Chapter 2. For this chapter and the rest of the course try this site to study from. The Biology of Mind. The Biology of Mind 8/7/2015

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1 For this chapter and the rest of the course tr this site to stud from The Biolog of Mind Os6sCFYbsKgodFWrwhw Chapter 2 The Biolog of Mind Neural Communication Neurons How Neurons Communicate How Neurotransmitters Influence Us The Nervous Sstem The Peripheral Nervous Sstem The Central Nervous Sstem Neural Communication The bod s information sstem is built from billions of interconnected cells called neurons. The bod is composed of cells Among these are nerve cells that conduct electricit and talk to one another b sending chemical messages across a tin gap that separates them Specific brain sstems serve specific functions We integrate info processed in these different brain sstems to construct our experience of sights and sounds, meanings and memories, pain and passion Our adaptive brain is wired b our experience The Endocrine Sstem The Brain The Tools of Discover: Having our Head Examined Older Brain Structures The Cerebral Cortex Our Divided Brain Right-Left Differences in the Intact Brain 1

2 Neural Communication Neurobiologists and other investigators understand that humans and animals operate similarl when processing information. Neuron A nerve cell, or a neuron, consists of man different parts. Note the similarities in the above brain regions, which are all engaged in information processing. Axons Awa Parts of a Neuron Action Potential Cell Bod: Life support center of the neuron. Dendrites: Branching extensions at the cell bod. Receive messages from other neurons. Axon: Long single extension of a neuron, covered with melin [MY-uh-lin] sheathto insulate and speed up messages through neurons. A neural impulse. A brief electrical charge that travels down an axon and is generated b the movement of positivel charged atoms in and out of channels in the axon s membrane. Terminal Branches of axon: Branched endings of an axon that transmit messages to other neurons. Threshold Action Potential Properties Threshold:Each neuron receives excitator and inhibitor signals from man neurons. When the excitator signals minus the inhibitor signals exceed a minimum intensit (threshold) the neuron fires an action potential. All-or-None Response:A strong stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials strength or speed. Think of a flushing toilet: 1. When ou depress lever, toilet flushes the same each time 2. A softer push of the lever will not create a flush at all since it did not reach the threshold 3. Refractor period: in order to flush again ou must wait till enough water fills up the tank. You cannot have 2 flushes in a row Intensitof an action potential remains the same throughout the length of the axon. 2

3 Snapse Neurotransmitters Snapse [SIN-aps]ajunction between the axon tip of the sending neuron and the dendrite or cell bod of the receiving neuron. This tin gap is called the snaptic gapor cleft. Neurotransmitters (chemicals) released from the sending neuron travel across the snapse and bind to receptor sites on the receiving neuron, thereb influencing it to generate an action potential. Reuptake How Neurotransmitters Influence Us Neurotransmitters in the snapse are reabsorbed into the sending neurons through the process of reuptake. This process applies the brakes on neurotransmitter action. Serotonin pathwas are involved with mood regulation. From Mapping the Mind, Rita Carter, 1989 Universit of California Press Dopamine Pathwas Neurotransmitters Dopamine pathwas are involved with diseases such as schizophrenia and Parkinson s disease. From Mapping the Mind, Rita Carter, 1989 Universit of California Press 3

4 Wooooo hoooooo!!! Lock & Ke Mechanism Neurotransmitters bind to the receptors of the receiving neuron in a ke-lock mechanism. Mouse Part Agonists Antagonists Caffeine blocks Cclic AMP which makes ou feel like our not tired anmore Nervous Sstem The Nervous Sstem Central Nervous Sstem (CNS) Peripheral Nervous Sstem (PNS) Nervous Sstem:Consists of all the nerve cells. It is the bod s speed, electrochemical communication sstem. Central Nervous Sstem (CNS):the brain and spinal cord. Peripheral Nervous Sstem (PNS):the sensor and motor neurons that connect the central nervous sstem (CNS) to the rest of the bod. 4

