Are electromagnetic fields the primary seat of consciousness?
New research suggests that fields generated by the brain may be where the main action is taking place
The conventional view in neuroscience circles is that neurons and their synapse firings are the key dynamics supporting consciousness. In other words, if we peer into the body and brain in search of the “neural correlates of consciousness” what we’ll find is that electrochemical synapse firings of various types, perhaps in particular areas of the brain, are the specific neural correlates of consciousness.
But what if this view overlooks a key set of physical features of the brain? What if various scales of electromagnetic fields (“EM fields”) generated by, but not identical with the brain, are in fact the primary seat of consciousness? In this view, neurons and synaptic transmission of information are necessary for consciousness, but they are not sufficient for consciousness.
We would then need to look to the spatially and temporally more fine-grained dynamics of local and global EM fields for the primary seat of consciousness. Under this view, rather than looking for neuronal correlates we look for “oscillatory correlates of consciousness” (OCC) (see figure 1) or what I have begun calling “the resonome,” or the “oscillome,” defined as the set of resonating fields that create consciousness in each moment. Oscillatory and synaptic dynamics, in this view, jointly comprise the neuronal correlates of consciousness.
This debate is highlighted in NIH researcher Douglas Fields’ new book The Electric Brain and he generally comes down in favor of the view that EM fields are functionally relevant and causally potent in the brain.
C. G. Hales coined the term “electromagnetic correlates of consciousness” (EMCC) in a 2014 paper on how the brain’s endogenous EM fields produce consciousness. EMCC and OCC are equivalent in terms of mammal brain. Figure 1 shows this simple taxonomy of various correlates of consciousness and suggests that the well-known “neural correlates of consciousness” should be divided into synaptic correlates and oscillatory or electromagnetic correlates of consciousness.
Let’s go through the various arguments in favor of each view.
Are electromagnetic fields merely epiphenomenal?
Some neuroscientists have considered the brain’s oscillating EM fields to be interesting but merely epiphenomenal features of the brain. Like the proverbial train whistle on a steam-powered locomotive, the EM fields are produced by the brain but they may just be noise. They don’t affect the underlying function of the brain.
Christof Koch, a long-time friend and sort-of colleague (I’m a mere philosopher of mind and he’s an actual neuroscientist and biophysicist) had this to say in a recent interview I conducted with him, in response to my question about EM fields possibly being the primary mechanisms of consciousness:
While at this early stage of the exploration of the brain it would be foolish to categorically rule out any physical process, as an electrophysiologist I’m less enthused about ascribing specific functions to specific frequency bands, let alone experience for two reasons.
Firstly, by and large, the causal actors between neurons that act at the time scale relevant for consciousness (5–500 msec) are action potentials that cause, in turn, synaptic release of packets of neurotransmitters. Most neurons fire highly irregular spike trains, more compatible with a random Poisson process than with a highly synchronized, clocked process of the sort we’re familiar with from electronic circuits. Yes, in a deeply asleep cortex, neuronal on-off states occur with a high degree of regularity every couple of 100 msec, leading to theta band oscillations. Furthermore, given the widespread feedback nature of excitatory pyramids cells and inhibitory interneurons, certain frequencies — such as in a broadly defined gamma band extending from 30 to perhaps 100 or more Hz — can be commonly found in the awake cortex. So yes, the EEG that is recorded from the scalp outside the skull and its sibling, the local field potential (LFP) that is recorded with thin electrodes inserted into cortex proper (through the skull), all show peaks at particular frequencies. Yet these are broad and are superimposed onto a 1/f^n type of power-law decay characteristic of many natural systems (see the figure).
Secondly, the extent to which oscillations in the LFP or the EEG have causal influence on firing pattern of neurons remains an open question. Consider the sounds the beating heart makes. These can be picked up by a stethoscope and can be used to diagnose cardiac conditions. However, there is no evidence that the body exploits these sounds for any function.
My own group has provided some electrophysiological in vitro evidence that oscillations in the extracellular field at particular frequencies may be able to entrain spikes in a cell-type dependent manner (Anastassiou, Perin, Markram & Koch Nature Neuroscience 2011). At this point, we do not know what role such so-called ephaptic coupling (to distinguish them from the more conventional synaptic coupling) play in the human brain.
Clearly, Koch is open to new evidence but he also makes it clear that he doesn’t currently view the evidence as supportive of the notion that EM fields (measured as LFPs or EEG) are causally potent in ways sufficient to be important for consciousness, let alone being the primary seat of consciousness.
