During a morning session, Benjamin Kozuch made the following argument:
- If Higher order theories are true, then prefrontal lesions should produce manifest deficits in consciousness (as defined by HOT).
- PF lesions do not produce manifest deficits in consciousness.
- Therefore, many HO theories are not true.
Liad Murdik, in her comments, adeptly pointed out that the PFC is commonly taken to be a center (location, module, etc.) of HO states by a number of people, but this might be a mistake. She explains: it does not follow from the notion that the PFC is associated with higher order mental capacity (i.e. what makes humans more cognitively advanced than, say, mammals without a PFC) that the PFC is the location of HO thought or states. HO thoughts and states could very well be the product of dynamic relationships between various cortices.
I find Mudrik’s distinction very important in discussions of evidence for HOT. I think of coma science research (Boly et al 2009) which demonstrates how wakefulness and attention correlate with connectivity in one’s global workspace (including numerous locations of the brain), but not with any one area of the brain. We might need new reasons for assuming that the PFC is the center if HO activity—if we are to continue assuming at all.
Boly, M., Balteau, E., Schnakers, C., Degueldre, C., Moonen, G., Luxen, A., … & Laureys, S. (2007). Baseline brain activity fluctuations predict somatosensory perception in humans. Proceedings of the National Academy of Sciences,104(29), 12187-12192.
Boly, M., Tshibanda, L., Vanhaudenhuyse, A., Noirhomme, Q., Schnakers, C., Ledoux, D., … & Laureys, S. (2009). Functional connectivity in the default network during resting state is preserved in a vegetative but not in a brain dead patient. Human brain mapping, 30(8), 2393-2400.
Vanhaudenhuyse, A., Noirhomme, Q., Tshibanda, L. J. F., Bruno, M. A., Boveroux, P., Schnakers, C., … & Boly, M. (2010). Default network connectivity reflects the level of consciousness in non-communicative brain-damaged patients. Brain, 133(1), 161-171.