Neuroscience and Behavior Lecture Notes PDF

Neuroscience and Behavior Plan for the day üThe nervous system üNeurons, neuronal communication, the brain üWhat influences our behavior? üNature and nurture üEvolution üHormones üIn-class time to work on assignment üWhat articles are acceptable?...

Neuroscience and Behavior Plan for the day üThe nervous system üNeurons, neuronal communication, the brain üWhat influences our behavior? üNature and nurture üEvolution üHormones üIn-class time to work on assignment üWhat articles are acceptable? 2 Checking in… 3 Lecture outcomes After this lecture, you will be able to … üDescribe the basic structure of a neuron üDescribe the process of neuronal communication üUnderstand the two divisions of the nervous system üName and describe basic functions/parts of the brain üList common neuroimaging techniques üExplain what factors influence our behavior 4 What are neurons? Building blocks of the nervous system They receive and send electrochemical messages All neurons have the same structure, but neurons vary by function and by location in the nervous system 5 Components of the neuron Neurons are composed of 3 basic parts: Dendrites Receive information from other neurons and send it to the cell body Soma (cell body) The largest part of the neuron that coordinates information processing tasks Keeps the cell alive Axon Transmits information to other neurons, muscles, or glands 6 Components of the Neuron - Myelin sheath In many neurons, the axon is covered by a myelin sheath – an insulating layer of fatty material Can transmit signals to other neurons, organs or muscles quickly The myelin sheath is composed of glial cells (support cells) Can digest dead neurons, provide nutritional support, form more myelin Demyelinating diseases (e.g. multiple sclerosis) – myelin sheath deteriorates, and transmission is slowed 8 Components of the Neuron- Synapse The gap between two neurons, where neurons communicate with one another Structure of the Synapse Major Types of Neurons Sensory Neurons – receive information from the outside world convey information to the brain via spinal cord Interneurons – connect sensory and motor neurons Motor neurons – initiate movement carry signals from the spinal cord to the muscles to produce movement Reflex Link to the video: https://www.youtube.com/watch?v=hGDvvUNU-cw&t=67s 13 Communication within and between Neurons Electrochemical action of neurons involve 2 stages: 1. Electrical Conduction: move an electric signal within a neuron, from the dendrites to the cell body, then throughout the axon 2. Chemical Transmission: transmit electric signals from one neuron to another via the synapse https://www.youtube.com/watch?v=iBDXOt_uHTQ&t=390s 15 1. The Resting Membrane Potential When cell membrane is at rest and not receiving information There is a difference in electrical charge between the inside and outside of a neuron’s cell membrane The inside the cell (intracellular) fluid is more negatively charged than outside (extracellular) The potential is around -70 millivolts (mV) More Sodium (Na+) outside the cell, and more Potassium inside (K+) the cell The next stage: Na+ come into the cell, K+ begins to leave the cell 16  2. Depolarization Action Potential When neuron receives a signal Na+ channels will be open, allowing Na+ ions to flow into the cell This reduce the negative charge inside the cell The internal charge of the cell becomes more positive, if it reaches the threshold (-50 to 55mv), it will trigger an action potential 17 3. Action Potential No action potential will take place unless reached the threshold level Once the threshold is reached, the action potential will always fire This is called all-or nothing principle The size of the action potential is the same for any neuron (+30 to 40 mV at peak) What happens? An action potential moves the signal all the way down the axon 18 4. Repolarization Returning to the resting membrane potential Action Potential Na+ channels will close K+ channels open, and move out of cell K+ channels remain open even after reaching the level of resting membrane potential Membrane potential move beyond -70mV (to - 80mV) A refractory period – another action potential is not possible 19 5. Hyperpolarization K+ channels close, allowing the return to the resting potential of -70 mV. The neuron can now generate another action potential 20 Let’s label! -70 -55 +30 to 40 Na+ K+ Resting potential Depolarization Action potential Repolarization Hyperpolarization Action potential in myelinated axons Myelin speeds the process When an electric current passes down the myelinated axon the charge jumps