Or are EM fields the main game in town?
Recent research is changing some minds and will, it seems, before too long convert an increasing number of observers to the view that EM fields are not only causally potent but may in fact be the main game in town.
I offer first two logical arguments for considering EM fields to be causally potent and possibly the primary seat of consciousness:
1) If the brain’s endogenous EM fields were only epiphenomenal, manipulating endogenous EM fields with exogenous EM fields (TMS, tACS, TDCS, etc.) would not lead to changes in consciousness. The epiphenomenal view of endogenous EM fields requires a one-way causal path: from neuroanatomy to LFPs (ECoG) and global EM fields (EEG/MEG). As manipulating the train’s whistle by changing its flowing air dynamics would have no impact on the function of the locomotive that produces the steam that blows the whistle, so manipulating the brain’s EM fields with exogenous EM fields would have no impact on consciousness. Yet we know from abundant data that there is a direct impact of various transcranial brain stimulation (TBS) techniques on consciousness. Since these tools, which include TMS, tACS, tDCS, and others, use exogenous EM fields of various types to achieve their effects, it would not be possible to have an impact on consciousness without the brain’s endogenous EM fields being causally potent.
2) Similarly, in physics there is a strong presumption of two-way causality. For example, in discussions about the existence and nature of the ether, in the latter part of the 19th Century and early 20th Century, some versions of the ether were proposed that were not causally impacted by ponderous matter, but the ether itself did exert influence on ponderous matter. Einstein, among others, critiqued this notion of the ether as “unnatural” because all other things in nature seemed to display a two-way causality (See Ludwik Kostro, Einstein and the Ether). The notion of EM waves as epiphenomenal only is a similar “unnatural” view of the physics of the brain and consciousness.
I like to think of the brain and its EM fields, as a useful metaphor, as a forest where the canopies of each tree are so tangled that they are indistinguishable — these canopies are the brain’s EM fields. When the canopy moves in the wind, there are various sub-levels of movement, but far higher resolution movements take place in the leaves and small branchlets of the canopy than are taking place in the larger branches and trunks of the trees, which will often not move at all in response to the wind. This tangled canopy is causally potent and capable of being acted on and acting at far finer spatial and temporal scales than are the trunks and larger branches of the trees, which support the canopy.
Under this analogy, then, the brain’s EM fields serve an important causal role due to their significantly finer resolution, spatially and temporally, allowing for more complex consciousness dynamics than would be available with synaptic transmission alone. The tangled canopy’s movement is a kind of standing wave, or set of overlapping standing waves, just as the various EM fields of the brain constitute various standing waves produced by but not identical with the brain.
In correspondence with Wolfgang Klimesch, a professor at the University of Salzburg and developer of the binary hierarchy brain body oscillation theory, he had this to say about Koch’s assertions on the causal potency of EM fields:
With respect to Christof’s view that LFP’s [and EEG] are too weak in order to play a role for higher brain functions, he is right if one [looks at] only one oscillation. The critical point is the interplay and sync between oscillations. Even if each oscillator is weak, sync between them can induce a strong and very selective force.
Klimesch further highlighted the work of Palva and Palva, and pointed me toward Siebenhühner et al. 2020 as the latest work from the Finnish lab. That paper states, in relevant part: “We posit that interareal CFC (cross-frequency coupling) may be essential for large-scale coordination of neuronal activity and investigate here whether genuine CFC networks are present in human resting-state (RS) brain activity.” They conclude: “We show that genuine interareal CFC is present in human RS [resting state] activity in both SEEG and MEG data…. The strength of CFS [cross-frequency phase synchrony] networks was also predictive of cognitive performance in a separate neuropsychological assessment.”
Let’s review a number of other recent studies that have directly suggested a causal role for electromagnetic fields in consciousness.
Buszaki 2004 states this view clearly: “These [electromagnetic field brain] oscillations are phylogenetically preserved, suggesting that they are functionally relevant. Recent findings indicate that network oscillations bias input selection, temporally link neurons into assemblies, and facilitate synaptic plasticity, mechanisms that cooperatively support temporal representation and long-term consolidation of information.”
