Introduction to Physiological Psychology

Transcription

1 Introduction to Physiological Psychology Review Kim Sweeney Today n Discuss Final Paper Proposal (due 3/10) n General Review 1

2 The article you choose for your final paper. n Scholarly Journal n Original Research Report n Related to the material we have covered/will cover in class n Topic you find interesting n At a level that feels achievable n Popular Press n Review article, Editiorial n Related to humanities, arts, history n Topic that puts you to sleep n At a level that feels hopeless Split Brains n Why do it? 2

3 The Nervous System n Reduction What s the point? n Generalization 3

4 Three major debates n Monism vs. n vs. Holism n Is the mind merely a product of brain activity? Can consciousness be reduced to neuronal activity? (Some) important names in the history of Behavioral Neuroscience n Descartes n Galvani n Muller n Flourens n Helmholtz n Golgi n Ramon y Cajal 4

5 The Nervous System n The nervous system is an electrochemical communication system that does 4 things: 1. It receives sensory messages from the external environment. 2. It organizes information and integrates it with already stored information. 3. It uses integrated information to send out messages to muscles and glands, producing organized movement and secretions. 4. It provides the basis for conscious experience. The Nervous System n Central Nervous System Brain and Spinal Cord n Peripheral Nervous System Everything else Image from BodyWorlds Exhibit 5

6 The Central Nervous System n Brain and Spinal Cord Well protected! n Command Center : Processes incoming information Processes senses, thoughts, emotions, behaviors Sends orders out to rest of body CNS - Directions Top, Superior, Dorsal Front, Anterior, Rostral Back, Posterior, Caudal Bottom, Inferior, Ventral 6

7 The Peripheral Nervous System SOMATIC Nervous System (interacts with the environment) AUTONOMIC Nervous System (regulates the body s internal environment) How information travels n What is the difference btwn afferent and efferent? n What kind of information is brought to the CNS via the somatic afferent nerves? n How about the autonomic afferent nerves? 7

8 Efferent Nerves of the ANS n SYMPATHETIC Nerves: MOVE!! Arousal, mobilization of resources n PARASYMPATHETIC Nerves: RELAX!! Preservation of resources Sympathetic Branch n Responds to physical or emotional challenge n Arouses the body n Fight-or-flight Pupil dilation Increased heart rate Parasympathetic Branch n Performs maintenance functions n Calms body to promote homeostasis n Rest and restore (/ and digest ) Pupil contraction Decreased heart rate 8

9 Planes in the Human Brain The image cannot be displaye Horizontal Midsagittal Coronal 9

10 Four Views of the Brain a. b. c. d. Humans walk on just two legs. They mess the whole system up!! 10

11 n Lateral n Medial n Ipsilateral n Contralateral The protection 11

12 The treasure Motor Cortex Sensory Cortex Frontal Parietal Occipital Temporal Cerebral Cortex- what makes us special! 12

13 Central Nervous System (CNS) n Motor cortex Controls all voluntary movement n Sensory cortex Registers and processes sensations Basic Structure of a Neuron 13

14 Differences between axons and dendrites: n Axons Take info from the cell body Smooth surface Generally only one per cell Are often myelinated Branch far (sometimes very far!) from the cell body n Dendrites Bring info to the cell body Rough surface (dendritic spines) Usually many per cell No myelin Branch near the cell body Cells of the Nervous System n Neurons: a nerve is a bundle of (axons of) neurons Specialized cells for the reception, conduction, and transmission of electrochemical signals Many sizes and shapes 14

15 Different kinds of neurons n Sensory Neurons: Connect sense receptors (e.g. skin, retina) to interneurons in the central nervous system n Interneurons: CNS neurons that process this information and transmit signals out to motor neurons. n Motor Neurons: carry outgoing information from central nervous system to other areas (muscles, glands) Types of glia 15

16 The withdrawal reflex Excitatory effects An inhibited withdrawal reflex n T The brain inhibits the motor neuron to prevent the dish from dropping 16

