The Brain AP Psychology Chapter 2
Techniques to Study the Brain • Brain lesions experimentally destroy brain tissue to study animal behaviors after such destruction • Usually done for scientific and medicinal purposes • Not done on humans – unethical
Techniques to Study the Brain • Naturalistic Observation • Alterations in brain morthpology are now being study and catalogued • EEG (Electroencephalography) • Electroencephalography (EEG) is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In clinical contexts,
Techniques to Study the Brain • MRI • Magnetic resonance imaging • Uses magnetic fields and radio waves to create computer generated images of brain tissue
Techniques to Study the Brain • PET Positron emission tomography • Visual display of activity that detects radio active form of glucose while brain performs a specific task
Phineas Gage • Phineas Gage is often referred to as one of the most famous patients in neuroscience. He suffered a traumatic brain injury when an iron rod was driven through his entire skull, destroying much of his frontal lobe. Gage miraculously survived the accident, but was so changed as a result that many of his friends described him as an almost different man entirely.
Phineas Gage http://www.youtube.com/watch?v=oPAqTP7058Q
Older Brain Structures The Brainstemisthe oldest part of the brain, beginning where the spinal cord swells and enters the skull. It is responsible for automatic survival functions.
Brain Stem The Medulla [muh-DUL-uh] is the base of the brainstem It controls autonomic functions and relays nerve signals between the brain and spinal cord. • respiration • blood pressure • heart rate • reflex arcs • vomiting
Brain Stem The Medulla [muh-DUL-uh] is the base of the brainstem that controls heartbeat and breathing.
Brain Stem The Thalamus [THAL-uh-muss]is the brain’s sensory switchboard, located on top of the brainstem. It directs messages to the sensory areas in the cortex and transmits replies to the cerebellum and medulla.
Pons The Pons plays a role in muscle coordination. Pons
Reticular Formation • Reticular Formationisa 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.
Cerebellum The “little brain” attached to the rear of the brainstem. It helps coordinate voluntary movements and balance.
The Limbic System The Limbic Systemisa 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. It includes the hippocampus, amygdala, and hypothalamus.
Amygdala [ah-MIG-dah-la] two almond-shaped neural clusters that are components of the limbic system and are linked to emotion (fear and aggression) http://www.youtube.com/watch?v=cu7A8LIzL1o
Hippocampus • Memory – Involved in processing new memories. • Everything you learn filters through hippocampus first. • Clive Wearing • http://www.youtube.com/watch?v=c62C_yTUyVg
Hypothalamus neural structure / below (hypo) the thalamus; Basic Drives: hunger thirst body temperature Sex drive (libido) helps govern the endocrine system via the pituitary gland is linked to emotion Sometimes referred to as the pleasure center Two Parts to Hypothalamus Ventromedial – “Vomit” Tells you when to stop eating Lateral – “ Lets Eat” Tells you when you are hungry
Reward Center 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). Sanjiv Talwar, SUNY Downstate
Hemispheres of the Brain • Left: • Language and logic • Right: • Spatial, creative
Why do most strokes affect the right side of the body? • Most strokes occur in the left hemisphere
Gyri – Elevated ridges “winding” around the brain. • Sulci – Small grooves dividing the gyri Cerebral Features: • Central Sulcus – Divides the Frontal Lobe from the Parietal Lobe • Fissures – Deep grooves, generally dividing large regions/lobes of the brain • Longitudinal Fissure – Divides the two Cerebral Hemispheres • Transverse Fissure – Separates the Cerebrum from the Cerebellum • Sylvian/Lateral Fissure – Divides the Temporal Lobe from the Frontal and Parietal Lobes
Gyri (ridge) Sulci (groove) Fissure (deep groove) http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
Cerebral Cortex CerebralCortex Cerebral Cortex - The outermost layer of gray matter making up the superficial aspect of the cerebrum. http://www.bioon.com/book/biology/whole/image/1/1-6.tif.jpg
The Cerebral Cortex(Thin layer of densely packed neurons: .0039-inch) • Cerebral Cortex • intricate fabric of interconnected neural cells that covers the cerebral hemispheres (20 billion nerve cells!) • body’s ultimate control and information processing center • The larger the cortex, more adaptability, capacity for learning • Wrinkles = fissures (3 sq ft w/o them!) • *Perceiving, thinking, speaking* • Glial Cells • cells in the nervous system that support, nourish, and protect neurons • Aka neuron nannies or glue cells
Lobes of the Brain (4) • Frontal • Parietal • Occipital • Temporal http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg * Note: Occasionally, the Insula is considered the fifth lobe. It is located deep to the Temporal Lobe.
