PSYC 100 L06 Study - Human Nervous System PDF

1 INTRODUCTION 8 HUMAN NERVOUS SYSTEM BASIC DIVISIONS OF HUMAN NERVOUS SYSTEM "third brain" = enteric nervous system in a way independent but can interact with autonomous nervous system 1 INTRODUCTION 9 PERIPHERAL NERVOUS SYSTEM PNS INCLUDES SOMATIC AND AUTONOMIC SYSTEMS ‣ Somatic Nervous S...

1 INTRODUCTION 8 HUMAN NERVOUS SYSTEM BASIC DIVISIONS OF HUMAN NERVOUS SYSTEM "third brain" = enteric nervous system in a way independent but can interact with autonomous nervous system 1 INTRODUCTION 9 PERIPHERAL NERVOUS SYSTEM PNS INCLUDES SOMATIC AND AUTONOMIC SYSTEMS ‣ Somatic Nervous System (SNS): transmits signals to CNS from muscles, joints, skin via nerves. CNS sends signals through SNS to muscles, joints and skin, to initiate, modulate, or inhibit movement. ‣ Autonomous Nervous System (ANS): Regulates internal environment of the body. Stimulates glands (e.g., sweat glands), and organs (e.g., heart, liver, lungs, pupils, etc). Nerves of ANS project signals from these targets to CNS. ‣ ANS divided into sympathetic and parasympathetic system. They are opposing systems in terms of outcomes. ‣ Sympathetic signalling: “fight or flight”; prepares body for action (e.g., in response to a threat). Chronic stress leads to increased activity of this system. ‣ leads the body to be optimased for fight optimised for figthting rather than thinking about food Parasympathetic signalling: “rest and digest”; returns body to resting state. work as opponent 1 INTRODUCTION 10 PERIPHERAL NERVOUS SYSTEM PNS INCLUDES SOMATIC AND AUTONOMIC SYSTEMS essential organs responsible for puting the body into these specific states 1 INTRODUCTION 11 ENDOCRINE SYSTEM ENDOCRINE SYSTEM COMMUNICATES THROUGH HORMONES ‣ Endocrine System. A communication network that influences thoughts, behaviours, actions. It works together with the nervous system (e.g., preparing body to deal with perceived threats). ‣ Endocrine system signals slower than nervous system. Uses hormones to influence brain and body; these hormones are released into blood stream and can have wide-spread effects on the body and brain. ‣ slower sys because you have to actually produces and distributes the hormones Endocrine system primarily controlled by hypothalamus, via signals to the pituitary gland, located at the base of the hypothalamus. 1 INTRODUCTION 12 ENDOCRINE SYSTEM example of the endoctrine system HYPOTHALAMUS-PITUITARY-ADRENAL GLAND (HPA) AXIS (STRESS RESPONSE) diffuse in kidney in response to hormone kidney produces cortisol Kidney memory is optimal if slightly elevated stress response but oposite if too much stress, like prolondged stress ‣ Hypothalamus (eg., in response to perceived stress) secretes hormones corticotropinreleasing hormone (CRH) that stimulates pituitary to release adrenocorticotropic hormone (ACHT), which increases cortisol production of the adrenal gland ‣ Cortisol (CORT), on the other hand, inhibits production of CRH and ACHT, in a negative feedback loop. 1 INTRODUCTION 13 HUMAN CENTRAL NERVOUS SYSTEM (CNS) CNS CONSISTS OF SPINAL CORD AND BRAIN CNS A LOT OF DIFF CELL TYPES ex : neurons 1 INTRODUCTION 14 RAMON Y CAJAL NEUROANATOMIST WHO WON NOBEL PRIZE IN 1906 Silver staining method discovered structures of the neurons it stains some neurons but not all Santiago Ramón y Cajal 1852-1934 1 INTRODUCTION 15 HUMAN NERVOUS SYSTEM NEURONS ARE A BASIC COMPONENT OF THE NERVOUS SYSTEM his major discovery : neurons not directly in contact point with each other a little gap between them > understanding that neuron have to communicate in a way if they are not directly link, how is that possible 1 INTRODUCTION 16 HUMAN CENTRAL NERVOUS SYSTEM (CNS) BUILDING BLOCKS OF CNS ARE NEURONS AND GLIAL CELLS neurons embedded into tissues other common cells in the