Recently principle component analysis (PCA) of intrinsic optical signal was applied for the study of spatial organization in feline and primate striate visual cortex (V1). It has been found that only first 50-100 principal components contained information related to the visual response. In the current study we went further and analyzed principle components of much higher order (up to 2000). In agreement with previous studies, higher principle components indeed did not contain any information related to a visual stimulation. However, we found very strong correlation between these components and higher cognitive processes in the brain. Here we report results from a study of 6 adult anesthetized and paralyzed monkeys (two Macaca Mulatta and four Macaca Fascicularis). In five monkeys distinctive mental images representing the subject engaged in mating and feeding activities were observed, while in one (unusually aggressive) monkey very clear picture of a violence directed toward experimenters has emerged. These results demonstrate that higher cognitive functions already exist at early stages of visual processing and they can be detected in high-order principle components that previously have been considered as a mere noise. Moreover, the fact that mental representations were clearly referenced to the subject's self, and not to another or "abstract" monkey, suggests that macaques are self-aware - the quality previously attributed only to humans and apes.