4 The Brain and Nervous System

Study of the Brain Neuroscientists Study the brain and the rest of the nervous system in hopes of gaining a better understanding of normal behavior and of the outer reaches of what is possible for this organ. Includes the study of the biological foundations of consciousness, perception, memory, emotion, and stress.

The Nervous System LO4.1 List the major parts of the human nervous system and describe their primary functions. The nervous system: A basic blueprint Nervous system function: Gather and process information, produce responses to stimuli, and coordinate the workings of different cells.

The Nervous System, cont’ LO4 The Nervous System, cont’ LO4.1 List the major parts of the human nervous system and describe their primary functions. 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

The Nervous System, cont’ LO4 The Nervous System, cont’ LO4.1 List the major parts of the human nervous system and describe their primary functions. The peripheral nervous system Handles the central nervous system’s input and output Somatic nervous system Autonomic nervous system Sympathetic nervous Parasympathetic nervous system

The Nervous System, cont’ LO4 The Nervous System, cont’ LO4.1 List the major parts of the human nervous system and describe their primary functions. Organization of the nervous system

Communication in the Nervous System LO4 Communication in the Nervous System LO4.2 Compare the functions of neurons and glial cells in the nervous system. Neurons The brain’s communication specialists, transmitting information to, from, and within the central nervous system. Glia Cells that provide support, nurture, and insulate neurons, remove debris when neurons die, enhance the formation and maintenance of neural connections, and modify neuronal functioning.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.2 Compare the functions of neurons and glial cells in the nervous system. Types of neurons

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.3 Describe each of the three main parts of a neuron, and explain their functions. The structure of the neuron Dendrites Receive information from other neurons and transmit it toward the cell body. Cell body Keeps the neuron alive and determines whether or not it will fire. Axon Extending fiber that conducts impulses away from the cell body and transmits them to other neurons.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.3 Describe each of the three main parts of a neuron, and explain their functions. Myelin sheath Fatty insulation that may surround the axon of a neuron. Prevents signals in adjacent cells from interfering with each other Speeds up the conduction of neural impulses

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.4 Explain how stem cells contribute to the process of neurogenesis. Neurogenesis: The birth of neurons Neurogenesis The production of new neurons from immature stem cells. Stem cells Immature cells that renew themselves and have the potential to develop into mature cells.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.4 Explain how stem cells contribute to the process of neurogenesis. Stem-cell research Embryonic stem cells hold the promise of medical advances, yet federal funding faces resistance from some advocates. In recent years, scientists have successfully reprogrammed cells from adult organs, most notably skin cells, to become stem cells. Patient-advocacy groups hope that transplanted stem cells will eventually help people recover from diseases of the brain and from damage to the spinal cord and other parts of the body.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.5 Outline the process by which neurons communicate with each other. How neurons communicate Axon terminals release neuro-transmitter. Neurotransmitter enters synapse. Neurotransmitter binds to receptors that it fits.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.5 Outline the process by which neurons communicate with each other. Action potential A brief change in electrical voltage that occurs between the inside and outside of an axon when a neuron is stimulated.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.5 Outline the process by which neurons communicate with each other. Neurotransmitter Chemical substance released by a transmitting neuron at the synapse and that alters the activity of a receiving neuron.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.6 Summarize the effects of some of the main neurotransmitters in the brain. Neurotransmitters Serotonin Dopamine Acetylcholine Norepinephrine GABA (gamma-aminobutyric acid) Glutamate

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.7 List four hormones that influence behavior, and describe the basic action of each one. The endocrine system Endocrine glands release hormones into the bloodstream. Hormones regulate growth, metabolism, sexual development and behavior, and other functions.

Communication in the Nervous System, cont’ LO4 Communication in the Nervous System, cont’ LO4.7 List four hormones that influence behavior, and describe the basic action of each one. The endocrine system Hormones Melatonin Regulates daily biological rhythms Oxytocin Secreted by the pituitary gland; enhances uterine contractions during childbirth, facilitates ejection of milk during nursing Adrenal hormones Involved in emotions and stress Cortisol, epinephrine, and norepinephrine Sex hormones Regulate development and functioning of reproductive organs Androgens, estrogens, and progesterone

Mapping the Brain LO4.8 Describe eight techniques researchers use for understanding the workings of the brain, and compare the strengths and limitations of each. Intervening in the Brain and Observing Behavior Lesion method This is the removal or disabling of a brain structure to gain better understanding of its function; this method is used only in animals. Transcranial magnetic stimulation (TMS) A method of stimulating brain cells, using a powerful magnetic field produced by a wire coil placed on a person’s head. Transcranial direct current stimulation (tDCS) A very small electric current is applied to an area of the cortex, the outer surface of the brain. Depending on the direction of the current, brain activity in that area is either temporarily stimulated or suppressed.