brain Glial cells most common microglia can move around, involved in response to damage repairing damage to neurons astrocytes, contact synapses and neurons, form third component of synapses oligo, important for signal transmition for neurons, wrap around axons insulating the axon, optimize signal transmission 1 INTRODUCTION 17 HUMAN CENTRAL NERVOUS SYSTEM (CNS) BASIC FUNCTION OF GLIAL CELLS IN THE CNS ‣ ‣ ‣ ‣ Function of neurons is communication in form of propagating electrical signals. ‣ Glial cells are an essential part of the nervous system supporting and contributing to functions of neurons (glia means “glue” in Greek). There are microglia and there are macroglia. ‣ Microglia protect CNS neurons. They are smaller than the other glial cells, and are mobile within the brain. They can metabolize dead tissue and are involved in keeping the CNS healthy. Astrocytes and oligodendrocytes are macroglia. Astrocytes: link neurons to blood vessels, forming part of the blood-brain barrier. They engulf synapses (i.e., where neurons connect), regulating neurotransmitter release during synaptic transmission. ensure substances cannot get in the brain = blood-brain barrier Oligodendrocytes: they surround axons in the CNS, forming the myelin sheath that insulates axons, which allows the electrical signal that travels in the axon to travel faster. NEURONS 2 2 NEURONS 19 INFORMATION FLOW IN REFLEXES NEURONS SPECIALISED FOR COMMUNICATION 2 NEURONS 20 ANATOMY OF NEURONS BASIC STRUCTURE OF NEURONS Node of Ranvier Vesicles with neurotransmitters Presynaptic terminal Postsynaptic terminal NEURONS 21 ANATOMY OF NEURONS THREE BASIC TYPES OF NEURONS (> 3300 types of brain cells in human brain ‣ A neuron is a specialized cell. From cell body (soma) two kind of cytoplasmic processes extend: a) one or more dendrites, and b) a single axon. ‣ Neurons can have different shapes, depending on their function and location. NEURONS 22 ANATOMY OF NEURONS THREE BASIC TYPES OF NEURONS (> 3300 types of brain cells in human brain) ‣ (a) Interneurons or associative neurons. Are neither sensory nor motor but connect neurons with other neurons. ‣ (b) Motor (efferent or effector) neurons. Send information from CNS to the body’s effectors (muscles/glands) ‣ (c) Sensory (receptor or afferent) neurons. Act as receptors of stimuli, or are connected to receptors. ‣ Sensory and motor neurons mostly outside (CNS); interneurons entirely within CNS (99% of neurons in body) 2 NEURONS 23 ANATOMY OF NEURONS INFORMATION FLOW IN THE NEURON Axon hillock 2 NEURONS 24 ANATOMY OF NEURONS INFORMATION FLOW IN THE NEURON 1. A signal is received at the dendritic spines, at the post-synaptic terminals, where the neuron synapses with the axon of another neuron. 2. This signal can produce an electric current that travels from the dendrite to the soma of the neuron. 3. If the signal accumulating at the axon hillock in the soma is strong enough, the receiving neuron will “fire”, i.e., it will produce an electrical impulse at the axon hillock. 4. This electrical impulse travels down the axon toward the terminal buttons (the pre-synaptic terminals). 5. When the electrical impulse reaches the pre-synaptic terminal, it can produce a chemical signal: the release of neurotransmitters. 6. When neurotransmitters reach the post-synaptic terminal of the receiving neuron: Go back to point 1 above. 2 NEURONS 25 THE ACTION POTENTIAL THE RESTING POTENTIAL: THE CONCEPT OF POTENTIAL ‣ Electrical potential refers to how much energy is stored up in a system. ‣ For example, a fully charged electrical AA battery has a potential of 1.5 V (volt) if it is not connected to an electrical circuit. ‣ When the battery poles are connected in an electrical circuit, the potential can be released and converted for example in light energy. 