Lecture 4 Biology (2) Pt1 PDF

PSY1101F Fall 2024 Lecture 4 PART 1 Biology and Neuroscience (2) General Announcements Remember to sign up for research participation  go to the course syllabus for instructions and a web link There may not be many studies showing now, but there wil...

PSY1101F Fall 2024 Lecture 4 PART 1 Biology and Neuroscience (2) General Announcements Remember to sign up for research participation  go to the course syllabus for instructions and a web link There may not be many studies showing now, but there will be soon Midterm Test 1 on October 8th (next week!) Please check your e-mail for details of what to study AND for instructions for taking the test There is a brain function practice chart in the LECTURES folder on BrightSpace From Last Class Wrap up explanation of Methods and Research Ethics Describe Neurons Structure and Function The action potential The release of neurotransmitters Define the term “neural network” Explain basics of how drugs work in the CNS Diagram the organization of the nervous system Examine brain structures and their functions Today’s Objectives Diagram the organization of the nervous system Examine brain structures and their functions Coordinating structures Neocortex (New Brain) structures Brief discussion of the endocrine system (as it relates to stress only) Explain several methods used by neuroscientists to study the CNS Explain the meaning of Gestalt principles (important for human perception) Examine the early processing in the visual system (eye and retina) Brief Review for Midterm 1 The Nervous System (and its divisions) Neural Networks: How the Nervous System is Organized 86 billion neurons make trillions of connections These are connections between dendrites and axons Groups of neurons form networks to accomplish different functions Neurons have to let the CNS know what is happening in the periphery and the CNS needs to control behaviour. How? Afferent nerves (bundles of axons) carry information from the senses and organs to the CNS Efferent axons send information to muscles and organs How is information sent? Action potentials and NTs Neuroplasticity – A Key Feature of CNS Function Neuroplasticity is “the ability of neurons and networks to change”. Some examples: We are born with many neurons but we lose many during development Neurons can change the number of dendrites Neurons can change the number of receptors on their dendrites Conscious and Non-Conscious Processing Neurons and networks do many things for us Your conscious experience of the world happens via the neocortex This is the outer 2.5 mm layer of your brain But much of what is happening (breathing, heart rate, etc.) is going on without your awareness via the medulla (part of the brainstem) You can become aware of these functions but they will happen even when you’re not paying attention to them The Nervous System: Main Divisions NS = The communication network of the body Very speedy Has three divisions (central, peripheral, and enteric) Division 1 – The Central Nervous System (CNS) Consists of the brain AND spinal cord (structures) Decision-making system (function) The Nervous System: Main Divisions Division 2 – The Peripheral Nervous System (PNS)  “peripheral” means “at the margin or border” The connection between the CNS and the rest of the body Consists of sensory and motor neurons (structures) Has two subdivisions (somatic & autonomic) Gathers and transmit information back and forth from the periphery to the CNS (function) The Nervous System: Main Divisions Division 3 – The Enteric Nervous System (ENS) The connection between the gut and the CNS Sometimes considered part of the PNS (but now known to be independent) Sheet of neurons lining the entire digestive system Communicates with the gut and sends information to the CNS CNS and PNS PNS Afferent and efferent connections to the CNS Afferents can come from the senses and from internal organs What are the orange lines on the figure?  Bundles of axons (white matter) CNS Brain and spinal cord Sends to PNS; Receives from PNS The Functional Divisions of the Human Nervous System (Not in your textbook; but explains well) Enteric Nervous System (controls gut) The Functional Divisions of the Human Nervous System PNS Two Divisions  Autonomic (I Enteric Nervous remember this as System “automated” - not (controls gut) quite right but it helps  Somatic -soma = body -so this one is about the body The Functional Divisions of the Human Nervous System Autonomic (ANS) Two Divisions  Sympathetic - Enteric Nervous Function is arousal System (of internal systems) (controls gut)  Parasympathetic - Function is calming (of internal systems) The Functional Divisions of the Human Nervous System Somatic (SNS) Two Divisions  Sensory input Enteric  Motor output (to Nervous System muscles) (controls gut) The Functional Divisions of the Human Nervous System Enteric (ENS) Two Divisions Enteric  Controls gut Nervous System  By communicating (controls gut) with both the gut and the CNS A closer look at the Somatic System cell bodies (grey matter) in the spinal cord long axons release ACh onto muscles muscles move Also (not shown) afferent cells receiving sensory information from the skin A closer look at the Autonomic System Sympathetic subdivision arouses and expends energy Allows voluntary movement Often called the “fight or flight” system “Go” system Parasympathetic subdivision calms and conserves energy, Allows involuntary A closer look at the Autonomic System Note that both subdivisions send messages to almost all internal organs, e.g., heart, lungs, stomach, etc. In this way, the internal systems remain “balanced” – but prepared for events Also, energy is conserved An overactive sympathetic system is  The Spinal Reflex: Communication between CNS and PNS Dorsal Root Back Ganglion Red = Sensory Blue = Motor Interneuron Front Parts of the Brain (and Their Functions) The Brain Brain accounts for about 2 percent of body weight and uses 20 percent of energy. So if I weigh 130 pounds (on a good day), my brain weighs only about 2.5 pounds but it uses 20% of my energy