RESUMO
In this work, magnetoencephalography was used to study the temporal dynamics of neural responses in 16 subjects (eight women, eight men) choosing among different day-to-day consumer items. At short latencies (< 150 ms), the evoked responses showed striate and extrastriate cortical activation common to the processing of general objects. At about 300 ms, women activated preferentially left posterior cortices, whereas men activated preferentially right temporal cortices. This may reflect sex/gender differences in cognitive strategies, emphasizing category-specific knowledge in women and spatial memories in men. At latencies greater than 500 ms, right parietal cortices were preferentially activated when previously bought or used items were chosen. In contrast, left inferior and right orbital cortices were preferentially activated when selecting less-known items. This may be interpreted as representing the neural correlates of decisions where the outcome is consistent with previous experience, and of choices which are 'difficult' in some sense. Analysis of coherent gamma-oscillations (20-45 Hz) revealed neural activity over left anterior and right dorsolateral cortices at long latency (> 1500 ms) when brand knowledge is low. This is consistent with the late binding of (brand) memories and evaluation of multiple sources of information when a choice is not obvious. gamma-Activity showed that women may activate larger neural networks when preference is high, suggesting that men and women exhibit different patterns of neural activity even though their overt performances are similar.
