Neuroscience

1. Neuroscience Psychology: A Concise Introduction2nd Edition Richard Griggs Chapter 2 Prepared byJ. W. Taylor V

2. The Journey… • The Neuron • The Nervous System and the Endocrine System • The Brain

3. The Neuron The Structure of a Neuron How Neurons Communicate Neurotransmitters, Drugs, and Poisons

4. Neurons and Glial Cells • Neurons are responsible for information transmission throughout the nervous system • Glial cells do not directly transmit information, but instead support neurons in their work by disposing of waste products of neurons, keeping their chemical environment stable, and insulating them

5. The Structure of a Neuron • Dendrites are the fibers that project out of the cell body, receiving information from other neurons • The cell body contains the nucleus of the cell and other biological machinery to keep the cell alive • The axon transmits messages through the neuron • The axon terminals are at the end of the axon and send messages to a different neuron

6. The Structure of a Neuron

7. How Neurons Communicate Communication withina neuron iselectrical Communication between neuronsischemical

8. The Electrical Impulse • Information from the dendrites is either excitatory (telling the neuron to generate an electrical impulse) or inhibitory (telling the neuron not to generate an electrical impulse) • The impulse is an “all or nothing” event, meaning that there either is or is not an electrical impulse • Stimuli of varying intensities are encoded by the quantity of neurons generating impulses and the number of impulses generated each second by the neurons

9. The Electrical Impulse • The myelin sheath is an insulating layer of fatty white substance that encases the axon, allowing electrical message to be transmitted faster within the neuron • Damage to the myelin sheath will slow electrical impulses, and can result in diseases like multiple sclerosis

10. Chemical Communication Between Neurons • Axon terminals contains sacs of neurotransmitters • These neurotransmittersare naturally occurring chemicals in the nervous system that specialize in transmitting information between neurons • Between the axon terminals of one neuron and the dendrites of another neuron is a small space called the synaptic gap, across which neurotransmitters are sent, allowing neurons to communicate

12. Brain Scans • Brain scans work because neurons require oxygen and other nutrients such as blood sugar • Positron Emission Tomography (PET) scans use a dose of radioactive glucose, which moves to the more-active areas of the brain • Functional Magnetic Resonance Imaging (MRI) detects active areas of the brain by highlighting those areas that require more oxygen

13. Neurotransmitters, Drugs, and Poisons Key terms: Agonists Antagonists Drugs and poisons that increase the activity of one or more neurotransmitters Drugs and poisons that decrease the activity of one or more neurotransmitters

14. Neurotransmitters 1. Acetylcholine (ACh) is involved in both learning and memory and muscle movement 2. Dopmaine impacts our arousal and mood states, thought processes, and physical movement 3. Serotonin and norepinephrine are neurotransmitters involved in levels of arousal and mood, and play a major role in mood disorders such as depression 4. GABA is the main inhibitory neurotransmitter in the nervous system; glutamate is the main excitatory neurotransmitter 5. Endorphins are a group of neurotransmitters that are involved in pain perception and relief

15. Acetylcholine (ACh) • Botulinum poison (botulin) is an antagonist that blocks the release of ACh at muscle junctures, leading to paralysis and even death • Curare is an antagonist that paralyzes the body by occupying the receptor sites for ACh, thereby preventing ACh from getting in and carrying its message to a neuron • Black widow spider venom is an agonist for Ach, causing the continuous release of ACh, flooding the synapse

16. Dopamine • Low levels are associated with Parkinson’s disease, and excessively high levels are associated with schizophrenia • L-Dopa is an agonist that increases production of dopamine • Anti-psychotic drugs are antagonists that block the receptor sites for dopamine so that this neurotransmitter cannot send its messages • Amphetamine acts as an agonist by stimulating the release of dopamine from axon terminals • Cocaine is an agonist that blocks the re-uptake of dopamine

17. Serotonin and Norepinephrine • Some antidepressant drugs work by blocking the reuptake of serotonin and norepinephine • Anti-depressant drugs like Prozac, Paxil, and Zoloft are selective serotonin reuptake inhibitors

18. GABA and Glutamate • Anti-anxiety drugs are agonists for GABA • Lack of GABA may contribute to epilepsy, a brain disorder resulting in uncontrolled movement and convulsions • Glutamate is involved in memory storage and pain perception. • Excessive glutamate can lead to neuron death; deficient glutamate has been proposed to explain schizophrenia

19. Endorphins • Morphine and heroin are agonists that bind to receptor sites, thereby increasing endorphin activity

20. The Nervous and Endocrine Systems The Central Nervous System The Peripheral Nervous System The Endocrine Glandular System Emotions and the Autonomic Nervous System

21. Nervous System Subdivisions

22. Types of Neurons • Interneurons exist only in the central nervous system • Sensory neurons carry information to the central nervous system from sensory receptors in the eyes, muscles, and glands • Motor neurons carry movement commands from the central nervous system to the rest of the body

23. The Central Nervous System Consists of the spinal cord and the brain • The spinal cord has two functions • Conduit for incoming sensory data and outgoing movement commands • Provides for spinal reflexes, which are simple automatic actions not involving the brain • The brain is the control center for the entire nervous system

24. The Peripheral Nervous System • Gathers information about the external environment and the body’s internal environment for the brain through sensory neurons • Serves as the conduit for the brain’s commands to the rest of the body through motor neurons

25. The Peripheral Nervous System Consists of two parts: • The somatic (or skeletal) nervous system carries sensory input from receptors to the CNS and relays commands from the CNS to the skeletal muscles to control their movement • The autonomic nervous system regulates our internal environment and consists of two parts • The sympathetic nervous system is in control when we are very aroused and prepares us for defensive action (such as running away or fighting) • The parasympathetic nervous system is in control when the aroused state ends to return our body to its normal resting state

