A review of the sufficient conditions for consciousness

Abstract

The neuroscience of consciousness has set out to find the sufficient conditions for subjective experience. Theoretical and empirical endeavours have placed a particular focus on the cortex and subcortex, whilst discounting the cerebellum. However, when looking at neuroimaging research, it becomes clear there is substantial evidence that cerebellar, cortical, and subcortical functions are correlated with consciousness. Neurostimulation evidence suggests that alterations in both the cortex and the cerebellum may provoke alterations in experience, however experimental stimulation of the subcortex may abolish, as well as induce, behavioural evidence of experience. Similarly, neuropsychological evidence shows that abnormalities in the cortex, subcortex and cerebellum may provoke changes in experience; but only damage to the oldest regions seems to completely obliterate experience. Finally, I review congenital and experimental decorticate cases and find that behavioural evidence of experience is compatible with the absence of the cortex. The evidence, taken together, indicates that the subcortex is sufficient for behaviours that suggest basic experiences. Based on the findings of this review, I emphasise both the importance of the individual’s developmental trajectory and the interdependencies between different neural systems (e.g., cortex, subcortex and cerebellum) in neurologically typical individuals.