Biological Bases of Behavior. It is all about the body!!!!

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1 Biological Bases of Behavior It is all about the body!!!!

2 Psychology and Biology Everything psychological is simultaneously biological. To think, feel or act without a body would be like running without legs. We are bio-psycho-social systems. To understand our behavior, we need to study how biological, psychological and social systems interact.

3 The Brain, The Mind and Psychology The human brain is the most complex system, natural or man made, in the world. About 3 lbs. Pinkish/gray in color About 100 billion nerve cells At a loss rate of 200,000 per day during our adult lives we still end up with over 98% of or brain cells. Relative Size of Human Brain Nerve Cells

4 Biopsychology Biopsychology: The specialty in psychology that studies the interaction of biology, behavior and mental processes. The mind thinking about the mind.

5 How Your Body Communicates Internally, your body has two communication systems. One works quickly, your nervous system, and one works slowly, your endocrine system. Endocrine System

6 The Nervous System It starts with an individual nerve cell called a NEURON.

7 Neurons: Our Building Blocks Neurons are cells specialized to receive, process and transmit information to other cells. Bundles of neurons are called nerves. 1. Axon 2. Dendrite 3. Motor neuron 4. Bundle of neurons 5. Outer sheath 6. Sensory neurons 7. Blood vessels

8 Neurons: The Messengers About 100 billion neurons (nerve cells) in the human brain Neurons have many of the same features as other cells Nucleus Cytoplasm Cell membrane

9 What a Neuron Looks Like

10 3 main tasks of neurons A neuron exists to perform 3 tasks: 1.) Receive information from the neurons that feed it. 2.) Carry information down its length. 3.) Pass the information on to the next neuron.

11 How Neurons Work The dendrite, or receiver part of the neuron, which accepts most of the incoming messages. Consists of finely branched fibers. Selectively permeable

12 How Neurons Work Dendrites complete their job by passing the incoming message on to the central part of the neuron called the soma. The soma, or cell body, contains the cell s nucleus and life-support machinery. The function of the soma is to assess all messages the cell receives and pass on the appropriate information, at the appropriate time.

13 How a Neuron Works When the soma decides to pass-on a message, it sends the message down the axon. The axon is a single, larger transmitter fiber that extends from the soma. This is a one way street

14 Axon The axon is the extension of the neuron through which the neural impulses are sent. Carries information to the next cell In some neurons, like those of the brain, the axons are very short. In others, like those in the leg, they can reach 3 feet long.

15 Myelin Sheath Protects & insulates the axon and the electric signal E.g. the orange plastic coating on an electrical cord. Speeds up the neural impulse Made up of Schwann cells (specific type of glial cells) Video: How does a Neuron work? t322-xxi#t=173

16 3 Types of Neurons While neurons can be different sizes and shapes, they all share a similar structure and function in a similar way. Neurons are broken into three categories based on their location and function: -Sensory Neurons -Motor Neurons -Interneurons

17 Types of Neurons Sensory neurons Sensory neurons, or afferent neurons, act like one-way streets that carry traffic from the sense organs toward the brain. The sensory neurons communicate all of your sensory experience to the brain, including vision, hearing, taste, touch, smell, pain and balance.

18 Types of Neurons Motor neurons Motor neurons, or efferent neurons, form the one-way routes that transport messages away from the brain to the muscles, organs and glands.

19 Types of Neurons Sensory and motor neurons do not communicate directly with each other. Instead, they rely on a middle-man. Interneurons Make up the majority of our neurons Relay messages from sensory neurons to other interneurons or motor neurons in complex pathways.

20 Action potential When the cell becomes excited, it triggers, which reverses the charge and causes the electrical signal to race along the axon. How does a Neuron fire? Resting potential The axon gets its energy from charged chemicals called ions. Has a slight negative charge This negative balance can be easily upset

21 Absolute Threshold The neuron is a mini decision maker. It receives information from thousands of other neurons-some excitatory (like pushing the gas pedal). Others are inhibitory (like pushing the breaks). If the excitatory signals, minus the inhibitory signals exceed a minimum intensity, called the absolute threshold, then action potential is realized.

