Electromagnetic field theory of consciousness
Explanation
Johnjoe McFadden, British biophysicist, has defended since 2002 the CEMI theory (Conscious Electromagnetic Information): consciousness is information integrated in the electromagnetic field generated by neural activity. It is not the activity of individual neurons that is conscious, but the global electromagnetic field they collectively generate.
The motivation is elegant. Active neurons generate electric and magnetic fields. These fields, summed across millions of synchronous neurons, produce a measurable cerebral electromagnetic field (this is what EEG and MEG capture). This field is not just an epiphenomenon: it feeds back onto the neurons themselves, modulating their activity.
The integration of information in this field is massive and intrinsic: unlike neural connectivity (which requires axons and synapses), a field is inherently integrated, all points communicate simultaneously. McFadden proposes that this integration is precisely what IIT identifies as necessary for consciousness, but physically realised as an electromagnetic field.
This hypothesis explains some difficult observations: the unity of consciousness (fields are intrinsically integrated), the rapidity of conscious integration (electromagnetic fields propagate at the speed of light), and the correlation between synchronised gamma oscillations and consciousness (oscillations generate broad coherent fields).
Empirical predictions are possible. If consciousness is an electromagnetic field, it should be sensitive to external magnetic fields. Transcranial magnetic stimulation (TMS) produces effects on consciousness consistent with this prediction. And anaesthetics could work by disrupting cerebral electromagnetic coherence, not necessarily by blocking individual neurons.
The theory is minoritarian but has gained defenders in theoretical neuroscience. It has the virtue of proposing a physical solution to the binding and integration problem, without invoking exotic quantum mechanisms. Its critics point out that cerebral electromagnetic fields are weak and the back-influence on individual neurons would be marginal. The debate continues.
Strengths
- Elegantly resolves phenomenal binding.
- Connects with familiar physics and electromagnetism.
- Potentially testable predictions.
- Coherent with oscillatory theories.
Main critiques
- Cerebral EM fields are relatively weak.
- Hard to distinguish causal vs. epiphenomenal role.
- Partial empirical evidence.
- Accused of promise without detailed mechanism.