Neuroscience and Behavior Schacter Gilbert Wegner PSYCHOLOGY Chapter 3 Neuroscience and Behavior Slides prepared by Randall E. Osborne, Texas State University-San Marcos

The Neuron Highly specialized cell that communicated information in electrical and chemical form A nerve cell

The Cell Body Processes nutrients and provides energy for the cell to carry out its functions; contains the nucleus of the cell Graphic from Hockenbury slides Key words: Cell body; soma; cell nucleus Interesting facts: The DNA in the nucleus of the cell has lost its ability to divide. therefore, when a neuron dies,for the most part, the adult brain cannot simply grow new neurons. (Note there are a few exceptions to this rule.) The relative inability to grow new neurons leads to two interesting questions: Q1: How do brain tumors (cancer) occur? A: Unlike neurons, glial cells can divide and grow new cells throughout one's lifetime. Most brain tumors are limited to glial cells, not neurons. Q2: If a person cannot grow new neurons, how does the brain change in order to accommodate new learning? A: One mechanism by which the brain adapts to help you learn new information involves the structure on the next slide: the dendrites.

Dendrites Multiple short fibers that extend from the cell body and receive information from other neurons or from sensory receptor cells

Axon The long, fluid-filled tube that carries a neuron’s message to other body areas 2 distinct parts tube-like structure branches at end that connect to dendrites of other cells Hockenbury slides (Schulman) Key words: axon; action potentials Interesting facts: - The diameter of an axon may vary from approximately 1mm-20mm. - An axon may travel long distances to reach it's destination (longest axon is approximately 3 feet in humans and 10 feet in giraffes).

Myelin Sheath A white fatty covering wrapped around the axons of some neurons that increases their communication speed Multiple sclerosis involves the break down of myelin in patches which causes the neural message to be slowed or interrupted Graphic from Hockenbury slides Key words: myelin sheath; action potentials; axon Interesting facts: - The myelin sheath is NOT a part of the axon. The myelin sheath is actually formed of glial cells (oligodendricytes and Schwann cells) that wrap around the axon. - You may have often heard the brain referred to as either white matter or gray matter. The myelin sheath appears white in nature. Hence, the term white matter refers to areas of the brain that are myelinated. Gray matter refers to areas of the brain that are unmyelinated. - When you accidentally cut yourself, you often visually notice that you've cut yourself before you actually feel any pain from the cut. The reason for this is that visual information uses myelinated axons; whereas, pain information uses unmyelinated axons. - The loss of myelin is a significant factor in the disease multiple sclerosis (MS). When myelin is lost, the high-speed transmission of information is slowed down or blocked completely, which could lead the person with the inability to walk, write or speak.

Neural Communication Two basic types Communication within the neuron electrical Communication between neurons chemical

Communication Within the Neuron Neurons communicate by means of an electrical signal called the Action Potential Action Potential- a brief electrical impulse by which information is transmitted along the axon of a neuron

Communication Within the Neuron Resting potential- state in which the neuron is prepared to activate and communicate its message if it receives sufficient stimulation

Resting Potential Graphic, Hockenbury slides

Depolarization Ahead of AP Graphic from Hockenbury slides

Repolarization follows Graphic from Hockenbury slides

Communication Between Neurons Synapse- the point of communication between two neurons

Communication Between Neurons Neurotransmitters- chemical messengers manufactured by a neuron

Types of Neurotransmitters Acetylcholine Dopamine Serotonin Norepinephrine GABA Endorphins

Neurotransmitters

Acetylcholine (Ach) Neurotransmitter that causes muscle contraction and is involved in memory function Alzheimer’s disease is associated with severe depletions of Ach Graphic, Hockenbury slides

Dopamine Neurotransmitter involved in the regulation of body movement, thought processes, and rewarding sensations Loss of dopamine-producing neurons is cause of Parkinson’s disease Schizophrenia is characterized by an excess of dopamine

Parkinson’s Disease Loss of dopamine-producing neurons in the Substantia Nigra (an area of the midbrain) is cause of Parkinson’s disease

Serotonin Neurotransmitter involved in sleep and emotions Low levels of serotonin have been associated with depression

Norepinephrine Neurotransmitter involved in learning and memory; a hormone manufactured by adrenal glands Helps body gear up in face of danger