22 Refractory Period Each action potential is followed by a brief recharging period known as the refractory period. After the refectory period, the neuron is capable of another action potential. Much like waiting for the flash to recharge on a disposable camera before you can take another picture.

23 The Neural Impulse Absolute refractory period Period immediately after an action potential when another action potential cannot occur Relative refractory period Period following absolute refractory period when a neuron will only respond to a stronger than normal impulse

24 All or Nothing Once the action potential is released, there is no going back. The axon either fires or it does not. This process is called the all-or-none principal. How do we detect a gentle touch from a slap? A strong stimulus, like a slap, can trigger more neurons to fire, more often, but not any stronger. Squeezing a trigger harder wont make the bullet go faster.

25 Depolarization & Polarization Depolarization Depolarized describes an axon that is firing Positive ions enter the axon, and cause other positive ions to move into the axon in the form of a neural impulse down the axon. Polarization "Polarized" describes an axon that is not firing Outside Axon = + ions Inside Axon= - ions

26 The Neural Impulse Graded Potentials A temporary shift in the electric charge in a tiny area of a neuron; transmitted along the cell membrane and may fade away if it doesn t reach its threshold of excitement Many subthreshold depolarizations are added together to produce an action potential (a process known as summation)

27 Neural Communication Cell body end of axon Direction of neural impulse: toward axon terminals

28 How Cells Connect Neurons do not actually touch each other to pass on information. The gap between neurons is called the synapse, synaptic space or synaptic cleft The synapse acts as an electrical insulator, preventing an electrical charge from racing to the next cell. Composed of the terminal button of one neuron, the synaptic space, and the dendrites or cell body of the receiving neuron

29 How Cells Connect To pass across the synaptic gap, or synaptic cleft, an electrical message must go through a change in the terminal buttons. This change is called synaptic transmission, and the electrical charge is turned into a chemical message that flows easily across the synaptic cleft.

30 How Cells Connect In the terminal buttons are small sacs called synaptic vesicles. These vesicles contain neurotransmitters (Chemicals released by synaptic vesicles) which are chemicals used in neural communication. Neurotransmitter molecules take 1/ th of a second to cross the synaptic gap When the action potential reaches the vesicles, they are ruptured and the transmitters spill out. If they have the right fit, the transmitters fit into the receptors like a key into a lock. Receptor sites: location on receptor neuron for specific neurotransmitter

31 Neural Communication

32 Reuptake Cells are very efficient. Neurotransmitters that are not absorbed by the connecting dendrite are reabsorbed by the sending neuron in a process called reuptake. The process of reuptake, for example, affects serotonin.

33 Some Neurotransmitters and Their Functions Neurotransmitter Function Examples of Malfunction Acetylcholine (ACh) Enables muscle action, learning and memory. With Alzheimer s disease, ACh producing neurons deteriorate. Dopamine Serotonin Influences movement, learning, attention and emotion. Affects mood, hunger, sleep and arousal. Excess dopamine receptor activity is linked to schizophrenia. Starved of dopamine, the brain produces the tremors and decreased mobility of Parkinson s disease. Undersupply linked to depression. Prozac and some other antidepressants raise serotonin levels. Norepinephrine Helps control alertness and arousal. Undersupply can depress mood. GABA (gamaaminobutyric acid) A major inhibitor neurotransmitter. Undersupply linked to seizures, tremors and insomnia. Glutamate A major excitatory neurotransmitter; involved in memory. Oversupply can overstimulate brain, producing migraines or seizures (which is why some people avoid MSG). **Neurotransmitters can function differently depending on where they are located in the nervous system.