from node to node Saltatory conduction – helps speed the flow of information down the axon Release of the neurotransmitter Neurotransmitters float across the synapse and bind to receptor sites on a nearby dendrite of postsynaptic neuron (receiving neuron) Neurotransmitter and receptor sites act like a lock and key system 24 The Nervous System and the Brain 25 Brain Development Divisions of the Nervous system Nervous system – the body’s communication network conveys electrochemical information throughout the body Two major divisions of the nervous system: Central Nervous system: is composed of the brain and the spinal cord Peripheral Nervous System: connects the central nervous system to the body’s organs and muscles  The Central Nervous System It processes sensory information then sends electro-chemical signals out to the peripheral nervous system for action Spinal Cord 1. The brain processes sensory information 2. Send signals for voluntary movement through the spinal cord to motor neurons Damage to the spinal cord breaks the connection from the brain to the sensory and motor neurons The Peripheral Nervous System Connects the central nervous system to the body Two major subdivisions: The somatic nervous system: involved in voluntary actions Conveys information into and out of the central nervous system The autonomic nervous system: involved in involuntary actions Control body organs and glands Works outside of conscious control The Autonomic Nervous System Two subdivisions: The sympathetic nervous system: prepares the body for action in threatening situations The parasympathetic nervous system: helps the body return to a normal resting state The Nervous System 32 Link the 4 pictures to the Peripheral Nervous System The basic portions of the Brain Hindbrain Midbrain Forebrain Structures of The Brain The Brainstem “Oldest” part of the brain – similar structures found in other animals Important survival Stops functioning = brain dead In charge of basic life functions. E.g., breathing, digestion, beating of heart, The Limbic System Doesn’t have clearly defined areas Encompass: regions from the forebrain and hindbrain Important for regulation of emotions, influence hunger, sleep-wake cycle, sexual desire, fear and aggression, memory 37 The Cerebellum Located at the back of the brain (hindbrain) Also called “small brain” Primarily involved in fine motor skills Movement and posture 38 The Cerebrum Outer surface of the brain The “newest” and advanced part of (cerebral cortex) the brain Involved with higher level processes such as cognitive, emotional, sensory and motor functions Supports communication of There are 2 cerebral hemispheres information across (right and left), connected by corpus hemispheres callosum Each hemisphere controls functions on the opposite side of the body (Contralateral Control) 39 Contralateral Control Typically, verbal ability is localized in the left hemisphere The right hemisphere: emotion, music, visual-spatial skills, creativity, recognition 40 The Cerebral Cortex Each hemisphere of the cerebral cortex is divided into four areas, or lobes: 1. Occipital Lobe 2. Parietal Lobe 3. Temporal Lobe 4. Frontal Lobe The Cerebral Cortex Occipital Lobe: Processes visual information Damage causes blindness The Cerebral Cortex Parietal Lobe: Processes information about touch and taste The Cerebral Cortex Temporal Lobe: Responsible for hearing and smell The Cerebral Cortex Frontal Lobe: Responsible for behavioral motor plans Complicated processes: planning, problem solving, speech, language use, etc. Neuroimaging techniques Positron Emission Functional Magnetic Resonance Imaging (fMRI) Topography (PET) è Look at changes in oxygen levels in blood flow è Inject radioactive substance Look at blood flow Poor temporal resolution: Can not tell when brain activity occurred Neuroimaging Electroencephalography (EEG) è Look at electrical activity Good temporal resolution (When brain activity occurred) Poor spatial resolution: Can not tell the accurate location of brain activity Neuroimaging Diffuse Optical Imaging (DOI) è Look at changes in light properties Good temporal and spatial resolution Checking in… 49 What influences our behavior? Nature or Nature? Olympic gold medalists Michael Phelps and Simone Biles is an example of the interplay between natural and nurtured talent Nature: A longer body glides more quickly through the water A shorter body can rotate and spin more easily Nurture: Work hard in training 50 Studies on Animal vs. Human § Animal study is easier o History of mating experiments o Fast replication § Obstacles to human study o Random assignment impossible