2 NEURONS 26 THE ACTION POTENTIAL THE RESTING POTENTIAL ‣ At rest, when a neuron is not active, the electrical charge inside and outside the neuron is different. ‣ This difference in charge is called a potential. It is the potential electrical charge that could be released. ‣ A neuron at rest has the resting potential of around -70 millivolts (-70 mV; i.e., there are more negatively charges inside the neuron than outside of it). 2 NEURONS 27 THE ACTION POTENTIAL ACTION POTENTIAL: A BRIEF CHANGE OF THE RESTING POTENTIAL Electrical stimulation ‣ If the electrical stimulation is strong enough, it exceeds the threshold of excitation and the axon of the stimulated neuron will fire an action potential. ‣ During the action potential, the neuron is briefly depolarized, so the membrane potential reaches about +40 mV. 2 NEURONS 28 THE ACTION POTENTIAL THE RESTING POTENTIAL: DIFFUSION AND ELECTROSTATIC PRESSURE Equilibrium ‣ Diffusion refers to the phenomenon that particles tend to move from a region of high concentration to a region of low concentration, eventually reaching equilibrium of equal dispersion. ‣ Diffusion results from Brownian movement, which correlates with temperature. ‣ Diffusion is a force that pushes particles down their concentration gradient. 2 NEURONS 29 THE ACTION POTENTIAL THE RESTING POTENTIAL: DIFFUSION AND ELECTROSTATIC PRESSURE ‣ Electrostatic pressure refers to the fact that equally electrically charged particles repel each other, and differently charged particles attract each other. ‣ Applied to neurons: ‣ negatively charged molecules (anions, such as Cl-) tend to move away from each other, and so do positively charged molecules (cations, such as Na+, K+). ‣ anions and cations are moving towards each other. 2 NEURONS 30 THE ACTION POTENTIAL ION CHANNELS IN THE NEURON MEMBRANE ‣ There are proteins in the neuronal membrane that form little channels (pores), connecting the inside of the neurons with the outside. Some of these proteins allow certain types of ions to pass. These channels are called ion channels. There are for example sodium channels, and potassium channels. ‣ Some ion channels open only under certain conditions, for example, when the potential across the neuron membrane has a certain value. These channels are called voltage-dependent ion channels. 2 NEURONS 31 THE ACTION POTENTIAL THE RESTING POTENTIAL: DIFFUSION AND ELECTROSTATIC PRESSURE forces neutralized ‣ ‣ forces unite forces neutralized The size of the coloured squares represents the approximate concentration of the molecules. At rest, the concentration of negative ions inside the neuron is larger than outside, which has more positively charged particles than the inside. Unequal distribution of K+ and Na+ causes resting potential. 2 NEURONS 32 POLLING@ MCGILL [P1] 2 NEURONS 33 THE ACTION POTENTIAL THE RESTING POTENTIAL: DIFFUSION AND ELECTROSTATIC PRESSURE ‣ In the extracellular space (the space outside the neuron), we find a lot of NaCl in solution, i.e., we find a high concentration of Na+ and Cl- in equal proportion, in a concentration much like seawater (that this is where life began). We also find potassium (K+). ‣ In the intracellular space (inside the neuron), we find many negatively charged large proteins (organic anions), K+, and about equal low amounts of Na+ and Cl-. ‣ As a consequence, during rest, the inside of the neuron has more negatively charged particles than the outside, which has more positively charged particles. This is why the resting potential of the neuron is negative. ‣ Dynamics of diffusion and electrostatic pressure that determine the resting potential ‣ Cl- is in greatest concentration outside, diffusion forces it inside. However, because there are many negatively charge organic anions inside, electrostatic pressure pushes Cl- out. ‣ K+ is higher concentrated inside – diffusion therefore pushes it out. However, the outside is positively charged, therefore at the same time electrostatic pressure pushes K+ in. ‣ Na+ is in greater concentration outside, so diffusion forces it inside. At the same time, because it is positively charged and the inside has more negatively charged particles, electrostatic pressure pushes Na+ also inside. This is why there is the sodium potassium pump. ‣ Organic anions (negatively charged) cannot leave the neuron. 