CH 2- Neuroscience and Behavior. 1- Brain cells ( neurons ) One-way movement only. Neuron. Your Brain: getting to know it.

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1 CH 2- Neuroscience and Behavior Your Brain: getting to know it This chapter = a users manual Key questions: How does it work? Can it be changed? Why do certain chemicals affect it? Can it be fixed if it gets hurt? 1 2 CH Organization 1- Brain cells ( neurons ) 1- Neuron (single-cell) level in the brain. How do individual brain cells work? 2- Nervous system. How is the brain hooked up to the whole body? Neurons = brain cells Ultimately all brain activity can be reduced to the firing of these cells Oh-my-gosh yours are firing now! 3- Whole brain. How is the brain specialized to do all it does? 3 4 Neuron Parts of the Neuron Cell Body Dendrites Axons Pg-44 One-way movement only Dendrites - Receive inputs from neighboring neurons Many, many dendrites per neuron Axons The cell s output structure send info to next cell One axon per cell ( cell s tail ) 5 6 1

2 Components of a Neuron dendrites soma axon terminal buttons myelin sheath 7 8 All or None Law A neuron can t fire just a little bit--it either fires or it doesn t Technical term: action potential (means neuron firing) 9 10 Neural Communication

3 Synapse = space between neurons Synaptic Transmission synapse Neurons never touch each other- (like islands) Synapse = filled with chemicals Called neurotransmitters Chemicals from 1 neuron go out the axon across the synapse - into the dendrite of the next neuron receptor site terminal button synaptic vesicle neurotransmitter Neurotransmitters are very specific like Lock and Key Neurotransmitter molecules have specific shapes Receptor molecules have binding sites One NT to know: Serotonin Involved in mood balance esp. depression Prozac works by keeping serotonin in the synapse longer, giving it more time to exert an effect SSRI selective re-uptake inhibitor

4 Another important NT -Dopamine How Subtle Your Brain Is! Involved in movement, attention, and learning Also key involvement in perception of pleasure & sensation So Dopamine is involved in addiction Dopamine example: Too much & you will experience schizophrenic symptoms (is this the cause of schizophrenia?) Too little & you will experience symptoms of Parkinson s Disease Key = BALANCE Endorphins The natural feel good chemical Control pain and pleasure Released in response to pain Runner s high feeling of pleasure after a long run is due to heavy endorphin release Neurotransmitter Summary After crossing the synapse, the neurotransmitter is either reuptaken or degraded Like left-over food throw it away or store it to use again More than 40 known types of NTs Different NTs have different effects Drugs = chemicals Summary: Key Concepts Chemicals work by affecting the neurotransmitters Stimulate or inhibit natural transmitters Mimic natural transmitters Help the uptake of natural transmitters Neuron structure All-or-nothing firing Synapse Neurotransmitters Receptors

5 II- The Nervous System Note the balance within the nervous system Balance a key concept in health (physical & mental) Sympathetic Nervous Systemthe up system Parasympathetic Nervous System down system dilates pupils accelerates heart, constricts arterioles dilates bronchi inhibits stomach motility & secretions constricts pupils stimulates tear glands slows heart constricts bronchi stimulates stomach secretion Endocrine System - hormones III- The whole brain Pituitary gland hormones affect the function of other glands Adrenal glands - hormones involved in human stress response Gonads hormones regulate sexual characteristics and reproductive processes

6 Developing Brain Neural tube beginning of nervous system develops at 2 weeks after conception Neurogenesis development of new neurons Brain major regions Brainstem Hindbrain Midbrain Forebrain Limbic system Cortex Cross-section of the Brain Cerebral cortex Limbic system Brainstem Brainstem Brainstem

7 Limbic System Limbic system Middle section of brain Focus = emotional regulation & reaction Your emotional brain The Cortex Your thinking brain It s convoluted (folded) to have more space In general, the larger the cortex the more intelligent the species is Cortex Specialization Localization Different sections of cortex called lobes Have different, specialized functions

8 The Cerebral Cortex Examples of Specialization Brain activity when hearing, seeing, and speaking words different areas Specialization, cont. Broca s area - plays role in speech production Wernike s area - plays role in plays in understanding and meaningful speech Where a brain injury occurs DOES matter! Frontal Lobes your Executive Functions voluntary movement attention goal-directed behavior Example: After Phineas Gage's frontal lobes were destroyed, his ability to plan, limit impulses, and reason were lost Last part of brain to develop Lateralization: Two Sides of your Brain Left hemisphere Right hemisphere Corpus callosum - connection

9 Left Hemisphere right hand touch and movement speech language writing for right handers Right Hemisphere left hand touch and movement spatial construction face recognition nonverbal imagery writing for left handers What if we cut the 2 halves of your brain apart? They did! Split-Brain Research & myths Brain Reactions The thinking brain (cortex) is different from the emotional brain (limbic system) Hard-wired: first reactions in emotional situations = processed by limbic system (emotional brain) NOT cortex (thinking brain) Understanding ADHD Emotional control = handled by the frontal lobe Which is the last part of brain to develop. That s why maturity is age-dependent ADHD frontal lobe doesn t have control That s where stimulant meds work

10 Brain Reorganization Plasticity the brain s capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development 55 10