5 The Nervous Sstem Kinds of Neurons Sensor Neuronscarr incoming information from the sense receptors to the CNS. Motor Neuronscarr outgoing information from the CNS to muscles and glands. Interneurons connect the two neurons. Interneuron Neuron (Unipolar) Sensor Neuron (Bipolar) Motor Neuron (Multipolar) Peripheral Nervous Sstem The Nerves Somatic Nervous Sstem:The division of the peripheral nervous sstem that controls the bod s skeletal muscles. Autonomic Nervous Sstem:Part of the PNS that controls the glands and other muscles. Nerves consist of neural cables containing man axons. The are part of the peripheral nervous sstemand connect muscles, glands, and sense organs to the central nervous sstem. Autonomic Nervous Sstem (ANS) Autonomic Nervous Sstem (ANS) Smpathetic Nervous Sstem:Division of the ANS that arouses the bod, mobilizing its energ in stressful situations. Parasmpathetic Nervous Sstem:Division of the ANS that calms the bod, conserving its energ. Smpathetic NS Arouses (fight-or-flight) Parasmpathetic NS Calms (rest and digest) 5

6 Central Nervous Sstem Central Nervous Sstem The Brain and Neural Networks Interconnected neurons form networks in the brain. Theses networks are complex and modif with growth and experience. The Spinal Cord and Reflexes Complex Neural Network Simple Reflex The Endocrine Sstem Hormones TheEndocrine Sstemisthe bod s slow chemical communication sstem. Communication is carried out b hormones snthesized b a set of glands. Hormonesare chemicals snthesized b the endocrine glands that are secreted in the bloodstream. Hormones affect the brain and man other tissues of the bod. For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar, and feelings of excitement during emergenc situations. Difference between hormones and neurotransmitters Onl difference is where the chemical is manufactured. Neurotransmitters are manufactured in neurons and other nervous sstem cells and located in the nervous sstem Hormones are manufactured b glands and based in the bod and bloddstream Pituitar Gland Is called the master gland. The anterior pituitar lobe releases hormones that regulate other glands. The posterior lobe regulates water and salt balance. 6

7 Throid & Parathroid Glands Regulate metabolic and calcium rate. Adrenal Glands Adrenal glands consist of the adrenal medulla and the cortex. The medulla secretes hormones (epinephrine and norepinephrine) during stressful and emotional situations, while the adrenal cortex regulates salt and carbohdrate metabolism. Gonads Sex glands are located in different places in men and women. The regulate bodil development and maintain reproductive organs in adults. If that last video helped Michael Britt The Psch Files I will post a link to m website. Check him out! He also has apps for the Iphone and mabe others now The Brain: Older Brain Structures TheBrainstemisthe oldest part of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival functions. Our brain stem is much like that of reptiles. Evolutionaril speaking, more than 200 million ears ago reptiles had preceded mammals. So it is sometimes referred to as the old brain The Medulla [muh- DUL-uh]is the base of the brainstem that controls heartbeat and breathing. Brainstem 7

8 The Thalamus [THALuh-muss]is the brain s sensor switchboard, located on top of the brainstem. It directs messages to the sensor areas in the cortex and transmits replies to the cerebellum and medulla. Brainstem Reticular Formationisa nerve network in the brainstem that plas an important role in controlling arousal. Brainstem Cerebellum The Brain Techniques to Stud the Brain The little brain attached to the rear of the brainstem. It helps coordinate voluntar movements and balance. A brain lesion experimentall destros brain tissue to stud animal behaviors after such destruction. Hubel (1990) Clinical Observation Clinical observations have shed light on a number of brain disorders. Alterations in brain morpholog due to neurological and pschiatric diseases are now being catalogued. Electroencephalogram (EEG) An amplified recording of the electrical waves sweeping across the brain s surface, measured b electrodes placed on the scalp. AJ Photo/ Photo Researchers, Inc. Tom Landers/ Boston Globe 8