34 Endorphins Feel good chemical Many of our most addictive drugs deal with endorphins. Also released during exercise Endorphins are not neurotransmitter molecules Classified as neuromodulatory, (modify the action of neurotransmitters through a number of effects associated with pain or pleasure).

35 How does it work? Neural Communication: Drugs can be. Agonists (excite) - make neuron fire They do this by amplifying or mimicking the sensation Agonist-opiates mimic the high produced naturally Antagonists (inhibit)- stop neural firing blocking the absorption of our neurotransmitters Antagonist-botulin blocks ACh (enables muscle action) Reuptake Inhibitors- block reuptake

36 Neural Communication Neurotransmitter molecule Receiving cell membrane This NT molecule fits the receptor site on the receiving neuron much like a lock and key. Receptor site on receiving neuron Agonist mimics neurotransmitter This agonist molecule excites. It is similar enough to the NT to mimic its effects on the receiving neuron. Morphine, for example mimics the actions of endorphins*. Antagonist blocks neurotransmitter This antagonist molecule inhibits. It has a structure similar enough to the NT to occupy the receptor cite and block its action, but not similar enough stimulate. Botulin, a food borne poison causes paralysis by blocking Ach release same as Botox!. *Endorphins are natural, opiate like NTs that are linked to pain control and pleasure.

37 Psychopharmacology Most psychoactive drugs (and toxins) work by blocking or enhancing synaptic transmission Botulism Blocks release of ACh at the neuromuscular junction, causing paralysis Botox is botulism toxin used to prevent facial muscles from making wrinkles

38 Caffeine Increases the release of excitatory neurotransmitters by blocking the inhibitory neurotransmitter adenosine Psychopharmacology Curare Can stun or kill prey quickly Blocks ACh receptors causing paralysis Antipsychotic medications Block dopamine receptors Reduces schizophrenic hallucinations

39 Psychopharmacology Cocaine Prevents reabsorption of dopamine Leads to heightened arousal of entire nervous system

40 Neural Plasticity The brain can be changed, both structurally and chemically, by experience. The ability for our brains to form new connections after the neurons are damaged. The younger you are, the more plastic your brain is. Rat studies show that an enriched environment leads to larger neurons with more connections Has also been shown in humans Recent research has uncovered evidence of neurogenesis, or the production of new brain cells, in human brains

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42 Central Nervous System The Brain and spinal cord

43 The Spinal Cord Complex cable of nerves that connects brain to rest of the body Carries motor impulses from the brain to internal organs and muscles Carries sensory information from extremities and internal organs to the brain

44 Peripheral Nervous System All nerves that are not encased in bone. Everything but the brain and spinal cord. Is divided into two categories.somatic and autonomic.

45 Somatic Nervous System Controls voluntary muscle movement. Uses motor (efferent) neurons.

46 Autonomic Nervous System Controls the automatic functions of the body. Divided into two categories the sympathetic and the parasympathetic

47 Sympathetic Nervous System Fight or Flight Response. Automatically accelerates heart rate, breathing, dilates pupils, slows down digestion.

48 Parasympathetic Nervous System Automatically slows the body down after a stressful event. Heart rate and breathing slow down, pupils constrict and digestion speeds up.

49 Reflexes Normally, sensory (afferent) neurons take info up through spine to the brain. Some reactions occur when sensory neurons reach just the spinal cord. Survival adaptation.

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51 The Brain Made up of neurons and glial cells. Glial cells support neural cells.

52 Glial Cells Cells that insulate and support neurons Create the myelin sheath Remove waste products Provide nourishment Prevent harmful substances from entering the brain

53 Ways to study the Brain!!! Accidents: Phineas Gage "American Crowbar Case". Phineas P. Gage ( ) was an American railroad construction Improbable survival of an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe Injury reported effects on his personality and behavior over the succeeding twelve years effects so profound that (for a time at least) friends saw him as "no longer Gage."