GABA (gamma-aminobutyric acid) Neurotransmitter that usually communicates an inhibitory message Alcohol and Anti-anxiety medications increase GABA activity in the brain

Endorphins Neurotransmitters that regulate pain perceptions; endogenous morphines Opiates attach to these receptor sites Acupuncture Runner’s high

Nervous System Central (brain & spinal cord) Peripheral somatic autonomic sympathetic parasympathetic

Nervous System Somatic Autonomic gather info. from external world complementary systems

Brain Images Brainstem Hindbrain Midbrain Forebrain Limbic system Cortex Discovering PSY p. 65. Figure 2.16

Hindbrain Hindbrain medulla reticular formation cerebellum pons

Medulla Breathing Heart rate Digestion Other vital reflexes swallowing coughing vomiting sneezing

Reticular Formation Network of neurons in the brainstem (and thalamus) Sleep and arousal Attention Myers, Exploring psy 4e Figure 2.10

Cerebellum Coordinated, rapid voluntary movements e.g., playing the piano, kicking, throwing, etc. Lesions to cerebellum jerky, exaggerated movements difficulty walking loss of balance shaking hands Hockenbury slides

Pons Helps coordinate movements on left and right sides of the body

Midbrain Midbrain Tectum Tegmentum Substantia Nigra

Substantia Nigra An area of the midbrain that is involved in motor control and contains a large concentration of dopamine-producing neurons These dopamine-producing neurons break down in those with Parkinson’s

Forebrain and Limbic System cerebral cortex Limbic System thalamus hypothalamus pituitary gland

Limbic System Limbic system hypothalamus Hippocampus amygdala

Hypothalamus regulates behaviors related to survival sexual behavior hunger, thirst sleep water and salt balance body temperature regulation circadian rhythms Important role in hormone secretion The hypothalamus is made up different subregions or nuclei. These nuclei generally differ in terms of gross anatomy and function. Sexual behavior: The medial preoptic and medial anterior hypothalamic nuclei of the hypothalamus are heavily involved in mating behaviors of animals. Damage to these areas results in a loss of mating behaviors. Electrical stimulation of these areas (or insertion of sex hormones in these areas) can elicit sexual behaviors. Hunger: Lesions to the hypothalamus can lead to severe obesity or extreme weight loss, depending upon the region damaged. Thirst: Electrical stimulation of the hypothalamus can cause an animal to start drinking even in animals that have plenty of water in their systems. Neurons in the supraoptic nucleus of the hypothalamus are sensitive to changes in the osmolarity of blood. These neurons control the secretion of vasopression, which is more commonly known as "anti-diuretic hormone" or ADH. ADH acts in the kidney to increase fluid retention. Sleep: Temperature regulation: Your body tries to keep the same body temperature regardless of how hot or cold it is outside. The hypothalamus helps maintain a constant body temperature. Hypothalamus contains temperature-sensitive neurons. Neurons in the posterior hypothalamus become active when you are cold; whereas, heat activates the anterior hypothalamus. Changes in body temperature can cause the hypothalamus to imitate such behaviors as shivering, hunger, adrenaline secretion and fever to help you get back to the proper body temperature. Circadian rhythms: the suprachiasmatic nucleus (or SCN) of the hypothalamus is thought to be involved in regulating the body's natural 24 hour rhythms.

Hippocampus A curved forebrain structure that is part of the limbic system and is involved in learning and forming new memories

Amygdala Forebrain structure and part of the limbic system that is involved in emotion and memories

Cerebral Cortex Cerebral cortex frontal lobe temporal lobe occipital lobe parietal lobe corpus callosum

Lobes of the Cortex Each cerebral hemisphere can roughly be divided into four regions or lobes Temporal Occipital Parietal Frontal

Temporal lobe An area on each cerebral hemisphere near the temples that is the primary receiving area for auditory information

Occipital lobe An area at the back of each cerebral hemisphere that is the primary receiving area for visual information

Parietal lobe An area on each hemisphere of the cerebral cortex that processes somatic information

Frontal lobe The largest lobe of each cerebral hemisphere; processes voluntary muscle movements and is involved in thinking, planning, and emotional control

Somatosensory and Motor Cortices