9 PET Scan MRI Scan PET (positron emission tomograph) Scanis a visual displa of brain activit that detects a radioactive form of glucose while the brain performs a given task. Courtes of National Brookhaven National Laboratories MRI (magnetic resonance imaging)uses magnetic fields and radio waves to produce computergenerated images that distinguish among different tpes of brain tissue. Top images show ventricular enlargement in a schizophrenic patient. Bottom image shows brain regions when a participants lies. Both photos from Daniel Weinberger, M.D., CBDB, NIMH James Salzano/ Salzano Photo Luc Reading/ Luc Illustrations The Limbic Sstem The Limbic Sstemisa doughnut-shaped sstem of neural structures at the border of the brainstem and cerebrum, associated with emotions such as fear, aggression and drives for food and sex. It includes the hippocampus, amgdala, and hpothalamus. The Amgdala [ah-migdah-la]consists of two lima bean-sized neural clusters linked to the emotions of fear and anger. Amgdala The Hpothalamuslies below (hpo) the thalamus. It directs several maintenance activities like eating, drinking, bod temperature, and control of emotions. It helps govern the endocrine sstem via the pituitar gland. Hpothalamus Rats cross an electrified grid for self-stimulation when electrodes are placed in the reward (hpothalamus) center (top picture). When the limbic sstem is manipulated, a rat will navigate fields or climb up a tree (bottom picture). Reward Center Sanjiv Talwar, SUNY Downstate 9

10 The Cerebral Cortex The intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is the bod s ultimate control and information processing center. Structure of the Cortex Each brain hemisphere is divided into four lobes that are separated b prominent fissures. These lobes are the frontal lobe(forehead), parietal lobe(top to rear head), occipital lobe (back head) and temporal lobe(side of head). FPOT Functions of the Cortex sensor homunculus: diagram showing how the cortex is parsed out to different parts of bod according to function. Visual Function TheMotor Cortex is the area at the rear of the frontal lobes that control voluntar movements. The Sensor Cortex (parietal cortex) receives information from skin surface and sense organs. The functional MRI (detects blood flow in parts of the brain being used) scan shows the visual cortex is active as the subject looks at faces. Courtes of V.P. Clark, K. Keill, J. Ma. Maisog, S. Courtne, L.G. Ungerleider, and J.V. Haxb, National Institute of Mental Health Auditor Function Association Areas The functional MRI scan shows the auditor cortex is active in patients who hallucinate. More intelligent animals have increased uncommitted or association areas of the cortex. 10

11 Language Aphasiais an impairment of language, usuall caused b left hemisphere damage either to Broca s area(impaired speaking) or to Wernicke s area (impaired understanding). Specialization & Integration Brain activit when hearing, seeing, and speaking words The Brain s Plasticit The brain is sculpted b our genes but also b our experiences. Plasticitrefers to the brain s abilit to modif itself after some tpes of injur or illness. Our Divided Brain Our brain is divided into two hemispheres. The left hemisphere processes reading, writing, speaking, mathematics, and comprehension skills. In the 1960s, it was termed as the dominant brain. Splitting the Brain A procedure in which the two hemispheres of the brain are isolated b cutting the connecting fibers (mainl those of the corpus callosum) between them. Courtes of Terence Williams, Universit of Iowa Corpus call someone Corpus Callosum Communication between hemispheres Martin M. Rother Split Brain Patients With the corpus callosum severed, objects (apple) presented in the right visual field can be named. Objects (pencil) in the left visual field cannot. 11

12 Divided Consciousness Tr This! Tr drawing one shape with our left hand and one with our right hand, simultaneousl. BBC Right-Left Differences in the Intact Brain People with intact brains also show left-right hemispheric differences in mental abilities. A number of brain scan studies show normal individuals engage their right brain when completing a perceptual task and their left brain when carring out a linguistic task. 12