal ganglia, thalamus, and motor cortex form a “loop” Decision to move a body part will involve activity in all of these regions Thalamus The actual motor command will come from Primary Motor Cortex Many of our movements are highly complex and require careful coordination – how is this possible? Exploring the Brain (Bear, Connors, Paradiso) CEREBELLUM Major role in making movements smooth and coordinated; helps refine movements Commonly damaged after strokes – typically leads to extreme difficulty with things like writing, speaking, and walking smoothly, which all require a high degree of coordination Exploring the Brain (Bear, Connors, Paradiso) NON-VOLITIONAL MOVEMENT Muscle groups all over our body engage in non-volitional, or automatic, movement Heartbeats, blinks, breaths – you can control the latter two if you want, but mostly you don’t think about them Largely under the control of brainstem nuclei, but projections from cortex can control them when we want to do so Reflexes – movements that happen automatically in response to a stimulus Spinal cord contains some basic circuitry for enabling quick reactions to dangerous stimuli (stepping on something sharp) Our eyes reflexively track certain kinds of moving stimuli – difficult or impossible to override this INTRODUCTION TO BIOPSYCHOLOGY FALL 2024 LECTURE 11D: LEARNING TO MOVE DR. SCUDDER PSY106 GOALS OF THIS SECTION Discuss how our nervous system figures out how to move our body in new ways LEARNING HOW TO MOVE During development (and often during adulthood as well), we need to learn to move our body in new ways to accomplish new goals This process involves multiple sensory areas (provide information about the world we’re trying to interact with and feedback on how we’re doing) and essentially all of the motor pathways we covered LEARNING HOW TO MOVE MOTOR LEARNING: KEY PRINCIPLES Movements are much bigger than they need to be Lots of different motions with various muscle groups – “trying out” different motor plans Typically inaccurate and ineffective at first Refinement over time – the effective movements of certain motor groups will be selected out for future use MOTOR LEARNING We can observe this “refinement” process at both the regional level (lots of cortex active at first, then only the essential areas for that movement) Can also see this at the neuronal level – lots of neurons are firing action potentials at first, but after time (and practice, and sleep), we’ll see only the vital ones firing MOTOR LEARNING IN THE CORTEX When you learn a new skill with your hand, the parts of your cortex responsible for controlling your hand will undergo synaptic plasticity Certain synapses will get stronger, others will get weaker During early stages of training, lots of neurons will be active and lots of new connections will rapidly form In later stages of training (and after sleep), the pattern of activity becomes refined – only the neurons that are necessary, and only the connections that are important are maintained while others are pruned PLASTICITY IN THE CORTEX Motor cortex (primary and secondary areas) is extremely plastic (changeable) – the neurons there can rapidly adjust the strength of their inputs and outputs to allow for different kinds of complex movements Additionally, damage to body parts leads to rapid re-mapping of motor regions If a rat’s whiskers are removed, the motor cortex that usually controls whisker movement is taken over by neighboring areas MOTOR LEARNING ELSEWHERE Synaptic plasticity (changes in the strength of individual connections) can be observed in the basal ganglia and cerebellum as well As we repeatedly engage in a set of movements, we gain more and more control over those movements, and the underlying steps become somewhat “automatic” “MUSCLE MEMORY” The term “muscle memory” is misleading – learning isn’t occurring at the level of motor neurons and muscles (the spinal cord has only very basic reflex circuitry contained in it) Instead, this refers to an acquired skill – a set of movements (like riding a bike) that your brain has spent a lot of time refining We generally don’t have to think about the individual steps once we learn them – we just decide to initiate that behavior, and everything else flows “automatically’ OTHER KINDS OF LEARNING? Learning new skills is just one type of learning that organisms engage in We have separate systems in our brain for other types of learning & memory More on that in Unit 3!  KEY CONCEPTS PFC and parietal cortex set high-level Motor planning regions send the goals, which are plan to a strip of the frontal lobe passed onto areas called primary motor cortex, which involved in motor is organized by body part planning Parkinson’s Disease is a movement disorder caused by loss of dopamine- Primary motor producing cells in the substantia nigra; to cortex sends treat it, the basal ganglia can be supported commands to with extra L-dopa or direct stimulation groups of neurons in the spinal cord that directly excite muscle fibers WEEK 7 KEY TAKEAWAYS By the end of this week, you should be able to: Identify the major components of the olfactory pathways that enable conscious perception of odors and emotional responses to them Describe the role of brain regions that contribute to decision- making and motor planning Explain how a decision to act becomes an action through components of the motor system Relate the pathology observed in Parkinson’s Disease to the motor symptoms of this disorder Identify tasks and behaviors that the cerebellum is important for Describe the overall process of motor learning and the parts of the brain where this occurs WEEK 7, NOV 11TH – 17TH One in-person lecture with new content (Wed) Read Week 7 Readings on Canvas Submit your Writing Assignment by Friday at 11:59pm Optional: attend a Zoom review session led by Dr. Scudder: Thurs 2-3pm (link on Canvas) Optional: Participate in Week 7 Discussion by Sunday at 11:59pm Optional: Attend a tutoring session No quiz this week Exam 2 will be held on Nov 18th – check out the page on Canvas for more information on how to prepare!