Sample questions from the Cognitive Neuroscience Written Entrance Exam

• What is the use of brain-imaging to study questions that cognitive science is investigating, e.g., the development of language and thought, the nature of cultural differences, and the origin of individual variation in competence?
• Biophysical approaches to study the release of a neurotransmitter from a presynaptic terminal.
• Linguists have developed sophisticated models of grammar. Imagine that the grammar of language X is known. Discuss how it relates to psycholinguistic models of how X is acquired, produced and perceived.
• A simple electric model of an excitable membrane incorporating passive and active properties.
• Consider the advantages and disadvantages of individual case studies and group studies, for drawing inferences about theories of the organisation of brain processes underlying cognitive disorders manifest in EITHER (i) adult neuropsychological patients or (ii) children with cognitive developmental disabilities.
• The role of neurotrophins in the peripheral and central nervous system.
• Briefly describe an experiment to investigate whether, at birth, the functional properties of the cortex in human infants are organized like those of adults.
• The formation of topographic maps during neuronal development.
• Briefly discuss the main advantages and disadvantages of current brain imaging techniques.
• The use of molecular biology techniques to perturb neuronal functions.>
• How would you design EITHER a functional imaging or a neuropsychology study to obtain theoretically useful information on one of the following: (i) category specificity in semantic memory (ii) apraxia (iii) the phonological route in reading (iv) apperceptive agnosia
• Discuss the different ways in which sensory information can be encoded.
• Briefly describe the physical basis of EEG recording.
• Describe different types of associative memory networks.
• People suffering from motor neuron disease or spinal cord injury would benefit from a technology that would utilize brain signals to control external devices, such as a joystick. Suppose that you have access to neuronal activity recorded at 100 electrodes, implanted chronically in the hand/arm region of primary motor cortex. Describe how you would "decode" this neural activity to control an external device in realtime.
• Information processing in the central nervous system may involve different time-scale. Discuss.
• Compare the roles of sodium, potassium, and calcium conductances in controlling neuronal excitability.
• Biophysical aspects of protein folding.
• What is the most significant advance in biology in the last 20 years? Justify your choice.
• Processes that can produce short and long term changes in synaptic efficacy.
• An example of sensory transduction at peripheral sensory organs.
• Experimental approach you would use to characterize a novel neurotransmitter receptor.
• Different mechanisms used by the cells to transduce signals from outside to inside.
• Describe biophysical and/or molecular biology methods used to study basic properties of voltage-activated membrane ionic channels.
• Discuss how voltage-activated membrane currents can influence the release of a neurotransmitter.
• Discuss the application of the stochastic theory to the analysis of single channel data and/or synaptic release data.
• Discuss the derivation of the Hodgkin-Huxley model to interpret the action potential of a nerve cell.
• Discuss the possible role of calcium ions in synaptic plasticity.
• Discuss experimental methods (biophysical or genetic) for the study of protein-protein interactions.
• Discuss intracellular protein trafficking: signals and proteins involved.
• Discuss the molecular basis of growth factors activity.
• Discuss how the human genome project is being carried out and its advantages and disadvantages.
• Describe one or more examples of how to employ molecular biology techniques to study Biophysics and Neuroscience.
• Describe one or more optical methods used to investigate physiological processes in the nervous system.
• Describe examples of intracellular mechanisms for signal transduction of membrane receptor activation.
• Describe the main biophysical mechanisms of chemical synaptic transmission and the experimental methods to study them.
• Discuss the mechanisms of transcriptional activation in mammalian cells.
• Briefly describe the most important principles of the anatomical organization of the cerebral cortex.
• Discuss the proposal that different mechanisms of synaptic plasticity (LTP, LTD) are involved in experience-dependent modifications of sensory cortical circuity.
• Illustrate the techniques and experiments necessary to demonstrate that a factor has a neurotrophic action.
• Discuss the role of spontaneous electrical activity in the development of functional connectivity.
• You have access to every methodological tool. Design an experiment to test possible regenerative properties of CNS neurons.
• Using a 100 x 100 geometric array of microelectrodes (10,000 electrodes), you can record neuronal activity in 1 ms time bins from some region of cerebral cortex believed to be involved with sensory processing. Thus you have available a spatially-temporally distributed record of activity. Invent analytical methods to compare the total pattern of activity when different sensory stimuli are delivered to the subject. Make neat sketches to illustrate your plan. Explain what each analytical method might be able to tell you about cortical sensory processing.
• A magazine carries the headlines "Every Man Will Be A Genius." In the article, scientists state that, very soon, they will have the technology to store very large quantities of information on silicone microchips and implant these chips in the human brain. For example, the contents of an entire encyclopedia could be put into the brain. (a) How is information stored by the brain different from information stored by a silicone chip? How is it the same? (b) What are the major challenges the scientists must face? For example, to what part of the brain should they connect the chip? How should they transfer information from the chip to the brain, and vice versa?
• Imagine having to take over as commander of an isolated Czarist outpost in the Caucasus. The only way to communicate any message, from military reports to letters by your men to their families, is to dispatch one of the men - and they are very few - either through dangerous Circassian-held territory, or via a long detour through the safer Ossetian wastelands. You can expect very few replacements for those who fail to return, and serious damage if they are intercepted. Use your imagination to complete and quantify this description with the definition of a cost function, dependent on parameters like the probabilities of the messenger(s) being caught and of the outpost being attacked and overrun. On this basis sketch an optimal strategy or schedule for using your communication channels.
• Forget Guido d'Arezzo. Devise an original notation for Western music, and briefly discuss its virtues and flaws as a coding system.
• Are the different uses of the term "working memory" compatible? Which of them has/have proved most fruitful for explaining (a) neuropsychological phenomena and (b) phenomena derived from other empirical methods?
• The Web is now thought to include some 800 million units (documents), whose local connectivity (number of links per document) follows a power law distribution: roughly 1/100 documents have more than 10 links, 1/14,000 more than 100 links, 1/2,000,000 more than 1,000 links. The "informational diameter" of the Web (mean shortest number of links to follow in order to go from one document to another) has been recently estimated to be 19. On the other hand, the human Cortex has been estimated to include some 8 billion units (pyramidal cells) whose local connectivity follows a unimodal distribution, peaked at, say, 40,000. Assuming half of these connections to be really local and half long-range, and both random, produce a back-of-the-envelope estimate of the informational diameter of the Cortex.
• As a solitary lighthouse watch on the Fair Isle, you have devised an efficient system to broadcast lyrics and ballads to poetry-avid seafarers: you apply a red, blue or yellow filter (or no filter) at every sweep of the light (3 per minute). Please tell us the code you have used, and how long it took you to broadcast William Wordsworth's "She Dwelt Among the Untrodden Ways" (351 characters including blank spaces).
• An axonal fiber branches and contacts a given postsynaptic cell at n synaptic release sites, each of which has an independent probability p of actually releasing a single vescicle of neurotransmitter after a presynaptic spike. The fiber carries spikes with a certain constant probability q per msec (a Poisson process of mean rate 1000 x q Hertz). If the postsynaptic signal decays away with time constant T, in which situation would you regard the variability of the signal as mainly spatial rather than temporal in nature? What if n=100, p=0.1, q=0.01, T=10 msec ?