Organization of the nervous system. The withdrawal reflex. The central nervous system. Structure of a neuron. Overview

Transcription

1 Overview The nervous system- central and peripheral The brain: The source of mind and self Neurons Neuron Communication Chemical messengers Inside the brain Parts of the brain Split Brain Patients Organization of the nervous system The central nervous system Brain Spinal cord A collection of neurons and supportive tissue running from the base of the brain down the center of the back. Actually and extension of the brain. Protected by spinal column The withdrawal reflex (automatic, does not involve the brain) Structure of a neuron Dendrites Receive information from other neurons and transmit toward the cell body Cell body Keeps the neuron alive and determines whether it will fire Axon Extending fiber that conducts impulses away from the cell body and transmits to other cells.

2 Structure of a neuron Which part of a neuron is tree-like or branchy? 1. Dendrites 2. The axon 3. The cell body. The nucleus How neurons communicate Which part of a neuron is tree-like or branchy? 1. Dendrites 2. The axon 3. The cell body. The nucleus Axon terminals release neurotransmitters. Neurotransmitter enters synapse. Neurotransmitter binds to receptors that it fits. Action potential Neurotransmitter A brief change in electrical voltage that occurs between the inside and outside of an axon when a neuron is stimulated. Chemical released by a transmitting neuron at the synapse and capable of affecting the activity of a receiving neuron

3 Major neurotransmitters Endorphins-brain s natural opiates, reduce pain promote pleasure Serotonin--sleep, mood, eating Dopamine--movement, learning, emotion Acetylcholine (Ach), muscle action, memory Norepinephrine- heart rate, learning, memory (GABA)-inhibitory The endocrine system The endocrine system Endocrine glands release hormones into the bloodstream Hormones regulate growth, metabolism, sexual development and behavior, and other functions. Hormones Mapping the brain Melatonin Regulates daily biological rhythms 1. Researchers study brains that have experienced disease or injury 2. Some Animal Studies Adrenal hormones Involves damaging and removing sections of animals brain and observing the effects. Involved in emotions and stress Cortisol, epinephrine, and norepinephrine 3. EEG. TMS Sex hormones 5. PET Regulate development and functioning of reproductive organs 6. MRI Androgens, estrogens, and progesterone

4 Electroencephalogram (EEG) Transcranial magnetic stimulation (TMS) A recording of neural activity detected by needle electrodes Involves delivering a large current through a wire coil on a person s head Can be used to Produce motor responses Temporarily inactivate an area of the brain Treat depression Positron emission tomography (PET Scan) A method for analyzing biochemical changes in the brain as they occur, using injections of a glucose-like substance containing a radioactive element Active areas have increased blood flow. Sensors detect radioactivity. Different tasks show distinct activity patterns. Diagnose abnormalities or just learn about normal brain Magnetic resonance imaging (MRI) Method for studying body and brain tissue Magnetic fields align certain ions and compounds. When field is removed, these molecules release energy as radio waves. Computer calculates tissue density from radio waves. Provides nice clear 3D images A tour through the brain Brain stem Cerebellum Thalamus Hypothalamus and pituitary gland Amygdala Hippocampus Cerebrum and lobes of the cerebral cortex The brain stem Pons Involved in sleeping, waking, and dreaming Medulla Responsible for certain automatic functions such as breathing and heart rate Reticular activating system Arouses cortex and screens incoming information

5 The cerebellum The thalamus Regulates movement and balance Relays sensory messages to the cerebral cortex Involved in remembering simple motor skills and acquired reflexes Includes all sensory messages except those from olfactory bulb Plays a small part in Analyzing sensory information Understanding words Hypothalamus and pituitary gland The amygdala Involved in emotions and drives vital to survival Fear, hunger, thirst, and reproduction Regulates autonomic nervous system Pituitary gland Small endocrine gland which releases hormones and regulates other endocrine glands Responsible for Arousal Regulation of emotion Initial emotional response to sensory information Plays important role in Mediating anxiety and depression Emotional memory The hippocampus The cerebrum(also called the cortex or the Modern Brain Responsible for Storage of new information in memory Comparing sensory information with what the brain expects about the world Largest brain structure Two cerebral hemispheres connected by the corpus callosum. Enabling us to form spatial memories for navigating the environment In charge of most sensory, motor, and cognitive processes Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter)

6 Lobes of the cerebral cortex Occipital lobes (visual cortex) Parietal lobes (somatosensory cortex) Temporal lobes Memory, language perception, emotion, and auditory cortex Frontal lobes Planning, creative thinking, language: also emotional regulation and complex motor movements Lobes of the cerebral cortex Omar bumps his head and is suddenly unable to see, although the doctor says there is nothing wrong with her eyes? Which part of her brain did Omar damage? 1. The amygdala 2. The hippocampus 3. The occipital lobe of the cerebral cortex. The parietal lobe of the cerebral cortex Omar bumps his head and is suddenly unable to see, although the doctor says there is nothing wrong with his eyes? Which part of his brain did Omar damage? 1. The amygdala 2. The hippocampus 3. The occipital lobe of the cerebral cortex. The parietal lobe of the cerebral cortex Phineas Gage-188 The corpus callosum Gage was a railroad construction foreman Millions of myelinated axons connecting the brain s hemispheres An 188 explosion forced a steel tamping rod through his head Provides a pathway for communication Others said he was no longer Gage Lost his job, worked as a sideshow exhibit If surgically severed to treat epilepsy, hemispheres cannot communicate directly

7 Split-brain experiment Split-brain experiment Subjects were presented information to one or the other side of their brains. Patients identified verbally the pictures to the right (e.g., boy s face). Right side goes to left brain, the verbal side. BUT, When patients were asked to POINT to the face seen, the patients pointed to the left (man s) picture. Research on split-brain patients shows us that 1. Nearly all right-handed and the majority of lefthanded individuals process language mainly in the left hemisphere. 2. Many researchers believe in left-hemisphere dominance because cognitive skills originate here. 3. Others insist right-hemisphere is just as important for spatial visual problem solving, art & music appreciation and is more intuitive.. The two hemispheres are more allies than opposites SO Where is The Self? Modern brain scientists explain the mind and the soul in physical terms as mainly a product of the cerebral cortex. Mind is a series of independent brain parts dealing with different aspects of thoughts (Dennett 1991). Mind is a loose confederation of mental systems all working without conscious awareness (Gazzaniga, 1998; Roser & Gazzaniga, 200). Frontal lobes may play a critical role. BUT the relationship between our subjective experiences and physical processes of the brain is complex and as we will see the environment plays a HUGE role too! Closing Wise Words I used to think that the brain was the most wonderful organ in my body. Then I realized well, look what's telling me this! -Emo Phillips, Actor & Comedian)