Default Mode Network in Autism and Pediatric Transcranial Magnetic Stimulation.

Why Default Mode Network and Autism ?

Autism spectrum disorder (ASD) is a heterogeneous condition that has several phenotypic and genomic features (1,2). Some characteristics of ASD include deficits in social interaction, lower social motivation, poorer social reciprocity, and undermentalizing, emotional reciprocity, pragmatic speech. The DMN is one of the most extensively studied functional networks and it is a key social brain network in ASD. Defauld Mode Network shows substantial overlap with several other “social brain” networks such as the mentalizing network and emotion recognition network (3,4). DMN is the most extensively studied brain network relevant to social cognition across Autism.

What parts of our brain represent DMN?

Some helpful information about anatomy, brain development that is related to DMN and Autism.

There is general agreement in the literature that the medial prefrontal regions, the temporoparietal junction, anterior and lateral temporal regions, anterior insula, and the posterior cingulate cortex/precuneus subserve several crucial social functions (5). Over the past three decades, a number of influential studies have consistently demonstrated that these are strongly intrinsically interconnected networks of brain structures. DMN—a large-scale brain network with hubs in the medial prefrontal cortex (mPFC), posterior cingulate cortex/precuneus (PCC), inferior parietal lobe (IPL), and temporal lobe structures (6,7).

What is the role and function of DMN? It has been described that the DMN specifically plays a role in self-referential thinking (8.9), thoughts about self versus others and theory of mind, and autobiographical memory (9). Default mode networks are significantly engaged during tasks involving social cognitive mental processes that are evaluative in nature. Besides socially relevant functions, the DMN is also linked with mind wandering, subjective value judgments and initiation of spontaneous thought processes. Prior studies found out DMN connectivity in healthy adolescents have suggested that there is a strengthening of connectivity in this network with age, particularly between anterior and posterior hubs from childhood to late adolescence, indicating increased integration in typical development (10).

Compared to adults’ adolescents have increased in functional activation of the prefrontal cortex also in response to social tasks. Increased functional connectivity between prefrontal cortex and temporal brain regions during adolescence is also related to increased social information processing during this age. Alco studies have suggested that DMN connectivity with other functional networks such as the central executive network becomes sparse from childhood to late adolescence, suggestive of increased autonomy and segregation of the DMN from task-related networks in typical development.

What happens if DMN is affected in ASD?

Disrupted DMN functional connectivity has been involved in several psychiatric conditions with associated social difficulties (11), including ASD. Disrupted DMN connectivity might be associated with social impairments in Autism. Interestingly , intra-DMN networks were more frequently underconnected in ASD. While ASD may be diagnosed earlier in life, there is evidence to suggest that functional connectivity patterns in individuals with this condition undergo substantial changes from childhood to adulthood, likely influenced by factors such as puberty and/or access to treatment interventions over the years.

MERT and Autism. Magnetic e-Resonance Therapy (MeRT) is a non-invasive, drug-free treatment that uses magnetic fields to improve brain function and communication in people with autism. MeRT uses transcranial magnetic stimulation (TMS) to target specific areas of the brain that are located on the midline of the forehead (FPZ) and/or posterior (PZ) location. This process is going under the close monitoring of a quantitative electroencephalogram (qEEG) and electrocardiogram (ECG/EKG) measuring brain activity and electrical signals. A treatment plan is created based on the brain’s unique pattern to synchronize Alpha waves in posterior, middle and frontal zones of the brain.

References

1. Crespi B, Badcock C. Psychosis and autism as diametrical disorders of the social brain. Behav Brain Sci (2008) 31(3):241–61; discussion 61-320. 10.1017/S0140525X08004214
2. Rapoport J, Chavez A, Greenstein D, Addington A, Gogtay N. Autism spectrum disorders and childhood-onset schizophrenia: clinical and biological contributions to a relation revisited. J Am Acad Child Adolesc Psychiatry (2009) 48(1):10–8. 10.1097/CHI.0b013e31818b1c63
3. .Mars RB, Neubert FX, Noonan MP, Sallet J, Toni I, Rushworth MF. On the relationship between the “default mode network” and the “social brain”. Front Hum Neurosci (2012) 6:189. 10.3389/fnhum.2012.00189
4. .Li W, Mai X, Liu C. The default mode network and social understanding of others: what do brain connectivity studies tell us. Front Hum Neurosci (2014) 8:74. 10.3389/fnhum.2014.00074
5. Blakemore SJ. Development of the social brain during adolescence. Q J Exp Psychol (Hove) (2008) 61(1):40–9. 10.1080/17470210701508715
6. Raichle ME, MacLeod AM, Snyder AZ, Powers WJ, Gusnard DA, Shulman GL. A default mode of brain function. Proc Natl Acad Sci U States A (2001) 98(2):676–82. 10.1073/pnas.98.2.676
7. Buckner RL, Andrews-Hanna JR, Schacter DL. The brain’s default network: anatomy, function, and relevance to disease. Ann New Y Acad Sci (2008) 1124:1–38. 10.1196/annals.1440.011
8. Gusnard DA, Akbudak E, Shulman GL, Raichle ME. Medial prefrontal cortex and self-referential mental activity: relation to a default mode of brain function. Proc Natl Acad Sci U States A (2001. a) 98(7):4259–64. 10.1073/pnas.071043098 [
9. Andrews-Hanna JR, Smallwood J, Spreng RN. The default network and self-generated thought: component processes, dynamic control, and clinical relevance. Ann New Y Acad Sci (2014) 1316:29–52. 10.1111/nyas.12360
10. Fair DA, Cohen AL, Dosenbach NU, Church JA, Miezin FM, Barch DM, et al. The maturing architecture of the brain’s default network. Proc Natl Acad Sci U States A (2008) 105(10):4028–32. 10.1073/pnas.0800376105
11. Whitfield-Gabrieli S, Ford JM. Default mode network activity and connectivity in psychopathology. Annu Rev Clin Psychol (2012) 8:49–76. 10.1146/annurev-clinpsy-032511-143049