lecture 7 bisc 205.pdf

BISC 205 Midterm – Animal Physiology Wed Oct 2 9:30AM Coverage: All material presented in lecture up to Fri Sept 27 (Introductory lecture – Lecture 10) 25-30 Multiple choice questions Choose ONE Answer - scantron sheet provided 4-5 Short answer questions Poin...

BISC 205 Midterm – Animal Physiology Wed Oct 2 9:30AM Coverage: All material presented in lecture up to Fri Sept 27 (Introductory lecture – Lecture 10) 25-30 Multiple choice questions Choose ONE Answer - scantron sheet provided 4-5 Short answer questions Point form is fine. Additional office hours posted on Canvas. BISC 205 MARK DISTRIBUTION: Midterm 1 25% - Animal Physiology Midterm 2 25% - Plant Physiology Final Exam 30% Tutorials 20%  Animal Physiology Midterm This information is posted on Canvas : Pre-Midterm extended office hours Mon Sept 23: 12:30-1:20PM Wed Sept 25: 1:00-2:00PM Fri Sept 27: 1:00-2:00PM Mon Sept 30: 1:00-2:30PM Tues Oct 1: 1:00-3:00PM B8244 and Zoom. Zoom link on course Canvas page. For Zoom you do not need to turn your video on. Animal Nervous System – Part 3 The vertebrate nervous system Functional anatomy of the CNS Learning and memory The Vertebrate Nervous System The vertebrate nervous system is made up of two parts: – The central nervous system (CNS) – The peripheral nervous system (PNS) Created with BioRender.com The Vertebrate Nervous System Created with BioRender.com The Vertebrate Nervous System - CNS The CNS is made up of the brain and spinal cord The Vertebrate Nervous System - PNS The PNS is made up of neurons outside the CNS Created with BioRender.com The Peripheral Nervous System The PNS consists of two systems with distinct functions: 1. The afferent division transmits sensory information to the CNS  The neurons monitor conditions inside and outside the body 2. The efferent division carries signals that allow the body to respond to the changed conditions in an appropriate way The Peripheral Nervous System The efferent division is divided into two systems: 1. The somatic nervous system carries out voluntary responses, which are under conscious control  Skeletal muscles serve as the effectors 2. The autonomic nervous system carries out involuntary responses, which are not under conscious control  Smooth muscle, cardiac muscle, and several glands serve as the effectors The Peripheral Nervous System Many organs are served by two functionally distinct types of autonomic nerves: 1. The parasympathetic nervous system promotes “rest and digest” functions that conserve or restore energy 2. The sympathetic nervous system prepares organs for stressful situations—“fight or flight” Neurons in the gastrointestinal tract are known as the enteric nervous system—it interacts with autonomic nerves and functions independently to regulate digestion (not shown) The Autonomic Nervous System Controls Internal Processes The Autonomic Nervous System Controls Internal Processes The parasympathetic nervous system promotes “rest and digest” functions that conserve or restore energy Parasympathetic nerves originate at the top of the spinal cord The Autonomic Nervous System Controls Internal Processes The sympathetic nervous system prepares organs for stressful situations— “fight or flight” Most sympathetic nerves originate in the spinal cord, but emerge along the middle of its length Animal Nervous Systems – Part 3 The vertebrate nervous system Functional anatomy of the CNS Learning and memory Anatomy of the CNS The spinal cord, which is made up of many nerves, serves as an information conduit Virtually all the information that enters the spinal cord is sent to the brain for processing Created with BioRender.com General Anatomy of the Human Brain (1 of 3) The brain consists of four main structures: – The cerebrum makes up the bulk of the brain, is divided into left and right hemispheres, and is involved in conscious thought and memory – The cerebellum coordinates complex motor patterns – The diencephalon relays sensory information to the cerebellum and controls homeostasis – The brain stem connects the brain to the spinal cord and is the autonomic centre for regulating the heart, lungs, and digestive system General Anatomy of the Human Brain (2 of 3) Each cerebral hemisphere also has four lobes: the frontal, parietal, occipital, and temporal lobes General Anatomy of the Human Brain (3 of 3) The two hemispheres are connected by a thick band of axons called the corpus callosum Mapping the Brain : Lesion Studies (1 of 4) Phineas Gage had an iron rod over 3 cm in diameter blasted through his skull, yet survived the accident – His personality changed dramatically—he was reported to be “fitful,” “irreverent,” and “obstinate” – The rod had damaged his frontal lobe, giving information that this area of the brain plays a role in personality and emotion Phineas Gage Teles RV. Phineas Gage's great legacy. Dement Neuropsychol. 