The Neurology of How We Feel

We are all familiar with the sensory aspects of day to day life. You might find that going to the gym or on long nature walks help you to feel calmer and more focused during the day. Or perhaps you know that massages, music, aromatherapy, or super spicy food help you feel more alive, grounded, and able to cope with your day-to-day. Most of us have built ourselves a sensory lifestyle without giving it too much thought. How these processes work, and the impact they have on our health and well-being, deserves as much attention as other domains of wellness. 

Our bodies and brains use specialized systems to register all the different sensory information in our environment and piece it together to build a complete picture of: what is going on around us, with our bodies, within our bodies, where we are, and what time of day it is. Sensory processing shapes our experiences in the world and impacts our feelings.

Touch, sight, sound, movement, body position, smell, taste, internal sensation. Each of these senses comes together to build your conscious reality. 

This brain-body process is taking place every second of every day and through the attention, it pays to external and internal information we form our perception of the world, our lived conscious experienced. 

How we sense, experience, and feel the world is critical to safety and helps us move our bodies, complete tasks, make friends, and fall in love. Making sense of sensation is what makes us successful.

We call this sensory processing.

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Sensory Health & Wellness

Sensory processing is the neurology of how we feel. The sensory messages we receive from our bodies and the world around us are responded to in everything we do in life - whether it’s the comfort we feel from a warm hug from a loved one, the joy from the music we listen to, the feeling of satiation after eating, the ability to stay upright on moving bus or the act of learning / mastering a sport. In each instance, our sensory systems contribute vital information that we use to be successful. We couldn’t do these things without our sensory systems. 

Our ability to process sensory data does not usually require conscious thought or cognitive effort. It provides emotional stability, a platform for social interaction, a sense of self, well-being, satisfaction, and/or accomplishment. Sensory processing can also influence every area of living including our preferences in diet, exercise, relationships, career, and hobbies. 

It is through the senses (sight, sound, touch, smell, taste, proprioception, interception, and vestibular input) that infants first learn about their caregivers, through touch that they first form attachments, and through smell that they identify their birth mother. In the early years of life, there are very few, if any, experiences that are not deeply sensory in nature. Indeed, most early experiences are entirely sensory and entirely emotional. This is how we form relationships, learn to communicate, and develop the foundation blocks for psychological well-being. All of these experiences enable us to develop solid brain architecture that sets us up for success in school and later in the workplace.

Sensory processing is where we learn that we can impact the world. First through our bodies as we lift our heads up against gravity, roll over, crawl, and stand. Also through play as we knock over blocks, shake a musical rattle, and drop items off the high chair tray. This is where our intention first starts to marry with the action that we take. We develop sense-of-self through these early experiences, we learn how to solve problems, we learn that we can impact objects and people, we develop executive function and theory of mind. We also develop motor skills that demonstrate increased finesse and coordination and become more and more gracious and refined with practice. 

The sensory domain is where the brain and body connect and thrive. It is through robust sensory processing that we develop resilience, and establish a tolerance for stressful situations, learn to be calm under pressure, and process experiences that are challenging or upsetting. With well-integrated sensory processing comes a wealth of daily sensory-affective and sensory-motor experiences that cultivates the development of autonomy, competence, interest in learning, goal orientation, sense of purpose, resilience, social engagement, and agency. 

Sensory processing is a critical aspect of well-being through the life-span and the bridge between physical and mental health.

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The Eight Sensory Systems

Most people are surprised to find out that we actually have eight sensory systems rather than five. Learn more about these eight systems in detail. Each of the eight sensory systems contributes to our sense of safety, to mastery of our own body, and to the resultant sensory-affective combination.

• Visual
• Auditory
• Tactile
• Olfactory
• Gustatory
• Vestibular
• Proprioception
• Interoception

Pioneering occupational therapist, psychologist, and neuroscientist A. Jean Ayres, Ph.D., likened SPD to a neurological “traffic jam” that prevents certain parts of the brain from receiving the information needed to interpret sensory information correctly.