17 The Neuron s Resting Membrane Potential n Difference in electrical charge between inside and outside of cell n Inside of the neuron is with respect to the outside n Resting membrane potential is about n Membrane is polarized (carries a charge) The Neuron at Rest n Na + n K. n Cl - is at equilibrium n Sodium-potassium pump active force that exchanges 3 Na + inside for 2 K + outside 17

18 Spatial summation Temporal summation The Action Potential n To fire or not to fire n Neurons receive excitatory and inhibitory signals (PSPs) An action potential is only triggered if the minimum threshold for net excitatory signals is reached All or none phenomenon 18

19 Rising Phase of the Action Potential n A stimulus causes the membrane potential to depolarize n When partial depolarization reaches the activation threshold, voltage-gated sodium (Na+) ion channels open: n Sodium ions rush in, so n The membrane potential hits the threshold of excitation (~ -65mV) and continues to depolarize (get more positive). +" Na +" -" -" Na +" Na +" +" Action potentials: Repolarization n Sodium ion channels close. n Depolarization triggers opening of voltage-gated potassium ion channels, so n K+ ions rush out of the cell, repolarizing and then (briefly) hyperpolarizing the membrane. Na +" K +" K +" +" Na +" Na +" K +" -" 19

20 The Action Potential Absolute Refractory Period n The moment the membrane potential hits +50 mv Na + voltage-gated channels are closed K + voltage-gated channels are opened. This causes K + ions to flow out, causing a repolarization of the membrane. n The period from the time the Na + voltage-gated channels are closed and the K + voltage-gated channels are opened to the time when the K + voltage-gated channels are closed again, is called the absolute refractory period: no further action potential can occur: The Na + voltage-gated channels are completely closed, so membrane cannot be depolarizated with an influx of Na + Ions 20

21 Relative Refractory Period n After the absolute refractory period, both Na+ and K+ voltage-gated channels remain closed for a time. Membrane potential is thus hyperpolarized (even more negative than at rest ) It would take more/stronger stimuli to bring the potential to threshold in order to create another action potential This period is called the relative refractory period The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. A. Depolarization B. Absolute refractory period (repolarization) C. Relative refractory period (hyperpolarization) What happens at the other end? 21

22 n Neurons communicate via electrochemical signals. The action potential is the electro part. Synaptic Transmission is the chemical part. How do we know that neurons communicate chemically? Synaptic Transmission of Chemical Signals: Structure of Synapses n Most common Axodendritic Axosomatic n Less common Dendrodendritic capable of transmission in either direction Axoaxonic may be involved in presynaptic facilitation/ inhibition 22

23 Anatomy of a synapse n Presynaptic membrane n Synaptic Cleft n Postsynaptic membrane What happens on the other side? n After crossing the synaptic cleft, the neurotransmitter binds to postsynaptic receptors. n Two kinds of receptors: Ionotropic receptors: Open ligand-activated ion channels- immediate PSP Metabotropic receptors: Activate signal proteins & G proteins- slower (and sometimes longer lasting) effect 23

24 Requirements at the synapse For the synapse to work properly, six basic events need to happen: n Production of the neurotransmitters Packaged in synaptic vesicles by Golgi complex n Storage of neurotransmitters n Release of neurotransmitters (exocytosis) n Binding of neurotransmitters to post-synaptic cell Lock and key mechanism n Generation of an action potential n Removal of neurotransmitters from the synapse: Reuptake, enzymatic degradation Reuptake, Enzymatic Degradation, and Recycling n As long as NT is in the synapse, it is active activity must somehow be turned off n Reuptake scoop up and recycle NT n Enzymatic degradation a NT is broken down by enzymes 24

25 Methods fmri n High Spatial Resolution n Low Temporal Resolution n Sensitive to what sorts of cognitive processes active n Good for mapping the brain and localizing function n Measures oxygen flow ERPs n Low Spatial Resolution n High Temporal Resolution n Sensitive to what sorts of cognitive processes active n Good for studying temporal order of cognitive processes that unfold rapidly in time n Measures electrical activity 25