2 NEURONS 34 THE ACTION POTENTIAL THE RESTING POTENTIAL: SODIUM POTASSIUM PUMP 2 NEURONS 35 THE ACTION POTENTIAL ION FLOW DURING ACTION POTENTIAL ‣ Resting potential at -70 mV. Then an electrical stimulation exceeds threshold of excitation: 1. Sodium channels are voltage dependent channels: they open, and Na+ rushes into neuron (driven by force of diffusion and electrostatic pressure). This depolarizes the neuron membrane potential. 2. When depolarization reaches a point close to 0 mV, potassium channels open. K+ leaves neuron due to force of diffusion (less K+ outside), and driven by electrostatic pressure from inside due to increase in positive charge from Na+ influx. 2 NEURONS 36 THE ACTION POTENTIAL ION FLOW DURING ACTION POTENTIAL 3. When depolarisation reaches about +40 mV, the sodium channels enter a refractory state and close: no more Na+ can enter the neuron. 4. The forces of diffusion and electrostatic pressure continue to force K+ out of the neuron. This reduces the positive charge inside the neuron, repolarising it, i.e., driving down the membrane potential. 5. When potential reaches resting potential, K+ channels close. 6. There is a slight hyperpolarisation the end, neuron reaches -70 mV. Sodium-potassium pumps restore resting potential. 2 NEURONS 37 THE ACTION POTENTIAL SUMMARY ACTION POTENTIAL 2 NEURONS 38 THE ACTION POTENTIAL SIGNAL PROPAGATION ALONG UNMYELINATED AXONS Axon hillock 2 NEURONS 39 THE ACTION POTENTIAL SIGNAL PROPAGATION ALONG UNMYELINATED AXONS 2 NEURONS 40 THE ACTION POTENTIAL SIGNAL PROPAGATION ALONG UNMYELINATED AXONS 2 NEURONS 41 THE ACTION POTENTIAL SIGNAL PROPAGATION ALONG UNMYELINATED AXONS 2 NEURONS 42 THE ACTION POTENTIAL SIGNAL PROPAGATION ALONG UNMYELINATED AXONS 2 NEURONS 44 THE ACTION POTENTIAL SALTATORY SIGNAL PROPAGATION ALONG MYELINATED AXONS Speed: 1 m/s 2 NEURONS 45 THE ACTION POTENTIAL SALTATORY SIGNAL PROPAGATION ALONG MYELINATED AXONS 2 NEURONS 46 THE ACTION POTENTIAL SALTATORY SIGNAL PROPAGATION ALONG MYELINATED AXONS 2 NEURONS 47 THE ACTION POTENTIAL SALTATORY SIGNAL PROPAGATION ALONG MYELINATED AXONS Speed: 100 m/s 2 NEURONS 48 THE ACTION POTENTIAL DIAMETER OF AXON INFLUENCES VELOCITY OF ACTION POTENTIAL Proprioceptors of skeletal muscle Ø 13-20 µm v 80-120 m/s MechanorecepPain, temperature, itch tors of skin Ø 6-12 µm v 36-75 m/s Ø 1-5 µm v 5-30 m/s Ø 0.2-1.5 µm v 0.5-2 m/s 2 NEURONS 49 THE ACTION POTENTIAL DIAMETER OF AXON INFLUENCES VELOCITY OF ACTION POTENTIAL 2 NEURONS 50 THE ACTION POTENTIAL DIAMETER OF AXON INFLUENCES VELOCITY OF ACTION POTENTIAL Resistance to ion flow smaller in axon with a large diameter. Direction of current flow Ion Ion Even with relatively more obstacles interfering with movement of ion, number of possible paths through axon higher for ions. This results in increased velocity of ion flow. 2 NEURONS 51 ANATOMY OF NEURONS BASIC STRUCTURE OF NEURONS Node of Ranvier Vesicles with neurotransmitters Presynaptic terminal Postsynaptic terminal 2 NEURONS 52 SIGNAL TRANSMISSION RELEASE AND BINDING OF NEUROTRANSMITTERS ‣ Neurotransmitter binding, depending on the transmitter and the receptor, can have a variety of outcomes. ‣ Some neurotransmitters can have an inhibitory effect (e.g., GABA): they make it less likely that the post-synaptic neuron will