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Causes of Disordered Sensory Processing (SPD)

The exact cause of Sensory Processing Disorder has not yet been identified. Preliminary studies and research suggest that SPD is often inherited. Prenatal and birth complications have also been implicated as causal in SPD, as well as certain environmental factors.  A summary of research into the causes and prevalence of SPD is included in Sensational Kids: Hope and Help for Children With Sensory Processing Disorder (New York: Perigee, 2014, 2^nd edition). written by Founder and current Executive Director of STAR Institute, Lucy Jane Miller Ph.D., OTR

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The Spectrum of Sensory Experiences 

Modulation of Sensation 
 
Heightened Sensitivity: Some neurodivergent individuals experience heightened sensitivity to sensory input. This can make sounds, sights, smells, being moved or moving, and even internal sensations feel overwhelmingly "big," "loud," or "intense." Experiencing sensation like this is difficult for outside observers to fully grasp. 

Lowered Sensitivity: Conversely, some people may have reduced sensitivity to sensory input. The world is experienced as somewhat muted, and sensation is not able to grasp attention in the same way. 

Of course, you can have heightened sensitivity to some sensory systems and reduced in others. You may even have some higher and lower responsivity within one system because each system is incredibly complex in itself. Think about all the ways your skin registers input —haptic feedback, vibration, temperature, and pressure. One person might feel a gentle touch intensely while being less aware of temperature changes, while another might find certain textures unbearable yet enjoy the sensation of soft fabrics. This intricate interplay highlights the unique and individualized nature of sensory experiences, demonstrating that our responses can be multi-faceted and fluid, rather than strictly categorized. 

Critically, many neurodivergent individuals have sensory modulation differences that don't fit neatly into categories of hypersensitivity (SOR) or hyposensitivity (SUR). Some register everything around them with the same level of intensity. This means that potentially threatening, every day, and benign/background stimuli can feel equally intense, regardless of how many times they've been encountered. For instance, the teacher's voice, the ticking of the clock, the buzzing of the air conditioner, and the bell signaling time for transition may all be equally intense, all "vying for the attention" of the individual. These individuals might look under-responsive or oblivious to stimuli, or overwhelmed/over responsive to stimuli but taking a deeper dive into what is going on is critical. 

A Note About Behavioral Responses to Sensory Modulation Differences 

How individuals respond or adapt to sensory differences is very personal and variable. Some individuals might actively seek out strong sensations, like bold flavors or deep pressure, or intense movement, to help them feel grounded, balanced, and in control. Others avoid sensation and wear sunglasses, noise reduction ear plugs, gloves, and choose activities with low sensory demand.  

Understanding Sensory Discrimination 

Sensory discrimination refers to how our brains and nervous systems recognize and interpret different sensory experiences, such as distinguishing between the sound of our mobile phone and our landline. For example, being able to listen for the "find my" chimes to locate our phone—whether it's hidden in a room or buried in a specific pocket in our backpack—shows just how finely tuned our sensory discrimination can be. This ability is crucial for creating a clear picture of our environment and understanding our place within it. Our past experiences play a significant role in this process; for instance, recalling the meaning and feelings associated with a particular smell helps us build a mental library that guides our responses to new sensory information. 

Sensory Motor Development  

Posture: The development of posture and our ability to maintain upright positions, from basic head control to advanced movements like arabesques, relies heavily on sensory integration and processing. This development is primarily supported by two key systems: the vestibular system, which helps us keep our head upright, organize our eyes, and detect our motion through space, and proprioception, which provides feedback about our body position and the speed at which our muscles are extending and contracting. Together, these systems enable us to adjust our posture and movements based on the sensory information we receive from our environment, forming the foundation for coordinated actions in our daily activities. 

Motor: Gross and fine motor development is built on sensory integration and processing and relies on a suite of skills we call “praxis”. Praxis is the ability to plan and carry out purposeful movements. This skill is essential for everything from learning to roll over, to riding a bike and mastering complex tasks like writing or playing sports. Effective praxis depends on the integration of our tactile, vestibular, and proprioceptive systems, which work together to inform our brains about body awareness and movement. This integration is crucial for developing skills like reaching for objects, grasping them, and moving through our environment. 

Sensory Processing Variability: Sensory processing isn’t static; it can fluctuate based on factors like stress, fatigue, or environmental changes. A person might find a certain fabric tolerable one day and unbearable the next, illustrating the dynamic nature of sensory experiences.