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Unformatted text preview: Neuroscience
Cerebrovascular accident (CVA) A stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. As a result, the affected area of the brain is unable to function, leading to inability to move one or more limbs on one side of the body, inability to understand or formulate speech or inability to see one side of the visual field. In the past, stroke was referred to as cerebrovascular accident or CVA, but the term "stroke" is now preferred.
Electroencephalography (EEG) -Device that measures and amplifies slight electrical changes on the scalp that reflect brain activity. -EEg uses electrodes on the scalp to record rapid chnages in brain electrical activity. -It can measures the brains reaction to lights, sounds, and other events. It provides little precision about the location of the brain. This is also used by sleep researchers to distinguish between sleep stages by recording brain waves with electrode attached to the scalp. Hindbrain w/functions -Pons and Medulla their functions are protective reflexes, infant reflexes, orienting reflex, cardiovascular, digestive, and respiratory reflex. -Medulla there is the inner cerebellum which deals with balance alcohol destroys this. There is the outer which is rapid automatic movements, timing of movement and thoughts. Midbrain w/functions Midbrain reticular formation is responsible for general arousal, sleep wake cycles, pain and perception. - Superior colliculi is responsible for visual targeting, pursuit eye movements. -Inferior colliculi is responsible for auditory targeting. Forebrain w/functions The forebrain consists of two hemispheres left and right. Each hemisphere is responsible for sensation and motor control on the opposite side of the body. The outer covering know as the cerebral cortex is especially prominent in humans. There are four lobes the occipital lobe, temporal lobe, parietal lobe, and frontal lobe. -Occipital lobe is at the rear of the head and is specialized for vision. People with damage to this are have cortical blindness. They have no conscious vision, no object recognition, and no visual imagery. -Temporal lobe of each hemisphere, located toward the left and right sides of the head, is the main area for hearing and some of the complex aspects of vision. People with damage to this area can no longer recognize faces. People with damage to another part become motion blind. Although thy can see the size and shape of an object they cannot track its speed or direction of movement. People with damage to the auditory parts of the temporal lobe are impaired at recognizing sequences of sounds. The part of the temporal lobe of the left hemisphere is important for language comprehension. People with damage to this are have trouble understanding speech and remembering the names and objects. The amygdala a subcortical structure deep within the temporal which responds strongly to emotional situations. Parietal lobe just anterior from the occipital lobe is specialized for the body senses including touch, pain, temperature, and awareness of location of body parts in space. Somatosensory Cortex a strip in the anterior portion of the parietal lobe, has cells sensitive to touch in different body areas. Damage to this impairs sensation to the corresponding body part. After parietal damage people see something bu cannot decipher where it is relative to their body part. Frontal lobe at the anterior pole of the brain includes the primary motor cortex important for the planned contol of fine movements such as moving one finger at a time. The anterior sections of the frontal lobe called the prefrontal lobe contribute to certain aspects of memory and to the organization and planning of movements that is decision making. People with damage to the prefrontal cortex often make impulsive decisions that hurt them. Prosopagnosia - comes from damage to the temporal lobe it is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact. The term usually refers to a condition following acute brain damage
Autonomic Nervous System w/ branches - section of the nervous system that controls the functioning o the internal organs, such as the heart. Autonomic means involuntary. For example a loud noise can suddenly increase your heart rate. You cannot decide to increase your heart rate your brain just naturally sends information to and receives information from the autonomic nervous system. It has two parts the sympathetic nervous system controlled by a chain of cells lying just outside the spinal cord, increases heart rate, breathing rate, sweating and other vigorous fight or flight activities. - The parasympathetic nervous system controlled by cells at the top and bottom levels of the spinal cord decreases heart rate, increases digestive activities, and in general promotes activites of the body that take place during relaxation. The docrine system a set of glands that produce hormones and release them into the blood. Limbic system w/functions It surrounds the thalamus. It is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, and limbic cortex, which support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from Latin limbus, meaning "border" or "belt". Reticular Formation w/functions is a part of the brain that is involved in actions such as awaking/sleeping cycle, lying down, and filtering incoming stimuli to discriminate irrelevant background stmuli. It is essential for governing some of the basic functions of higher organisms, and is one of the oldest portions of the brain
Orienting response -also called orienting reflex, is the reflex that causes an organism to respond immediately to a change in its environment.
