Autism 101-Sensory Processing

Greetings Earthlings! 🙂

So today I’m going to briefly introduce you to the issue of sensory processing for people on the spectrum. This is a very broad topic, but I’ll expand on the issues in more detail at a later stage 🙂

Many individuals on the autistic spectrum struggle to process every day sensory information. Sounds, textures, smells, lights, even colours (boys in particular struggle to process the colour yellow) can overload the nervous system and greatly upset us, effect our behavior or even trigger a meltdown.

But why?

In autism, our senses can be either hyper or hypo sensitive (sometimes even both) to stimuli at different times. Our senses are heightened- smells are stronger, sounds are louder. As a result of this, stimuli reverberate all the more intensely in our brains.

Think of the brain as a computer server at exam time where everyone is logging in at once. Too much information has been entered into the system, but the server can only cope with so much. The entire system becomes overwhelmed and the server crashes.

Here’s just a quick video simulation of sensory overload.

Warning for those on the spectrum– this video contains flashing lights, bright colours and loud, sudden noises

For me personally, I have many (mild) issues with sensory processing. Smells, tastes and textures are a daily struggle. For example, I don’t think I’ll ever be able to eat a salad as the smell alone makes me want to throw up- I’m dreading what pregnancy may one day bring! 😛 😉

Loud or irritating  noises, (especially repetitive ones), too can be a challenge. Don’t get me started on the shock I get when a passing bus makes that giant hiss/woosh sound or a car honks the horn unexpectedly!! 😛

Most days, you’re lucky and the offending stimulus passes quickly, but other times it can get the better of you. I recently had a near meltdown on holiday from a cocktail of excessive heat, hunger, exhaustion and social frustration.

Top Tip– Keep on top of your hunger/thirst. I’ve discovered this past year that an excess of either will make me act really loopy! 😛

When you’re hit by sensory overload, it feels as though your head is caught in a vice grip. Your mind is screaming, unable to focus on anything else but the source of discomfort.

The worst part of it I find is coming across as a complete basket case when overloaded. You don’t get the most sympathetic of looks when you complain about a persistent noise- few can understand how it’s making your brain hurt.

So what does science have to say about sensory processing?

Sensory integration involves three basic sensory systems:

• The tactile system (touch)- comprises a series of nerves passing information from the skin to the brain
• The vestibular system (sound)- comprises a series of structures in the inner ear involved in movement detection
• The proprioceptive system-a series of receptors in the muscle (proprioreceptors) which feed information to the brain about the body’s position

These three systems share a close but complicated relationship which allow us to experience, process and respond to different stimuli. Dysfunction in this network can cause hyper/hypo sensitivity, in addition to problems with coordination, behavior and academic issues.

Evidence from brain imaging studies has also shown that autists experience stronger responses in the brain to sensory stimuli in areas that process sensory information and the amygdala- an area that is involved in attention, emotional reactions and threat response.

But why is this?

Several studies have found evidence of hyper-excitability and hyper-connectivity in the autistic brain.

Evidence shows that in many cases of autism, the neurons located in the sensory cortex of the brain are more sensitive and excitable than others. This is kind of like how a person can be more ticklish in some parts of the body than another- the nerves in the underarm are more excitable than those of the arm.

The autistic brain has also shown signs of hyper-connectivity, where regions of the brain are excessively connected- like an overloaded plug!

This amplifies memory formation, sensory processing and causes an autist to be hyper-emotional, which can make the world painfully intense. Scientists have theorized that autists prefer safe, controlled and predictable environments as a coping mechanism to actively avoid this pain.

Finally, studies have indicated that sensory issues, in addition to a number of other autistic behaviors, may be linked to neurotransmitter (chemical messengers between body and brain) levels in the body. As previously discussed, some neurotransmitters are dysregulated in autism. Evidence suggests that in cases of autism, there are higher levels of excitatory neurotransmitters, and lower levels of inhibitory (i.e. calming) neurotransmitters. These high levels of excitatory neurotransmitters cause neurons to fire excessively, which can influence sensory perception and processing.

I’ll expand a little bit more on the individual sensory issues at a later stage 🙂

Enjoy your week everyone 🙂

Aoife