Mapping the Brain LO4.8 Describe eight techniques researchers use for understanding the workings of the brain, and compare the strengths and limitations of each. Intervening in Behavior and Observing the Brain Electroencephalogram (EEG) A recording of neural activity detected by electrodes. Alternatives to an electroencephalogram: Event-related potentials (ERP) PET scan (positron-emission tomography) Magnetic resonance imaging (MRI) Functional magnetic resonance imaging (fMRI)

A Tour through the Brain LO4 A Tour through the Brain LO4.9 List and describe three main structures in the brain stem, and explain the primary functions each structure performs. 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 the cortex and screens incoming information

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.10 Describe the structure and function of the cerebellum. The cerebellum Regulates movement and balance Involved in remembering simple skills and acquired reflexes

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.11 Describe the structure, function, and location of the thalamus, hypothalamus, pituitary gland, amygdala, and hippocampus. The thalamus Relays sensory messages to the cerebral cortex Includes all sensory messages except those from olfactory bulb

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.11 Describe the structure, function, and location of the thalamus, hypothalamus, pituitary gland, amygdala, and hippocampus. The hypothalamus and the pituitary gland Involved in emotions and drives vital to survival Regulates autonomic nervous system Pituitary gland

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.11 Describe the structure, function, and location of the thalamus, hypothalamus, pituitary gland, amygdala, and hippocampus. The amygdala Responsible for arousal, Regulation of emotion, initial emotional response to sensory information Plays important role in mediating anxiety and depression, and emotional memory

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.11 Describe the structure, function, and location of the thalamus, hypothalamus, pituitary gland, amygdala, and hippocampus. The hippocampus Responsible for Storage of new information in memory Comparing sensory information with what the brain expects about the world Enabling us to form spatial memories for navigating the environment

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.12 Describe the structure of the cerebrum, and explain the function of the corpus callosum. The cerebrum Largest brain structure; two cerebral hemispheres connected by the corpus callosum (bundle of nerve fibers connecting the two cerebral hemispheres) In charge of most sensory, motor, and cognitive processes Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter)

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.13 Sketch the location of each of the lobes of the cerebral cortex, and explain the major functions each lobe performs. Lobes of the cerebral cortex Occipital lobes (visual cortex) Contain visual cortex Parietal lobes (somatosensory cortex) Pressure, pain, touch, and temperature Temporal lobes Memory, perception, and emotion Left lobe: Wernicke’s area Frontal lobes Emotion, planning, creative thinking, and take initiative Left lobe: Broca’s area

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.13 Sketch the location of each of the lobes of the cerebral cortex, and explain the major functions each lobe performs. Lobes of the cerebrum

A Tour through the Brain, cont’ LO4 A Tour through the Brain, cont’ LO4.13 Sketch the location of each of the lobes of the cerebral cortex, and explain the major functions each lobe performs. 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.”

Two Hemispheres of the Brain LO4 Two Hemispheres of the Brain LO4.14 Discuss the basic format of a split-brain experiment, and describe what the results of such experiments reveal about the functioning of the cerebral hemispheres. The two hemispheres of the brain The two hemispheres control opposite sides of the body. If there is damage to the left hemisphere: May lose ability to speak or understand language, difficulty reading, identifying objects, making gestures, describing events If there is damage to the right hemisphere: Difficulty identifying faces, interpreting emotional expressions, understanding music or art

Two Hemispheres of the Brain LO4 Two Hemispheres of the Brain LO4.14 Discuss the basic format of a split-brain experiment, and describe what the results of such experiments reveal about the functioning of the cerebral hemispheres. Split-brain experiment Patients were presented information to one or the other side of their brains. Patients identified verbally the pictures to the right (e.g., boy). When patients were asked to point to the face seen, the patients pointed to the left picture.

Two Hemispheres of the Brain LO4 Two Hemispheres of the Brain LO4.14 Discuss the basic format of a split-brain experiment, and describe what the results of such experiments reveal about the functioning of the cerebral hemispheres. Split-brain experiment

Two Hemispheres of the Brain LO4 Two Hemispheres of the Brain LO4.14 Discuss the basic format of a split-brain experiment, and describe what the results of such experiments reveal about the functioning of the cerebral hemispheres. Two hemispheres: Allies or opposites? Research on split-brain patients shows us. . . Nearly all right-handed and the majority of left-handed individuals process language mainly in the left hemisphere. Many researchers believe in left-hemisphere dominance. Others insist right hemisphere is important for spatial visual problem solving, comprehending non-verbal sounds, and some language abilities.

The Flexible Brain LO4.15 Define neural plasticity, and summarize some of the main evidence that the brain has the ability to change in response to new experiences. Plasticity The brain’s ability to change and adapt in response to experience, through neurogenesis, or by reorganizing or growing new neural connections.

The Flexible Brain, cont’ LO4 The Flexible Brain, cont’ LO4.16 Summarize five cautions surrounding whether sex differences in anatomical brain size are linked to sex differences in behavior. “His” and “her” brains? Yes, there are differences between men’s and women’s brains. There do appear to be sex differences in lateralization of the amygdala. Men’s right amygdala gets continual input from the rest of the brain. Females get continual input from the left amygdala.

The Flexible Brain, cont’ LO4 The Flexible Brain, cont’ LO4.16 Summarize five cautions surrounding whether sex differences in anatomical brain size are linked to sex differences in behavior. What do differences mean for behavior? Supposed differences are stereotypes. Brain difference does not necessarily explain behavior or performance. Brain difference does not account for differences in behavior across situations. Sex differences in the brain could be the result rather than the cause of behavioral differences. Studies of the brain difference focus on different areas.