and unethical (we can’t assign babies to specific Could nonaggressive dogs raise aggressive parents!) dogs to be less aggressive? Nature-Nurture Research Methods Behavioral Genetics – Empirical science of how genes and environments work together to influence our behavior § Adoption Studies Nature-Nurture Research Methods § Twin Studies Monozygotic Twins (Identical) Dizygotic Twins (Fraternal) One zygote (egg), %DNA Two zygotes, %DNA Quantifying Nature-Nurture Heritability Coefficient – A measure of genetics’ influence of a trait (varying 0 to 1) Measures how strongly differences among individuals for a trait are related to differences among their genes  What have we learned so far? The more genetically related people are, the more similar they are — height, weight, intelligence, behaviors and attitudes (e.g., divorce, political attitudes), personality, mental illness (e.g., schizophrenia, anorexia nervosa) More genetic relation = More similar  However… Not all behavior traits are completely inherited Both genes and environment play a significant role in shaping traits Genes interact with the environment GxE Too much childhood stress experienced èIncrease susceptibility to depression, heart disease, stroke Nutrition and epigenetics èYou are what you eat! Genes Environment Epigenetics Epigenetics: The environment can change the way genes are expressed (or not expressed) Identical twins are more similar when they are young As they become older, their individual unique experiences will cause some genes (and not others) to express Over time, identical twins come to look and behave differently, and have different risk levels for serious illness 57 The Role of Evolution in Behavior Two classes of adaptations 1. Survival adaptations Evolved craving for fat and sugar during food shortages Sweat glands to cool off during hot temperatures Fear encourages us to avoid threat 2. Adaptations for reproduction – mate competition The evolution of characteristics not because of survival advantage, but rather because of mating advantage Sexual selection theory 58 Evolutionary Psychology Focus on psychological adaptations – Identify what mechanisms of the mind have evolved to solve specific problems of survival or reproduction Psychological adaptations interact with culture E.g., In Japen, reproductive success is high a person make contributions to group success (as opposed to gaining individual accomplishments) More attractive to mates = more reproductive success  Evolutionary Psychology Theories Sexual Strategies Theory - Humans have evolved a menu of mating strategies, which are selected based on culture, social context, parental influence, and personal mate value Women Men § Possession of resources § Youth § Health § Access to resources § Attractiveness § Commitment Looking for more Looking for more fertile mates ambitious mates Factors that influence behavior/mood Hormones Hormones may play a role in aggressive behavior (androgen) Parental behavior (cortisol ) Love (oxytocin) Behavioral endocrinology The presence of others can cause or buffer stress Give a speech alone vs. with two people When interacting with people who belong to different social groups Having social support Social psychology/ social neuroscience 61  Reflection Exercise: § Instructions: § On the Reflection Exercise 1 Discussion on NTU COOL, please provide your name and student number. Then, have a think about what you have learned today. § What was the most important thing you have learned? And how could you relate to your life? § Were there any facts that were surprising? Assignment: Selecting articles Where to search for articles? 63  Assignment: Selecting articles What is a recent article? An article that has been published within one year. Why? Example article: https://www.nature.com/articles/s41598-024-65533- z#Sec1?utm_campaign=related_content&utm_source=HEAL TH&utm_medium=communities 64 Assignment: Selecting articles What is a peer-reviewed article from a journal? Week 2 An article that was reviewed by scholars with expertise in the field before being accepted for publication. 65 Assignment: Selecting articles What is a primary research article? An article where authors describe a study or an experiment that they have conducted using their collected data. It cannot be a letter to the editor, a commentary, a book review, study protocol, or other review articles (e.g., scoping review, systematic review, or meta-analysis). 66 Also not a scientific blog post Blog link: https://communities.springernature.com/ posts/how-did-they-feel-a-mental-health- check-up-with-community-dwelling- adults-before-and-during-covid-19 67