©1999 Prentice Hall Neurons, Hormones, and the Brain Chapter 4

©1999 Prentice Hall Neurons, Hormones and the Brain The central nervous system. The peripheral nervous system. Communication in the nervous system. Neurotransmitters. Mapping the brain. A walk through the brain. Are there “his” and “hers” brains?

©1999 Prentice Hall 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 Protected by spinal column.

©1999 Prentice Hall The Withdrawal Reflex

©1999 Prentice Hall Peripheral Nervous System Somatic Includes the nerves that are connected to sensory receptors and skeletal muscles. Autonomic The sympathetic nervous system mobilizes bodily resources and increases the output of energy during emotion and stress. The parasympathetic nervous system operates during relaxed states and that conserves energy.

©1999 Prentice Hall Organization of the Nervous System

©1999 Prentice Hall Communication in the Nervous System The structure of the neuron. Different kinds of neurons. How neurons communicate. Action potential. Chemical messengers in the nervous system. Neurotransmitters. Major neurotransmitters. Opioids and substance P. Endocrine system. Hormones.

©1999 Prentice Hall Structure of a Neuron Dendrites receive information from other neurons and transmit towards 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.

©1999 Prentice Hall Structure of a Neuron Myelin Sheath Fatty insulation that may surround the axon of a neuron.

©1999 Prentice Hall Different Kinds of Neurons

©1999 Prentice Hall How Neurons Communicate Axon terminals release neurotransmitter. Neurotransmitter enters synaptic gap. Neurotransmitter binds to receptors that it fits.

©1999 Prentice Hall Action Potential A brief change in electrical voltage which occurs between the inside and outside of an axon when a neuron is stimulated. It produces an electrical impulse.

©1999 Prentice Hall Neurotransmitter A chemical substance that is released by a transmitting neuron at the synapse and that alters the activity of a receiving neuron.

©1999 Prentice Hall Major Neurotransmitters Serotonin Dopamine Acetylcholine (ACh) Norepinephrine Gamma amino butryic acid (GABA) Glutamate Endorphins

©1999 Prentice Hall Opioids and Substance P

©1999 Prentice Hall The Endocrine System Endocrine glands release hormones into the bloodstream. Hormones regulate growth, metabolism, sexual development and behavior, and other functions.

©1999 Prentice Hall Hormones: Long Distance Messengers Melatonin. Adrenal Hormones. Cortisol, epinephrine, and norepinephrine. Sex Hormones. Androgens, estrogens, and progesterone.

©1999 Prentice Hall Mapping the Brain Lesion method. Electroencephalogram (EEG). Transcranial magnetic stimulation (TMS). Positron-Emission tomography (PET). Magnetic resonance imaging (MRI).

©1999 Prentice Hall Mapping the Brain Lesioning Involves damaging and removing sections of brain in animals, then observing their effects. Transcranial magnetic stimulated (TMS) Stimulates brain cells using a powerful magnetic field produced by a wire coil placed on the head. Can be used to temporarily inactivate neural circuits.

©1999 Prentice Hall Electroencephalogram (EEG) A recording of neural activity detected by electrodes.

©1999 Prentice Hall Positron Emission Tomography (PET) A method for analyzing biochemical activity in the brain, 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.

©1999 Prentice Hall 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 clear, 3D images.

©1999 Prentice Hall A Walk Through the Brain 3 Major Regions The brain stem. The cerebellum. The thalamus. The hypothalamus and the pituitary gland. The amygdala. The hippocampus. The cerebrum and lobes of the cerebral cortex..

24 ©1999 Prentice Hall 3 Major Regions of the Brain Hindbrain Located in the skull’s rear, is the lowest portion of the brain. = 3 parts medulla, pons, cerebellum Midbrain Located between the hindbrain and forebrain responsible for connecting the two - (reticular activating system) (substantia nigra) Forebrain the brain’s largest and most complex region encompassing thalamus, hypothalamus, limbic system, cerebrum

©1999 Prentice Hall The Brain Stem - Hind/Midbrain Pons involved in sleeping, waking and dreaming. Medulla responsible for certain automatic functions such as breathing and heart rate. Reticular activating system (or formation) arouses cortex and screens incoming information.

©1999 Prentice Hall The Cerebellum Regulates movement and balance. Involved in remembering simple skills and acquired reflexes. Plays a part in analyzing sensory information, solving problems and understanding words

©1999 Prentice Hall The Thalamus Relays sensory messages to the cerebral cortex. “Traffic Officer” - “Server” Includes all sensory messages except those from olfactory bulb.

©1999 Prentice Hall Hypothalamus and Pituitary Gland Involved in emotions and drives vital to survival including fear, hunger, thirst, and reproduction. Also regulates autonomic nervous system. The pituitary gland is a small endocrine gland which releases hormones and regulates other endocrine glands. Pituitary Gland

©1999 Prentice Hall The Amygdala Responsible for arousal and regulation of emotion and the initial emotional response to sensory information. Plays important role in mediating anxiety and depression.

©1999 Prentice Hall The Hippocampus Responsible for the storage of new information in memory. Compares information with what the brain has come to expect about the world. “Gateway to memory” because it enables us to navigate through the environment.

©1999 Prentice Hall The Cerebrum Largest brain structure. 19/13/3 lbs. 1/1, /10, /60 Consists of upper part of brain and divided into two cerebral hemispheres which are connected by the corpus callosum. In charge of most sensory, motor and cognitive processes. Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter). only 3 millimeters thick - 70% neurons in the central nervous system Corticalization - increase in size and wrinkling

©1999 Prentice Hall Lobes of the Cerebral Cortex Occipital lobes. Visual cortex. Parietal lobes. Somatosensory cortex. Temporal lobes. Memory, perception, emotion and auditory cortex. Left lobe, Wernicke’s area. Frontal lobes. Emotion, planning, creative thinking and motor cortex. Left lobe, Broca’s area.

©1999 Prentice Hall Lobes of the Cerebral Cortex

©1999 Prentice Hall Phineas Gage Gage was a railroad construction foreman An 1848 explosion forced a steel tamping rod through his head Others said he was “…no longer Gage…” Lost his job, worked as a sideshow exhibit

©1999 Prentice Hall The Corpus Callosum Millions of myelinated axons connecting the brain’s hemispheres. Provides a pathway for communication between the hemispheres. If surgically severed for treatment of epilepsy, hemispheres cannot communicate directly.

©1999 Prentice Hall Split-Brain Experiment

©1999 Prentice Hall Split-Brain Experiment Subjects were presented information to one or the other side of their brains. Patients identified verbally the pictures to the right (i.e., boy). When asked to point to the face seen, the patients pointed to the left picture.

©1999 Prentice Hall Are There “His” and “Hers” Brains? After analyzing 49 studies of sex differences in brain anatomy, researchers found small differences between the two groups and larger differences within groups. There does appear to be sex differences in lateralization of language. Males show left hemisphere activation only. Females, left and right. There also appears to be differences in amounts of gray matter. Females have more.

©1999 Prentice Hall 3 Ways to Interpret These Findings These supposed differences are stereotypes. A biological differences does not necessarily have implications for behavior and performance. Sex differences in the brain could be the result rather than the cause of behavioral differences.