SENSITIVITY TO SMELL
The sense of smell differs from the other senses in that the nerves involved connect directly to the limbic system in the brain – the seat of our emotional responses. These brain regions are involved not only in identifying smells, but also in emotional reactions and motor responses. For this reason the sense of smell can have an unconscious effect on our emotions and reactions. Individuals who are hypersensitive (oversensitive) to smell may be emotionally overreactive, while those who are hyposensitive (undersensitive) may have rather flat emotional responses.
Food choices can be affected too, as foods may be rejected on the basis of their strong smell. The senses of smell and taste are closely linked. For this reason, individuals who are hypersensitive to smell may also be oversensitive to taste, and become picky eaters. Conversely, those who have a very poor sense of smell may eat indiscriminately or even try to eat inappropriate items.
Individuals who are hypersensitive to smell are also likely to be sensitive to chemical stimuli. Their behaviour can therefore be influenced by odours emanating from household products, furnishings etc.
SENSE OF TASTE - GUSTATION
Gustation is the sense of taste. Flavour is perceived as each food activates a different combination of the basic tastes – sweet, sour, salty, bitter and umami. Umami means delicious and is mimicked by the flavour enhancer monosodium glutamate (MSG). Most foods have a distinctive flavour as a result of their taste and smell being perceived simultaneously. Other sensory modalities, such as temperature and texture, may contribute to the food tasting experience.
Gustation is important to basic behaviours such as the eating and the control of digestion. Gustatory cells connect to a number of regions in the brainstem which are involved in swallowing, salivation, gagging, vomiting, digestion and respiration. Information is also distributed to areas of the brain involved in processing the palatability of foods, motivation to eat, satiety and food preferences.
SENSE OF TOUCH - TACTILITY
Our sense of touch provides us with information about the texture, form, position and temperature of objects, and also processes the sensations of pressure and pain. If there are issues with the development of the sense of touch, people can become either undersensitive or oversensitive to touch. This will not only affect functions that directly depend on touch, but also related systems such as spatial awareness, and motor skills such as handwriting.
The thumb tip and tongue are more sensitive to touch than other parts of the body and therefore most affected by hypersensitivity to touch. Many people will develop a pencil grip which avoids contact between the thumb and the writing instrument, and this can seriously affect their control and the ease and neatness of their handwriting. Many will be picky eaters, rejecting food on the basis of its texture.
Humans have a fundamental need for touch and research has shown that some kinds of touch activate neurotransmitters in the brain which help control anxiety. Any reduction in access to this experience in early childhood as a result of oversensitivity to touch can have a serious effect on the child’s emotional development. This may affect not only close relationships, but also self-confidence and the development of the interpersonal skills so important at school and in the workplace.
Children whose sense of touch is immature may be driven to continue to explore their environment by touching things long after this behaviour is regarded as acceptable.
BALANCE – THE VESTIBULAR SYSTEM
The vestibular system, in the inner ear, is important for the development of balance, movement, our ability to listen and pay attention, and our visual processing – our brain’s ability to make sense of what it sees. Vestibular immaturities are capable of causing problems with gross motor skills such as sports activities, fine motor skills such as handwriting, and any tasks involving efficient eye movements, such as reading, dealing with columns in maths and copying from the board.
KINAESTHESIA
Kinaesthesia is the faculty of being aware of the position and movement of parts of the body by means of sensory nerves (proprioceptors) within the muscles, joints etc., and the sensation producing that awareness. It results in awareness of overt movements of bones and joints and overt or covert movements of muscles and tendons.
VISION
Vision concerns eyesight and visual focus – short sight, long sight and astigmatism – which should be checked and, if necessary, corrected by an optician. It is not the same as visual processing, which happens at a neurological level.
HEARING
Hearing essentially concerns the processes occurring in the outer, middle and inner ear in response to a sound stimulus. Problems with any part of this functioning might lead to a ‘hearing difficulty’ which should be checked by an audiologist.
‘Hearing’ is not the same as ‘Listening’, which is the process by which we make sense of what we hear and happens at a neurological level.
