Sensory processing in autism

Sensory processing difficulties are a diagnostic feature of Autism Spectrum Disorder as described in the DSM-V (3:15). In fact, between 93% and 96% of individuals with autism experience sensory processing differences “to such an extent that they significantly impact daily functioning” (4:00). Dr. Shafai emphasizes that sensory difficulties continue across the lifespan, although studies generally focus on children and youth (4:30). 

The speaker defines the optimal attention and arousal window (OAAW) as when we are “both alert and calm depending on what’s happening” (5:40). When we dip below or above this window, we can adjust our sensory environment to offset the unbalance (6:15). However, for individuals with atypical sensory processing, the highs and lows are more extreme and can lead to hyper- or hypo- reactivity (8:00). Dr. Shafai discusses sensory receptor types and concentrations (12:15) throughout the body and shares quotes about painful sensory experiences from autistic adults (11:00).

Brain development and sensory processes

The presenter details two crucial steps in brain development and how they differ in individuals with autism:

Atypical neuronal migration

Dr. Shafai relates layered brain development to traveling from sea level through higher elevations (16:05) and describes how each new ecosystem (layer) contains plants and animals (neurons) specifically adapted for that environment. When plants or animals (neurons) move to higher elevations (layers), they can interrupt the balance of a new ecosystem. Such atypical neuronal migration is evident in some individuals with autism within the first three months in the womb (17:50).

Synaptic pruning 

Humans are born with billions of synapses or connections in the brain where neurons talk to each other (15:40). As we develop, the brain removes synapses we do not need (synaptic pruning), much like a forest path will expand given the necessary resources or disappear when people stop using it (20:05). However, the brains of some individuals with autism maintain extra pathways between cells that are close to one another, minimizing energy and resources available to expand big “highways” connecting other parts of the brain (21:00).

Dr. Shafai describes how extra connections within a local sensory area create excess “noise” and make it difficult for the brain to filter out unimportant sensory information (21:50). She touches on multisensory integration (e.g., looking at a person’s face and hearing what they say) (25:20) and how weak connections between distant areas (e.g., sensory regions and social parts of the brain) make sensory comprehension in social contexts challenging (23:05). 

Aging and sensory systems

The speaker outlines how sensory systems typically change with age and some differences observed in individuals with autism (28:00 – 42:40). She notes that our understanding of how atypical sensory symptoms change over time is limited as sensory symptoms in adults are relatively understudied (43:00). 

“Autistic children eventually grow into autistic adults. And we need to be able to recognize that challenges don’t go away” (44:50). 

The presenter discusses limitations (45:28), future directions for research (48:30), and resource development (50:08). Dr. Shafai provides examples of successful collaborative sensory programs and tool kits (50:40) and closes with a Q&A session covering social skills, sensory difficulties in war zones and natural disasters, picky eating, sensory integration and neuroplasticity, OT specialists, self-regulation, and much more (52:48).