I recently attended the above course facilitated by the Sensory Integration Network. The course outlined the link between sensory integration, sensory processing and autism. A brief overview of the neuroscience relating to the sensory systems was provided linking the development and learning within the brain. Finally a link was formed between the sensory systems with observable behaviours within children who have autism.
Sensory processing is reliant on the organisation of the brain’s interpretation and responsiveness to stimulus from the body and environment via the Central Nervous System (CNS) (Schaff & Miller, 2005), so that the body may optimally learn, behave and perform effectively in the environment (Bundy et al 2002). The brain receives information through sensory neurons, once the brain has interpreted the messages; it then sends signals to the body using the motor neurons (Berger 2002).
Autism and sensory processing – what is the connection?
• 70% of children with autism have sensory modulation difficulties (Adamson et al 2006).
• 90% of children with autism have motor difficulties (Green 2006).
Sensory integration theory was developed over thirty years ago by Dr A. Jean Ayres, an Occupational Therapist, who had advanced additional training including educational psychology and neuroscience (Miller et al 2007). Dr Ayres explained through her theory how children with various disabilities were affected by sensory processing difficulties (Miller et al 2007). Dr Ayres was one of the first within her profession as an Occupational Therapist to develop and implement a programme containing a core theoretical framework, based upon neuroscience research (Smith Roley et al 2007).
When the body and brain work together to process sensations, the individual is able to effectively learn, develop, move and behave in a way which is functionally productive (Bundy et al 2002). If the brain is unable to process sensory input, it would result in impaired sensory processing, which would affect and impact on functional behaviours, this is known as sensory integrative dysfunction (Miller et al 2007).
Pollock (2009) highlighted that Ayres (1972) identified a common theme and hypothesised that children who displayed difficulties within meaningful functional behaviours also had sensory integration problems.
In the peripheral nervous system lies the different sensory receptors, which receive input from the environment, it is hypothesized that sensory problems are based upon neurological dysfunction in the central nervous system (CNS) which is made up of the spinal cord and brain (Ayres 2005; Patestas & Gartner, 2006).
Sensory modulation is the brain actively working to balance both inhibitory and excitatory influences received from sensory input from the environment on the brain (Ayres 1979). Sensory modulation occurs when sensory stimuli is received by an individual who is unable to process the information appropriately using their central nervous system to respond accordingly using physiological reactions and behavioural responses (Miller et al 2007). When an individual is able to modulate these senses, they are then able to effectively interact within various environments by utilising graded or adaptive responses (Lane, 2002)
When behavioural and physiological responses do not correspond with the sensory input being received e.g. the body is under or over responsive in relation to what is perceived a normal response; this is known as sensory modulation dysfunction (SMD) (Miller, Coll & Schoen 2007). This can be the body interpreting the signals as being dangerous or completely avoiding the signals being received thus resulting in a chaotic response (Adamson et al 2006).
Dahl Reeves (2001) identifies four types of modulation concerns, which include: physiological responses that are inconsistent, behavioural responses that prevent acquisition of skills, emotional responses interfering with social interactions and cognitive responses responsible for driving thoughts, feelings and behaviours. One conceptual model was devised by Miller et al (2007) who presented a proposed nosology of diagnosis of sensory processing disorder (SPD) with SMD as a category. Miller et al (2007) categorises SMD within one of three different subtypes including: sensory over responsive (SOR); individual’s responding fast with great intensity or duration preventing functional responses to stimuli, it is also known as defensiveness, sensory under responsive (SUR); is the non-respondent to sensory stimuli within their normal environments leading to withdrawal or lack of inner drive to interact with others or explore their environment, or sensory seeking (SS); the need for an unusual amount of sensory input (Miller et al 2007). These categories are helpful when linking the neurological thresholds and the functional behaviours observed within clients in relation to a particular sensory system.
It is common knowledge that there are five senses that a human being possesses: taste, touch, smell, vision and hearing. The National Autistic Society (2014) recognises that here are two other senses, which are used unconsciously and are not as commonly known, they are proprioception and vestibular. Sensory integration theory focuses mainly on the proximal senses, which are the vestibular, tactile and proprioceptive and are important to a child’s development in early life, in the womb (Ayres 2005). Ayres believed and accentuated that these embryonic and primary senses create a good foundation that can be built upon (Ayers 2005).
