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NATS 1860 Final Exam 2013.docx

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Natural Science
NATS 1860
Keith Schneider

NATS EXAM 2. Briefly explain each of the following imaging techniques, including which signals are being measured from the brain, and describe one strength and one weakness Functional MRI:  Detects small signal due to blood flow  Infer dynamic neuronal activity changes Strength  Good combination of temporal and spatial resolution Weakness  Indirect inference of neuronal activity through secondary measure (blood flow) PET: Position emission tomography  Detects gamma rays emitted by a radioactive tracer isotope that is attached to molecules (e.g. glucose in blood)  Can measure neuronal activity by proxy though blood flow Strength  Can trace different substances Weakness  Worse spatial and temporal resolution than fMRI EEG: Electroencephalography  The activity of neurons in your brain involves electrochemical activity  A very small but detectable eclectic field can be measured on the surface of the scalp using sensitive electrodes and amplifiers Strength  Good temporal resolution Weakness  Long and uncomfortable subject setup MEG: Magnetoencephalography  Similar to EEG, but involves magnetic fields instead of electric field Strength  Improved setup time and subject comfort compared to EEG Weakness  Confined to signals at surface of brain TMS: Transcranial magnetic stimulation  Very strong but brief magnetic pulse is applied near surface of head  Induces electrical current flow on surface of brain Strength  Allows manipulation of neuronal activity and thus causal inference Weakness  Limited to surface of brain NIRS: Near infrared spectroscopy  Shine infrared light through skull  Detects changes in absorption due to blood flow Strength  Non-invasive, very safe, good for infants Weakness  Does not work in every subject Optical Imaging:  Directly view the surface of the cortex using a video camera  Electrical activity can also be measured by using a voltage-sensitive dye Strength  Allows measurement and comparison of both intrinsic and electrical activity Weakness  Confined to the surface of the brain Electrophysiology:  Directly record action potentials and other electrical activity in neurons by placing electrodes in the brain Strength  Activity of multiple individual neurons can be directly compared Weakness  Records from small number of neurons 3. Compare and contrast the human brain and a digital computer, including memory capacity, processing, speed, and the capabilities of understanding and being intelligent or conscious. Describe one ability that a computer excels at but a human brain doesn’t and vise versa  Digital computers are good at implementing simple rules quickly and exact. They can out perform brains in many simple tasks - Symbolic manipulations (algebra), repetitive calculations, chess  Brains are good at making judgments, inferences, and generalizations. They are prone to error, but they can solve many problems that are presently untenable with machines - Face recognition, speech recognition, language  Brains and machines can both solve the same tasks as the other, only they are much slower at tasks which they are not specialized at 5. Define consciousness what objects and animals are or could be conscious? Why? Defend your answer Consciousness is the awareness of environmental and cognitive events such as the sights and sounds of the world as of ones memories, thoughts, feeling, and body sensations  Humans become aware of themselves and recognize themselves at 18 months and older Animals that recognized themselves in the mirror are bonobos and chimpanzees, orangutans, gorillas, bottlenose dolphins, orcas, elephants 6. What is the difference between “weak” artificial intelligence (AI) and “strong” AI? Which do you think is true, and why Weak AI  Suitably programmed machines can stimulate human cognition (computer can stimulate a mind) Strong AI  Suitably programmed machines are capable of cognitive mental states (computer is or can be a mind) 7. What is attention? Describe what happens when you pay attention to a stimulus. What happens to the stimuli that you are not paying attention to? What purpose does attention serve in the brain? Attention is taking possession of the mind, in the clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentrations of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others. Too many events occur simultaneously in the environment to pay attention to all of them at once; so selective attention is used to focus on those stimuli relevant to current activity. (For example, you might not generally pay much attention to wind direction, but you do if you're flying a kite or hitting a golf ball.) Motor set when attending to a stimulus, an individual organizes muscular responses, a motor set, to be ready for the particular attention situation. A perceptual set is the readiness to interpret a stimulus in a certain way. A mental set is a predisposition to think about a situation or a problem in a specific way. Stimulus intensity. If other stimulus factors are comparable, a more intense stimulus attracts more attention than does a more subtle one. For example, a loud siren gets more attention than a faint one. Stimulus changes. Stimulus changes elicit more attention than does sameness or monotony. Attention serves the brain in types of attention; spatial attention: all neurons are enhanced whose receptive fields lie within a restricted region of space, independent of their feature tuning. Feature based attention; all neurons tuned to specific features are enhanced and object based attention; all neurons are enhanced that are tuned to an arbitrary set of features and locations. 8. Describe the primary distinction between implicit and explicit memory. For each type of memory, give an example of three tasks that require it. Why is
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