fire. Some have an excitatory effect (e.g., glutamate): they make it more likely that the post-synaptic neuron will fire. 2 NEURONS 53 SIGNAL TRANSMISSION CONTROL OF NEUROTRANSMITTER RELEASE ‣ ‣ ‣ ‣ Synapse consists of: presynaptic terminal, synaptic cleft, postsynaptic terminal. It also includes glial cells (astrocytes), that enclose these three parts. Autoreceptor: senses the amount of released neurotransmitter to regulate exocytosis (i.e., release of neurotransmitters). Reuptake: a reuptake mechanism “recycles” neurotransmitter from the synaptic cleft, moving it back into the presynaptic terminal. Some antidepressants interfere with this process for the neurotransmitter serotonin (SSRIs). Enzymatic degradation: enzymes in the synaptic cleft degrade released neurotransmitters. 2 NEURONS 54 SIGNAL TRANMISSIONS AGONISTS & ANTAGONISTS MODULATE NEUROTRANSMISSION Eg: Benzodiazepines (anti-anxiety), agonist for GABA-A receptor Eg: Ketamine (narcotic), antagonist for NMDA receptor 55 2 NEURONS Top Hat SIGNAL TRANMISSIONS OVERVIEW OF MAJOR NEUROTRANSMITTERS 2017-09-18, 10:39 AM Table 3.1: Example Neurotransmitters and Associated Drugs This table outlines a few of the many neurotransmitters 2 NEURONS 56 SIGNAL TRANMISSIONS CHART OF PSYCHOACTIVE SUBSTANCES Drug class: Subgroup: Benzodiazepines Specific drugs: Examples: Diazepam (Valium), clonazepam (Klonopin), lorazepam (Ativan), temazepam (Restoril), flunitrazepam (Rohypnol), triazolam (Halcion), alprazolam (Xanax) Benzodiazepine agonists Zolpidem (Ambien), eszopiclone (Lunesta), zopiclone, zaleplon (Sonata) Barbiturates Phenobarbital, pentobarbital, thiopental (sodium pentothal, sodium amytal), secobarbital Sedatives Alcohol Gammahydroxybutyrate (GHB), GBL, 1,4-butanediol Mechanism: Major effects: Side effects: Any medical use: Drowsiness, falls, Agonist at Calm, relaxed muscles, impaired coordination, benzodiazepine site on sleepy impaired memory, the GABA-A receptor dizziness Anxiety, insomnia, epilepsy, many other diseases Mainly just sleepy, sometimes hallucinations and sleep-like states Insomnia Same as above Same as benzodiazepines Same as benzodiazepines, plus Calm, euphoric, sleepy breathing suppressed, terrible withdrawal, death Same as Opens BK potassium benzodiazepines, plus channels nausea, vomiting, (hyperpolarizing Calm, euphoric, loss of breathing suppressed, neurons), closes SK inhibitions (facilitates terrible withdrawal potassium channels in socializing, talking, (including psychosis reward center of brain singing, sex), relaxed and seizures), brain (causing DA release), damage, various probably other effects diseases, death Same as Agonist at GHB receptor Euphoric, energetic, benzodiazepines, plus (may desensitize it or sleepy, calm (mix of nausea, vomiting, inhibit GABA), agonist stimulant and sedative breathing suppressed, at GABA-B receptor effects) psychosis, seizures, death Agonist at barbiturate site on the GABA-A receptor Amphetamine (Adderall), methamphetamine (Desoxyn), methylphenidate (Ritalin), phentermine, 4Euphoric, energetic, Anxiety, paranoia, methylaminorex, phenmetrazine Increase release and able to work, psychosis, high blood (Preludin), methcathinone, fenfluramine inhibit reuptake of 5-HT, concentrate, stay pressure, heart attack, (Pondimin, Fen-Phen), dexfenfluramine DA, and NE. awake. Reduces stroke, brain damage https://ocw.mit.edu/ans7870/SP/SP.236/S09/lecturenotes/drugchart.htm (Redux), pseudoephedrine (Sudafed), appetite. when used excessively ephedrine, phenylpropanolamine (old Epilepsy, other diseases in the past and more rarely today Alcohol withdrawal Narcolepsy (improves cataplexy, not simply a sleep aid) ADHD, narcolepsy, obesity, rarely depression 2 NEURONS 57 SIGNAL TRANSMISSION SUMMARY OF CORE EVENTS AND CONCEPTS ‣ When the action potential