In the previous 3 parts of this series, we have seen what is sensory processing (here), how the sensory feedback loop helps us learn (here) and how it helps infants learn skills (here).
In this part, we are going to discuss what happens when our sensory system does not work properly. This is called sensory processing dysfunction (SPD).
Just to recap how sensations are processed at various levels in the brain:
• Level 1 stop (brainstem) is like the security of a large complex. Each and every sensation is stopped to check for safety.
• Level 2 (midbrain) is the door where the sensations are gauged – “What is it”, “Do I know it” & “is it important”.
• Level 3 (sensory cortex) is where correct response is given.
• Level 4 (also sensory cortex) is storing the information to be used in similar situations that may occur in the future.
All of us have certain sensory quirks. Some people are affected by loud noises, some by the “feel” of certain fabrics, some don’t like swings etc; but usually these quirks don’t affect our daily lives.
However having a genuine sensory processing dysfunction does affect normal day to day living and behavior. Let me explain how.
First, most sensory issues and behavior issues look exactly the same! For example a child who refuses to get dressed. We could easily misinterpret this as “defiant behavior”. But the truth is something else entirely, that the child cannot bear certain textures of clothing. Diagnosis of SPD requires careful investigation of symptoms and triggers over several sessions. Secondly , SPD presents differently at each of the four levels of processing. Let me explain how:
At Level 1 (Brainstem):
Can you imagine if there was no security guard at your complex gate? Any random person(s) could come in , picnic in your lawn, park in your spot, throw garbage in the stairs, …you get it. You would be constantly bombarded with inconsistent information and any time you leave your home, you will be on high alert unable to anticipate anything.
This is exactly what happens to kids too. The world feels disorganized to them and they do not know how to behave consistently for the same given situation, since they don’t know if any given situation is safe or not.
The ability to maintain an optimal level of alertness for the day and its different requirements is called regulation. This happens at the brainstem level. Children with level one processing dysfunction have problems maintaining this balance. Hence their responses (behavior) are not appropriate to the situation.
Another aspect of regulation is the ability to modify it based on needs (termed modulation). A child unable to make these adjustments will have trouble transitioning from one activity to another and will have problems with changes to their environment.
At level 2 (Midbrain):
What happens if there is a stranger at your door? You ask questions trying to determine more about that person before deciding how to proceed. Similarly, if the sensations are not clear, the child will try to seek more inputs to get clarity.
The other response you have is to just shut the door without explanation. The child may not respond to any inputs or does not want to be involved with anything.
Behaviorally both these kids seem unable to focus on details.
At level 3 (sensory cortex):
When sensations are identified and labeled properly, the appropriate response is given. When this is interrupted, an appropriate response will not be given.
Imagine you were competing in a hurdles race. When you practice your brain ‘learns’ exactly how high to leap so you cross the hurdle. If proper identification and labeling did not happen (brain did not store the height of the hurdle) you will not be able to leap over it. You would either not cross it or leap unnecessarily high.
Issues with this process lead to coordination and clumsiness. Children will have difficulty in completing daily activities like dressing, brushing teeth, riding bicycles etc
At level 4 (also sensory cortex):
Can you picture yourself at day one of your professional life? Everything was uncertain and you paid attention to every single detail. But as you got efficient at work there were so many details you could plan and execute in advance or even delegate. If you could not get efficient, you would get “stuck”. You could not multitask because you had to pay careful attention to each and every task every single time.
Just like that, kids with level four processing issues cannot build on previous learning. They do not get efficient at tasks. They cannot build on previous learning and therefore get “stuck” at lower levels. For example take reading , these kids may be stuck at the level of sounding out words and not progress further. This may look like they don’t want to read; but in reality it is because they are not able to get efficient at reading.
To conclude, movements, speech, behaviors and higher level executive functions like reasoning, logic and abstract thinking are just some aspects of our daily lives. A slightly disturbance to this finely tuned system is enough to cause a drastic life change.
I hope through this four part series I have established the importance of sensory systems in every moment of the day. Look out for our coming posts on activities for each of these senses and more discussion on sensory processing. Till then,
Happy Parenting!
Puja.
References:
Degangi GE, , Dipietro JA, Greenspan SI, Porges SW. Psychophysiological characteristics of the regulatory disordered infant. Infant behavior and development, 1991. 14(1); 37-50.
Koziol LF, Budding DE, Chidekel D. Sensory integration, sensory processing and sensory modulation disorders: putative functional neuroanatomical underpinnings. Cerebellum 2011. 10; 770-792.
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