Protective & pathological reflexes Coughing ,sneezing ay reflexes that protect your inner body. Infant & pathological reflexes Reflexes you are born with that sometimes come back later in life. An example is in babies when they are held and you drop their head their arms come up to grab something. Another example is in monkeys when their mother fears a predator is near they drop the baby and it automatically grabs onto them. Reflex Is a rapid automatic response to a stimulus such as an unconscious adjustments of your legs while you are walking or quickly jerking your hand away from something hot. Saccades vs. smooth tracking eye movements Quick jump in the focus of the eyes from one point to another. Corpus callosum -a set of axons that connect the left & right hemispheres of the cerebral cortex
Phrenology -was once considered a science -focuses on personality and character
"Binding problem" The question of how separate brain areas combine forces to produce a unified perception of a single object. A nave explanation would be that all parts of the brain funnel their information to a little person in the head who puts it all together. However research on the cerebral cortex has found no central processor that could serve that purpose. Parkinson's disease -condition that affects about 1% of people over 50. symptoms vary. in initiating voluntary movement, slow movement, tremors, ridigity, and depressed mood. All of these symptoms can be traced to a gradual decay of a pathway of axons that release the neurotransmitter dopamine. One common treatment is the drug L-dopa.
Effects of prefrontal damage and prefrontal lobotomy -Reduced behavioral spontaneity ("flat affect"): become passive, monotone, social disengagement -Similar pre vs. post IQ's: can't think of higher meaning, hard to alternate (where am I now? Where do I need to be?) -Concrete verbalizations -Perseveration -Failure to sequence behavior (poor following of instructions) -Loss of strategic thinking: just jump into tasks, respond to events w/ out reflection -> don't plan for future -Pseudodepression -Pseudopsychopathy: do whatever they want, unable to stop themselves/can't see consequences of actions
Language areas of brain -left side of brain (if right handed -> left side brain dominant, left handed -> right side brain dominant) -Broca's area: condition characterized by inarticulate speech and by difficulties with both using and understanding grammatical devices prepositions, conjunctions, word endings, complex sentence structures, and so forth -Primary motor cortex: strip in the posterior part of the frontal cortex that controls fine movements, such as hand and finger movements -arcuate fasciculus -primary auditory cortex: -wernicke's area condition marked by difficulty recalling the names of objects and impaired comprehension of language. -angular gyrus -primary visual cortex
Nonfluent (Broca's) and fluent (Wernicke's) aphasias nonfluent aphasias: responsible for connection words/signs, can make words but trouble with connecting words, order, switching of verbs; condition characterized by inarticulate speech and by difficulties with both using and understanding grammatical devices propositions, conjunctions, word endings, complex sentence structures, etc. -fluent aphasias: know what want to say, but wrong words come out; condition marked by difficulty recalling the names of objects and impaired comprehension of language
Neglect syndrome This occurs mostly in patients with strokes it is when one hemisphere of the brain is damaged and the opposite side starts to not work. Hemispheric lateralization is where the hemispheres are specialized for certain tasks. For almost all right handed people and more than 60% of left handed people, parts of the left hemisphere control speech. For the other left handers both hemispheres control the speech. PEOPLE WITH RIGHT Hemisphere damage often can't tell when a speaker is being sarcastic and they frequently don't understand jokes. The hemispheres pass information back and forth through the corpus callosum a set of axons o the cerebral cortex. Convolutions (wrinkles) in neocortex and reason -increases the area and number of neurons within the confined space of the skull cavity -> a space that must remain confined due to limitations of birth process
Contralateral control w/ rationale -nerves go down from brain and exit through vertebrate of spinal column -left half brain controls right side of body, right half brain controls left side of body ->>>>> no one knows why: predator??
Effects of split-brain preparation -split brain patient: someone whose corpus callosum has been cut; feels something with the left hand but cannot describe it because the information goes to the right (nonspeaking) hemisphere -if communication between the two hemispheres is lost, then each hemisphere becomes partly independent of the other
Neurotransmitters w/ examples Are chemicals that are stored in the terminal of an axon and that when released activate receptors of other neurons. Neurotransmitter molecules molecules diffuse across a narrow gap to receptors on the postsynaptic neuron which is the neuron on the receiving end of the synapse. A neurotransmitter fits into the receptor like a key fits into a lock. Its presence there produces either an excitatory or an inhibitory effect on the postsynaptic neuron. Depending on the neurotransmitter and the type of receptor the attachment enables either the positively charged or negatively charged ions to enter the postsynaptic cell. If the positive charges outweigh the negative charges enough for the cell to reach its threshold it produces an action potential. An alteration of a particular kind of synapse will affect some behaviors more than others. Cell body (soma) -Part of the neuron that contains the nucleus of the cell. It is one of the three parts of a neuron. Axon -single, long thin straight fiber w/ branches near its tip. Transmits. Some vertebrates axons are covered with myelin an insulating sheath that speeds up the transmissions of impulses along an axon. As a rule an axon transmits information to other cells, and the dendrites or cell body of each cell receives that information.