MUSCLE TONE
Muscle tone is the degree of tension or readiness to respond in resting muscles. It is developed through movement involving the tightening and relaxing of muscles, which is controlled by the vestibular system, but the sense of touch is involved too. For most people, issues with muscle tone involve tone being a little too low or a little too high.
If muscle tone is a little too low there may be problems with muscular response, which may make people appear a little slow to respond. There may be issues with posture, endurance, standing still, binocular vision, or appropriate pencil grip. Sometimes there can be problems with articulation in speech, non-verbal communication and interpreting the body language of others.
If muscle tone is a little too high there may be a muscular response that is too rapid, leading to people reacting before they have had time to fully process the data required for a reasoned response. Any issues with muscle tone are likely to affect motor skills.
PROPRIOCEPTION
Proprioception is our subconscious sense of where our body is in space. It tells us about the position of our bodies, or parts of our bodies, in relation to their environment and each other. Proprioception lets us know where we are in space without having to look. It is important for the development of spatial perception which is relevant to some aspects of maths.
People with proprioceptive difficulties often appear rather clumsy and may generally invade other people’s space. As they do not have a clear sense of their own boundaries they often find it difficult to respect those of others.
Proprioceptive issues often lead to a fear of the dark and difficulties getting to sleep. It is common for babies to scream when they are put down in their cots, even if they are already asleep. There are often both physical and emotional insecurities and an excessive need for reassurance.
MOTOR PLANNING
The brain’s ability to understand, plan and carry out a physical task. If this is severe, speech may be delayed or disorganised, children may not seem to know how to play and it will be hard to imitate the actions of other people. Problems are more often seen at subtle level. In this case, thoughts may be poorly organised, handwriting may be slow or poorly formed, and it may take people a long time to get started on written work.
FEAR-BASED REFLEXES
The Moro reflex is the most well-known of the fear-based reflexes which can affect our well-being. This reflex is based in the vestibular system. It should be integrated in the first few months of life to make way for the adult startle reflex. If this does not happen, or if the reflex surfaces later as a result of a traumatic event, it results in hypersensitivity to any or all sensory stimuli, and often emotional over-sensitivity as well. Problems with balance and co-ordination are common, as is motion sickness. People who are hypersensitive to sound often have difficulty in tuning out background noise, and can suffer auditory confusion. Similarly, they can have difficulty in ignoring any material in their visual field, so that their eyes tend to wander to the periphery.
Photosensitivity can result in difficulties with the glare of black print on white paper which affects reading stamina, and people often prefer to read in dim light. Reactive hypoglycaemia often develops, which means that blood sugar levels dip and concentration suffers unless the diet is adapted. Food allergies are common. People with retained Moro reflexes can be anxious, insecure, prone to mood swings, hyperactive or lacking in energy. They find it difficult to change, which makes it hard for them to accept criticism, and also needing to control events, so they themselves do not have to adapt. Low self-esteem is a particular problem.
The Fear Paralysis Reflex is a withdrawal reflex which should be integrated before birth. The foetus responds to stress in utero by freezing and withdrawing, but as its responses to touch mature, this reaction occurs less often, ultimately ceasing to occur. If the reflex is retained after birth, withdrawal and/or fear paralysis responses may continue and seriously affect an individual’s behaviour and ability to handle stress. It is very important that withdrawal responses are understood, because they can often be seen as non-compliant behaviour. If a child is confronted when in withdrawal they will be unable to reason and could respond with aggression.
VISUAL PROCESSING
Visual processing is the process by which the brain interprets the images received by each eye and this happens at a neurological level. Visual processing for close work requires more maturity and is more sensitive to stress than distance processing, so this is the area where problems are most often seen. A child’s visual system is not fully mature until they are about seven years old. Reading, spelling, maths and hand-eye coordination tasks are all very dependent on the mature development of visual processing skills.
AUDITORY PROCESSING - LISTENING
The medical term applied to the listening process is ‘central auditory processing’, often abbreviated now to ‘auditory processing’. It is not the same as hearing, which can be tested by audiologists in various ways and improved with the use of hearing aids. Central auditory processing is the way the brain uses the auditory information which enters each ear to control our ability to listen, think and speak.
Most people with central auditory processing difficulties do not have hearing difficulties, although there may have been an early history of ear infections and blocked ears. It is particularly important to know if a child has difficulty with central auditory processing because they are often thought to be naughty – or not very clever – if they cannot listen and respond properly.
