Associação do polimorfismo Maoa-VNTR com o desempenho em tarefa de estimativa de tempo e na assimetria da banda alfa no córtex pré-frontal durante a tarefa

Abstract

The temporal perception is an innate ability of several species of animals, being an essential characteristic for basic cognitive functions like learning and decision making. Among the different neurotransmitters that have been involved with the modulation of the internal clock, serotonin (5-HT) stands out in various experiments with humans and animals. However, it is not yet known how genetic polymorphisms associated with 5-HT regulation may contribute to variations in the way we process the temporal dimension. The present work, with a sample of 97 male subjects, aimed to investigate how the variable number of tandem repeats (VNTR) in the promoter region of the MAOA gene can contribute to the interindividual differences in the performance in the estimation task and asymmetry of the alpha band in the prefrontal cortex. Subjects estimated the time (1, 4, 7 and 9s) concomitant with electroencephalographic uptake. The subjects were genotyped by polymerase chain reaction (PCR) and classified according to the number of repeats as having high alleles (H-MAOA, n = 59) or low expression (L-MAOA, n = 38). Through a logistic regression, the genotype was predicted significantly by the absolute error in

1s and by the greater activity of the alpha band to the left of the ventrolateral pre- frontal cortex (VLPFC) in 7s (p <0.005). The L-MAOA subjects tended to err less in

1s and to underestimate the time intervals (1, 4, 7 and 9s). However, no main effect of the genotype was found on the asymmetry of the prefrontal cortex in the two-way analysis of variance. The anterior prefrontal cortex, dorsolateral prefrontal cortex, and VLPFC showed predominance of activity in the right hemisphere, which corroborates the well-known importance of the right hemisphere for the perception of time in lesion studies and transcranial magnetic stimulation. The MAOA-VNTR polymorphism is shown to be an important marker for temporal response, which may be associated with the role of 5-HT modulation for impulsivity, attention and working memory, which are important aspects of temporal processing.