How the autistic brain functions differently
Autism Spectrum Disorder is characterised by differences in social communication and interaction, alongside restricted or repetitive behaviours and differences in behavioural flexibility as well as sensory processing.
These characteristics are linked to differences in brain structure, brain region function, and connectivity between brain regions. These neurological differences affect how the brain processes, filters and integrates information, helping to explain many of the symptoms associated with autism.
One of the key areas of research in autism is functional connectivity — how different regions of the brain communicate with each another. Autistic brains can show differences in how brain regions coordinate activity, with a common pattern of greater connectivity between closely related regions but reduced connectivity between more distant regions. This may mean that information is processed strongly within individual systems but is less efficiently integrated across the brain.
For example, differences in connectivity involving the Default Mode and Salience networks can affect the ability to identify which information is most important, filter out unnecessary information, and integrate information across different domains, such as sensory, emotional, social and cognitive information. These differences in large-scale brain integration may therefore contribute to many of the communication, attention and social characteristics seen in autism.
A recent study has discovered two distinct connectivity patterns in autistic brains demonstrating two subtypes. A hypo-connectivity subtype showing reduced communication between brain regions, and hyper-connectivity subtype showing increased synchronization and communication across brain networks. The Hypoconnected circuits were traced to a range of biological processes affecting synapses, which connect brain cells. The hyperconnected circuits were related to immune system-related pathways. Hypoconnectivity can result in an under stimulated brain and may help explain why some people use stimming, which can provide self-generated sensory and motor stimulation to engage underactive reward and motor networks.
Sensory processing is key feature in ASD experienced by 90–96% of individuals diagnosed. These differences in sensory processing affect how their nervous system receives, organizes, and interprets stimuli and can strongly impact daily functioning, anxiety, and communication. These differences means sounds, lights, textures, smells and other sensations may be experienced with heightened or diminished sensitivity. This may result in avoiding sensations or seeking soothing sensations.
Sensory processing is thought to involve differences in how the brain filters, integrates and responds to information from the senses, including altered communication between sensory regions and networks involved in attention and perception. It involves integration by several brain regions including the prefrontal cortex, temporal lobe areas, and cerebellum, all of which have shown to have structural and functional differences in ASD. These differences in sensory integration can make it difficult to respond appropriately to sensory inputs and become overwhelming, while other sensations may require stronger stimulation to be noticed.
This difference in information processing can also contribute to strengths such as attention to detail, pattern recognition and deep knowledge in areas of interest.
The systems responsible for processing sensory information can also be driven by an underlying excitation-inhibitory imbalance a common finding in autism, with increased concentrations of glutamate (primary excitatory neurotransmitter) and decreased concentrations of GABA (primary inhibitory neurotransmitter). An excess of glutamate paired with the scarcity of GABA could cause hyperexcitability of the neurons and the nervous system.
Another key characteristic of autism is differences in communication and language processing. It is hypothesized that the deficits in social cognition and related cognitive functions results from reduced synchronization between these key brain regions during different social and emotional tasks. The ‘Social Brain Network' involves tasks such as perception of personal identity, facial expression imitation, perception of facial expressions and eye gaze tasks, taking another person’s perspective and emotion processing which are all processed in different brain regions. This understanding makes it easy to see how issues with connectivity between these regions can impact communication ability.
Excessive neural noise is another cause of communication disruptions, which involves altered aperiodic signal patterns. The brains aperiodic signal is the constant, electrical activity humming underneath your standard brain waves. When balance is disrupted, the background hum gets louder and more disorganized, creating internal “neural noise” that acts like heavy radio static, that disrupts the auditory processing centers ability to efficiently process human speech. These differences in brain electrical activity may help explain why some have greater difficulty with communication than others.
Autistic attention processes can also work differently, with connectivity of the prefrontal cortex playing an important role in the symptoms presented. This region carries out executive functions, and differences here can contribute to many of the everyday challenges experienced by autistic people, including difficulties with focus, organisation, task initiation and following through on goals. Rather than constantly shifting attention between many sources of information, an autistic person may become deeply focused on a particular subject or activity.
This intense focus can make it difficult to switch tasks or stop an enjoyable activity, but it can also allow someone to develop an exceptional depth of knowledge and expertise.
The autistic brain is highly complex, with each person’s brain being unique, and these are just some of its diversity of function. Autism is not a brain that is broken or deficient, but a different pattern of brain development and information processing. These differences can create both challenges and strengths, depending on the individual and their environment.
If you’d like to explore what may be contributing to your symptoms and challenges, naturopathic support offers a personalised, whole-person approach to understanding the underlying factors and finding a way forward towards better health & wellbeing.