Main Idea There are many parts in the

Main Idea: • There are many parts in the human brain that work together to coordinate movement and stimulate thinking and emotions.

The Brain Techniques to Study the Brain • A brain lesion experimentally destroys brain tissue to study animal behaviors after such destruction. • Remember, the hippocampus was removed from rats at various times after learning a maze. Hubel (1990)

Clinical Observation Clinical observations have shed light on a number of brain disorders. Alterations in brain morphology due to neurological and psychiatric diseases are now being catalogued. Tom Landers/ Boston Globe

Studying the Living Human Brain • Animal studies and clinical observations are useful, but often, such as when we need to diagnose or treat illness, we want to know what is happening inside the brain of a living human. • For this we have: • EEG: Electroencephalogram • MRI: Magnetic resonance imaging • PET Scan: Positron emission tomography • CT Scan (or CAT Scan): Computerized Tomography

Electroencephalogram (EEG) An amplified recording of the electrical waves sweeping across the brain’s surface, measured by electrodes placed on the scalp. AJ Photo/ Photo Researchers, Inc.

MRI: Magnetic Resonance Imaging • MRI uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of brain tissue. • Top images show ventricular enlargement in a schizophrenic patient. Both photos from Daniel Weinberger, M. D. , CBDB, NIMH • Bottom image shows brain regions when a participants lies. James Salzano/ Salzano Photo Lucy Reading/ Lucy Illustrations

PET Scan: Positron Emission Tomography • Detects gamma rays emitted by a radioactive form of glucose while the brain performs a given task. Courtesy of National Brookhaven National Laboratories • PET Scan is a visual display of brain activity

CT Scan: Computerized Tomography • X-ray rotates around head. • May be done with or without contrasting dye. • Images taken from different angles are assembled into 3 -D image • CT scan produces much more detailed image than x-ray of bone and soft tissue

The Brain

Brain stem Cerebrum Cerebellum

Cerebrum

Cerebellum

Brain Stem

The Brain Stem: Older Brain Structures The Brainstem is the oldest part of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival functions.

Brainstem

Thalamus The Thalamus [THAL-uhmuss] is the brain’s sensory switchboard, located on top of the brainstem. 1. 2. 3. 4. It directs messages to the sensory areas in the cortex and transmits replies to the cerebellum and medulla. To medulla To cerebellum

Pons The Pons plays a role in muscle coordination. Pons

Reticular Formation • Reticular Formation is a nerve network in the brainstem that plays an important role in controlling arousal. • Damage to this causes a disorder called narcolepsy in which a person falls asleep suddenly during the daytime and cannot resist the sleep.

Medulla The Medulla [muh-DUL -uh] is the base of the brainstem that controls heartbeat and breathing.

Cerebellum • The “little brain” attached to the rear of the brainstem. • It helps coordinate voluntary movements and balance. • Implicit (procedural) memory.

The Limbic System • The Limbic System is a doughnut-shaped system of neural structures at the border of the brainstem and cerebrum • Associated with emotions such as fear, aggression and drives for food and sex.

Amygdala The Amygdala [ah-MIG-dah -la] consists of two lima bean-sized neural clusters linked to the emotions of fear and anger.

Hypothalamus • Hypothalamus lies below (hypo) the thalamus. • Directs maintenance activities like eating, drinking, body temperature, and control of emotions. • It stimulates or inhibits pituitary gland other endocrine glands

Reward Center Sanjiv Talwar, SUNY Downstate Rats cross an electrified grid for self-stimulation when electrodes are placed in the reward (hypothalamus) center (top picture). When the limbic system is manipulated, a rat will navigate fields or climb up a tree (bottom picture).

The Cerebral Cortex The intricate fabric of interconnected neural cells that covers the cerebral hemispheres. It is the body’s ultimate control and information processing center.

Structure of the Cortex Each brain hemisphere is divided into four lobes

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

Visual Function • Notice the visual cortex is located in the occipital lobe. Courtesy of V. P. Clark, K. Keill, J. Maisog, S. Courtney, L. G. Ungerleider, and J. V. Haxby, National Institute of Mental Health • The functional MRI scan shows the visual cortex is active as the subject looks at faces.

Auditory Function • The auditory cortex contains distinct subregions that are important for decoding complex sound. • Auditory cortex is in the temporal lobe.

5. The motor cortex is involved in sensory–motor feedback, in controlling movements needed to produce music using an instrument. 5 3 2. information travels through the brainstem and midbrain to the 1 auditory cortex. 1. Sound waves enter ear, and are turned into neural impulses by the inner ear 2 4 4. The frontal lobe is involved in emotional evaluation. 3. information from the auditory cortex interacts with many other brain areas, especially the frontal lobe, for memory formation and interpretation.

Auditory Hallucinations The functional MRI scan shows the auditory cortex is active in patients who hallucinate.

Association Areas More intelligent animals have increased “uncommitted” or association areas of the cortex.

Language Aphasia is an impairment of language, usually caused by left hemisphere damage either to Broca’s area (impaired speaking) or to Wernicke’s area (impaired understanding).

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 modify itself after some types of injury or illness.

Our Divided Brain Our brain is divided into two hemispheres. The left hemisphere processes reading, writing, speaking, mathematics, and comprehension skills. In the 1960 s, 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. Martin M. Rother Courtesy of Terence Williams, University of Iowa Corpus Callosum

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.

Try This! Try drawing one shape with your left hand one with your right hand, simultaneously. BBC