Psychological Foundations Biopsychology Cells in the Nervous System

Psychological Foundations Biopsychology

Cells in the Nervous System • Glial cells provide physical and metabolic support to neurons, including neuronal insulation and communication, and nutrient and waste transport • Neurons (right) act as interconnected information processors

Neuron Structure

Neuron Structure: Synapses, Neurotransmitters, and Receptors • The synapse is the space between two neurons and site of communication • Neurotransmitters are chemical messengers that bind to receptors on the next neuron • Receptors, proteins on the cell surface where neurotransmitters attach, vary in shape, with different shapes “matching” different neurotransmitters

How Neurons Communicate: Resting Potential At resting potential, Na+ is more highly concentrated outside the cell in the extracellular fluid, whereas K+ is more highly concentrated near the membrane in the cytoplasm or intracellular fluid. Other molecules, such as chloride ions and negatively charged proteins (brown squares), contribute to a positive net charge in the extracellular fluid and a negative net charge in the intracellular fluid.

How Neurons Communicate: Action Potential During the action potential, the electrical charge across the membrane changes dramatically

How Neurons Communicate: Reuptake involves moving a neurotransmitter from the synapse back into the axon terminal from which it was released

Psychoactive Drugs • Psychoactive drugs correct neurotransmitter imbalances • Agonists mimic a neurotransmitter at the receptor site and, thus, strengthen its effects • Antagonists block the normal activity of a neurotransmitter at the receptor

The Nervous System • The central nervous system (CNS) consists of the brain and spinal cord • The peripheral nervous system (PNS) is comprised of the somatic and autonomic nervous systems

Central and Peripheral Nervous System

The Peripheral Nervous System • The somatic nervous system transmits sensory and motor signals to and from the central nervous system • The autonomic nervous system controls the function of our organs and glands, and can be divided into the sympathetic and parasympathetic divisions • Sympathetic activation prepares us for fight or flight • Parasympathetic activation is associated with normal functioning under relaxed conditions

PNS: the Autonomic Nervous System

The Endocrine System • The endocrine system consists of a series of glands that produce chemical substances known as hormones • Hormones regulate behaviors such as aggression, mating, and parenting of individuals • Hormones influence behavior, and behavior can sometimes influence hormone concentrations • The study of psychology and the endocrine system is called behavioral endocrinology

The Parts of the Endocrine System

The Brain: Lateralization • Each hemisphere controls the opposite side of the body • There is some specialization of function, especially language • The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum, that allows the two hemispheres to communicate with each other

The Brain: Plasticity The brain’s ability to change, adapt, and reorganize itself is called brain plasticity

Forebrain, Midbrain, and Hindbrain

Forebrain: The Lobes of the Brain The forebrain is divided into four lobes.

Forebrain: The Frontal Lobe • Contains the motor cortex (below) involved in planning and coordinating movement • Contains the prefrontal cortex responsible for higherlevel cognitive functioning • Contains Broca’s area essential for language production

Forebrain: The Parietal Lobe • Contains the somatosensory cortex which processes sensory information • Organized topographically, which means that spatial relationships that exist in the body are maintained on the surface of the somatosensory cortex

Forebrain: The Temporal Lobe • Contains the auditory cortex which processes auditory information and Wernicke’s area (below) which is important for speech comprehension • Also associated with memory and emotion

Forebrain: The Occipital Lobe • Contains the primary visual cortex, which interprets visual information • Organized retinotopically, which means there is a close relationship between the position of an object in a person’s visual field and the position of that object’s representation on the cortex

Forebrain: Thalamus The thalamus serves as the relay center of the brain where most senses are routed for processing

Forebrain: The Limbic System • Amygdala: structure involved in our experience of emotion and tying emotional meaning to our memories • Hippocampus: structure associated with learning and memory • Hypothalamus: structure that regulates sexual motivation and behavior and a number of homeostatic processes; serves as an interface between the nervous system and the endocrine system

Midbrain • The substantia nigra (Latin for “black substance”) and the ventral tegmental area (VTA) contain cell bodies that produce the neurotransmitter dopamine, and are critical for movement. • The reticular formation is centered in the midbrain and is important in regulating the sleep/wake cycle, arousal, alertness, and motor activity.

Hindbrain • The medulla controls the automatic processes of the autonomic nervous system, such as breathing, blood pressure, and heart rate • The pons connects the brain and spinal cord • The cerebellum controls balance, coordination, movement, and motor skills

Brain Imaging Techniques • Computerized tomography (CT) scan • Electroencephalography (EEG) • Functional magnetic resonance imaging (f. MRI) • Magnetic resonance imaging (MRI) • Positron emission tomography (PET) scan

Nature or Nurture? Do your genetics and biology dictate your personality and behavior, or is it your environment and how you were raised? Tools to explore this debate: • Adoption study • Twin studies • Quantitative genetics

Human Genetics The theory of evolution by natural selection says that organisms that are better suited for their environment will survive and reproduce Genetic variety contributes to a species’ adaptation to its environment • Mutation: sudden, permanent change in a gene

Gene Environment Interactions • The range of reaction: genes set definite limits on potential, and environment determines how much of that potential is achieved • Genetic environmental correlation • Our genes influence our environment, and our environment influences the expression of our genes • Epigenetics studies how the same gene can lead to different results

The Epigenome • The human genome is the DNA instructions for building the proteins that carry out a variety of functions in a cell • The epigenome is made up of chemical compounds and proteins that attach to DNA and turn genes on or off, controlling the production of proteins in particular cells • The epigenome can be altered through various experiences and environments

Practice Question • Imagine you are on an airplane preparing to jump out for your first-ever experience skydiving • Which nervous systems would be involved, and in what way? How would your endocrine system react? • What role would the forebrain, midbrain, and hindbrain play in your skydiving experience?

Quick Review • What are the basic structures of a neuron and the function of each structure? • How do messages travel through the neuron? • What is the role of the nervous system and endocrine systems? • What are the parts of the brain? • How do nature, nurture, and epigenetics influence personality and behavior?