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Chapter 2: Brain and Behavior. Neuron and Its Parts Neuron: Individual nerve cell; 100 billion in brain –Dendrites: Receive messages from other neurons.

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Presentation on theme: "Chapter 2: Brain and Behavior. Neuron and Its Parts Neuron: Individual nerve cell; 100 billion in brain –Dendrites: Receive messages from other neurons."— Presentation transcript:

1 Chapter 2: Brain and Behavior

2 Neuron and Its Parts Neuron: Individual nerve cell; 100 billion in brain –Dendrites: Receive messages from other neurons –Soma: Cell body; body of the neuron –Axon: Carries information away from the cell body –Axon Terminals: Branches that link the dendrites and soma of other neurons

3 Figure 2.1

4 Main Parts of the Neuron

5 Figure 2.2

6 The Nerve Impulse Resting Potential: Electrical charge of an inactive neuron Threshold: Trigger point for a neuron’s firing Action Potential: Nerve impulse

7 More on Nerves Ion Channels: Tiny holes through the axon membrane Negative After-Potential: When a neuron is less willing to fire Synapse: Microscopic space between two neurons over which messages pass

8 Figure 2.3

9 Figure 2.4

10 Windows Mac OS 8-9Mac OS X Neuron and Neural Impulse

11 Neurotransmitters Chemicals that alter activity in neurons; brain chemicals –Acetylcholine: Activates muscles –Dopamine: Muscle control –Serotonin: Mood and appetite control Receptor Site: Areas on the surface of neurons and other cells that are sensitive to neurotransmitters or hormones

12 Normal Synaptic Transmission of Dopamine

13 Windows Mac OS 8-9Mac OS X Synaptic Transmission

14 Figure 2.6

15 Neural Regulators Neuropeptides: Brain chemicals that regulate activity of other neurons –Enkephalins: Relieve pain and stress; similar to endorphins –Endorphins: Released by pituitary gland; also help to relieve pain Placebos raise endorphin levels

16 Interaction of Endorphins & Opiates

17 Nerves and Neurons Nerves: Large bundles of axons and dendrites Myelin: Fatty layer of tissue that coats axons –Multiple Sclerosis (MS) occurs when myelin layer is destroyed; numbness, weakness, and paralysis occur

18 Nerves and Neurons (cont.) Neurilemma: Thin layer of cells wrapped around axons outside brain and spinal cord; forms a tunnel that damaged fibers can follow as they repair themselves Neurogenesis: Production of new brain cells; brain loses thousands of cells each day and grows new neurons at same time to replace them

19 Neural Networks Central Nervous System (CNS): Brain and spinal cord Peripheral Nervous System: All parts of the nervous system outside of the brain and spinal cord

20 Two Divisions of the Peripheral Nervous System Somatic System: Links spinal cord with body and sense organs; controls voluntary behavior Autonomic System: Serves internal organs and glands; controls automatic functions such as heart rate and blood pressure

21 Two Divisions of the Autonomic Nervous System Sympathetic: Arouses body; emergency system Parasympathetic: Quiets body; most active after an emotional event

22 Figure 2.7

23 Figure 2.8

24 Figure 2.9

25 The Spinal Cord Spinal Nerves: 31 of them; carry sensory and motor messages to and from the spinal cord Cranial Nerves: 12 pairs that leave the brain directly without passing through the spinal cord; also work to communicate messages

26 The Spinal Cord and Behavior Reflex Arc: Simplest behavior in which a stimulus provokes an automatic response Sensory Neuron: Nerve cell that carries messages from the senses toward the CNS Motor Neuron: Cell that carries commands from the CNS to the muscles and glands Effector Cells: Cells capable of producing a response

27 Researching the Brain Ablation: Surgical removal of tissue Deep Lesioning: A thin wire electrode is lowered into a specific area inside the brain; Electrical current is then used to destroy a small amount of brain tissue Electrical Stimulation of the Brain (ESB): When an electrode is used to activate target areas in the brain Electroencephalograph (EEG): A device that detects, amplifies, and records electrical activity in the brain

28 Figure 2.10

29 Brain Imaging Techniques Computed Tomographic Scanning (CT): Computer-enhanced X-ray of the brain or body Magnetic Resonance Imaging (MRI): Uses a strong magnetic field, not an X-ray, to produce an image of the brain and body

30 More Brain Imaging Techniques Functional MRI (fMRI): MRI that makes brain activity visible Positron Emission Tomography (PET): Computer-generated color image of brain activity, based on glucose consumption in the brain

31 Figure 2.11

32 Figure 2.16

33 Cerebral Cortex Outer layer of the cerebrum Cerebrum: Two large hemispheres that cover upper part of the brain Corticalization: Increase in size and wrinkling of the cortex Cerebral Hemispheres: Right and left halves of the cerebrum Spatial Neglect: Right hemisphere stroke victims pay no attention to the left side of visual space