Fries 2015, which further develops his influential “communication through coherence” hypothesis of brain communication makes the argument in the context of neural synchrony (emphasis added):
Neuronal communication has classically been conceived of as being determined by structural anatomical connectivity and by activity-dependent changes to the anatomical (ultra)structure of the connection. I propose that even in the absence of changes in (ultra)structural connectivity, neuronal synchronization as an emergent dynamic of active neuronal groups has causal consequences for neuronal communication. If neuronal communication depends on neuronal synchronization, then dynamic changes in synchronization can flexibly alter the pattern of communication. Such flexible changes in the brain’s communication structure, on the backbone of the more rigid anatomical structure, are at the heart of cognition.
Thut et al. 2011 examines the effect of rhythmic TMS on the brain and concludes that it causes local entrainment of natural oscillatory signatures. As discussed above, it is reasonable to suggest that this kind of TBS (transcranial brain stimulation) technique, which interacts directly with endogenous EM fields, is evidence for the causal potency of such fields.
Similarly, Romei et al. 2016 concludes that there is causal evidence that intrinsic beta-frequency is relevant for enhanced signal propagation in the motor system, as shown through rhythmic TMS.
Gallotto et al. 2017, looking at the “oscillatory correlates of visual consciousness,” found that “activity in the alpha-band (7–13 Hz) may index, or even causally support, conscious perception.”
Perhaps the most compelling recent research in favor of the causal role of EM fields can be found in a 2019 paper from Dominique Durand’s team at Case Western Reserve University. Chiang et al.’s paper, “Slow periodic activity in the longitudinal hippocampal slice can self-propagate non-synaptically by a mechanism consistent with ephaptic coupling,” examined slow oscillations (<1 Hz) and possible ephaptic field coupling (non-synaptic coupling) in mouse hippocampus from decapitated mice. The paper found that slow oscillations could trigger synaptic activity in neurons that were not synaptically connected. The paper states: “Results support the hypothesis that endogenous electric fields, previously thought to be too small to trigger neural activity, play a significant role in the self‐propagation of slow periodic activity in the hippocampus.”
Given the remarkable results found by the Chiang team, the journal (The Journal of Physiology) required them to replicate their results before publishing their paper, which they did. Dominique Durand, the primary investigator on the Chiang et al. paper, was as surprised as everyone else about their results: “It was a jaw-dropping moment, for us and for every scientist we told about this so far.”
Koch, in the same interview mentioned above, had this to say of Durand and Chiang’s work: “As an experimentalist, I am skeptical of these claims, in particular given their statistical validity and effect size. Of course, at this point, no neuronal mechanisms, can be definitely ruled out (including exotic macroscopic quantum effects), as long as they don’t violate the laws of physics.”
A number of other papers have focused on the causal potency of EM fields, including Riddle et al. 2020, looking at “causal evidence” for theta and alpha bands in working memory; Somer et al. 2020, looking at theta-phase dependence for memory performance; Samaha et al. 2020, finding that the speed of alpha band oscillations can predict visual temporal granularity; and Lakatos et al. 2019, a review of entrainment by various oscillations and its role in the brain, concluding (citations omitted): “These studies also provided evidence for brain oscillations being causally implicated in cognitive functions and in driving excitability fluctuations. For instance, rhTMS [rhythmic Transcranial Magnetic Stimulation] at alpha frequency over parietal areas causes visual perception to fluctuate in an alpha cycle, that is, to entrain at the alpha frequency.”
Other studies have less directly suggested a causal role for EM fields.
Tallon-Baudry et al. 2004 looked at oscillating field synchrony in monkey brain and memory performance, concluding: “Our findings suggest that the successful performance of a visual short-term memory task depends on the strength of oscillatory synchrony during the maintenance of the object in short-term memory.”
Atasoy et al. 2015, looking at brain connectome-specific harmonic electromagnetic waves, states: “Remarkably, the critical relation between the neural field patterns and the delicate excitation–inhibition balance fits the neurophysiological changes observed during the loss and recovery of consciousness.”
Vanrullen 2016 examines perceptual cycles and reviews the literature supporting the notion that perception and consciousness is a stream of snapshots. While not addressing causality of EM fields directly, it is implicated with the statement: “Recently popularized single-trial analyses of electrophysiological signals can be used to probe the causal influence of spontaneous brain states (such as the phase of oscillatory cycles) on perception.”
Meyer et al. 2017 looked at EEG state-dependent memory function in lab rats conditioned to a fear response induced by electric shocks and subjected to various intrahippocampal chemical injections, including gaboxadol. They conclude: “Activation of hippocampal extrasynaptic GABAAR via GBX [gaboxadol] can cause state-dependent learning. Here we show that GBX may cause this effect by increasing delta and reducing gamma oscillations in the hippocampus and disrupting retrieval-induced hippocampal–cortical theta coherence.” While a chemical intervention was performed, these researchers suggest that the chemical intervention leads to changes in the EM fields and those field changes are the proximate cause of the observed changes to memory.
