SENSORY PROCESSING

Sensory processing refers to how the brain registers, interprets and uses information from the sensory systems.

The sensory systems include sight, hearing, taste, touch, smell, body awareness and balance. Sensory input from the environment is constantly bombarding our brain through all our senses. All sensory input, except for smell, is filtered by the brain stem before being sent to other areas of the brain.

Playing in the Playground

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The sensory input is either:

  • Screened out or ignored if it is deemed to be unimportant or insignificant – example: dust particles in the air. They are all around us, but we tend not to see them unless they are in the sunlight or for some reason there is an overabundance of them.

  • Noticed and then assigned relevant importance so that it is sent to the appropriate area of the brain for a response – example: a car honks at us and we turn and look to see if we need to do anything further.

  • Habituated or eventually ignored if the input is constant or doesn’t’ change much over time – example: wearing a watch or ring.

 

The brainstem is responsible for the regulation of many bodily functions including breathing, heart rate, swallowing and temperature. From a sensory perspective, it also controls or regulates our arousal from sleep to wakefulness. This is an important concept as we can use sensory input to change our arousal state.

 

We need sensory input for our brain to develop and to continue to function properly. Although there is still much more to learn about brain function, research suggests that we may be able to use sensory input to develop improved neural circuitry. It is also important to know that neural plasticity, the ability of the brain to form new neural connections, has been found to continue throughout our lifespan. 

© 2005 D. Saunders B.Sc., OT Reg. (Ont.)

Sensory Modulation:

Sensory Modulation is the brain's regulation of its own activity. Modulation involves matching the body's energy level, and attention to the demands of the environment. It requires the brain to filter information and attend to certain information while disregarding other stimulation. When an individual overresponds, under-responds, or fluctuates in response, to sensory input in a manner that is disproportional to that input, we say that the person has a sensory modulation disorder. The most common types of sensory modulation disorder are tactile or sensory defensiveness, gravitational insecurity, aversive responses to movement, and poor sensory registration. Modulation is NOT always being "quiet and calm". For example, being quiet, calm, and almost falling asleep at a loud basketball game is not typical; just as a being excessively loud and rambunctious in a classroom or library setting is not typical. A well operating system with typically functioning modulation would be able to cheer loudly for their favorite basketball team, and then immediately shift gears to be able to stand in line to order refreshments. An example of poor sensory modulation to the sense of touch would be to withdraw from and shout out, as if in pain, when getting foam soap on their hand.

Sensory Discrimination:

Sensory Discrimination is the ability to correctly register (or recognize) sensory input on a neurological level to use it functionally. When our sensory systems are functioning correctly (meaning they are registering and responding to incoming sensory input correctly) we can discriminate or know things about ourselves and the world around us without testing them out every time. For example, we know which way is up even if we are upside down; we can tell the difference between a penny and a quarter without looking at it; we can anticipate how much force to use when picking up an egg shell compared to a closed can of pop; and we can tell the difference between a safe touch and a threatening touch (feeling something crawling on your arm vs. a gentle pat on the arm). We also use emotional discrimination within this due to the fact that the way we interpret information is influenced by our own history, relationship with others, and our relationship with the environment.

Sensory Organisation - Praxis:

Planning and sequencing involves planning and ordering new muscle (motor) actions (known as praxis). It involves first generating an idea of what you want to do (ideation), figuring out how you are going to do it (motor planning), and then doing or carrying out what you wanted to do (execution). Integration of the brain and the senses (e.g. touch, movement, vision, hearing) are required for good planning and sequencing. People with poor planning and sequencing may have to think harder to complete new physical tasks due to poorly integrated information from the sensory systems.

Pyramid of Learning Diagram

First layer:

Tactile (somatosensory) systemreceptors in the skin receive, interpret and monitor touch, texture, pain, temperature and pressure. Along with the proprioceptive system, it provides the foundation for the development of body scheme and motor planning. Good touch information is required for fine motor and handwriting development and it is an important factor in the modulation of emotion, e.g. bonding between a child and parent. Tactile information is an important factor in eliciting defence mechanisms, e.g. to pain. Some children with tactile processing difficulties experience unusual or defensive reactions to non-noxious touch.

Vestibular system – this is an important foundation for balance and postural control. The sensory system, based in the inner ear, monitors head position and the effects of gravity, e.g. when turning the head, doing somersaults etc., and allows the body to resist the force of gravity. The pull of gravity through the body midline provides the vestibular system with an important reference point for directionality, organisation in space, and awareness of body position and planes. The vestibular system influences eye movements, muscle tone, bilateral integration, and helps to integrate information from all the senses. Stimulation of the vestibular system also affects “arousal” levels whereby some movements tend to be calming and others excitatory. Difficulties with postural stability contribute to issues of attention regulation, e.g. being able to sit upright on a chair.

Proprioceptive system – information gained through receptors in the muscles and joints provide the sense of body position and movement. Proprioceptive feedback, combined with touch, is necessary for development of body scheme, which in turn enables effective and efficient planning of movement sequences, “programming “of automatic patterns of movement, and feedback/feedforward mechanisms to take place. Good proprioceptive feedback is required for developing handwriting, i.e. the technical formation of individual letters, and later, whole words, are gradually learnt and “programmed”, so that they become memories whereby the movements can be easily and automatically reproduced on demand. This then enables the child to concentrate on the work content.

