Individual differences in the vibrotactile perception of a “simple” pattern set

Discriminative capacities for vibrotactile spatiotemporal patterns were examined in 62 college students with three tasks: identification, masking, and discrimination of the letters “X” and “O” presented tactually on the Optacon, a reading machine for blind persons. Individual differences in performance and interrelations among scores within and across paradigms were explored. In identification, most persons quickly achieved consistently better than 90% performance, but others failed to identify the patterns above 80%, even after prolonged training. The same performance variance was found when the task was repeated by 23 Naval student pilots. Masking and discrimination measured susceptibility to interference when patterns followed one another closely in time. The resulting functions were typical, with poorest performance at short stimulus onset asynchronies. Again, a wide range of performance was seen. Individual performance, however, appeared to be consistent across tasks, suggesting that abilities in a variety of pattern-perception tasks might be predictable.     

The biological efficacy of the transfer function

The most popular neural network strategy is back propagation. This strategy initiated general interest in neural networks among researchers. While back propagation can solve nonlinear problems, it is considered to be a poor example of neuron functioning. Recently, Gardner (1993) has made a strong case for a back propagating phenomenon in networks of living neurons. In this paper, we present a few simple computational examples that investigate another component of the typical back propagation network. The effects of varying transfer functions are illustrated along with the resulting variations in possible synaptic weights. Graphic presentations in 3-D space of the relationship between transfer functions and synaptic weights suggest neural analogies of cell-firing rate and network control.     

Increased regional cerebral glucose metabolism and semantic memory performance in Alzheimer's disease: A pilot double blind transdermal nicotine positron emission tomography study

Nicotinic receptor dysfunction and impaired semantic memory occur early in Alzheimer's disease patients (AD). Previous research implied that nicotine's ability to enhance alertness, arousal, and cognition in a number of nonclinical populations was a function of its ability to stimulate CNS nicotinic cholinergic receptors. In this study it was hypothesized that transdermal administration of nicotine would increase both regional cerebral glucose metabolism (rCMRglc) and semantic memory (as assessed by verbal fluency). Two mild AD and two elderly controls underwent positron emission tomography scanning during a double blind nicotinic agonist verbal fluency challenge procedure. rCMRglc increases occurred in both AD patients, but not controls. In the two AD patients, verbal fluency scores increased by an average of 17%. One elderly control's verbal fluency increased, and the other decreased. These findings suggest that nicotine's effect on metabolism and verbal fluency is due to its ability to stimulate the cholinergic system.     

Prediction of school attendance problems

Predictions of school attendance problems were made for 262 14-yr-old school children on the basis of intelligence, social class and personality (extraversion-introversion) differences. The overall success of prediction was highly significant, though this was achieved largely by one school group alone. The results are discussed in terms of future early identification and therefore prevention of problems.