ATTENTION
In order to be able to focus attention in a busy environment people need to be able to listen effectively, use their eyes appropriately for close work and copying tasks, organise their thoughts for analysis and communication and connect up different bits of information in areas all over their brain quite quickly. Memory systems also need to be working well. If there is difficulty in any of these areas, tasks may start to become too challenging and then focus may only be maintained for short bursts.
It is also important that these skills are not disrupted by hypersensitivity to environmental stimuli forcing the individual to tune out in order to protect themselves. Both children and adults can be over-sensitive in some or all of their senses, so their world can be too bright, too noisy, too smelly and they can over-react to things they touch and taste. Where most children are developing their ability to use all their senses effectively these children will be learning how to protect themselves from overwhelm and they may be constantly distracted by stimuli in their environment that others would ignore. If these problems are carried into adulthood there can be major issues with working in noisy environments, such as open plan offices, leading to low stress tolerance and vulnerability to overwhelm.
Some individuals may be more prone to employing selective attention techniques than others. This is often the case for children who are destined to become experts in their chosen field or who may develop particular skills in creative areas.
BRAIN INTEGRATION
Brain integration is the term for the process of communication between the left and right sides of our brain and the brain’s ability to make connections in general. For most people the left brain is the logical, systematic side and the right brain is the emotional, visual, creative side. So good brain integration allows people to connect up information held all over the brain quickly and accurately so they can master increasingly complex physical, mental and emotional processes. However, there can be problems with brain integration – in just one area, in several areas, or globally, resulting in poor auditory, visual, motor or emotional functioning, or difficulties with comprehension and response. Typical early skills requiring brain integration are dressing, tying shoelaces, riding a bicycle and learning to swim.
Brain integration is important for reasoning skills, comprehension, understanding consequences and making mature judgements. Mature visual integration is required for good literacy skills. Auditory integration is important for speech, word-finding and understanding directions. Motor integration underpins skills such as handwriting and proficiency in sport and physical activities.
Blocks to brain integration can affect emotional processing as people are forced to process information predominantly on one side of the brain. This can result in an inability to combine the left-brained logical, sequenced view with the emotional and big picture processing of the right brain. There may be an overly emotional response with a lack of logical reasoning or a tendency to focus on the facts and logic without seeing the emotional aspects and the wider context.
LATERALISATION
Laterality refers to the dominance of one side of the brain in controlling particular functions, or of one of a pair of organs, such as the eyes or hands. For example, the majority of people are right-handed; most footballers will be either left-footed or right-footed. In most people, one side of the body is uniformly dominant, usually the right side. If dominance is not clearly established on one side or the other, this may lead to delays and issues with the way the brain processes information.
Immature lateralisation is often a factor in reading difficulties, particularly if eye dominance is not fully established. Reversals in letters and words may be observed in reading and spelling. A lack of ear dominance may affect listening skills and speed of processing. Many people do not have dominance established on the same side and this is not necessarily a problem. Creative individuals often have a left dominant eye and right dominant hand, for example, and this allows greater access to the creative areas of the brain.
If people experience trauma they can sometimes block access to processing areas in one side of the brain or the other associated with the traumatic event. This can lead to dominance moving to the ‘wrong’ side of the brain where processing is less efficient. For example, an individual may move to left ear dominance as a result of trauma and process auditory information first in the right brain. This slows down processing and may restrict access to the logical, sequenced functions of the left brain. As the right brain is the emotional side of the brain they may also over-react emotionally to what they hear.
DIFFERENTIATION
Differentiation is the ability to control the movement of one part of the body without another area becoming involved. If the brain has not fully matured in this respect, the person may perform movements which they don’t intend to, particularly when they are focused on an activity such as listening. They may be able to listen, or to keep still, but probably cannot focus on both at the same time. Unintentional movements may include fidgeting, drumming on the table, humming and rocking backwards and forwards in the chair.
Issues with differentiation are quite strongly associated with the development of tics and some people have difficulty preventing themselves from engaging in obsessive thoughts and actions. Both are related to an imbalance in levels of the neurotransmitter dopamine, which is also responsible for the control of motivation.
