Biological Approach to Understanding

Transcription

1 Biological Approach to Understanding

2 Standards Techniques used to study the brain in relation to behavior The choice of techniques used to correlate the brain with behaviour is based on a variety of factors including opportunity, available technology and costs. An awareness of these limitations as well as the strengths of these different techniques is important when evaluating the contribution they have made to understanding behaviour. Localization Students should understand the concept of localization and how the function of different parts of the brain is determined as well as the limitations of this model.

3 Neuroplasticity The development of neural networks through repetition and neural pruning is both genetic and subject to environmental influences. Neural networks can change developmentally, over time or after injury. This is termed neuroplasticity. Neurotransmitters & their effect on behavior The effect of neurotransmitters on human behaviour can be explained using an appropriate example. Neurotransmitters allow the impulse to cross a synapse (excitatory) or stop the impulse and prevent it from crossing a synapse (inhibitory). Neurotransmitters are themselves affected by agonists which amplify their effect and antagonists which reduce their effect. As a result, neurons working together can produce a large variety of effects resulting in a complex repertoire of behaviours. As a result any claim of cause and effect should be treated with caution.

4 Hormones and behavior The effect of a hormone on human behaviour can be examined using one or more examples. Pheromones & behavior There is increasing evidence that pheromones may play a role in human behaviour, however, none are conclusive. A discussion on the effect of pheromones on behavior is a useful exercise in critical thinking.

5 Genes & behavior The evidence for links between genes and certain types of behaviour requires critical evaluation in the light of environmental factors. Genetic Similarity Genetic similarity is referred to as relatedness. The greater the genetic similarities between two individuals or a group of individuals the higher the degree of relatedness. An awareness of the degree of relatedness between MZ and DZ twins, siblings, parents and children, and parents and adopted children provides a critical perspective in evaluating twin or kinship studies.

6 Evolutionary explanations for behavior If genes code for behavior as well as physical traits, then behaviour is subject to evolutionary pressures in the same way that physical traits are subject to evolutionary pressures. The role of animal research in understanding human behavior (HL) For all three topics in the biological approach, and with reference to research studies, HL students should study the following. The value of animal models in psychology research. Whether animal research can provide insight into human behaviour. Ethical considerations in animal research.

7 Key Concept Everything we study in bio psych should come back to this: Humans evolved to live in cultures; cultures that required the evolution of complex biologically based language and cognitive abilities for development Jamison, 2010

8 History of Mind Ancient Conceptions About Mind Plato correctly placed mind in the brain. However, his student Aristotle believed that mind was in the heart. Today we believe mind and brain are faces of the same coin. Everything that is psychological is simultaneously biological. 8

9 The Nervous System Nervous System: Consists of all the nerve cells. It is the body s speedy, electrochemical communication system. Central Nervous System (CNS): the brain and spinal cord. Peripheral Nervous System (PNS): the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body. 9

10 The Nervous System 10

11 Central Nervous System The Spinal Cord and Reflexes Simple Reflex 11

12 Peripheral Nervous System Somatic Nervous System: The division of the peripheral nervous system that controls the body s skeletal muscles. Autonomic Nervous System: Part of the PNS that controls the glands and other muscles. 12

13 Autonomic Nervous System (ANS) Sympathetic Nervous System: Division of the ANS that arouses the body, mobilizing its energy in stressful situations. Parasympathetic Nervous System: Division of the ANS that calms the body, conserving its energy. 13

14 Autonomic Nervous System (ANS) Sympathetic NS Arouses (fight-or-flight) Parasympathetic NS Calms (rest and digest) 14

15 The Amazing Phineas Gage & Localization of Brain Function Phineas Gage Article Tech Sheds Light 15

16 The Brain s Plasticity The brain is sculpted by our genes but also by our experiences. Plasticity, or neuroplasticity, refers to the brain s ability to modify itself. Often after some type of injury or illness. Does this anytime neurological connections are rearranged due to learning or experience 16

17 Localization & Language Aphasia is an impairment of language, usually caused by left hemisphere damage either to Broca s area (impaired speaking) or to Wernicke s area (impaired understanding). 17

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19 Splitting the Brain A procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them. *Sperry & Gazzaniga* Courtesy of Terence Williams, University of Iowa Corpus Callosum Martin M. Rother 19

20 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. 20

21 Divided Consciousness 21

22 Try This! Try drawing one shape with your left hand and one with your right hand, simultaneously. BBC 22

23 Non-Split Brains 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 carrying out a linguistic task. 23

24 Localization and Language pt. 2 Compare Hull & Vaid with Kim & Hirsch (Companion book, pg. 43)

25 The Nerves Nerves consist of neural cables containing many axons. They are part of the peripheral nervous system and connect muscles, glands, and sense organs to the central nervous system. 25

26 Neural Communication The body s information system is built from billions of interconnected cells called neurons. Estimated that there are b/w billion that can make 13 trillion connections 26

27 Neuron A nerve cell, or a neuron, consists of many different parts. 27

28 Neurotransmission & Action Potentials Neurotransmission is the process by which messages are sent between neurons When an individual neuron fires it is called an action potential it s an all or nothing response it either fires or doesn t

