Semir Zeki

Semir Zeki FMedSci FRS is a British neurobiologist who has specialized in studying the primate visual brain and more recently the neural correlates of affective states, such as the experience of love, desire and beauty that are generated by sensory inputs within the field of neuroesthetics. He was educated at University College London (UCL) where he was Henry Head Research Fellow of the Royal Society before being appointed Professor of Neurobiology. Since 2008 he has been Professor of Neuroesthetics at UCL.

Zeki's early work was mainly anatomical in nature and consisted in charting visual areas in the primate (monkey) brain by studying their connections, leading him to define several visual areas lying anterior to the primary visual cortex (area V1) of the brain. This was followed by recording from single cells in these areas, which led him to the view (a) that there is a functional specialization in the visual cortex, with different visual areas undertaking different visual tasks, such as the processing of colour, motion and form and (b) that the visual brain processes these different attributes in parallel.

He later showed, using brain imaging techniques, that the same principles apply to the organization of the human visual brain. In recent work he has shown that parallel processing appears to extend beyond the mere processing of visual signals to their grouping in parietal cortex. His work on colour vision was influenced by the work and methods of Edwin H. Land, whose techniques he employed in his physiological and brain imaging experiments, and which led him to the view that colour is constructed by the brain and that a specialized visual area, area V4, is critical to this process.

These findings raised the question of how the signals processed in these separate visual areas are integrated to give a unified picture of the visual world. In psychophysical experiments undertaken with colleagues, he showed that we perceive, and become aware of, different visual attributes at different times, with colour preceding motion by about 80 ms and form (orientation) by about 40 ms, leading to the view that there is a temporal asynchrony in vision which is the result of different processing speeds for different attributes. This in turn led him to suggest that visual consciousness is not unified; rather there are many visual micro-consciousness which are distributed in time and space, and that activity in each visual area can acquire a conscious correlate without the necessity of reporting to another cortical area, though acknowledging that there must be other enabling systems, possibly located in the reticular formation. Thus, functional specialization manifests itself in the temporal sequence with which we see different attributes such as colour

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