Differentiation issues will almost certainly interfere with the very complex eye movements required for accurate and rapid reading. People may appear to have no reading difficulty but they will not choose to read small print for long periods and they may be relatively slow completing tasks that involve a lot of reading.
MEMORY
Memory systems in the brain are very complex. The most easily understood is the basic short-term visual and auditory memory circuit based on the hippocampus. If short-term memory is disrupted it may be difficult to transfer information to be stored in long-term memory but good quality sleep is also very important for this process. Working memory is more complex, and certain areas of the brain are specialised for dealing with simple memory, complex memory, and memories of medium complexity. Both auditory and visual short-term memory skills are critical for literacy development
It is essential that we do not consciously recall every event in our lives, because our brains would be overloaded with useless information, so there is a filtering system based on Pleasure and Punishment. We remember things primarily because we find them interesting or pleasurable, or because we will be in trouble if we forget them.
Memory can be directly disrupted by processing difficulties elsewhere, and also by stress. There are also a number of neurotransmitters involved, and dysfunctions in these neurotransmitters can seriously affect memory. For example, dopamine is very much involved in the brain’s perception of reward and punishment, and therefore motivation. If there is disruption to this circuitry, children will subconsciously think information is not worth remembering. Glutamate balance is also vital, because glutamate balance is necessary for people to be able to focus their attention on an auditory or visual stimulus, and also for the information to be transferred efficiently to long-term storage.
LISTENING
Listening ability depends fundamentally on central auditory processing ability, one of the more basic building blocks of sensory integration, and it is always important to fully assess any potential difficulties in this area. There are other factors involved in the listening process, however.
In some cases, listening ability is affected by problems with biochemical imbalances, often associated with imbalances in the microbiome in the gut. If this is the case, people may struggle to stay focussed in any situation and some days may be better than others, depending on their exposure to certain foods. Sometimes there can be emotional difficulties, often associated with low self-esteem, in which case listening difficulties are likely to occur in situations where individuals are put under pressure. Many parents will be familiar with ‘selective listening difficulties’, where children fail to listen when they are asked to do something – often this has to do with a subconscious reaction to a particular tone of voice.
Some people have a very high level of functioning in the right brain and are naturally inclined to day-dreaming and becoming immersed in their own individual thoughts. They may struggle to stay focussed on listening to something which does not particularly interest them. Children with this pattern may mature into very creative, imaginative people with a strong sense of purpose.
It is always important to assess every aspect of a listening difficulty, to seek to understand the issues, correct dysfunctions but also understand and support different learning styles.
PROCESSING SPEED
As with all higher order skills, speed of processing issues can be associated with a number of different dysfunctions – and sometimes there are no dysfunctions at all, simply a different way of processing information that may in time prove to be beneficial.
Speed of processing is fundamentally determined by the activity of the fast processing systems in the brain and the level of brain integration. The fast-processing system is known as the magnocellular system and it controls visual and auditory processing in situations where speed is important, such as when visually scanning a line of print or processing a stream of language. Brain integration systems are much more complex, but both are strongly affected by the effects of stress and overload.
Brain integration describes the way in which information is connected up between different areas of the brain, particularly between the two cerebral hemispheres. The two halves of the brain are connected by a bundle of nerve fibres – the corpus callosum – and any or all of these connections can be slow for some reason, causing a different range of problems. Connections at the back of the brain control visual integration, whereas auditory integration takes place much further forward, for example. Connections to areas of processing which are not working well are likely to be slow too.
Processing speed is also controlled by individual learning styles. Some people are perfectionists and will consider it much more important to provide their best response rather than a quick response. Some people have issues with time awareness and will always struggle to excel in timed conditions, even though they can process information very quickly in the right situation.
It is often the case that individuals have a processing style which favours considering every possibility and making a host of different associations before offering a final solution. This is a bit like choosing to use B roads rather than motorways to reach a particular destination – it may take a long time to get there, but it could be a much richer experience. These people may enrich our lives by discovering new ways of doing things or through their contribution to the creative arts.
It is important to seek to correct genuine speed of processing dysfunctions and any associated difficulties, but it is equally important to understand individual learning styles and nurture and value people’s gifts.