2020 Dec;14(4):419-421. doi: 10.1590/1980-57642020dn14-040013. PMID: 33354296; PMCID: PMC7735047.  Ratiu P, Talos IF, Haker S, Lieberman D, Everett P. The tale of Phineas Gage, digitally remastered. J Neurotrauma. 2004 May;21(5):637-43. PMID: 15165371 Polygon data is generated by Database Center for Life Science(DBCLS)., CC BY-SA 2.1 JP , via Wikimedia Commons -Wikimedia Commons Mapping the Brain : Lesion Studies (2 of 4) Paul Broca developed methods for mapping the cerebrum by studying the mental abilities of people who have suffered brain damage or lesions – These studies provide evidence that functions are localized to specific brain areas – While studying an individual who could understand language but could not speak, Broca discovered a lesion in the man’s frontal lobe https://www.nidcd.nih.gov/health/aphasia Aphasias Broca’s aphasia – difficulties in speaking – in the production of language. Wernicke’s aphasia - difficulties producing meaningful speech and comprehension of language. https://www.nidcd.nih.gov/health/aphasia Mapping the Brain : Lesion Studies (3 of 4) Henry Gustav Molaison had a part of his temporal lobe and about two-thirds of his hippocampus removed during surgery – He survived and had normal intelligence and memories of his childhood, but no short-term memory – Leading to the hypothesis that the hippocampus and temporal lobe are necessary for the formation of new memories By Images are generated by Life Science Databases(LSDB). https://commons.wikimedia.org/w/index.php?curid=7887142 Mapping the Brain : Lesion Studies (4 of 4) Stoke is a disruption of blood supply to the brain, often affecting a specific region. Effects are observed on the opposite (“contralateral”) side of the body. Warning signs of a stroke – motor difficulties on one side of the body. One side of Asked to face drooping raise both Created with BioRender.com arms https://www.pennmedicine.org Many historical and modern studies have shown that motor and sensory afferent nerves project to the contralateral side of the brain. Mapping the Brain : Modern Imaging Studies (1of 5) Functional Magnetic resonance Imaging (fMRI) https://news.fsu.edu/news/science-technology/2016/10/24/fsu-unveils-floridas-advanced-mri-machine/ Mapping the Brain : Modern Imaging Studies (2 of 5) BioRender (2022). Structural vs Functional MRI Scan. https://app.biorender.com/biorender-templates/figures/all/t-639bce9af01b71c072258776-structural-vs-functional-mri-scan Mapping the Brain : Modern Imaging Studies (3 of 5) fMRI results to word reading in a single subject: https://med.nyu.edu/thesenlab/research-0/research-functional-magnetic-resonance-imaging-fmri/ Mapping the Brain : Modern Imaging Studies (4 of 5) https://med.nyu.edu/thesenlab/research-0/research-functional-magnetic-resonance-imaging-fmri/ fMRI results to word reading in a single subject: Mapping the Brain : Modern Imaging Studies (5 of 5) https://med.nyu.edu/thesenlab/research-0/research-functional-magnetic-resonance-imaging-fmri/ MRI group results to word reading in 10 subjects Brain Mapping Conclusions: Specific Brain Areas Have Specific Functions Historical data, lesion studies, stroke studies, and modern imaging studies have revealed that different regions of the brain are specialized for specific functions. Motor and sensory afferent nerves project to the contralateral side of the brain. Some higher brain functions are lateralized to one side of the brain e.g. language. Specific Brain Areas Have Specific Functions Specific Brain Areas Have Specific Functions Top view (Front) Left Right hemisphere hemisphere Left hemisphere Created with BioRender.com Specific Brain Areas Have Specific Functions Top view (Front) Left Right hemisphere hemisphere Left hemisphere Created with BioRender.com Specific Brain Areas Have Specific Functions Top view (Front) Left Right hemisphere hemisphere Left hemisphere Created with BioRender.com Specific Brain Areas Have Specific Functions Top view (Front) Left Right hemisphere hemisphere Left hemisphere Created with BioRender.com Recall: Mapping the Brain : Modern Imaging Studies (5 of 5) https://med.nyu.edu/thesenlab/research-0/research-functional-magnetic-resonance-imaging-fmri/ MRI group results to word reading in 10 subjects https://www.canada.ca/en/public-health/services/publications/diseases-conditions/stroke-in-canada.html https://www.canada.ca/en/public-health/services/publications/diseases-conditions/stroke-in-canada.html https://www.pennmedicine.org Animal Nervous System – Part 3 The vertebrate nervous system Functional anatomy of the CNS Learning and memory Learning and Memory Learning and memory are closely related and are often studied in tandem Learning is an enduring change in behaviour that results from a specific experience in an individual’s life Memory is the retention of learned information Learning, memory, & Synapses Learning and memory involves some type of short-term or long- term