Toca que o cérebro também dança: efeito da ritmicidade de tons auditivos sobre parâmetros comportamentais e eletrofisiológicos da execução de uma tarefa de soma aritmética

Abstract

Sequences of stimuli presented between 125-2000 ms (0.3-8Hz) may impact on perception, motor responses and cognition. Dynamic Attending Theory postulates oscillations of attention, that may synchronize by entrainment to rhythmic events from environment. Rhythm perception has been shown to involve classical motor areas, notably basal ganglia. These sub-cortical nuclei has been also linked to executive functioning, due to existence of cortical-striatum-thalamic-cortical loops. Since executive function is based on prefrontal cortex activity, this work aims to characterize effect of auditory rhythmic stimuli on motor behavior, executive function and electrophysiological responses. Sample (n=24) was previously calculated by G*Power 3.1 software. Participants were submitted to finger tapping and executive tasks (sequential arithmetic sum), while auditory tones were played or not. Our results show motor synchronization for ISI 500 ms, and increased variability for ISI 350 ms and 650 ms. Autonomic electrophysiological responses did not show any changes, except for a decreased heart rate at ISI 350 ms, Non-Synchronized Condition. Delta-Gama Modulation Index is negatively correlated with hitrate for ISI 350 ms, but positively correlated with hitrate at Synchronized Condition. ISI impacts on hitrate, but a larger modulation of both ISI and auditory stimuli over Reaction Time is shown. Our results suggest an “optimal entrainment range”, centered at 500 ms, and an increased likelihood for involuntary synchronization at this point. Besides, results suggest so-called cold and hot executive functions are independent processes, and also that nervous system may activate different processing ways for different temporal contexts. These findings also corroborate the existence of a rhythmic processing mode, however, with decreased performance through high speed processing request.