reaches the pre-synaptic terminal, it is converted from an electrical signal into a chemical signal. ‣ First, the action potential causes Ca2+ entry into the presynaptic terminal. This promotes that vesicles loaded with neurotransmitters (proteins) fuse with the presynaptic membrane. ‣ This causes neurotransmitters to be released into the synaptic cleft. There, they diffuse and eventually bind to receptors (proteins), that swim in the membrane of the post-synaptic cell. ‣ There are several different types of receptors in the post-synaptic membrane of neurons in the CNS. Each receptor can bind a particular neurotransmitter. For example, the AMPA and NMDA receptors are glutamate receptors, binding the neurotransmitter glutamate. ‣ Binding the neurotransmitter can cause a specific action of the receptor. For example, some receptors can form channels that allow electrically charged molecules (ions) to enter the post-synaptic terminal. Now the chemical signal has been converted back into an electrical signal. ‣ This influx of electrically charged molecules can cause a depolarisation of the post-synaptic neuron, which can then lead to the neuron firing an action potential. Some neurotransmitters can have the opposite outcome, they are inhibitory, not excitatory. ‣ Some receptors do not lead to changes in charge when neurotransmitters bind to them, but they influence biochemical processes in the neuron, which can change the structure or functioning of the neuron. ‣ Released neurotransmitters are removed from the synapse by enzymatic degradation or reuptake into the presynaptic terminal. ‣ Some psychopharmacological drugs influence these processes. SSRIs (selective serotonin reuptake inhibitors) for example artificially increase the amount of the neurotransmitter serotonin in the synapse, which is used as antidepressant treatment. THE HUMAN BRAIN 3 3 THE HUMAN BRAIN 59 HIPPOCAMPUS HIPPOCAMPUS ESSENTIAL FOR SPATIAL AND EPISODIC MEMORIES 3 THE HUMAN BRAIN 60 NEURONS FORM NETWORKS EXAMPLE HIPPOCAMPUS Santiago Ramón y Cajal 1852-1934 Cajal 1894 Proc Roy Soc Lon 3 THE HUMAN BRAIN 61 NEURONS FORM NETWORKS EXAMPLE HIPPOCAMPUS brain structure connected grouping of functions 3 THE HUMAN BRAIN 62 GROSS ANATOMY TWO HEMISPHERES, CEREBELLUM, FISSURE, GYRI, SULCI gyrus and sulcus like the disgusting things at the top this disposition = a mean of increasing the amount of neurons 3 THE HUMAN BRAIN 63 GROSS ANATOMY LOBES AND FISSURES 3 THE HUMAN BRAIN 64 GROSS ANATOMY POSTERIOR VIEW chiasma = where left eye input would me tansmitted to right 3 THE HUMAN BRAIN 65 GROSS ANATOMY CORPUS CALLOSUM ‣ ‣ Corpus callosum consists of millions of myelinated axons that connect the two hemispheres. Importance of this connection apparent in split brain patients fiber bundle 3 THE HUMAN BRAIN 66 GROSS ANATOMY white between it countains faty tissue CORPUS CALLOSUM: SPLIT BRAIN PATIENT cure epilepsy prevent it to go from one half to the other so it cannot spread HEALTHY BRAIN BRAIN WITHOUT CORPUS CALLOSUM 3 THE HUMAN BRAIN 67 GROSS ANATOMY CONTRALATERAL HEMISPHERIC ORGANIZATION 3 THE HUMAN BRAIN 68 GROSS ANATOMY HEMISPHERIC ORGANISATION “You Are Two” https://www.youtube.com/watch?v=wfYbgdo8e-8 3 THE HUMAN BRAIN 69 GROSS ANATOMY HEMISPHERIC ORGANISATION ‣ Because the hemispheres are somewhat specialized, in split brain patients two independent forms of knowledge exist. ‣ Left hemisphere critical for language: if split patient sees object with right eye, this is projected into the left hemisphere, and therefore the object can be named. ‣ What patient sees with left eye (projected to right hemisphere), cannot be named because right side does not have access to language system. However, patient can choose this item with the left hand (controlled by right side). 