29 Refractory Period Refractory Period: After a neuron fires an action potential it pauses for a short period to recharge itself to fire again. 29

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31 Synapse A junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. This tiny gap is called the synaptic gap or cleft. 31

32 Neurotransmitters (chemicals) released from the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it to generate an action potential. Neurotransmitters 32

33 Lock & Key Mechanism Neurotransmitters bind to the receptors of the receiving neuron in a key-lock mechanism. 33

34 Agonists 34

35 Antagonists 35

36 Reuptake Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process applies the brakes on neurotransmitter action. 36

37 Neurotransmitter Acetylcholine Dopamine Endorphins Norepinephrine Serotonin Neurotransmitters Function(s) Enables muscle action, learning & some memory (muscle memory - more specifically, habits) Influences voluntary movement, learning, feelings of pleasure Painkillers, lead to feelings of euphoria Alertness & arousal stimulates sympathetic nervous system Affects mood, hunger, sleep, and arousal (primary drives) limbic 37 system

38 How Neurotransmitters Influence Us? Serotonin pathways are involved with mood regulation. From Mapping the Mind, Rita Carter, 1989 University of California Press 38

39 Dopamine Pathways Dopamine pathways are involved with diseases such as schizophrenia and Parkinson s disease. From Mapping the Mind, Rita Carter, 1989 University of California Press 39

40 Kasamatsu & Hirai, 1999 Sensory deprivation of Buddhist monks After 48 hours hallucinations Blood samples show increase of Serotonin Activates hypothalamus & frontal cortex Serotonin altered perception

41 Martinez & Kesner, 1991 Acetylcholine and Memory Rats learned to navigate a maze Block ACh in group of rats, prevent its reuptake in others, and control group Group 1 slowest at going through maze Group 2 faster than both other groups and fewer mistakes

42 Remember It is reductionist to suggest that complex behavior is a product of the right mix of chemicals in our brains Neurotransmission plays a role but cannot explain behavior alone Read Purple Book Effects of Nt on Behavior

43 Localization of Brain Function & the Reward Center - James Olds (1950 s) Rats cross an electrified grid for self-stimulation when electrodes are placed in the reward center called the Nucleus Accumbens - Robert Heath (1950 s) similar research on humans (no shock grid), patients push button themselves B-19 did it 1500 times in 3 hours to the point of euphoria. Disconnected despite his protests. Pg. 44 Companion Sanjiv Talwar, SUNY Downstate 43

44 The Brain Techniques to Study the Brain A brain lesion experimentally destroys brain tissue to study animal behaviors after such destruction. Hubel (1990) 44

45 Clinical Observation Clinical observations have shed light on a number of brain disorders. Alterations in brain morphology due to neurological and psychiatric diseases are now being catalogued. Tom Landers/ Boston Globe 45

46 Electroencephalogram (EEG) An amplified recording of the electrical waves sweeping across the brain s surface, measured by electrodes placed on the scalp. AJ Photo/ Photo Researchers, Inc. 46

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48 CT Scans

49 PET Scan PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of glucose while the brain performs a given task. 49

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51 MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce computergenerated images that distinguish among different types of brain tissue. Top images show ventricular enlargement in a schizophrenic patient. Bottom image shows brain regions when a participants lies. fmri shows actual brain activity in video while subjects engage in behaviors. Most frequently used. MRI Scan & fmri Both photos from Daniel Weinberger, M.D., CBDB, NIMH James Salzano/ Salzano Photo Lucy Reading/ Lucy Illustrations 51

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54 Near-Infrared Spectroscopy (NIRS) Non-invasive optical imaging that uses low levels of light to measure blood flow as a measure of a brain s activity. Used for brain mapping and brain function n motor and visual studies

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56 Discussion Do you think doctors should scan patients to let them know if they have a predisposition for mental illness? What effect(s) do you think this could have on the individual? Could brain scanning tech be misused? Does the potential misuse of technology & knowledge mean that it should not be pursued?

57 The Endocrine System The Endocrine System is the body s slow chemical communication system. Communication is carried out by hormones synthesized by a set of glands. 57

58 Hormones Hormones are chemicals synthesized by the endocrine glands that are secreted in the bloodstream. Hormones affect the brain and many other tissues of the body. For example, epinephrine (adrenaline) increases heart rate, blood pressure, blood sugar and feelings of excitement during emergency situations. 58

59 Hormone Glands Function Adrenaline Adrenals Arousal, Fight or Flight, Tend & Befriend Cortisol Adrenals Arousal, Stress, Pain Control, Memory, Inhibits Insulin from breaking down Glucose Melatonin Pineal Regulation of sleep Oxytocin Pituitary & Hypothalamus Attachment: Parents to offspring, mates etc. Tissue Repair Testosterone & Estrogen Gonads Sexual Development, Mood, Aggression Crane, 2009

60 Pheromones

61 Mirror Neurons TED Talk rons_that_shaped_civilization?language=en (7:43) Nova (13:50) Example dex=2&list=pl8w7oxrplxbxnyw-9i9wz38q7rk7cbxiy Rubber Hand