27. The Endocrine Glandular System • Not part of the nervous system • Works with the autonomic nervous system in responding to stress, and plays a role in basic behaviors and bodily functions such as sex, eating, metabolism, reproduction, and growth • Endocrine glands secret hormones, which are chemicals carried by the bloodstream to target sites throughout the body

28. The Endocrine Glandular System • Endocrine glands are controlled by the hypothalamus, which controls the most influential gland, thepituitary • Releases hormones essential for human growth and that direct other glands to release their hormones • Some other glands: • Thyroid gland affects our growth and maturation • Adrenal glands are involved in metabolism and help trigger the “fight or flight” response with commands from the autonomic nervous system • The pancreas is involved in digestion and maintaining blood-sugar levels

29. The Endocrine Glandular System

30. Components of Emotion An emotion is a complex psychological state that involves three components: Physical Behavioral Cognitive A physiological state of arousal triggered by the autonomic nervous system An outward expression including facial expressions, movements and gestures An appraisal of the situation to determine which emotion we are experiencing and how intensely

31. Components of Emotion • The physical component • Includes the “fight or flight” response of the autonomic nervous system • Heart rate and breathing increase, blood pressure surges, start sweating, pupils dilate, digestion slows • The behavioral component • Is the product of motor neurons • The facial-feedback hypothesis assumes that the facial muscles send messages to the brain, allowing the brain to determine which emotion is being experienced • The cognitive component • Includes an appraisal of the situation to determine what emotion we are experiencing

32. Theories of Emotion James-Lange Theory Cannon-Bard Theory Schachter-Singer Two-Factor Theory

33. James-Lange Theory • Contends that autonomic nervous system physiological arousal is a response to a stimulus, and that such a physiological response is subsequently interpreted as the emotion • For example, if you are crossing the street and see a car speeding toward you, your autonomic nervous system is aroused (e.g., increased heart rate). Based on this arousal, you interpret the stimulus as threatening and pick up your pace across the street.

34. Cannon-Bard Theory • Contends that arousal patterns for different emotions are too physiologically alike to be able to determine what emotion is being experienced • Instead, an emotion-provoking stimulus sends messages to both the peripheral nervous system and the brain • The brain produces the emotional feeling, the autonomic nervous system produces the physiological response, and the motor neurons produce the behavioral response

35. Schachter-SingerTwo-Factor Theory • Contends that there are two important determinants of emotion: • Physiological arousal tells us how intense the emotion is • The cognitive appraisal of the entire situation allows us to identify the emotion, leading to the emotional feeling

36. Integrating the Theories • LeDoux (1996) contends that there are different brain systems for different emotions • Fear, for example, does not require higher-level cognitive processing and is generated almost instantaneously by the amygdala • More complex emotions, however, such as love or guilt, that do not require instantaneous responding for survival, may require higher-level processing

37. The Brain Going up the Brain Stem Processing in the Cerebral Cortex Specializations of the Left and Right Hemispheres Consciousness and the Sleeping Brain

38. Case 1: A Landscape Artist

39. Case 2: A Professional Wrestler

40. Case 3: A Student Source: Sheldon, J. P. (2000). A neuroanatomy teaching activity using case studies and collaboration. Teaching of Psychology, 27, 126-128.

41. The Central Core • The brain stem • The medulla links the spinal cord to the brain and is involved in regulating heartbeat, blood pressure, digestion, and swallowing • The reticular formation is a network of neurons running up the center of the brain stem and into the thalamus that is involved in controlling our different levels of arousal and awareness • The cerebellum is involved in the coordination of our movements, our sense of balance, and motor and procedural learning • The thalamus, located at the top of the brain stem, serves as a relay station for incoming sensory information (except smell) • The basal ganglia are on the outer sides of the thamalus and are concerned mainly with the initiation and execution of physical movements

42. The Central Core Brain Structures

43. The Limbic System • Plays a role in our survival, memory, and emotions • The hypothalamus control the pituitary gland, the autonomic nervous system, and plays a major role in regulating basic drives such as eating, thirst, and sex • The hippocampus is involved in the formation of memories • The amygdala plays a major role in regulating our emotional experiences, especially fear, anger, and aggression

44. The Limbic System

45. Processing in the Cerebral Cortex • Thecerebral cortexis the most important brain structure, serving as the information processing center for the nervous system • Is where perception, language, memory, decision making, and all other higher-level cognitive processing occur • Consists of two hemispheres connected by a band of neurons called the corpus callosum, allowing the two hemispheres to communicate

46. Brain Lobes 1. Thefrontal lobe is the area in the front of each hemisphere and in front of the central fissure and above the lateral fissure 2. Theparietal lobe is the area located behind the central fissure and above the lateral fissure 3. Thetemporal lobe is located beneath the lateral fissure 4. Theoccipital lobe is located in the lower back of each hemisphere

47. The Four Lobes and the Sensory-Motor Processing Areas

48. The Motor Cortex • The frontal lobe strip of cortex, directly in front of the central fissure in each hemisphere, allows us to move different parts of our body • Each hemisphere controls the voluntary movement of the opposite side of the body (a contralateral relationship) • Amount of motor cortex devoted to a specific body part is related to the complexity and precision of movement of which that part is capable

49. The Somatosensory Cortex • The parietal lobe strip of cortex, directly behind the central fissure in each hemisphere, is where body sensations of pressure, temperature, limb position, and pain are processed • Contralateral relationship • Amount of sensorimotor cortex devoted to a body part is directly proportionate to the sensitivity of that body part

50. Homunculi for the Motor Cortex and the Somatosensory Cortex