structural or chemical change in the neurons responsible for these processes – Structural changes - modifications in the number of synapses – Chemical changes – biochemical changes which result lasting alterations in synaptic responsiveness (efficacy/strength) A change in the responsiveness of a synapse is termed synaptic plasticity Recall from last lecture: Documenting Changes in Synapses Eric Kandel has focused on an animal much easier to study than any vertebrate—the sea slug Aplysia californica When its siphon is touched, the sea slug responds by withdrawing its gill to protect it from predators The reflex is produced by sensory neurons that are activated by touch and motor neurons that project to a gill muscle Documenting Changes in Synapses Aplysia also withdraw their gills when given an electrical shock – If shock is paired with a light touch that wouldn’t normally produce a response, Aplysia will learn to withdraw its gill in response to a light siphon touch alone In the gill-withdrawal reflex, the neurons involved in learning release the neurotransmitter serotonin Model System: Aplysia californica gill withdrawal reflex Model System: Aplysia californica gill withdrawal reflex To Tail Motor neuron to gill To Syphon Created with BioRender.com Animation - Model System: Aplysia californica gill withdrawal reflex Purves et al, Neuroscience, 2018 Synaptic Plasticity – A lasting change in synaptic strength/efficacy (1of5) Tail Purves et al, Neuroscience, 2018 Synaptic Plasticity – A lasting change in synaptic strength/efficacy (2of5) Simultaneous activation of the tail and syphon neurons results in increased activation of the gill motor neuron and gill withdrawal. To Tail Motor neuron to gill Increased gill withdrawal To Syphon Created with BioRender.com Synaptic Plasticity – A lasting change in synaptic strength/efficacy (3of5) Simultaneous activation of the tail and syphon neurons also causes lasting biochemical changes in the syphon neuron. To Tail Motor neuron to gill Increased gill withdrawal To Syphon Created with BioRender.com Synaptic Plasticity – A lasting change in synaptic strength/efficacy (4of5) Simultaneous activation of the tail and syphon neurons also causes lasting biochemical changes in the syphon neuron. To Tail Increased gill withdrawal Motor neuron to gill To Syphon Created with BioRender.com Synaptic Plasticity – A lasting change in synaptic strength/efficacy (5of5) Because of these biochemical changes, the slug “remembers” the association between the shock of the tail and touch of the syphon. Subsequent touches of only the syphon result in increased gill withdrawal. Increased gill withdrawal Created with BioRender.com Additional Mechanisms of presynaptic enhancement underlying behavioural sensitization in Aplysia With repeated training this pathway can also stimulate gene expression and generation of additional synapses Purves et al, Neuroscience, 2018 SUMMARY- Mechanisms of presynaptic enhancement underlying behavioural sensitization in Aplysia Simultaneous activation of the tail and syphon neurons results in increased activation of the gill motor neuron and gill withdrawal. Simultaneous activation of the tail and syphon neurons also causes lasting biochemical pathways to be activated in the syphon neuron. Because of these biochemical changes, the slug “remembers” the association between the shock of the tail and touch of the syphon. Subsequent touches of the syphon result in increased neurotransmitter release from the siphon neuron. Thus subsequent touches of the syphon result in increased gill with drawl. With repeated training this pathway can also stimulate gene expression and generation of additional synapses. Overview - Learning, memory, & Synapses Learning, memory, and the control of complex behaviours involve molecular and structural changes of synapses. ie Changes in synapses form the molecular basis of learning and memory. A change in the responsiveness of a synapse is termed synaptic plasticity. At least some aspects of long-term memory also involve changes in gene expression. Animal Nervous System – Part 3 Learning Objectives: Describe the major subdivisions of the mammalian nervous system. Describe (in general terms) the functions of the sympathetic and parasympathetic nervous systems. Describe the major structures of the human brain Describe the main functions of the major regions of the human brain Describe how we learned about the functions of different regions of the brain. Describe some of the specialised regions of the brain. Describe the projection of sensory and motor neurons to the brain. Describe the warning signs of a stroke. Explain the structural and biochemical basis of learning and memory in the Aplysia model system. Describe the basis of learning and memory in the brain. Animal Nervous System – Part 3 The vertebrate nervous system Functional anatomy of the CNS Learning and memory END