Lobes of the Brain - Frontal • The Frontal Lobe of the brain is located deep to the Frontal Bone of the skull. • It plays an integral role in the following functions/actions: • - Memory Formation • - Emotions • - Decision Making/Reasoning • - Personality (Investigation: Phineas Gage) Investigation (Phineas Gage) Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Lobes of the Brain - Parietal Lobe • The Parietal Lobe of the brain is located deep to the Parietal Bone of the skull. • It plays a major role in the following functions/actions: - Senses and integrates sensation(s) • Spatial awareness and perception • (Proprioception - Awareness of body/ body parts in space and in relation to each other) Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Lobes of the Brain – Occipital Lobe • The Occipital Lobe of the Brain is located deep to the Occipital Bone of the Skull. • Its primary function is the processing, integration, interpretation, etc. of VISION and visual stimuli. Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
Lobes of the Brain – Temporal Lobe • The Temporal Lobes are located on the sides of the brain, deep to the Temporal Bones of the skull. • They play an integral role in the following functions: • Hearing • Organization/Comprehensionof language • Information Retrieval (Memory and Memory Formation) Modified from: http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
The Cerebral Cortex • Motor Cortex • at the rear of the frontal lobes / controls voluntary movements • What parts of body occupy most cortical space? • Fingers and mouth (require most precise control)
Cerebral Cortex • Sensory Cortex • at the front of the parietal lobes / registers and processes body sensations • The more sensitive the body region, the more area occupied in the sensory cortex
* Note: Homunculus literally means “little person,” and may refer to one whose body shape is governed by the cortical area devoted to that body region. Q: What do you notice about the proportions depicted in the aforementioned homunculus? A: They are not depicted in the same scale representative of the human body. Q: What is meant by depicting these body parts in such outrageous proportions? A: These outrageous proportions depict the cortical area devoted to each structure. - Ex: Your hands require many intricate movements and sensations to function properly. This requires a great deal of cortical surface area to control these detailed actions. Your back is quite the opposite, requiring limited cortical area to carry out its actions and functions, or detect sensation. Back-Hom.
The Cerebral Cortex • Functional MRI scan shows the visual cortex activated as the subject looks at faces
Association Areas • More intelligent animals have increased “uncommitted” or association areas of the cortex • Association areas = 75% of cortex • Interprets, integrates and acts on info processed by sensory areas • Associates sensory input with stored memories (complex mystery)
Language and the Brain • Broca’s Area • Location: lower left frontal lobe • Major Function • directs muscle movements making speech • Speech Production • Involved in the analyzing the grammatical structures of sentences • Composition • Contains the motor neurons involved in the control of speech
Broca’s Aphasia • Aphasia refers to the speech impairment caused by brain damage • Patients know what they want to say but have a hard time getting it out. • Spoken sentences lack prepositions and conjunctions • They are typically able to comprehend words and produce sentences however they must be simple grammatical sentences. • Reading and writing are not as affected however, it can be in some cases • http://www.youtube.com/watch?v=f2IiMEbMnPM
Wernickes Area • Locations • Left temporal lobe • Major Function • Involved in the interpretation of speech • Known as the language comprehension center • Vital for locating appropriate words from memory to express meaning
WernickesAphacia • Trouble with speech comprehension • Can’t produce meaningful sentences. Can string together words but what they say is nonsensical • Leave out key words and substitute random or invented words • Talk excessively • http://www.youtube.com/watch?v=dKTdMV6cOZw
Specialization and Integration • Brain activity when hearing, seeing, and speaking words
Brain Reorganization • Plasticity • brain’s capacity to modify itself • brain reorganizes / compensates after damage, injury • children have the most plasticity • Example: blind and braille- one finger used: sense of touch invades visual cortex • http://www.youtube.com/watch?v=2MKNsI5CWoU
Review Question • When stroking the face of someone who’s hand has been amputated, why did the subject feel the sensation not only on his face, but also on his amputated (“phantom”) fingers? Answer: Hand area of the sensory cortex is no longer used, thus fibers from other sensory areas invade the space. (Note that the hand area is between the face and arm regions of the sensory cortex.) In other words…. Plasticity!
Our Divided Brain Severed Corpus Callosum http://www.youtube.com/watch?v=lfGwsAdS9Dc