Changes in the power and coherence of alpha-activity and heart rate variability (HRV) were studied in students with different performance levels in logical tasks. In those students who reached high scores in the cognitive tests, we observed higher lability of alpha-activity and HRV; the values and their ratios varied among the stages of intellectual activity. In these subjects, a decrease in the spectral power of alpha-band was more pronounced than in other groups. We also observed changes in the interhemispheric coherence and in the structure of coherent interactions in the alpha-range at different stages of task performance. In contrast, the number and structure of coherent interactions in individuals who showed lower results did not significantly vary at different stages of task performance. As compared with this group, the students with higher test results showed a more pronounced decrease in the total spectral power (TP) and an increase in the low frequency/high frequency (LF/HF) ratio which returned to the initial level after the end of the tests. In students with better results in these cognitive tests, the dynamics of RRNN, TP, HF, and LF/H F during task performance correlated with the dynamics of interhemispherical alpha-band coherence.