Presentation
Our senses are what define our experience as humans— hearing, smell, touch, taste, sight, and many more. Put together, these senses form experience, life, and real moments. But what happens when your brain can’t process these senses properly? This essay will be talking about what senses are and the result of their loss or impairment, as it’s a very serious problem.
Firstly, in order to understand the consequences of the loss of our senses, it is necessary to understand how they work when they’re completely fine. The process first begins with the sensory receptors detecting stimuli from the environment and the body. The brain then processes and organises this sensory information (integration) and regulates the intensity and nature of responses to a certain sensory input. The final step involves coordinating sensory information with motor and behavioural responses. An example of this is when we smell a flower, so our sensory receptors detect a stimulus from the environment (smell of the flower), which is processed, organised, and its response is regulated and coordinated.
Multi-sensory integration is the process of merging information from various senses to form a more comprehensive and precise understanding of the surroundings. The concept that our senses collaborate effectively in space relies on each neuron maintaining a precise record of the information it receives from various regions. Interestingly, even when our eyes move, this record must remain stable. However, recent research indicates that our bodies are not always perfect at compensating for these movements, and this phenomenon appears to manifest differently in various neurons and brain regions. If our receptive fields are not registering accurately, it could significantly disrupt the harmonious functioning of our senses (1).
Another big part of sensory processing is when there are sensory deficits; therefore, the person isn’t able to or has a reduced ability to perceive and process sensory information within the body. Examples of this are impairments in hearing, sight, touch, smell, taste, or proprioception. Our vision, which is our dominant sense and controls most of our life, can be impaired due to many neurological conditions, which can result in blindness to half their field of vision, misalignment of the eyes, inability to steadily look at an object or to track an object, or loss of depth perception. Another consequence of neurological conditions is the impairment of hand-eye coordination, the capacity to associate visual stimuli with auditory information, the ability to retain visual information, the capacity to identify objects, and the ability to perceive one’s position relative to surrounding objects. Another big part of our lives is hearing, which allows us to communicate, have conversations, or even listen to our favourite music, but this can also suffer from damage due to brain injuries and result in partial or total hearing loss. Sensory deficits can also appear as loss of smell or taste, as one results from the other normally (3).
Sensory overload is described as an intense feeling of overwhelm when the brain experiences too much input from different senses, and can’t process them. Sensory overload, or overstimulation, is a common experience that everyone encounters at some point in their lives. However, it disproportionately affects individuals with Autism and ADHD, manifesting more frequently and intensely in these groups. It is important to note that experiencing sensory overload does not necessarily indicate the presence of Autism or ADHD. Heightened sensory sensitivity can also be attributed to other conditions such as sensory processing disorder, anxiety, post-traumatic stress disorder (PTSD), and Tourette’s syndrome. Some triggers of sensory overload are loud or disruptive noises, overload of visual information, sensitivity to textures, tastes and smells, changes in routine and fatigue. Some signs of sensory overload are heightened irritability, feeling wound up or even the urge to self stimulate (4).
Even though all these processes are here, we usually don’t notice them. This is due to brain adaptability, a process known as sensory adaptation, which allows the brain to focus on new or changing stimuli by reducing responsiveness to constant sensory information (5). Some examples of this are turning down background noise, smell adaptation.
Another very interesting topic related to sensations are sensory disorders, such as synesthesia, a neurological condition where a stimulus from one sense leads to automatic experiences in other senses. An example of this is someone who, when they listen to music, sees colors or shapes (6) or sensory processing disorder, where the brain has difficulty receiving and responding to sensory information (7). A topic that’s related to this is the misinterpretation of sensory input, when the brain incorrectly processes real stimulus that differs from objective reality. Some examples of this are illusions, where someone may misinterpret real sensory input, for example, they might see a snake, when they’re really looking at a rope, or hallucinations, where sensory experiences occur without an external stimulus, for example hearing voices when no one is talking (8).
Meditation, particularly mindfulness meditation, can serve as a potent tool for managing sensory input. By concentrating on present moment awareness, individuals can develop a heightened capacity to observe and regulate their responses to sensory stimuli, which may lead to a reduction in feelings of overwhelm and an enhancement of overall sensory processing.
Taste is essentially the capacity to detect specific chemicals in one’s immediate surroundings. Ocean-dwelling bacteria were sensing nearby nutrients and swimming towards them at least two billion years ago. Sight, or at least the ability to detect light, was another bacterial innovation, but true image-forming eyes did not evolve until multicellular animals appeared around 570 million years ago. By then, many single-celled organisms had also evolved the ability to sense touch. Smell typically refers to the ability to detect chemicals carried in the air, so this sense had to wait around another 70 million years for the first land animals to emerge. Hearing in air came last, as sound waves are weak compared to electromagnetic waves such as light, and require specialised structures to amplify the signal, especially for high frequencies. Fully-functioning ears did not evolve until 275 million years ago. However, in 2015, Danish researchers suggested that lungfish may have had a rudimentary sense of hearing. These fish were probably the earliest vertebrates to begin making forays onto land, around 375 million years ago, using their fins to ‘walk’ from one shallow pond to another. The study suggests that they could detect low-frequency sounds in the air via vibrations of their head, providing an early forerunner of what eventually evolved in land animals to become the middle ear and eardrum (9).
In conclusion, the human sensory system is a remarkably complex and dynamic interface between the body and the world. Through multisensory integration, our brains synthesise diverse inputs to create coherent perceptions and guide behaviour. However, this system is not without vulnerability, as sensory deficits and overload highlight the delicate balance required for optimal functioning. The brain’s adaptability, evident in practices like meditation, demonstrates its resilience and capacity for change. Finally, the evolution of the senses reminds us that perception is not fixed but continuously shaped by environmental pressures and survival needs. As science advances, our comprehension of sensory systems will continue to evolve, offering new paths for enhancing well-being, treatment, and human potential.