 

Olfactory System:: or sense of smell, is used for smelling and the ability to smell is important for nutrition, protection from danger and quality of life. The olfactory system is connected directly to our limbic system, which is the part of the brain which is involved in her behavioural and emotional responses including our fight / flight response. It also links to our memory system, and supports us with attachment and bonding. Over-responsivity in the  olfactory system, can be a  source of anxiety due to more intense odours and stronger associations between the stimuli and the emotional connection. Under responsivity in the limbic system means that a person has to seek more input to gain the stimuli and therefore interfere with daily living.  

Visual System: Vision provides use with the ability to understand and interpret what we see with our eyes. Our eyes receive information about the world around us including whether it is dark or light, whether there is colour and whether there is movement. Our visual system supports our motor systems, especially when we are not receiving information from the rest of our body i.e., somatosensory difficulties. Our eyes also support our fig / flight response as they tell us about the danger around us and enable us to prepare our bodies to act when required.

 

Auditory Sense: Our auditory sense, our ears provide us with the ability to interpret information from the world around by listening, and responding. Our auditory system provides us with low and high frequency information, and also rhythm. It enables us to understand what is being said to us, and how we interpret this information. Low frequency tones are also picked up by the tactile, proprioception and vestibular receptors (Frick et al, 2012). Again, the auditory system is directly linked to our physiological regulation. The middle ear is less able to hear human voices and instead is tuned to hear low-frequency sounds associated with danger and predators. A chronically shut off stapedius will cause auditory hypersensivities and a faulty neuroception of danger or threat to life, turning off the vagal break and activating the sympathetic gas pedal.

 

Gustatory Sense: or taste provides us with information about what is in our mouth. Our tongue is responsible for this and receives taste sensations, and support us to remain safe. This is due to the fact that our tongue can tell us what is safe or harmful by the chemical makeup of the food.

Second layer:

Body Scheme: Body scheme is the awareness of your body through movement. It enables us to understand our body parts and their relative position in space in both 2 Dimensional and 3 Dimensional.. In order to achieve this the body much be continually updated with information by undertaking movement, and needs to gain the information both centrally (brain processes) and peripheral (sensory systems) to support and develop this.

 

Reflex maturity: Retained primitive reflexes can lead to developmental delays related to disorders like ADHD, sensory processing disorder, autism, and learning disabilities. The persistence of primitive reflexes contributes to issues such as coordination, balance, sensory perceptions, fine motor skills, sleep, immunity, energy levels, impulse control, concentration and all levels of social, emotional, and intellectual learning. 

 

Ability to screen input: or Habituation, is the most basic form of learning. It enables us to responds to a specific stimulus whilst filtering our irrelevant information for example in our auditory or visual system. For example; being able to pay attention to the teacher in a busy classroom.

Pyramid of Learning Diagram

Postural security: enables us to maintain a controlled, upright position in order to engage in various static (still) and dynamic (movement) based activities. It is controlled by our central nervous system and provides us with the confidence in maintaining an upright posture when tested i.e., unbalanced ground. The main systems involved in this are the visual, vestibular and somatosensory systems. If a child does not have postural security, they can presents with Gravitational insecurity. Gravitational insecurity refers  to  an  excessive  fear  of  ordinary  movement,  being  out  of  an  upright position, or having one’s feet off the ground. Children with this fear are uncomfortable with gravity, and their reactions are out of proportion to any real danger that exists or to any postural deficits the child may have.

 

Awareness of two sides of the body (bilateral integration): The ability to coordinate the right and left sides of the body, and to cross the body midline, is an important foundation for the development of many gross and fine motor skills, e.g. using cutlery. Crossing the midline is a prerequisite for developing bilateral integration. Bilateral integration is an essential skill, if tasks such as learning to fasten buttons, tying shoelaces and manipulating cutlery are to be undertaken in an efficient and effective manner.

 

Motor planning: is the ability to work out the plan of action before engaging in a motor activity. This enables us to move our body in a way we want i.e., running or jumping. When developing motor planning, you must try something and then gain feedback from this to then adjust and try the task again. This enables a person to be efficient in the movement.

Pyramid of Learning Diagram

Third layer:

Auditory language skills; is the ability to interpret, retain, organize, and manipulate spoken language for higher level learning and communication. This is why we work so closely with our Speech and Language counterparts.

Visual-spatial perception: is the ability to tell where objects are in space in relation to their environment, which can include your own body parts. It involves being able to  select, organize, and utilize visual information to create an understanding of meaningful patterns.  People use visual-spatial processing skills for many tasks, from tying shoes to reading a map.

Attention centre functions: is basically the ability to ability to look at, listen to and think about tasks over a period of time.

Eye-hand coordination: means the ability of the vision system to direct and coordinate the information received through the eyes to control, guide, and direct the hands in the execution and accomplishment of a task. This includes handwriting.

Ocular motor control: Ocular-motor control is the systematic exploration of the visual field, including fixation and tracking, crossing midline, binocular accommodation, visual scanning and quick localisation.

Postural adjustment: are defined as the activation of postural muscles in a feedforward, unconscious manner before a voluntary movement begins i.e., shifting in your seat. This enables us to keep our postural stability without having to attend to our body position continuously, therefore, allowing our concentration and attention to go onto other tasks.

Top tier:

Academic learning which is classed as the acquisition of skills that form the core of the general curriculum in schools including mathematics, language arts, social studies, and science

 

Daily living skills can be divided into personal and instrumental activities of daily living (ADLs), are routine, self-care tasks in which most people participate on a daily basis without assistance. These include everything from using the toilet and washing, to undertaking domestic tasks within the house or the community.

 

Behaviour is described as the way in which one acts or conducts themselves. 

Pyramid of Learning Diagram