Chapter 3 Neuroscience: The Biology of Behavior

Objectives 3.1 Overview: The Components of Biological Bases of Behavior Describe how neuropsychology and neuroscience relate to the study of psychology. Explain how the nervous system conducts signals to and from various parts of the body and brain. 3.2 Neural Communication Identify the structural elements of the nervous system. Recognize the types and structure of neurons.

Objectives 3.3 Nervous System Organization Compare and contrast the peripheral nervous system and the central nervous system. 3.4 The Brain Identify the different areas of the brain and the functions they control.

Objectives 3.5 The Endocrine System Discuss the role of endorphins and the endocrine system as communication mechanisms in the nervous system. 3.6 Genetics Discuss the role of genetics in psychology.

The Components of Biological Bases of Behavior Neuropsychology: Studies the connection between neuroscience (the study of the brain and the nervous system) and bodily systems and behavior –Links the physical body with behavior –Explains how the brain processes thoughts/emotions

Nervous System A collection of organs including neurons and supportive systems; consists of all the neurons in the central and peripheral nervous system –Neuron: A nerve cell –Hormones: Chemical messengers that are produced by endocrine glands

Glia Support and protect neurons Compose approximately 50% of the total volume of the brain Manage and organize the nervous system by directing where neurons grow Control how neurons communicate and connect

Neurons Neurons communicate information throughout the nervous system. –Interneuron: A neuron that communicates only with other neurons –Afferent nerve fibers: Neurons that move information toward the brain and spinal cord –Efferent nerve fiber: A type of neuron that carries impulses away from the central nervous system © Sebastian Kaulitzki/ShutterStock, Inc.

Types of Neurons Sensory neuron: A neuron that is responsible for carrying external stimuli to the central nervous system for processing Motor neuron: A type of neuron that interfaces with muscles and glands Mirror neuron: A type of neuron that fires when an individual watches an action and when performing the action

The Structure of a Neuron (slide 1 of 3) Dendrite: A nerve cell structure that receives information from other cells Soma: The part of the neuron that keeps the cell alive and contains the genetic material for the cell Axon: The part of the neuron that carries the nerve impulse away from the soma

The Structure of a Neuron (slide 2 of 3) Nerves - Bundles of neurons. Myelin sheath - A fatty substance that insulates the axon and enables efficient transmission. Axon terminal -The part of the neuron that discharges and recycles also called the terminal button. Terminal button - The part of the neuron that discharges and recycles neurotransmitters also called the axon terminal.

The Structure of a Neuron (slide 3 of 3)

Neurotransmitters and Synapses Neurotransmitters: Chemical messengers that transmit information from one neuron to another Synapse: An area that includes three structures: –presynaptic neuron: The terminal button of the sending neuron –synaptic gap/cleft: The space between one neuron and the next –postsynaptic neuron: The receptor sites on dendrite of the receiving neuron

How Neurons Communicate Figure 03.04: Neurons don't touch, instead they communicate through synaptic transmission.

Action Potentials Figure 03.05: The action potential will determine if a neuron will fire.

Action Potentials Depolarize: The process by which an axon becomes more positive All-or-none law: The concept that either a neuron fires or it doesn’t. Repolarize: The process by which a neuron’s axon will return to the resting potential Absolute refractory period: The point after an action potential when the neuron cannot produce another action potential no matter the intensity of the stimulation

Action Potentials Synaptic vesicle: A sac that contains neurotransmitters in the axon terminal Receptor site: An area on the dendrite that receives neurotransmitters

Postsynaptic Potential Postsynaptic potential: Changes in the dendrite of the receiving neuron as the result of its binding with neurotransmitters –Excitatory Postsynaptic Potential: Causes a positive voltage shift in the resting potential of the postsynaptic neuron, triggering the neuron to fire. –Inhibitory Postsynaptic: Causes a negative voltage shift in the resting potential of the postsynaptic neuron, preventing the neuron from firing.

Neural Networks Synaptic Pruning:- The destruction of less active synapses to organize an improve efficiency of the neural connections Data from Abitz, M., Nielsen, R. D., Jones, E. G., Laursen, H., Graem, N., & Pakkenberg, B. (2007). Excess of neurons in the human newborn mediodorsal thalamus compared with that of the adult. Cerebral Cortex, 17 (11), 2573–2578. doi: /cercor/bhl163

Multitasking Neurotransmitters

Nervous System Organization Figure 03.08: The nervous system consists of a central (red) and peripheral (blue) nervous system.

Peripheral Nervous System Figure 03.09: The sympathetic nervous system gets us ready to fight, freeze or flee, while the peripheral nervous system calms us down.

Central Nervous System The central nervous system consists of: –Spinal cord - a collection of neurons that run from the base of the brain and down your back, protected by a spinal column –Brain

Studying the Brain (slide 1 of 3) Electrical stimulation: A technique used to stimulate neural networks in the nervous system (also known as deep brain stimulation) Transcranial magnetic stimulation (TMS): A procedure that uses electromagnetic coils to activate nerve cells in the brain

Studying the Brain (slide 2 of 3) Electroencephalograph (EEG): A device that measures the electrical activity in the brain Computerized tomography (CT): Uses computer enhanced X rays that are helpful at examining brain structures. Also called CT scans © xpixel/ShutterStock, Inc.

Studying the Brain (slide 3 of 3) Positron emission tomography (PET): Uses radioactive glucose to indicate areas of activity Magnetic resonance imaging (MRI): Uses magnets and radio equipment to produce detailed images Functional magnetic resonance imagining (fMRI): used to measures changes in blood flow © Science Source/Photo Researchers, Inc.

The Hindbrain Figure 03.14: Hindbrain structures support vital bodily processes.

The Midbrain Midbrain: Part of the brainstem involved in control of sensory processes –Substantia nigra: A midbrain structure that is responsible for initiation of movement

Forebrain

Forebrain: Limbic System Figure 03.16: The limbic system is a group of structures that surround the brainstem.

Cerebrum and Cerebral Cortex

Hemispheres Figure 03.18: A photograph of the brain showing the cerebral hemisphere (purple) and the corpus callosum (green). © Martin M. Rotker/Photo Researchers, Inc.

Lateralization of Function

Plasticity Plasticity: The ability of the nervous system to adapt by creating new neural pathways –Structural plasticity: The brain’s ability to change in response to the environment –Functional plasticity: The capacity to change areas of the brain that are responsible for activities

The Endocrine System (slide 1 of 2)

The Endocrine System (slide 2 of 2) Endorphins: Chemicals linked to pain perception and reward Adrenal glands: Important glands of the endocrine system consisting of the adrenal cortex and the adrenal medulla Gonads: An organ that secretes sex hormones

Genetics

Adaptation Adaptation:- A process by which a characteristic increases in a population because it makes reproduction or survival more likely Fitness: The contribution an individual makes to the gene pool of the next generation. Natural selection: Varying success in reproduction resulting from the interaction of an organism with the environment

Heritability and Family Studies Data from Devlin, B., Daniels, M., & Roeder, K. (1994). The heritability of IQ. Genetics, 137, 597–606. Data from Plomin, R. (1999). IQ and human intelligence. American Journal of Human Genetics, 65 (5), 1476–1477.