Main Surface Features Memorizing names is necessary but doesn’t give you the whole picture Always attach functions to structures when you can There is a table for you to fill in and use as a study guide (check BrightSpace in the Lectures folder) Compare table with figures  The Cerebrum and Cortex Cortex is a thin layer of interconnected neurons (cell bodies, grey matter) Cerebrum has two hemispheres Each hemisphere has four lobes:  frontal  parietal  occipital  temporal  The Cerebral Cortex: Basic Functions of Lobes (they do more than this, but this is a start) ontal eaking, muscle movements, planning, judgment rietal nsory input for touch and body position cipital ceives information from visual fields (so... vision) mporal ceives information from ears (so... language, music, hearing) Older Brain Structures Less complex brain in primitive vertebrates handles basic survival functions. More complex brain in advanced mammals (including humans) contain new Stefan Klein/imagebroker/Alamy brain systems built on the old. The brainstem and related areas are similar in all mammals Basic Life Functions Medulla  at base of the brainstem  controls heartbeat and breathing  swallowing Pons above medulla a bridge between upper and lower structures helps regulate arousal coordinates sensory information with information from the Basic Life Functions Reticular Activating System a nerve network running through the medulla and pons plays an important role in controlling arousal (you need it in order to be awake) involved in the ability to focus on the task at hand filters irrelevant Sensory Inputs (notice where they come from) Notice where the sensory information is coming from and where it goes to Somehow, the brain must combine this information What would happen if it didn’t? Coordinating (Modifying Behaviour) Many structures involved Many are “sub-cortical” (below the level of cortex) We’ll go through these in the order shown in the text (no particular order is necessary for understanding) Coordinating (Modifying Behaviour) The limbic system contains a loop of connected structures and pathways regulates our endocrine (hormone) systems regulates emotions part of memory function Coordinating (Modifying Behaviour) Amygdala linked to emotion linked to fight/flight system emotional memory (connections to cortex and hippocampus) overactivity associated with anxiety damage here leads to inappropriate behaviour in emotional situations  Coordinating (Modifying Behaviour) Hippocampus neurons activated when we are forming memories. synapses strengthen when exposed to high- frequency stimulation over time. new memories and imagination connected to amygdala for memory of emotionally important events (for survival) also important for spatial navigation  Coordinating (Modifying Behaviour) Hypothalamus Directs several maintenance activities (body temp, sex, hunger etc)  homeostasis Helps govern endocrine system via the pituitary gland Cingulate Gyrus ventral to the neocortex but it’s still a type of cortex increased activity in this area in response to pain and social exclusion both when people experience physical pain and when they are excluded socially focuses attention on  Coordinating Movement Basal Ganglia consist of caudate nucleus, globus pallidus, putamen these structures receive information from cells in the midbrain (a structure called the substantia nigra) responsible for voluntary movement (starting and stopping) learning to make Coordinating Movement Basal Ganglia So... the basal ganglia receive a lot of information from other areas (almost everywhere) concerning: internal state external environment memory of movements Coordinating Movement Basal Ganglia and Parkinson’s Disease Important points Cells in the substantia nigra die Less neurotransmitter (dopamine) is released onto cells in the basal ganglia Symptoms are consistent with the function of the basal ganglia Difficulty initiating movement, tremors Disease affects mainly people over the age of 65, but occasionally those younger Disease is progressive – treatable with drugs in the early stages Video recommended in your textbook https://www.youtube.com/watch?v=RtXU11ueKkQ More About Coordination The Cerebellum (”little brain”) coordinates with different brain areas via the pons many inputs Functions adjustments of timing, planning, and rhythm of movements coordinates sensory input with ongoing movement posture and balance The Thalamus Located in the center of the brain at the top of the brainstem Contains many nuclei (clusters of cells) The cortex receives inputs from the thalamus for decisions about what to pay The Thalamus Often called a “sensory relay” Information from all the senses (except smell) has its first synapse in the thalamus  An Aside: Localizing Function People get very excited about saying what function goes with what part of the brain Some analogies showing why the job of understanding function is so tricky. If you unplug your TV and it stops working, do you assume that the function of producing a picture is the job of the plug/power cord? If your car engine won’t start after the battery dies, do you assume that the battery is responsible for all engine function? Take-away message: Complex functions don’t happen in one place! Neocortex (New Brain) Main Surface Features Neocortex is the outer layer of the brain cortex is a “bark- like” layer about 2.5mm thick there are gyri (bumps or ridges) and sulci (valleys)  the cortex is folded into the skull; why? Main Surface Features Cortex contains primary and association areas Primary areas where sensory information arrives for frontal lobes, where motor messages are initiated Association areas extra processes combining with other sensory input Main Surface Features How does our brain differ from other primates? Far more connections in the frontal lobe Thickness of the neocortex Cells and Networks in Cortex Cortex is an intricate network of networks 6 layers Cortical neurons from each layer have axons that connect to designated areas These axons connect with other networks of neurons in cortex and other brain areas