Engage My Brain

THE TACTILE SYSTEM
http://www.spdaustralia.com.au/the-tactile-system/

The Somatosensory System or Tactile System, includes multiple types of sensation from the body - light touch, pain, pressure, temperature, and joint and muscle position sense (also called proprioception). However, these modalities are lumped into three different pathways in the spinal cord and have different targets in the brain. The first modality is called discriminative touch, which includes touch, pressure, and vibration perception, and enables us to “read” raised letters with our fingertips, or describe the shape and texture of an object without seeing it. The second grouping is pain and temperature, which is just what it sounds like, and also includes the sensations of itch and tickle. The third modality is called proprioception, and includes receptors for what happens below the body surface: muscle stretch, joint position, tendon tension, etc. This modality primarily targets the cerebellum which needs minute-by-minute feedback on what the muscles are doing.

The central nervous systems ability to process tactile sensory input is distorted in the child with SPD and causes the child great discomfort. Their brain may register even the most subtle sensations as extreme irritation or even painful and he may respond in an abnormally reactive way such as grimacing or pulling away from the stimulus.

The central nervous system must rely on five sensory nerve receptors in the skin to keep it informed about its environment. These receptors are; light touch (surface), pressure (deep), temperature (hot & cold) and pain. It is quite possible for one type of receptor to be sensitive and the other normalized. This explains why he may tolerate light touches, but dislike firm hugs; or hate tags and hair cuts.

1. HYPERSENSITIVITY TO TOUCH (over-responsive, tactile defensiveness)

2. HYPOSENSITIVITY TO TOUCH (under-responsive)

3. POOR TACTILE PERCEPTION AND DISCRIMINATION:
 

• has difficulty with fine motor tasks such as buttoning, zipping, and fastening clothes   

• may not be able to identify which part of their body was touched if they were not looking

• may be afraid of the dark

• may be a messy dresser; looks disheveled, does not notice pants are twisted, shirt is half untucked, shoes are untied, pants are unzipped, one pant leg is up and one is down, etc.

• has difficulty using scissors, crayons, or silverware

• continues to mouth objects to explore them beyond appropriate age

• has difficulty figuring out physical characteristics of objects; shape, size, texture, temperature, weight, etc.

• may not be able to identify objects by feel, uses vision to help; such as, reaching into backpack or desk to retrieve an item

THE AUDITORY SYSTEM
http://www.spdaustralia.com.au/the-auditory-system-2/

The ear can hear many different sounds either through air-conduction or bone-conduction. These sounds must be accurately received by the ear, then be sent to relevant parts of the brain to be analysed and acted upon.

In the case of language, spoken words are received as sound pressure waves. In the middle ear the sound pressure waves are converted to vibrations of the ear bones and transmitted through the bone to the inner ear. Here the vibrations are subsequently converted into electrical impulses, which are in turn sent to the brain cortex and the temporal lobe where the signals are interpreted as words. It is at this point that the meaning of the sounds is decoded. Once the meaning is assigned, the brain can then move to the task of evaluating the information and forming response strategies.

Auditory processing is a term used to describe what happens when your brain recognizes and interprets the sounds around you. Humans hear when energy that we recognize as sound travels through the ear and is changed into electrical information that can be interpreted by the brain. The “disorder” part of auditory processing disorder (APD) means that something is adversely affecting the processing or interpretation of the information.

Children with APD often do not recognize subtle differences between sounds in words, even though the sounds themselves are loud and clear. For example, the request “Tell me how a chair and a couch are alike” may sound to a child with APD like “Tell me how a couch and a chair are alike.” It can even be understood by the child as “Tell me how a cow and a hair are alike.” These kinds of problems are more likely to occur when a person with APD is in a noisy environment or when he or she is listening to complex information.

SIGNS OF AUDITORY DYSFUNCTION: (no diagnosed hearing problem)

1. HYPERSENSITIVITY TO SOUNDS (auditory defensiveness):
 

• distracted by sounds not normally noticed by others; i.e., humming of lights, refrigerators, fans, or clocks ticking

• fearful of the sound of a flushing toilet (especially in public bathrooms), vacuum, hairdryer, squeaky shoes, or a dog barking

• startled by or distracted by loud or unexpected sound

• bothered/distracted by background environmental sounds; i.e., lawn mowing or outside construction

• frequently asks people to be quiet; i.e., stop making noise, talking, or singing

• runs away, cries, and/or covers ears with loud or unexpected sounds

• may refuse to go to movie theaters, parades, skating rinks, musical concerts etc.

• may decide whether they like certain people by the sound of their voices

HYPOSENSITIVITY TO SOUNDS (under-registers):
 

• often does not respond to verbal cues or to name being called

• loves excessively loud music or TV

• appears to “make noise for noise’s sake”

• seems to have difficulty understanding or remembering what was said

• appears oblivious to certain sounds

• appears confused about where a sound is coming from

• talks self through a task, often out loud

• had little or no vocalizing or babbling as an infant

• needs directions repeated, says “what” frequently

THE PROPRIOCEPTIVE SYSTEM
http://www.spdaustralia.com.au/the-proprioceptive-system/

Proprioception is the process by which the body can vary muscle contraction in immediate response to incoming information regarding external forces, by utilizing stretch receptors in the muscles to keep track of the joint position in the body.

Proprioception and kinesthesia, the sensation of joint motion and acceleration, are the sensory feedback mechanisms for motor control and posture. These mechanisms along with the vestibular system, a fluid filled network within the inner ear that can feel the pull of gravity and helps the body keep oriented and balanced, are unconsciously utilized by the brain to provide a constant influx of sensory information. The brain can then send out immediate and unconscious adjustments to the muscles and joints in order to achieve movement and balance.

Proprioception, also often referred to as the sixth sense, was developed by the nervous system as a means to keep track of and control the different parts of the body. An example that enables one to best understand this sensory system is one showing what happens if this sensory system is no longer there. A normal person is able to move a finger, knowing where and what the finger is doing, with little effort. The normal person could just volunteer the finger to move back and forth and proprioception would make this an easy task. Without proprioception, the brain cannot feel what the finger is doing, and the process must be carried out in more conscious and calculated steps. The person must use vision to compensate for the lost feedback on the progress of the finger.

SIGNS OF PROPRIOCEPTIVE DYSFUNCTION:

1. SENSORY SEEKING BEHAVIORS:
 

• seeks out jumping, bumping, and crashing activities  

• stomps feet when walking

• kicks his/her feet on floor or chair while sitting at desk/table

• bites or sucks on fingers or arms and/or frequently cracks his/her knuckles

• loves to be tightly wrapped in many or weighted blankets, especially at bedtime

• prefers clothes to be as tight as possible

• loves/seeks out “squishing” activities

• enjoys bear hugs

• excessive banging on/with toys and objects

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