Cognitive Neuroscience: 1996 Admission Exams

Please answer three (3) of the following:

(1) Certain neurons in the insular cortex are sensitive to the taste of salt, and respond to the concentration c of NaCl in a solution with a mean firing rate

r = ln [c/k + 2]

where k=0.000001M is a constant. Stronger firing carries, however, more intrinsic variability, since each response on any given trial is normally distributed with standard deviation equal to twice the square root of the mean rate. Suppose that you have to use the responses of N such neurons to discriminate between two solutions, one having 101% and the other 99% NaCl from a reference concentration. How would you choose the reference concentration to maximize your confidence in the discrimination?


(2) Discuss the role of neurotrophic factors
(3) Discuss the proposal that the mechanisms of synaptic plasticity demonstrated in vivo (LTP and LTD) are involved in real behavioral learning.
(4) Discuss the intracortical anatomical and functional circuitry of one sensory system.
(5) Maps of several types (e.g. retinotopic, somatotopic, tonotopic) have been found in different parts of the brain. Hypothesize what might be the functional/computational advantages of having sensory information arranged in a map rather than in a disordered way.
(6) Suggest one or more models that can address the brain mechanisms underlying the perception of object motion in space with and without eye movements.
(7) Briefly describe the steps which might be essential to teach an experimental animal of your choice to fixate a target in space for a few seconds.
(8) Discuss the cortical plasticity involved in one sensory experience-dependent paradigm.
(9) Two theories of hippocampal function are based on (1) spatial maps and (2) memory. Choose one of the two theories, summarize and explain it, and give evidence in favor and against it.
(10) A farmer with mesial temporal lobe atrophy, following an ischemic episode in 1993, impresses the doctor by being able to remember in detail the Christmas dinner he had with his family in 1988, including where everybody was sitting and what he or she ate. In contrast, the patient does not recall which 3 dishes he has just had at his favorite café an hour ago. Subsequent investigations, however reveal that the patient's extended family (2 couples with one child each) have for many years a fixed booking for Christmas at the same round table of a downtown restaurant, which offers a choice among 3 menus. Husbands sit facing their wives, and neither husband nor wife order the same menu, more the same as their child's. The cafe, instead, has a choice of 17 dishes. By comparing probabilities, would you conclude that what the patient remembers about Christmas is really more than what he has forgotten about his recent lunch?
(11) Briefly describe the major functions of the parietal lobes in humans.
Taking one specific cognitive process such as (but not limited to) face recognition, verbal short-term recall, or error correction, discuss the way neuropsychological investigations of the impairments of neurological patterns can provide information about its functional organization in the brain.
(13) What type of assumption underlie functional imaging studies of the processes involved in carrying out specific tasks? Discuss with respect to one concrete example such as (but not limited to) reading or retrieval from long-term memory whether such studies are likely to greatly change our understanding of how processes operate.
(14) Consider, with reference to any specific cognitive domain or neuropsychological syndrome, whether or not computational models based on connectionist principles have been an advance on alternative theoretical accounts based on other approaches.
Edited by: F.P. Battaglia, SISSA, Trieste, Italy. batta@sissa.it