Touch sensations come into our brains from every part of our skin surface and from inside our body allowing the brain to create an accurate image of our body. However, only a small amount of touch (tactile) input that enters the brain reaches our conscious awareness, as the brain filters out much of the tactile stimuli such as touch with clothing and movement from air. Yet the fact that we are not consciously aware of much of these sensations does not mean they are not important. We need this continuous tactile input to help organise the brain – depriving the brain of touch stimulation can seriously affect brain development.
Prior to birth babies already develop tactile awareness in the womb so that by the time the baby is born they associate touch with comfort and security. Over time the sense of touch becomes part of exploration and is essential for the functioning of balance, motion and orientation. Specialised touch receptors in the skin feed information back to the brain to identify heat, cold, pain and pressure, but also body position and movement. This relationship between touch and movement is apparent when considering the sense of proprioception (our ability to know where our body is in space).
Some tactile input is extremely specific – in particular our fingers, hands and mouth produce tactile information that goes straight to higher parts of the brain, producing very strong sensations, whereas our feet or back, for instance, provide less specific input.
The detailed picture that is formed by sensations from the hand allows us to develop and perform very precise tasks. Writing is a good example of how the input from the hands needs to be very specific. Each bit of tactile information allows the brain to respond very quickly and accurately to ensure the correct muscles are being used. The exact points where the pencil touches the fingers provide the brain with the information it needs to tell the muscles how to hold and move the pencil. As you can see this kind of detail is crucial for our hands, yet our feet and other parts of the body do not need such specific information. We do require, however, continuous input from our whole body to keep our tactile system active and healthy.
As with all the other senses, we can be over or under sensitive to touch, or even have a combination of both, being over-sensitive in certain part of our body, whilst being under-sensitive in other parts. It is also possible to be, for instance, over-sensitive to pressure, but not being able to sense pain that well. Many of our clients report tactile over-sensitivity, requiring them to cut out the labels in clothing. Others may like to sleep under heavy blankets, or roll themselves tightly into a cover at night, in order to provide sufficient tactile feedback of the body to inform it where it is, so as not to fall out of bed.
Tactile sensations form part of the intricate and important relationship between the mouth and the hand, which can express itself in low muscle tone in the mouth and tongue, leading to possible difficulties with speech production and writing. The neuro-developmental programme, in particular, looks in detail at these areas.