3 THE HUMAN BRAIN 70 GROSS ANATOMY LOBES AND THEIR PRINCIPAL FUNCTIONS until 26, change in frontal lobe h i 3 THE HUMAN BRAIN 71 GROSS ANATOMY LOBES AND THEIR PRINCIPAL FUNCTIONS hippocampus encodes events as they happens amnesia memory 3 THE HUMAN BRAIN 72 GROSS ANATOMY LOBES AND THEIR PRINCIPAL FUNCTIONS 3 THE HUMAN BRAIN 73 GROSS ANATOMY LOBES AND THEIR PRINCIPAL FUNCTIONS spatial processing, some visual processing 3 THE HUMAN BRAIN 74 GROSS ANATOMY LOBES AND THEIR PRINCIPAL FUNCTIONS 3 THE HUMAN BRAIN 75 GROSS ANATOMY PENFIELD’S MAPPING STUDIES no pain sensation in the brain so if the person has a tumor in the brain you can give local anesthesia, they do not feel but conscious so the person can be stimulated, how do you feel ? do be sure you do not cut language function for example 3 THE HUMAN BRAIN 76 GROSS ANATOMY PENFIELD’S MAPPING STUDIES “Dr. Wilder Graves Penfield Canadian Medical Hall of Fame Laureate 1994” https://www.youtube.com/watch?v=QkzUocE3d3o 3 THE HUMAN BRAIN 77 GROSS ANATOMY PRIMARY MOTOR AND SENSORY CORTEX if bleeding in the brain due accident blood need to go somewhere, hole in spinal cord, basal ? so in compresses this area, then you are done cause breathiing system here like it compresses essential function remembered song from her past, show certain brain areas have specific functions, showed brain had a precise organisation he organized this basal ganglia to survive pons between two part balancing hearing taste 3 THE HUMAN BRAIN 78 BRAIN STEM BRAIN STEM: BASIC SURVIVAL FUNCTIONS ‣ Brain stem is the superior end of spinal cord. ‣ Brain stem a main communication pathway between brain and body. ‣ Houses nerves that control basic functions, such as breathing, heart rate, swallowing, vomiting, urinating, orgasm. ‣ Reticular formation: projects into cerebral cortex, affects general alertness. Involved in sleep regulation. 3 THE HUMAN BRAIN 79 CEREBELLUM CEREBELLUM ESSENTIAL FOR MOVEMENT ‣ Cerebellum (“little brain”) critical for proper motor function. For example, damage causes head tilt, balance problems. ‣ Cerebellum essential for motor learning and motor memory. It operates independently. ‣ Cerebellum also involved in planning, event memory, language, emotions. 3 THE HUMAN BRAIN 80 SUBCORTICAL STRUCTURES THALAMUS: SENSORY RELAY ‣ Thalamus is gateway to cortex. With the exception of odour information, it receives all other sensory modalities. Smell, the oldest and most fundamental sense, has a direct route to cortex. ‣ During sleep, thalamus partially shuts down incoming sensory stimulation. 3 THE HUMAN BRAIN 81 SUBCORTICAL STRUCTURES HYPOTHALAMUS AND BASAL GANGLIA ‣ ‣ ‣ Hypothalamus (below thalamus). Indispensable for survival. ‣ Involved in motivated behaviours, e.g, thirst, hunger, aggression, lust. Receives afferents from almost every body and brain region. Affects functions of many internal organs, regulates body temperature, blood pressure, blood glucose levels. 3 THE HUMAN BRAIN 82 SUBCORTICAL STRUCTURES HYPOTHALAMUS AND BASAL GANGLIA ‣ ‣ ‣ Basal ganglia are critical for planning and producing movement. ‣ Nucleus accumbens is part of basal ganglia, and is important for reward processing and motivating behaviour. This involves dopamine activity in the nucleus accumbens. Afferents from entire cerebral cortex. Efferents to motor centres of brain stem. Damage can cause tremors and rigidity in Parkinsons’s disease, or loss of movement control in Huntington’s disease. 3 THE HUMAN BRAIN 83 SUBCORTICAL STRUCTURES THE LIMBIC SYSTEM ‣ ‣ Hippocampus essential for episodic and certain spatial memories. ‣ Amygdala modulates processes in the hippocampus (and other brain regions), might signal importance of events, thus increasing their likelihood of being retained. Hippocampus and amygdala densely connected. Amygdala processes emotions, such as fear.