The neurosciences have made great strides in gaining a better understanding of the brain and its relation to cognitive processes. It is nevertheless striking, especially in these early years of the 21st century, that we continue to face persistent questions on brain-mind relationships. In his book ' The Brain’s Representational Power – On Consciousness and the Integration of Modalities' UvA neuroscientist Cyriel Pennartz investigates how the sensory qualities we consciously experience can be explained in terms of cognitive processes.
‘As argued by the Australian philosopher David Chalmers, we are still confronted with the ‘Hard Problem’ in this field,’ says Pennartz. ‘For example, how can a physical object such as the brain with its billions of nerve cells generate subjective and qualitative experiences like seeing colours? How is it possible that the trillions of electrical impulses constantly flashing through our brains enable us to taste a good Chardonnay?’
Pennartz takes us back to the Age of Enlightenment, when the emergence of sensory experiences began to be studied intensively. Examining the consequences of brain damage and experimental interventions, he asks to what extent neural structures could be ‘peeled away’ until consciousness is finally lost. He concludes that neural systems for language, movement, emotion and memory are not essential for consciousness, in contrast with perceptual systems.
Which features of perceptual systems would explain their peculiar position? This question leads to a quest through the anatomy and physiology of the brain, and along theoretical models also used in artificial intelligence. Extant computer models can tie neurons together in all kinds of ways to solve mathematical problems, but even these models fail in solving the consciousness issue. Will computers never be able to generate subjective experiences, or did we just not find the correct solutions yet?
Pennartz charts the requirements brain networks have to meet in order to qualify as a conscious system, and indicates possible mechanisms as to how this may happen. A key element in his view is that the brain generates complex representations. These representations do not arise from one single modality (like seeing or hearing) but originate from interactions between modalities. This way the brain constructs 'best guesses’ of what is going on in the outside world and within the body. This model permits our conscious experiences to have qualitative properties like smell, touch and pain – which can be, however, only 'felt' at a higher level of brain organisation. At the same time, this higher level is compatible with lower levels at which neurons organise themselves into networks and supernetworks. This allows this representational theory to reconcile the brain being purely made up of matter with the production of a rich palette of experiences that are just as ‘real’ as the underlying substance. Finally, Pennartz places the theory in the context of the current brain-mind philosophy, addressing questions such as: which animal species have consciousness? Could robots ever have conscious experiences?
Prof. Cyriel M.A. Pennartz is professor of Cognitive and Systems Neuroscience at the University of Amsterdam. He is affiliated with the Center for Neuroscience of the Swammerdam Institute for Life Sciences and is involved in the UvA's Brain and Cognition research priority area.
Cyriel M.A. Pennartz: The Brain’s Representational Power – On Consciousness and the Integration of Modalities (MIT Press, september 2015). ISBN: 9780262029315.