34 Split Brains Corpus Callosum: Bundle of fibers connecting cerebral hemispheres In Split Brains, Corpus Callosum is cut; done to control severe epilepsy (seizure disorder) Result: The person now has two brains in one body This operation is rare and is often used as a last resort

35 Figure 2.21

36 The Corpus Callosum

37 Figure 2.18

38 Right Brain/Left Brain Humans use 95 percent of our left brain for language

39 The Left Hemisphere Left hemisphere is better at math, judging time and rhythm, and coordinating order of complex movements –Processes information sequentially

40 The Right Hemisphere Right hemisphere is good at perceptual skills, and at expressing and detecting other’s emotions –Processes information simultaneously

41 Figure 2.20

42 Figure 2.30

43 Central Cortex Lobes Areas bordered by major grooves or fissures or defined by their functions Occipital Lobe: Back of brain; vision center Parietal Lobe: Just above occipital; bodily sensations such as touch, pain, and temperature (somatosensory area)

44 The Occipital Lobe

45 The Parietal Lobe

46 The Last Two Lobes Temporal Lobe: Each side of the brain; auditory and language centers Frontal Lobe: Movement, sense of smell, higher mental functions –Contains motor cortex; controls motor movement

47 Figure 2.23

48 The Temporal Lobe

49 The Frontal Lobe

50 Figure 2.24

51 When the Brain Fails to Function Properly Association Cortex: All areas of the cerebral cortex that are not primarily sensory or motor in function Aphasia: Speech disturbance resulting from brain damage

52 Broca’s Area Language area related to grammar and pronunciation –If damaged, person knows what s/he wants to say but can’t say the words

53 Wernicke’s Area Wernicke’s Area: Related to language comprehension; in left temporal lobe –If damaged, person has problems with meanings of words, NOT pronunciation

54 Figure 2.28

55 Subcortex All brain structures below cerebral cortex; immediately below cerebral hemispheres Hindbrain (Brainstem) Medulla: Connects brain with the spinal cord and controls vital life functions such as heart rate and breathing

56 More Subcortex Structures Pons (Bridge): Acts as a bridge between brainstem and other structures; influences sleep and arousal Cerebellum: Located at base of brain; regulates posture, muscle tone, and muscular coordination

57 The Brainstem

58 Subcortex: Reticular Formation (RF) Reticular Formation: Inside medulla and brainstem –Associated with alertness, attention, and some reflexes (breathing, coughing, sneezing, vomiting) Reticular Activating System (RAS): Part of RF that activates cerebral cortex –Its alarm clock

59 Forebrain Structures are part of Limbic System: System within forebrain closely linked to emotional response and motivating behavior Thalamus: Relays sensory information on to the cortex; switchboard Hypothalamus: Regulates emotional behaviors and motives (e.g., sex, hunger, rage, hormone release)

60 More Forebrain Structures Amygdala: Associated with fear responses Hippocampus: Associated with storing permanent memories; helps us navigate through space

61 The Limbic System

62 Figure 2.27

63 Figure 2.26

64 Endocrine System Glands that pour chemicals (hormones) directly into the bloodstream or lymph system Pituitary Gland: Regulates growth via growth hormone

65 Pituitary Problems Too little means person will be smaller than average –Hypopituitary Dwarfs: As adults, perfectly proportioned but tiny –Treatable by using growth hormone; will add a few inches –Treatment is long and expensive

66 Endocrine System (cont.) Too much growth hormone leads to giantism (excessive body growth) Acromegaly: Enlargement of arms, hands, feet, and facial bones; due to too much growth hormone released late in growth period –Andre the Giant Pituitary also governs functioning of thyroid, adrenals, and gonads

67 Figure 2.29

68 The Pineal Gland Regulates body rhythms and sleep cycles –Releases hormone melatonin, which responds to daily variations in light

69 The Thyroid Gland Thyroid: In neck; regulates metabolism –Hyperthyroidism: Overactive thyroid; person tends to be thin, tense, excitable, nervous –Hypothyroidism: Underactive thyroid; person tends to be inactive, sleepy, slow, obese

70 The Adrenal Glands Adrenals: Arouse body, regulate salt balance, adjust body to stress, regulate sexual functioning; located on top of kidneys –Releases epinephrine and norepinephrine (also known as adrenaline and noradrenalin)

71 The Adrenal Glands (cont.) Adrenal Medulla: Source of epinephrine and norepinephrine Adrenal Cortex: Produces hormones known as corticoids –Regulate salt balance –Deficiency in some types will cause powerful salt cravings in humans

72 Adrenal Hormones Epinephrine arouses body; is associated with fear Norepinephrine arouses body; is linked with anger

73 Adrenal Problems Oversecretion of adrenal sex hormones can cause virilism: exaggerated male characteristics (Bearded woman) –May also cause premature puberty if occurs early in life

74 Figure 2.31

75 Handedness Preference for right or left hand in most activities Dominant Hemisphere: Term usually applied to the side of the human brain that produces language Lateralization: Specialization in abilities of brain hemispheres

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