PubMed · 5046666
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J R Pierce. 1972. Communication.. https://pubmed.ncbi.nlm.nih.gov/5046666/
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Inheritance of a defect in a neuronal mechanism that regulates response to auditory stimuli was studied in nine families with multiple cases of schizophrenia. The defect, a decrease in the normal inhibition of the P50 auditory-evoked response to the second of paired stimuli, is associated with attentional disturbances in schizophrenia. Decreased P50 inhibition occurs not only in most schizophrenics, but also in many of their nonschizophrenic relatives, in a distribution consistent with inherited vulnerability for the illness. Neurobiological investigations in both humans and animal models indicated that decreased function of the alpha 7-nicotinic cholinergic receptor could underlie the physiological defect. In the present study, a genome-wide linkage analysis, assuming autosomal dominant transmission, showed that the defect is linked [maximum logarithm of the odds (lod) score = 5.3 with zero recombination] to a dinucleotide polymorphism at chromosome 15q13-14, the site of the alpha 7-nicotinic receptor. Despite many schizophrenics' extremely heavy nicotine use, nicotinic receptors were not previously thought to be involved in schizophrenia. The linkage data thus provide unique new evidence that the alpha 7-nicotinic receptor gene may be responsible for the inheritance of a pathophysiological aspect of the illness.
A modified dual-task approach was employed with 7- to 9-year-olds in an effort to determine whether one of the classic M-power measures, the digit placement task, is indeed capacity-limited. To this end, a computerized version of a three-item digit placement task was administered in addition to three other computerized tasks: a four-item digit placement task, simple reaction time (RT) to a tone presented alone, and reaction time to a tone occurring during the performance of another three-item digit placement task. Careful examination of the data revealed that several critical assumptions concerning the use of the dual-task procedure were successfully met. This permitted a test of the extent to which dual-task RTs were predictive of accuracy in the harder, four-item digit placement task. Not only was this relationship significant, but after partialling out other possible sources of variance, a significant correlation remained, indicating that the digit placement task is indeed capacity-limited.