Many neuroscience publications indicate that the brain is modular and composed of different networks 🧠

The key to successful brain stimulation (and brain photobiomodulation) is to focus on networks that hold the most importance to your objective.

The Vielight Neuros are designed to deliver near-infrared (NIR) light to the default mode network (DMN) of the brain.

This article will address the importance of the DMN and the value of targeting this network using photobiomodulation (PBM).

What is the Default Mode Network?

The Default Mode Network

Figure 1 – Regions of the Default Mode Network

The Default Mode Network (DMN) is a network of highly interconnected brain regions responsible for internal modes of cognition.

The DMN has been linked to the general health of the brain and is involved in various domains of cognitive and social processing.

The term “default” initially arose from the discovery of the network’s heightened activity during idle periods (aka. when you are not actively thinking), implying that this network is active by default. Since then, additional research has shown this to be a misnomer. The DMN is also active when your brain is engaged in thinking, such as remembering one’s past or thinking about what might happen in the future.[41, 42, 43]

The DMN includes hubs such as the Medial Prefrontal Cortex (mPFC), the Ventromedial Prefrontal Cortex(vMPFC), the Precuneus, the Inferior Parietal Lobule(IPL), Lateral Temporal Cortex (LTC) and the Posterior cingulate cortex(pCC). Findings from diffusion MRI and resting state fMRI show that neurons in the DMN regions are linked to each other through large tracts of axons and this causes activity in these areas to be correlated with one another. [22],[23]

The roles of the Default Mode Network

The Default Mode Network (DMN) plays several crucial roles concerning brain functions. Its roles are linked to what defines us as human beings from a cognitive perspective. It plays several vital tasks in memory functions, imagination, self-referencing, and socializing. Who you are as a person is theorized to be stored within these hubs.

The DMN is likely the neurological basis for the self [22]

  • Autobiographical information: Memories of collection of events and facts about one’s self
  • Self-reference: Referring to traits and descriptions of one’s self
  • Self-emotional state: Reflecting about one’s own emotional state

Thinking about others [23]

  • Theory of mind: Thinking about the thoughts of others and what they might or might not know
  • Emotions of other: Understanding the emotions of other people and empathizing with their feelings
  • Moral reasoning: Determining a just and an unjust result of an action

Remembering the past and thinking about the future [23]

  • Remembering the past: Recalling events that happened in the past
  • Imagining the future: Envisioning events that might happen in the future
  • Episodic memory: Detailed memory related to specific events in time
  • Story comprehension: Understanding and remembering a narrative

The Value of Targeting the Default Mode Network with Pulsed 810nm NIR energy

Since its discovery, interest has grown in the clinical utility and implications of the DMN. The clinical significance of the DMN has been established or implicated in neurological and neuropsychiatric disorders. Therefore, maintaining the health and improving the performance of the DMN is of particular value. This is why the Vielight Neuro is designed to deliver NIR light transcranially using four diodes targeted at the DMN.

Dysfunction of the DMN has been associated with Alzheimer’s disease, autism, schizophrenia, depression and other neurologic diseases,  Parkinson’s, [25] [26] multiple sclerosis (MS) [27] and post-traumatic stress disorder (PTSD). [28]  Targeting  the DMN via PBM may therefore be an important therapeutic strategy in the treatment of these diseases. The table below summarizes the research done to date using Vielight technology for various diseases related to the DMN.


Summary of DMN findings in neurological and neuropsychiatric conditions.

Neurologic ConditionRelation to the DMNVielight Photobiomodulation Studies
Alzheimer’s Disease
  • Decreased functional connectivity between posterior and anterior portions of the DMN [31]
  • Overlap between the DMN and patterns of amyloid deposits [32]
  • PBM increased connectivity between the posterior cingulate cortex and lateral parietal nodes within the default-mode network in the PBM group. [36] (Link)
  • Significant improvement after 12 weeks of PBM (MMSE, p < 0.003; ADAS-cog, p < 0.023). Increased function, better sleep, fewer angry outbursts, less anxiety, and wandering were reported post-PBM. There were no negative side effects. [37] (Link)
Parkinson’s Disease (AD)
  • Coordinated activity of striatum and the DMN [33]
  • Network disruptions in the DMN and CEN — heightened activation and dysfunctional connectivity [34]
  • Measures of mobility, cognition, dynamic balance and fine motor skill were significantly improved (p < 0.05) with PBM treatment for 12 weeks and up to one year. [38] (Link)
Traumatic Brain Injury
  • DMN connectivity strength predicts emotion recognition and level of social integration in TBI. [30]
  • Increased perfusion in the frontal, temporal, and occipital lobes and the hippocampus after 8 weeks of PBM treatments. [39] (Link)
  • Pending publication: Department of Neurology, University of Utah for TBI/concussion with pro football players. Here is a documentary-style interview with the researchers and participants: https://www.youtube.com/watch?v=YTxITq7j9iE&ab_channel=VielightInc
Autism Spectrum Disorder
  • Structural and functional disruptions to key nodes of the DMN, their connectivity with each other, and atypical patterns of connectivity with other brain regions play an important role in the symptomatology of ASD. [35]
  • tPBM was associated with a reduction in ASD severity, as shown by a decrease in CARS scores during the intervention (p < 0.001). A relevant reduction in noncompliant behavior and in parental stress have been found. Moreover, a reduction in behavioral and cognitive rigidity was reported as well as an improvement in attentional functions and in sleep quality. [40]

Anatomy of the DMN: roles of the hubs

The DMN is composed of several hubs that also perform their own individualized tasks.
This is an introduction to the different hubs of the DMN and what their roles are in the human brain.

