Vielight devices are general wellness products. They are not intended to diagnose, treat, cure, or prevent any disease or medical condition, including traumatic brain injury, concussion, or chronic traumatic encephalopathy. The research summarized below is presented for educational purposes and does not constitute claims about device performance or indications for use.

Enhancing the Default Mode Network: why a headset only reaches half of it

The most-targeted network in brain photobiomodulation runs deeper than the skull. Here is what that means for how light is delivered.

There is a reasonable assumption built into most brain photobiomodulation devices on the market: that the brain is a surface you can illuminate. Place near-infrared emitters against the scalp, and the cortex underneath receives energy. Add more emitters, add more coverage.

That assumption works for the cortex. It does not work for the Default Mode Network.

The DMN is the network that nearly every brain PBM device claims to target, and for good reason. It is the network most closely tied to memory, self-reference, imagination and social cognition. But it is not a patch of surface tissue. It is a distributed system whose hubs sit at the midline, behind the sinuses, and deep in the medial temporal lobes. A transcranial array reaches the outer nodes of that network and stops.

This is the reason the Vielight Neuro was engineered as an intranasal-transcranial system rather than a headset alone.

What the imaging is starting to show

Until recently this was an engineering argument rather than an observed one. That is changing.

Researchers at the Rotman Research Institute at Baycrest and the University of Toronto used BOLD-fMRI to compare where the brain responds when near-infrared light is delivered to the forehead versus through the nasal cavity. Their reported finding is that intranasal delivery produced responses in subcortical tissue, including the thalamus, which forehead-only delivery did not reach. The authors describe intranasal delivery as an energy-efficient route to cortical and subcortical stimulation. [44]

A companion study from the same group, published in Brain Stimulation, reported that four minutes of pulsed intranasal PBM was associated with measurable changes in cerebrospinal fluid dynamics, at roughly five percent of the energy required by transcranial delivery to produce a comparable effect. [45]

Note on evidence status: reference [44] is a preprint and has not yet completed peer review. Reference [45] is peer reviewed. Both were conducted in healthy adults and describe physiological responses, not clinical outcomes.

Taken together, these observations point at something specific. The route matters, not just the dose. Two devices delivering the same wavelength at the same frequency can produce different spatial coverage depending on where the light enters.

What the Default Mode Network actually is

The DMN is a set of highly interconnected brain regions responsible for internal modes of cognition. Diffusion MRI and resting-state fMRI show that neurons across these regions are joined by large axonal tracts, which is why their activity is correlated with one another. [22][23]

The word “default” is a historical accident. The network was named for its heightened activity during idle periods, which implied it was simply what the brain does when nothing else is happening. Later work showed this to be a misnomer. The DMN is also highly active during directed internal thought: recalling your past, imagining your future, considering what someone else is thinking. [41][42][43]

The picture has widened again since. The DMN is now known to engage during tasks driven by external perceptual input, including language comprehension and social perception. Work published in PNAS in 2026 proposed an organizational principle to explain how one network handles both, describing sender and receiver subdivisions within the DMN that separate perceptually driven from memory-guided processing. [47]

Its hubs include the medial prefrontal cortex (mPFC), the ventromedial prefrontal cortex (vmPFC), the precuneus, the inferior parietal lobule (IPL), the lateral temporal cortex (LTC), and the posterior cingulate cortex (pCC). The hippocampal formation, within the medial temporal lobes, is closely coupled to the network.

Its documented roles cluster into three groups. [22][23]

Is the DMN the seat of consciousness?

This claim circulates, and it is worth addressing directly, because the accurate answer is more interesting than the claim.

No, and consciousness research does not frame it that way. The two dominant theories point elsewhere. Global Neuronal Workspace Theory locates conscious experience in the global broadcasting of information across prefrontal and parietal regions. Integrated Information Theory locates it in a posterior temporo-parietal-occipital “hot zone.” In 2025, the Cogitate Consortium published an adversarial collaboration in Nature that tested both theories directly across 256 participants using fMRI, MEG and intracranial EEG. Information about conscious content was found in visual, ventrotemporal and inferior frontal cortex. The results challenged key tenets of both theories, and the DMN was not the proposed answer in either. [48]

What the DMN evidence does show

DMN connectivity breaks down under anesthesia and in disorders of consciousness, and tends to reorganize as consciousness returns. That is a real and repeatedly observed relationship. It establishes the DMN as a correlate of conscious state, and a plausible imaging biomarker for tracking recovery. It does not establish it as the source.

A 2026 study in Brain examining surgically disconnected hemispheres made the distinction explicit. The authors reported that the presence of DMN activity fulfils a necessary condition for preserved consciousness, then stated plainly that this does not support the reverse inference that such activity alone confirms consciousness is present. [49]

The evidence that cuts the other way

Reviews of DMN topography across altered states describe something that a simple “seat of consciousness” account cannot absorb. Both reduced states, such as anesthesia and unresponsive wakefulness syndrome, and elevated states, such as meditation and psychedelic experience, are characterized by a flattening of the brain’s DMN-centric organization. They differ in their dynamics, not in the direction of that flattening. [50]

If the DMN were the seat of consciousness, suppressing its dominance should suppress experience. In psychedelic states it does close to the opposite.