The proprioceptive system uses the muscles and joints to tell the body where it is in space and how each body part is moving.
The vestibular system enables the body to maintain balance, sustain posture and interpret how it is moving in space.
The tactile system is related to the skin all over the body and is the organ of touch. Touch is perceived through different nerve receptors at different depths in the skin, and detects the following: light unexpected touch, deep pressure, pain and temperature. The main purpose for touch is to discriminate. It has a strong emotional and social role.
Below are some examples indicating under and over responses and seeking behaviour within each of the above sensory systems:
Under – clumsy or bumping into objects.
Over – theory states that you can never receive too much proprioceptive input.
Seeker – rough with peers, bangs down on tables with items, bumping or crashing deliberately into objects or people.
Under – prefers table work to sports, clumsy or poor balance.
Over – avoids swings, climbing equipment, fear or steps or experiences motion sickness.
Seeker – bouncing up and down, spinning or rocking.
Under – poor pencil grip, messy eater or will often drop items.
Over – dislikes grooming, dislikes labels or certain clothing material or overreacts to unexpected physical contact.
Seeker – Fidgets, loves messy play or strokes and touches everything.
• ADAMSON, A., O’HARE, A., and GRAHAM, C., 2006. Impairments in sensory modulation in children with autism spectrum disorders. British Journal of Occupational Therapy. 69. pp.357-364.
• AYRES, A.J., 1979. Sensory Integration and the child. Los Angeles: Western Psychological Services.
• AYRES, A.J., 2005. Sensory Integration and the child. 25th anniversary edn. Los Angeles: Western Psychological Services.
• BERGER, D.S., 2002. Music Therapy, Sensory Integration and the Autistic Child. London: Jessica Kingsley Publishers Ltd.
• BUNDY, A.C., LANE, S.J., and MURRAY, E.A., 2002. Sensory Integration: Theory and Practice. 2nd edn. Philadelphia: F.A. Davis Company.
• DAHL REEVES, G., 2001. From Neuron to Behaviour. In: SMITH ROLEY, S., BLANCHE, E., and SCHAAF, R., Understanding the Nature of Sensory Integration with Diverse Populations. San Antonio, Texas: Therapy Skill Builders.
• LANE, S.J,. 2002. Sensory Modulation. In: A.C. BUNDY, S.J. LANE, and E.A. MURRAY, Eds. 2nd edn. Sensory Integration Theory and Practice. Philadelphia: F.A. Davis Company. pp. 101-122.
• MILLER, L.J., ANZALONE, M.E., LANE, S.J., CERMAK, S.A., and OSTEN, E.T., 2007. Concept evolution in sensory integration: a proposed nosology for diagnosis. American Journal of Occupational Therapy, 61(2), pp.135-140.
• MILLER, L.J., COLL, J.R., and SCHOEN, S.A., 2007. A Randomized Controlled Pilot Study of the Effectiveness of Occupational Therapy for Children With Sensory Modulation Disorder. The American Journal of Occupational Therapy, 61(2), pp.228-238.
• PATESTAS, M.A., and GARTNER, L.P., 2006. A textbook of neuroanatomy. Oxford: Blackwell science.
• POLLOCK, N., 2009. Sensory integration: A review of the current state of the evidence. Occupational Therapy Now, 11(5), pp.6-10.
• SCHAAF, R.C., and MILLER, L.J., 2005. Occupational Therapy using Sensory Integrative Approach For Children With Developmental Disabilities. Mental Retardation and Developmental Disabilities Research Reviews, 11, pp.143-148.
• SMITH ROLEY, S., MAILLOUX, Z., MILLER-KUHANECK, H., and GLENNON, T., 2007. Understanding Ayres Sensory Integration. OT Practice, 12(17), pp.CE1-CE8.
• THE NATIONAL AUTISTIC SOCIETY., 2014-last update, The sensory world of autism [Accept difference. Not indifference], [online]. Available: http://www.autism.org.uk/living-with-autism/understanding-behaviour/the-sensory-world-of-autism.aspx [Accessed 27th April 2015].
Joanne Harries, OT