54 Electrical Recordings Mapping brain function requires working brain Neuroscientists- conduct research on brain or nervous system Electrical Recordings records electrical activity Electroencephalograph (EEG) monitors electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp Invented by Hans Berger Sums & amplifies potentials in the brain

55 Electric Recordings 6-10 recording electrodes attached to skull Translated into brain waves Different brain waves associated with different states of mental activity Used to diagnose brain damage and neurological disorders

56 Lesioning Lesioning destroying a piece of brain Inserting electrode into brain structure & passing high frequency electric current through it Burns tissue & disables structure Use stereotaxic instrument device used to implant electrodes at precise locations of the brain

57 Electrical Stimulation of Brain AKA ESB involves sending a weak electric current into a brain structure to activate it Delivered through electrode, but current is different Close but doesn t duplicate normal signals

58 CT Scans Computerized Tomography Scan (CT) computer enhanced X ray of brain structure Multiple x rays shot Computer combines images to make vivid horizontal slice of brain Least expensive Used to look for abnormalities in brain

59 Position Emission Tomography Scan (PET) Examine brain function, mapping out actual activity in the brain over time. Radioactively tagged chemicals introduced into brain Serve as markers for blood flow or metabolic activity Can be monitored by X rays Provide color coded map of brain

60 MRI & fmri Scan Magnetic Resonance Imaging Scan (MRI) uses magnetic fields, radio waves, & computerized enhancements to map out brain structure Better images than CT scans 3 dimensional pictures with high resolution Functional Magnetic Resonance Imaging (fmri) consists of several variations of MRI technology that monitor blood and oxygen flow in the brain to identify areas of high activity Provides structural & functioning information in same image Monitors brain activity in real time

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62 The Brain For creatures with more complex brains, there are three levels. Creatures with complex brains all share a similar stalk, the brain stem. The brain stem is the part of the brain with the longest ancestry Even the most simple creatures have this part of the brain On top of the brain stem, in more evolved creatures, are the limbic system and the cerebral cortex.

63 The Brain Stem Connects brain to the spinal cord The brain stem is made up of four regions: medulla pons reticular formation thalamus.

64 Brain Structures Some scientists divide the brain up into three parts. Hindbrain Midbrain Forebrain

65 Hindbrain Structures on top of our spinal cord. Controls basic biological structures. The brain in purple makes up the hindbrain.

66 Medulla Oblongata Located just above the spinal cord. Heart rate Breathing Blood Pressure The medulla operates on autopilot without our conscious awareness, like most of our brainstem.

67 Pons Located just above the medulla. Connects hindbrain, midbrain and forebrain together. Maintains the sleep-wake cycle Involved in facial expressions.

68 Cerebellum Bottom rear of the brain-means little brain. Coordinates fine muscle & body movements. Like tracking a target.

69 Midbrain Midbrain & Forebrain Coordinates simple movements with sensory information. Contains the reticular formation: arousal and ability to focus attention. Forebrain Makes us human. Largest part of the brain. Made up of the Thalamus, Limbic System and Cerebral Cortex.

70 Thalamus In Forebrain Receives sensory information and sends them to appropriate areas of forebrain. Like a switchboard. Everything but smell.

71 Limbic System EMOTIONAL CONTROL CENTER of the brain. Made up of Hypothalamus, Amygdala and Hippocampus.

72 Hypothalamus Pea sized in brain, but plays a not so pea sized role. Body temperature Hunger Thirst Sexual Arousal (libido) Endocrine System

73 Hippocampus & Amygdala Hippocampus is involved in memory processing. Amygdala is vital for our basic emotions. More involved in volatile emotions like anger.

74 Cerebral Cortex Top layer of our brain. Contains wrinkles called fissures. The fissures increase surface area of our brain. Made up of densely packed neurons we call gray matter Glial Cells: support brain cells. Laid out it would be about the size of a large pizza.