Where the idea comes from

A 2025 review by Luppi, Lyu and Stamatakis proposed an integrative view of the DMN as the anatomical and functional nexus for convergence and divergence in the human brain, arguing that a breakdown of DMN spatiotemporal continuity collapses the cortical functional hierarchy and the integration of self and world into a coherent stream. [51] It is a serious proposal, and it is a hypothesis, presented as one by its authors rather than as a settled finding.

There is one substantive overlap worth noting. The precuneus and posterior cingulate cortex sit within both the DMN and the posterior hot zone that Integrated Information Theory identifies. So these hubs are of genuine interest to consciousness researchers, whatever the eventual verdict on the network as a whole.

The better-supported claim, and the one this article rests on, is narrower and more useful: the DMN appears to underpin the narrative self, the sense of a continuous person with a past, a future and a social world. That is not the same as consciousness, and it is interesting enough on its own terms.

The hubs, and how each one is reached

The Vielight Neuro places four transcranial LEDs over the outer nodes of the network and one intranasal emitter that delivers light through the nasal cavity toward the deeper anterior and medial structures. The demonstration below shows the resulting energy footprint across a calvaria model.

Reached transcranially

Medial prefrontal cortex (mPFC)

Behind the forehead, within the frontal lobe. The mPFC plays a regulatory role in attention, inhibitory control, habit formation, and working, spatial and long-term memory. [1] It is also one of the more commonly affected regions in head injury.

Precuneus

A section of the superior parietal lobe, and widely considered the core hub of the DMN. [9] Its cognitive roles include self-consciousness [5], spatial memory [6], episodic memory [7] and source memory, meaning recall of where a memory or piece of knowledge came from. [8] It also supports motor imagery [10], the mental rehearsal of action used in sport training and neurological rehabilitation, and motor coordination. [11]

Inferior parietal lobule (IPL)

Located bilaterally in the rear half of the brain. The IPL is a convergence zone for several of the most distinctive human capacities: language, pattern learning, mathematical operations [12], and the perception of emotion in faces.

Posterior cingulate cortex (pCC)

Found around the midline. The pCC is a central node of the DMN, highly connected, and communicating with several brain networks at once. [13] Cerebral blood flow and metabolic rate in the pCC run roughly 40 percent above the brain-wide average. [14][15]

It has been linked to spatial memory, autobiographical memory [16], and working memory performance. [17] It is also implicated in the dorsal attention network and the frontoparietal control network. [14] Notably, the pCC activates during self-related thinking and deactivates during meditation and effortless mind wandering. [20]

Temporal lobes

Sitting behind the ears, the temporal lobes are the second largest lobe and process visual stimuli such as faces and scenes, auditory signals including speech, language comprehension, and visual memory. The dominant lobe, usually the left, handles language and verbal recall. The non-dominant lobe handles non-verbal material such as visuospatial information and music.

Where the intranasal route matters

Ventromedial prefrontal cortex (vmPFC)

The vmPFC sits directly above the eyes and nose, at the base of the frontal lobe. It contributes to decision-making, self-control, and the regulation of emotional responses [2][3], as well as the cognitive evaluation of morality. [4]

Its position is the problem. Reaching the vmPFC from the scalp means traversing the full thickness of the frontal bone and the tissue above it. The nasal cavity sits immediately beneath it, separated by comparatively thin bone. This is the anatomical basis for Vielight’s patented intranasal approach.

Hippocampal area and medial temporal structures

The hippocampus lies within the temporal lobes and supports the conversion of short-term to long-term memory, along with the spatial memory that enables navigation. It is among the first regions to show damage in Alzheimer’s disease and other dementias, which is why short-term memory loss and disorientation appear early. [18]

Although it is a small subregion, it is deep, and depth is precisely what transcranial delivery struggles with.

Why researchers keep returning to the DMN

Altered DMN connectivity has been observed in a range of neurological and neuropsychiatric conditions, including Alzheimer’s disease, Parkinson’s disease, autism, schizophrenia, depression, multiple sclerosis and post-traumatic stress disorder. [25][26][27][28][29] That pattern is what has made the network a recurring focus of investigator-led research.

The table below summarizes findings reported by independent research groups that used Vielight devices, alongside what the literature says about DMN involvement in each condition. These are published research observations. They are not indications for use, and they do not describe intended uses of Vielight general wellness products.

These studies vary in design and size. Several are pilot studies, case series or retrospective analyses without control groups, and their findings require replication in larger controlled trials before conclusions can be drawn.

The engineering rationale

The thesis behind the Vielight Neuro was to select the DMN and its hubs deliberately, because of the roles they play in self-awareness, memory, emotion, imagination, and mathematical and language processing.

Choosing the target was the first decision. Choosing the delivery route was the second, and it is the one that separates itPBM from transcranial-only approaches. Four transcranial emitters cover the outer nodes. The intranasal emitter addresses the anterior and medial structures that a headset cannot reach efficiently, and the Baycrest imaging work suggests that route reaches deeper than the cortex. [44][45]

A network is only as well served as its least-reachable hub. That is the whole argument.

Read more on the Vielight Neuro’s design

General wellness device. Not intended to diagnose, treat, cure, or prevent any disease. Individual results vary. Research cited on this page was conducted by independent investigators and is presented for educational purposes only.

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