Modules 4 & 6. The Biology of Mind

Transcription

1 Modules 4 & 6 The Biology of Mind 1

2 Neuron Billion - Communication System

3 Glial cells Cell body (nucleus) Dendrites Axon Axon Terminals (terminal buttons) Synaptic cleft 3

4 4

5 Communication Within a Neuron Receptors on Dendrites - Sensory (chemical reactions) - Chemicals from other neurons - Chemicals from endocrine glands - Chemicals from outside sources (e.g., Drugs) Chemical Messages can be Excitatory or Inhibitory. Effect on dendrite is a summed effect. - threshold 5

6 Action Potential - all or none law - digital message (yes/no) - one strength - one speed - one way (dendrite to Axon) 6

7 Inside and outside of neuron are fluid environments. Fluid chemicals have ionic charges. - sodium and potassium Resting Potential - inside negative relative to outside. - sodium-potassium pump 7

8 If threshold is reached at dendrite, then an action potential begins. Gates in membrane open allowing sodium to flow in. Inside becomes more positive. Momentary change in charge. Passed along the membrane, carrying message to Axon Terminal. 8

9 Myelin Sheath - Nodes of Ranvier 9

10 Effects of Myelin Allows action potential to skip along the membrane. - speeds conduction. Brain neurons have no myelin (appear gray) Sensory and Motor neurons have myelin (appear white) 10

11 Myelin and Multiple Sclerosis 11

12 Terminal Branches Terminal Button Neurotransmitters (chemicals) are released into Synaptic space. 12

13 Communication - within neuron (electric potential). - between Neurons (neurochemical). 13

14 Neurotransmitters are cleared from the synaptic space by 1) re-uptake into the terminal button 2) destroyed by enzymes 14

15 Neurotransmitters effects on behavior depends on which receptor Acetylcholine (ACh) Motor control (paralysis) Attention and Memory (Alzheimer s) Dopamine Emotions, learning, memory & Motor control Too Much Schizophrenia Too Little Parkinson s 15

16 Serotonin too little associated with Depression Endorphins nature s pain killer 16

17 Hormones - Chemical Messengers released by endocrine glands into the blood system - many are identical to neurotransmitters - have wider reaching, longer lasting effects 17

18 Permanent Effects e.g., puberty Temporary effects e.g., metabolism (Insulin and Thyroxin) Hormones also effect mood e.g., premenstrual syndrome 18

19 Hormone Disorders Diabetes Thyroid disorders Depression Hormones as drugs Problem: They effect a wide range of functions = large number of side effects. 19

20 Fen/Phen (Redux) - effect hunger drive/increases metabolism - also effects maintenance of heart valve (lethal side effect) Steroids - effect development of muscles - also effects mood and thought processes in the brain. 20

21 Nervous System 21

22 Nervous System Central Nervous System (CNS) - Brain and Spinal Cord Spinal Cord 1. carries messages to & from Brain Sensory Neurons Sensory info to CNS Motor Neurons from CNS to muscles and glands 22

23 2. Reflexes - fast, automatic actions Sensory message Interneuron Motor Message 23

24 Autonomic Nervous System 1) Sympathetic - readies the body for fight or flight Heart rate Blood Pressure breathing Digestion 2) Parasympathetic - relaxation response 24

25 Module 5 Older Brain Structures Thalamus Reticular formation Pons & Medulla Cerebellum Limbic system Hypothalamus * Know the major functions 25

26 Module 6 Cerebral Cortex Sensory- motor functions use about 20% of cortex. Association Areas. (thinking, memory...) uses about 80% of cortex 26

27 Localization of Function Specific areas of the brain have specific functions. Damage to specific areas produces specific function deficits. 27

28 Ways of studying the brain 1) Lesion studies (done on animals) 2) Case studies of brain damaged individuals. - relate behavior to brain areas. 3) Imaging techniques CAT scans PET scans FMRI 28

29 Cortex has 2 halves (hemispheres) Each controls opposite side of the body. Each hemisphere has 4 lobes 1) Frontal Lobe - Primary motor cortex (controls movement) - prefrontal cortex (planning of movements and working memory) 29

30 Frontal Lobotomies Nerve connections to the prefrontal lobe are severed. - done to control violence and aggression Results: loss of ability to plan and carry out even simple tasks. 30

31 2) Parietal Lobe - primary somatosensory cortex Sensations and location of body parts Unilateral Neglect - can sense the neglected side but fail to to attend to it. 31

32 3) Occipital lobe - primary visual cortex 4) Temporal Lobe - primary auditory (hearing) area. - complex aspects or vision - face blindness - motionblindness 32

33 Corpus Callosum Band of Neurons connecting the two hemispheres. Video 33

34 Split Brain Studies Left Hemisphere - Language - critical thought (making sense) Right hemisphere - spatial ability - face recognition 34

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37 Within the left hemisphere there are 2 areas for language Brocas s area - frontal lobe - production of speech Wernike s area - temporal lobe - comprehension of speech Damage causes aphasia (speech disorder) 37

38 Can a person recover from brain damage? - neurons are not replaced. - plasticity of the brain - other parts take over function of damaged parts. - requires retraining 38