75 Areas of the Cerebral Cortex Divided into eight lobes, four in each hemisphere (frontal, parietal, occipital and temporal). Any area not dealing with our senses or muscle movements are called association areas.

76 Frontal Lobe Abstract thought and emotional control. Contains Motor Cortex: sends signals to our body controlling muscle movements. Contains Broca s Area: responsible for controlling muscles that produce speech. Damage to Broca s Area is called Broca s Aphasia: unable to make movements to talk.

77 Parietal Lobes Contain Sensory Cortex: receives incoming touch sensations from rest of the body. Where would this girl feel the most pain from her sunburn? Most of the Parietal Lobes are made up of Association Areas.

78 Association Areas Any area not associated with receiving sensory information or coordinating muscle movements.

79 Motor and Sensory Cortexes

80 Occipital Lobes In the back of our head. Handles visual input from eyes. LATERALIZED - predominantly on one side. Right half of each retina goes to left occipital lobe and vice versa. Contains Visual Cortex: interprets messages from our eyes into images we can understand.

81 Temporal Lobes Process sound sensed by our ears. Interpreted in Auditory Cortex. NOT LATERALIZED. Contains Wernike's Area: interprets written and spoken speech. Wernike's Aphasia: unable to understand language: the syntax and grammar jumbled.

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83 Specialization and Integration in Language

84 Brain Activity when Hearing, Seeing, and Speaking Words A Stroke of Insight Case Study

85 Hemispheres Divided into a left and right hemisphere. Contralateral (opposite side)-controlled- left controls right side of body and vice versa. Pop" psychology myth- Lefties better at being creative, righties better at logic. not supported through research on lateralization Both hemispheres contribute to both kinds of processes

86 Split-Brain Patients Corpus Collosum attaches the two hemispheres of cerebral cortex. When removed you have a split-brain patient.

87 Split Brain Patients Disruption of or interference with the connection between the hemispheres of the brain Communication between the two sides of the brain is inhibited

88 Testing the Divided Brain

89 Split Brain When split-brain patients are shown an image only in their left visual field (the left half of what both eyes take in) They cannot vocally name what they have seen because (1) The image seen in the left visual field is sent only to the right side of the brain; (2) For most people, the speech-control center is on the left side of the brain (3) Communication between the two sides of the brain is inhibited.

90 Split Brain Thus, the patient cannot say out loud the name of that which the right side of the brain is seeing. In the case that the speech-control center is on the right side of the brain, the image must now be presented to only the right visual field to achieve the same effect.

91 Split Brain If a split-brain patient is touching a mysterious object with only the left hand, while also receiving no visual cues in the right visual field, the patient cannot say out loud the name of that which the right side of the brain is touching. This can be explained in three steps: (1) Each cerebral hemisphere of the primary somatosensory cortex only contains a tactile representation of the opposite (contralateral) side of the body (2) For most humans, the speech-control center is on the left side of the brain (3) Communication between the two sides of the brain is inhibited. In the case that the speech-control center is on the right side of the brain, the object must now be touched only with the right hand to achieve the same effect.

92 The Endocrine System

93 Endocrine System Controlled by the hypothalamus. Helps coordinate & integrate complex psychological reactions Secrete hormones into the bloodstream Hormones serve to organize the nervous system and body & activate behavior, such as sexual behavior Ovaries & Testes Reproduction OVARIES produce estrogen & progesterone TESTES (GONADS) Testosterone, produces sperm

94 The Endocrine System Thyroid gland Secretes hormones (primarily thyroxin) that control metabolism Parathyroid glands Control levels of calcium and phosphate which in turn controls levels of excitability Pineal gland Secretes melatonin which regulates the sleep-wake cycle Pancreas Regulates blood-sugar levels Secretes insulin and glucagon

95 The Endocrine System Pituitary gland Referred to as the master gland because it regulates many other glands Gonads Ovaries and testes secrete estrogens and androgens Adrenal glands Secretes hormones in reaction to stress

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