Medial prefrontal cortex (mPFC)

The medial prefrontal cortex is located within the brain’s frontal lobe. This region is located behind the forehead.

Figure 2- Prefrontal Cortex

The medial prefrontal cortex plays a regulatory role in several cognitive functions including attention, inhibitory control, habit formation and working, spatial and long-term memory. [1]

The mPFC is a common region of injury in traumatic brain injury.

Ventromedial prefrontal cortex (vmPFC)

The ventromedial prefrontal cortex is also located within the brain’s frontal lobe. This region is located right above the eyes and nose.

The ventromedial prefrontal cortex plays a role in decision-making, self-control, and the regulation of emotional responses. [2, 3]

It is also involved in the cognitive evaluation of morality. [4]

Precuneus

The precuneus is a small section of the superior parietal lobe and it is thought to be the core hub of the DMN. [9]

It is involved in several vital cognitive and visuospatial roles as outlined below.

Figure 3 – Precuneus

Cognitive roles:
• Self-consciousness (such as self awareness) [5]
• Spatial memory (remembering different locations as well as spatial relations between objects) [6]
• Episodic memory (remembering everyday events) [7]
• Source memory (remembering the origin of a memory or of knowledge) [8]

Visuospatial:
• Motor imagery. [10] Motor imagery is used in sport training as mental practice of action, neurological rehabilitation.
• Motor coordination. [11]
Motor coordination is the orchestrated movement of multiple body parts as required to accomplish intended actions, like running or throwing.

Inferior parietal lobule (IPL)

Figure 4 – Inferior Parietal Lobule

The inferior parietal lobule is located on the left and right side of the rear-half of the brain.

The IPL supports some of the most distinctive human mental capacities:

The inferior parietal lobe is a foremost convergence zone of diverse mental capacities, several of which are potentially most developed in the human species.

Targeting the IPL with PBM holds great potential to improve cognitive performance in professions that require mathematical or analytical ability.

Posterior cingulate cortex

The posterior cingulate cortex (pCC) can be found around the midline of the brain.

The pCC forms a central node in the default mode network of the brain.

Figure 5 – Posterior Cingulate Cortex

It is highly connected and communicates with various brain networks simultaneously and is involved in diverse functions. [13]

Cerebral blood flow and metabolic rate in the pCC are approximately 40% higher than average across the brain. [14], [15]

Memory

The pCC has been linked to:

  • Spatial memory (remembering different locations as well as spatial relations between objects)
  • Autobiographical memories (autobiographical memory is a memory system consisting of episodes recollected from an individual’s life)
    the pCC does not show this activity when affected by Alzheimer’s Disease. [21]
  • Working memory performance (abnormalities of the ventral pCC is related to a decline) [17]

Intrinsic control networks

The pCC has also been strongly implicated as a key part of several intrinsic control networks. [14], [15]

  • The dorsal attention network(control of visual attention and eye movement)
  • The frontoparietal control network (involved in executive motor control). [14]

Meditation

The pCC has been found to be activated during self-related thinking and deactivated during meditation and undistracted, effortless mind wandering. [20] These results track closely with findings about the role of the pCC in the DMN.

Temporal lobes

The temporal lobes (TL) sit behind the ears and are the second largest lobe.

Figure 6 – Temporal Lobes

The TL is involved in processing sensory input for:

  • Visual processing (complex stimuli such as faces and scenes)
  • Auditory processing (processes signals from the ears into meaningful units such as speech and words)
  • Language comprehension
  • Visual memory (visual memoryis the ability to remember what something looks like)

The dominant temporal lobe, which is the left side in most people, is involved in understanding language and learning and remembering verbal information.

The non-dominant lobe, which is typically the right temporal lobe, is involved in learning and remembering non-verbal information (e.g. visuo-spatial material and music).

For language learners and musicians, a well-performing temporal lobe plays a crucial role in maximizing performance in these areas.

Hippocampal area

The hippocampus can be found within the temporal lobes.

Figure 7 – Hippocampal Area

The hippocampus plays important roles in the formation of:

In Alzheimer’s disease (and other forms of dementia), the hippocampus is one of the first regions of the brain to suffer damage [18] short-term memory loss and disorientation are included among the early symptoms.

While a relatively small subregion within the temporal lobes, the hippocampal area plays important roles in memory and is an region of interest in concurrent neurological research.

Conclusion: Engineering pathway for brain photobiomodulation of the DMN

At Vielight, our thesis behind the Vielight Neuro was to select the DMN and its hubs because of its and their many important roles in human cognitive processes, such as self-awareness, memory, emotions, imagination, mathematical and language processing.

Additionally, through our patented intranasal technology, we are able to reach the vMPFC with pulsed 810nm NIR energy, an advantage that is unique to the Vielight Neuro versus anything else out there.

To read more on the Vielight Neuro’s design, follow this link: https://www.vielight.com/understanding-the-vielight-neuro/

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