PSYC 1020H Unit 4 Biological Bases Slides PDF

PSYC 1020H, Unit 4 October 8-9, 2024 1 PSYC 1020H Biological Bases of Behaviour 1. Nervous system...

PSYC 1020H, Unit 4 October 8-9, 2024 1 PSYC 1020H Biological Bases of Behaviour 1. Nervous system 2. Neural communication 3. Structure of the brain 2 1. NERVOUS SYSTEM (NS) handles interacting network of billions of neurons sending electrochemical signals throughout the body translate into sensations, feelings, thoughts, actions © Kateryna V. Keefer, 2024 1 PSYC 1020H, Unit 4 October 8-9, 2024 3 Organization Nervous System (NS) (CNS) (PNS) - brain & spinal cord - nerves connecting CNS to organs & muscles 4 Peripheral (PNS) Somatic (SNS) Autonomic (ANS) - actions - conveys sensory info to CNS - passes commands from CNS to skeletal muscles à sensory neurons à ß motor neurons ß © Kateryna V. Keefer, 2024 2 PSYC 1020H, Unit 4 October 8-9, 2024 5 Peripheral (PNS) Somatic (SNS) Autonomic (ANS) - /automatic bodily functions - passes CNS commands to blood vessels, internal organs, glands Autonomic (ANS) 6 “rest & digest” “fight or flight” © Kateryna V. Keefer, 2024 3 PSYC 1020H, Unit 4 October 8-9, 2024 Central (CNS) 7 Spinal Cord Brain - relays info between brain & PNS - directs mental processes - controls - regulates basic life functions ß interneurons à 8 Spinal cord injury different spinal nerves connect different parts of the body to the brain the injury à intact paths & normal function the injury à severed paths & loss of function © Kateryna V. Keefer, 2024 4 PSYC 1020H, Unit 4 October 8-9, 2024 9 2. NEURAL COMMUNICATION 2 types of cells in the nervous tissue: 1. Neurons 2. Glial cells 10 Glial cells support/helper cells for neurons nutrition, maintenance, protection insulation (myelin) © Kateryna V. Keefer, 2024 5 PSYC 1020H, Unit 4 October 8-9, 2024 11 Neurons specialized nerve cells receive & transmit info 3 basic parts: - cell body - several dendrites - one axon 12 Structure of a neuron - Fill in the blanks and SPEW! B) F) A) C) E) D) © Kateryna V. Keefer, 2024 6 PSYC 1020H, Unit 4 October 8-9, 2024 13 B) A) 14 C) neural impulse © Kateryna V. Keefer, 2024 7 PSYC 1020H, Unit 4 October 8-9, 2024 15 neural impulse D) 16 Action potential of signal WITHIN a neuron electrical signal that sends info along the axon triggered if total strength of all incoming signals from dendrites exceeds a firing threshold all-or-none action (either fire or don’t) © Kateryna V. Keefer, 2024 8 PSYC 1020H, Unit 4 October 8-9, 2024 17 Neuron membrane 1. potential: polarized (negative charge inside) 2-3. potential: de- then re-polarize (positive charge inside) 4. period: hyper-polarized à cannot fire temporarily 18 E) neural impulse © Kateryna V. Keefer, 2024 9 PSYC 1020H, Unit 4 October 8-9, 2024 19 Demyelinating disease damaged myelin sheath à slow/distorted neural signals à axon deterioration/loss à neurological problems - movement, sensation, cognition, internal organs - e.g., Multiple Sclerosis 1 m/s vs. 100 m/s 20 F) neural impulse © Kateryna V. Keefer, 2024 10 PSYC 1020H, Unit 4 October 8-9, 2024 Synapse x 1,000s 21 microscopic junction between axon terminals of the sending neuron and dendrites or soma of the receiving neuron of signal BETWEEN neurons 22 Neurotransmitters (NT) chemical messengers that carry the signal across the synaptic gap Excitatory: Inhibitory: - the signal - the signal - higher likelihood of - lower likelihood of new action potential new action potential © Kateryna V. Keefer, 2024 11 PSYC 1020H, Unit 4 October 8-9, 2024 23 Synaptic transmission: Start Pre-synaptic 1) action potential (sending) axon stimulates release of Vesicles Neurotransmitter NT from vesicles into the synaptic gap Synaptic gap Post-synaptic (receiving) dendrite 24 Synaptic transmission: Action Pre-synaptic 2) NT bind to matching (sending) axon receptor sites on the receiving neuron à boost or inhibit likelihood of a new action potential Receptor site Post-synaptic (receiving) dendrite © Kateryna V. Keefer, 2024 12 PSYC 1020H, Unit 4 October 8-9, 2024 25 Synaptic transmission: End Pre-synaptic 3) NT are cleared from the (sending) axon synapse à bind to autoreceptors on the sending neuron Reuptake Auto- pump à reuptake back into receptor the sending neuron Enzyme à broken down by enzymes in the synapse à diffuse out of the synapse Post-synaptic (receiving) dendrite 26 Types of neurotransmitters (NT) 100s of chemicals, act within different regions of NS have different, multiple effects on mind and behaviour common NTs: Endorphins Glutamate Dopamine GABA Norepinephrine Acetylcholine Serotonin © Kateryna V. Keefer, 2024 13 PSYC 1020H, Unit 4 October 8-9, 2024 27 Practice Questions: Neurotransmitters 28 Psychoactive drugs alter neurotransmitter (NT) activity in synapses Agonists = or enhance NT effects Antagonists = or inhibit NT effects various mechanisms of action via: - synthesis - receptor binding - release - reuptake © Kateryna V. Keefer, 2024 14 PSYC 1020H, Unit 4 October 8-9, 2024 29 Direct agonists the action of NT bind to the same receptor sites Natural activate them à produce the same effect neurotransmitter e.g., Opioids are direct agonists for endorphins à calm, euphoric, analgesic, hibernate Agonist 30 Indirect agonists the action of NT - increase synthesis of NT - stimulate release of NT - block reuptake/removal of NT more NT in the synapse for longer to bind to receptors à stronger, longer effect of NT e.g., stimulants are indirect agonists for dopamine & norepinephrine © Kateryna V. Keefer, 2024 15 PSYC 1020H, Unit 4 October 8-9, 2024 31 Example: Cocaine blocks reuptake of dopamine & norepinephrine à pleasure, reward seeking, high energy, ↑HR Normal reuptake Cocaine blocking reuptake 32 Direct antagonists (blockers) the action of NT bind to the same receptor sites but do NOT activate them à block the effect Natural Antagonist neurotransmitter © Kateryna V. Keefer, 2024 16 PSYC 1020H, Unit 4 October 8-9, 2024 33 Example: Naloxone direct antagonist for endorphins knocks opioids off the endorphin receptors, then binds to them and blocks them à used to reverse opioid overdose 34 Indirect antagonists the action of NT - decrease synthesis of NT - prevent release of NT - speed up removal of NT less NT in the synapse available to bind to receptors à weaker, shorter effect of NT © Kateryna V. Keefer, 2024 17 PSYC 1020H, Unit 4 October 8-9, 2024 35 Example: Botulinum toxin indirect antagonist for acetylcholine (ACh) prevents release of ACh from vesicles at the neuromuscular junction à paralyzed muscle control Botulinum toxin ACh ACh Less ACh receptors released Muscle Normal action Inhibited action 36 Practice Questions: Agonist or Antagonist? Curare is a poison that blocks acetylcholine receptors at the neuromuscular junction. Prozac is a medication that blocks the reuptake of serotonin into the presynaptic terminal. Psilocybin is converted into psilocin, which binds to and stimulates serotonin receptors. Benzodiazepines are medications that increase the sensitivity of GABA receptors. © Kateryna V. Keefer, 2024 18 PSYC 1020H, Unit 4 October 8-9, 2024 37 Neural connections in the brain Grey matter 86 billion neurons (cell bodies, 150K km of axonal fibers dendrites) 100s trillion synapses fire several times per sec White matter (myelinated axons) Severe Healthy Alzheimer’s 38 Neural networks/pathways behaviours & mental events = unique patterns of neural activation distributed throughout the brain “The mind is what the brain does” © Kateryna V. Keefer, 2024 19 PSYC 1020H, Unit 4 October 8-9, 2024 39 3. STRUCTURE OF THE BRAIN Bottom to top: Forebrain basic life functions at Midbrain “lower” levels Hindbrain complex functions at “higher” levels all parts interact together 40 Practice Questions: Brain Structures © Kateryna V. Keefer, 2024 20 PSYC 1020H, Unit 4 October 8-9, 2024 41 HINDBRAIN coordinates info passing to & from the spinal cord basic life functions involuntary, visceral 42 Medulla extension of the spinal cord controls vital functions (breathing, heart rate, BP) damage will kill you - e.g., alcohol/opioid overdose © Kateryna V. Keefer, 2024 21 PSYC 1020H, Unit 4 October 8-9, 2024 43 Reticular formation (RF) regulates sleep/wakefulness Moruzzi & Magoun (1949): stimulated RF of sleeping cats à woke suddenly, remained alert severed RF from rest of brain à cats fell into irreversible coma Zzzz 44 Cerebellum “little brain” controls fine motor skills, balance fine-tuning & coordination (not initiation) of movement © Kateryna V. Keefer, 2024 22 PSYC 1020H, Unit 4 October 8-9, 2024 45 Pons “bridge” relays info to cerebellum from the rest of the brain involved in movement 46 MIDBRAIN Tectum uses sensory input to orient body toward/away from stimuli Tegmentum Tectum Tegmentum is involved in movement & arousal; synthesis of dopamine - e.g., impaired in Parkinson’s © Kateryna V. Keefer, 2024 23 PSYC 1020H, Unit 4 October 8-9, 2024 47 FOREBRAIN Basal ganglia Thalamus subcortical structures (core) Hippocampus cerebral cortex (outer layer) Hypothalamus Amygdala 2 hemispheres (R/L) divided by corpus callosum 48 Subcortical structures Basal ganglia deep inside the brain Thalamus Hippocampus Hypothalamus Amygdala © Kateryna V. Keefer, 2024 24 PSYC 1020H, Unit 4 October 8-9, 2024 49 Basal ganglia Basal ganglia set of structures direct intentional movements, posture interface with motor cortex, midbrain, cerebellum (dopamine pathway) - e.g., impaired in Parkinson’s 50 Thalamus relay station for the senses Thalamus filters & transmits sensory info to various parts of the cortex © Kateryna V. Keefer, 2024 25 PSYC 1020H, Unit 4 October 8-9, 2024 51 Hypothalamus regulates biological needs (hunger, thirst, sex, temperature) “reward” centre (dopamine) Hypothalamus connects brain to the endocrine system (via pituitary gland) controls ANS 52 Limbic system loose network of structures involved in motivation, emotion, learning, memory where subcortical structures interface with the cortex Hippocampus Hypothalamus Amygdala © Kateryna V. Keefer, 2024 26 PSYC 1020H, Unit 4 October 8-9, 2024 53 Hippocampus learning and memory Hippocampus consolidates and indexes new memories into long-term storage (stored throughout the cortex) 54 Amygdala emotional processes attaches emotional significance to previously neutral events learning of fear/reward responses Amygdala - overactive in PTSD, anxiety - underactive in psychopathy © Kateryna V. Keefer, 2024 27 PSYC 1020H, Unit 4 October 8-9, 2024 55 Cerebral cortex surface layer of L and R cerebral hemispheres each hemisphere has 4 lobes most complex behaviors - movement initiation, perceptions, higher mental processes 56 Hemispheres contralateral control – each hemisphere controls functions of the opposite side of the body corpus callosum – band of nerve fibers that passes info across hemispheres lateral specialization – differential functions of R and L hemispheres à split-brain patients © Kateryna V. Keefer, 2024 28 PSYC 1020H, Unit 4 October 8-9, 2024 57 Occipital lobe primary visual cortex à processes inputs from eyes (relayed via thalamus) - colour, shape, motion association areas project into temporal lobe à make sense of primary info - recognition, location 58 Temporal lobe hearing & language primary auditory cortex à processes inputs from ears (relayed via thalamus) - timbre, pitch, volume association areas à make sense of primary info (speech, music, source) © Kateryna V. Keefer, 2024 29 PSYC 1020H, Unit 4 October 8-9, 2024 59 Damage to LEFT temporal lobe Wernicke’s Area lose ability to understand spoken language can still produce language (Broca’s area), but sentences are meaningless 60 Damage to RIGHT temporal lobe lose ability to recognize different types of sounds - rhythm, pitch, melodies produce “wooden” flat speech language comprehension is NOT impaired © Kateryna V. Keefer, 2024 30 PSYC 1020H, Unit 4 October 8-9, 2024 61 Parietal lobe somatosensory cortex processes inputs from skin (relayed via thalamus) - touch, pressure, temperature, pain 62 Sensory Homunculus (Parietal) each area of somatosensory cortex maps onto a specific part of the body (on the opposite side) more sensitive body part à larger cortex area devoted to it somatosensory cortex © Kateryna V. Keefer, 2024 31 PSYC 1020H, Unit 4 October 8-9, 2024 63 Frontal lobe: Motor cortex controls initiation of voluntary movement - sends commands to the basal ganglia à midbrain à pons à cerebellum à spinal cord motor homunculus more dexterous part à larger cortex area devoted to it motor cortex 64 Frontal lobe: Prefrontal cortex (PFC) Executive Control System monitors, organizes, integrates, directs higher-order mental functions - intelligence, abstract thinking, reasoning, planning, self-control, memory retrieval - emotion regulation, personality © Kateryna V. Keefer, 2024 32 PSYC 1020H, Unit 4 October 8-9, 2024 65 Neuroplasticity ability of the brain to re-wire itself in response to experience Hebb’s Learning Rule: neural circuits that are repeatedly activated become stronger, faster, more sensitive “Neurons that fire together, wire together” Donald Hebb https://www.youtube.com/watch?v=ELpfYCZa87g © Kateryna V. Keefer, 2024 33