Weineck et al. 2020 examined bat calls and echolocations and found that gamma synchrony patterns were predictive of when bats would issue a call. If synchrony patterns are predictive in ways that synaptic dynamics are not, it suggests that EM fields are causal.
“Oscillopathies” as evidence for EM field causal potency
There is also a growing body of knowledge connecting various brain and cognitive dysfunctions with “oscillopathies,” which are problems with the brain’s normal field oscillations. If this link is well-established experimentally — in terms of dysregulated EM field oscillations being tightly correlated with various brain and cognitive dysfunctions — this is another type of substantial evidence for the view that EM fields are causal. I list some of this interesting new research below:
- Alzheimer’s: Iaccarino et al. 2016 Gamma frequency entrainment attenuates amyloid load and modifies microglia
- Parkinson’s: Lakatos et al. 2019 describe how oscillation dysregulation is implicated in Parkinson’s
- Schizophrenia: Learning disabilities linked to schizophrenia may be caused by oscillopathies; Tononi’s new book chapter on sleep disorders, depression and schizophrenia
- Epilepsy: Neureka Challenge
- Depression: Cole et al. 2020 found that a new intermittent TBS technique was 90% effective at mitigating depression in patients who did not respond to traditional depression medications; Tononi’s new book chapter on sleep disorders, depression and schizophrenia
- Insomnia: 2016 review of sleep spindles in sleeping disorders; slow intracranial oscillations (tACS) help insomnia
The flipside of oscillopathies: high function induced by exogenous EM fields
There is also a growing body of data showing that entrainment of certain frequencies with exogenous EM fields can improvement various types of performance.
Two recent papers (2019 and 2020) from a team led by Rodriguez-Larios found a consistently higher occurrence of theta:alpha harmonic oscillations correlated with arithmetic tasks in a controlled setting. Similarly, decoupling of this cross-frequency relationship correlated with resting states, and even lower occurrence of the harmonic relationship correlated with advanced meditators’ brain states during meditation, per the research team’s hypothesis. The 2019 paper states in summary that “the present study suggests that transient numerical ratios between the peak frequencies of two brain rhythms are of functional relevance for cognitive processing.”
Klimesch and his team found, in work going back as far as 2003, that exogenous alpha fields, applied with repetitive TMS to the cranium, could improve cognitive performance in humans.
As discussed above, it is hard to explain why exogenous EM fields would impact consciousness in these kinds of measurable ways if the brain’s endogenous EM fields weren’t causally relevant.
So, which is it? Synaptic transmission or local and global EM fields?
We will not resolve this debate definitively here, since significant additional research will be required to flesh out the notion that EM fields may be causally potent in the manner I’ve suggested. Nevertheless, the growing weight of evidence and logic seems to favor the view that EM fields are causal in terms of exerting top-down causal influence on synaptic firing, while also being subject to bottom-up causal influence from the brain’s neuroanatomical backbone (to use Fries’ terminology).
The production of consciousness from its physical substrate is indeed a gestalt, requiring all levels of physical process for the production and sustaining of conscious states. However, this growing body of evidence, sketched here in the most general terms, suggests that the primary seat of consciousness is in the fields generated by the brain and body, and that these fields are causally potent.
Field theories of consciousness
There are many field theories of consciousness, with theories developed by Roy John, Johnjoe McFadden, Susan Pocket, Benjamin Libet, C. G. Hales, and Mostyn Jones, being probably the most prominent in recent years. Field theories were first proposed in the 1940s by Kohler, Wallach and Held. Mostyn Jones’ 2013 paper, “Electromagnetic-field theories of mind,” is a great overview of this history.
My own General Resonance Theory of consciousness includes electromagnetic fields as a possible seat of consciousness, and the same holds with any physical field. EM fields differ, in my approach, in that while other physical fields like gravity or nuclear forces could be the seat of consciousness in some systems, EM fields are capable of far more complex and fast-acting consciousness — which life has harnessed through natural selection in ways that probably aren’t possible for gravity and nuclear fields.
The evidence reviewed in this article shows that while far from being a settled issue at this juncture there is a growing body of evidence that EM fields are not only heavily implicated in consciousness, but are likely to be the primary seat of consciousness.