EXPLORING PSYCHOLOGY EIGHTH EDITION IN MODULES David Myers PowerPoint Slides Aneeq Ahmad Henderson State University Worth Publishers, © 2011 The Biology of Mind The Brain Module 4 Older Brain Structures The Brain Stem CLOSE UP: The Tools of Discovery – Having Our Head Examined The Thalamus The Reticular Formation The Cerebellum The Limbic System The Cerebral Cortex Structure of the Cortex Functions of the Cortex The Brain’s Plasticity Our Divided Brain Splitting the Brain Right-Left Differences in the Intact Brain Older Brain Structures The brainstem is the oldest part of the brain and central core of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival functions. The Medulla [muh-DUL-uh] is the base of the brainstem that controls heartbeat and breathing. CLOSE UP: The Tools of Discovery – Having Our Head Examined Lesion [LEE-zhuhn]: tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue. Electroencephalogram (EEG): an amplified recording of the waves of electrical activity that sweep across the brain’s surface, measured by electrodes on the scalp. PET Scan Courtesy of National Brookhaven National Laboratories PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of glucose while the brain performs a given task. MRI Scan MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce computer generated images of soft tissue, showing brain anatomy. fMRI (functional MRI): technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans, showing brain function. Both photos from Daniel Weinberger, M.D., CBDB, NIMH MRI scan of a healthy individual (left) and a person with schizophrenia (right) The Brainstem and the Thalamus The brainstem, including the pons and medulla, is an extension of the spinal cord. The thalamus is attached to the top of the brainstem. The reticular formation passes through both structures. Older Brain Structures Thalamus: brain’s sensory switchboard, located on top of the brainstem; directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla. Reticular Formation: nerve network in the brainstem that plays an important role in controlling arousal. Cerebellum The cerebellum [sehr uh - BELL-um] is the “little brain” attached to the rear of the brainstem. It helps coordinate voluntary movements and balance. The Limbic System The Limbic System is a neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives. Amygdala The Amygdala [ahMIG-dah-la] consists of two lima bean-sized neural clusters linked to the emotions of fear and anger. Hypothalamus The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating, drinking, body temperature, and control of emotions. It helps govern the endocrine system via the pituitary gland. Hypothalamus Reward Center Rats cross an electrified grid, accepting painful shocks, for self-stimulation when electrodes are placed in the reward (hypothalamus) center. The Cerebral Cortex The cerebral [seh - REE-bruhl] cortex is the intricate fabric of interconnected neural cells that covers the cerebral hemispheres. The body’s ultimate control and information processing center. Structure of the Cortex Each brain hemisphere is divided into four lobes that are separated by prominent fissures. These are the frontal lobe (forehead), parietal lobe (top to rear head), occipital lobe (back head) and temporal lobe (side of head). Functions of the Cortex The Motor Cortex is the area at the rear of the frontal lobes that control voluntary movements. The Sensory Cortex (parietal cortex) receives information from skin surface and sense organs. Visual Function The functional MRI scan shows the visual cortex is active as the subject looks at a photo. Courtesy of V.P. Clark, K. Keill, J. Ma. Maisog, S. Courtney, L.G. Ungerleider, and J.V. Haxby, National Institute of Mental Health Association Areas More intelligent animals have increased “uncommitted” or association areas of the cortex. Neurons in these areas integrate information. Language: Specialization and Integration Brain areas involved in language processing • Language: Specialization and Integration Aphasia: impairment of language, usually caused by left-hemisphere damage either to Broca’s area or Wernicke’s area. Broca’s area: controls language expression; an area of the frontal lobe, usually in the left hemisphere, directs muscle movements involved in speech. Wernicke’s area: controls language reception; usually in the left temporal lobe, involved in language comprehension and expression. Specialization & Integration Brain activity when hearing, seeing, and speaking words The Brain’s Plasticity The brain is sculpted by our genes but also by our experiences. Plasticity refers to the brain’s ability to change by reorganizing after damage or by building new pathways based on experience. Evidence suggests that, contrary to long - held belief, adult mice and humans can also generate new brain cells, through neurogenesis, or the formation of new neurons. Our Divided Brain Our brain is divided into two hemispheres. The left hemisphere processes reading, writing, speaking, mathematics, and comprehension skills. In the 1960s, it was termed as the dominant brain. Splitting the Brain A procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them. Split Brain Patients With the corpus callosum severed, objects (apple) presented in the right visual field can be named. Objects (pencil) in the left visual field cannot. Testing the Divided Brain Try This! Try drawing one shape with your left hand and one with your right hand, simultaneously. BBC Right-Left Differences in the Intact Brain People with intact brains also show left-right hemispheric differences in mental abilities. A number of brain scan studies show normal individuals engage their right brain when completing a perceptual task and their left brain when carrying out a linguistic task.