Dendrites One of the widely branching structures of neuron that receive transmissions from other neurons. Axon terminals (terminal buttons) -Bulge at the end of an axon from which the axon releases a chemical called a neurotransmitter
Synapse Specialized junction between one neuron and another: at this point one neuron releases a neurotransmitter, which either excites or inhibits the next neuron. Pre- and post-synaptic membranes The neurotransmitters molecule diffuse across narrow gap to receptors on the post synaptic neurons, the neuron on the receiving end of the synapse. Resting potential and Action potential -axon not stimulated -> resting potential -electrical polarization across the membrane (or covering) of an axon Action potential: excitation that travels along an axon at a constant strength, no matter how far it must travel -all-or-none law -advantage: action potentials from distant places reach places at full strength -disadvantage: slower than electrical conduction -information is conveyed along an axon by an action potential, which is regenerated without loss of strength at each point along the axon -mechanism of action potential: an action potential depends on the entry of the sodium into the axon; anything that blocks this flow will block the action potential Glial cells (glia) and functions -nervous system cells that support the neurons in many ways: insulating them, synchronizing activity among neighboring neurons, and removing waste products. Sensory neurons carry information from the the sense organs to the central nervous system, where neurons process the information, compare it to past information, and exchange information with other neurons -Probable Functions of Glial Cells -Possibly, a slow second signal system (calcium waves), running in parallel, and interacting, with neurons -Blood-brain barrier -Support structure during neurogenesis -Myelin sheaths -Neurotrophic functions
Neurotransmitter reuptake "All-or-none" law An action potential is a yes-no or on-off message, like a standard light switch. This principle is known as the all-or-none law. Post-synaptic receptors -The neuron at the receiving end of the synapse. The neuron fits into the receptor like a key fits into a lock. Endocrine glands and functions -A set of glands that produce hormones and release them into the blood. Hormones controlled by the hypothalamus and pituitary gland also regulate the other endocrine organs. Set of glands that produce hormones and release them into the bloodstream. Sensation and Perception
Psychophysics Absolute threshold -intensity at which a given individual can detect a sensory stimulus 50% of the time; a low threshold indicates the ability to detect faint stimuli. Detection, discrimination, recognition, scaling Sensory coding Limen Subliminal perception Is the idea that a stimulus can make us do something even whne it is presente to us faintly or briefly.
Types of retinal cells and functions Fovea Central part of the retina that has a greater density of receptors, especially cones than any other part of the retina Its adapted for highly detailed visions. Blind spot The retinal area where the optic nerve exits. Trichromatic theory Our receptors respond to three primary colors. Color vision depends on the relative rate of response by three types of cones. We are excites by certain wavelengths that giv of certain colors. Opponent-process theory There are four basic colors red ,green, yellow, and blue. We perceive color not in terms of independen colors but in terms of a sytem of paired opposites-red versus green, yellow versus blue, and white versus black. Retinex theory Nature of "color-blindness" Pitch and frequency, Loudness and amplitude Conduction vs. nerve deafness Place theory, frequency theory, volley principle Frequency principle= low frequency up to 100Hz sound wave vibrate all hair cells produce action potential in synchrony with sound waves. Volley principle= mid range frequencies (1004000Hz) sound waves excite a few hair cells. Place principle= high frequency beyond 4000Hz
Methods of sound localization Vestibular system and structures involved Vestibular system responsible for balance monitors movement of your head its in the ear receptors in the semicular canal. Gate theory of pain The idea that pain messages must pass through gate, presumably in the spinal cord, that can block the messages. Placebo Neurotransmitters involved in pain Endorphins Neurotransmitters that inhibit the release of substance p and thereby weaken pain sensations. Endorphins are also released by happy events such as sex or good music. Phantom limb When you lose a limb in an accident or through amputation sometimes you will feel like that limb is still there even though it is not.
Olfaction -The sense of smell. THE Olfactory receptors located on the mucous membrane in the rear air passages of the nose. Pheromones -Nonhuman mammals identify each other through this which are chemicals released into the environment. Nearly all animals rely on this for sexual communication.
Signal detection theory -is the study of people's tendencies to make hits, correct rejections, misses, and false alarms. The theory originated in engineering, where it applies to such matters as detecting radio signals in the presence of noise. In a signal detection experiment, people's responses depend o their willingness to risk a miss or a false alarm. Gestalt approach -a field that focuses on our ability to perceive overall patterns constancies in vision. Figure and ground is you must distinguish the objects form the background. Reversible figures stimuli that can be perceived in more than one way. Motion detection: - induced movement - stroboscopic movement - phi effect Depth perception Our perception of distance - retinal disparity the difference in the apparent postion of an object as seen by the left and right retinas. - ocular convergence - binocular cues the retinal disparity that depends on both eyes. monocular cues (for example, motion paralla enables a person to judge depth and distance with just one eye or when both eyes see the same image, as when you look at a picture. ...
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- Winter '08