Sensory processing
Sensory processing is the process that organizes and distinguishes
into usable functional outputs.It has been believed for some time that inputs from different sensory organs are processed in different areas in the brain. The communication within and among these specialized areas of the brain is known as functional integration.
Overview
It has been believed for some time that inputs from different sensory organs are processed in different areas in the brain, relating to
Sensory processing deals with how the brain processes sensory input from multiple sensory modalities. These include the five classic senses of
Basic structures involved
The different senses were always thought to be controlled by separate lobes of the brain,[7] called projection areas. The lobes of the brain are the classifications that divide the brain both anatomically and functionally.[8] These lobes are the Frontal lobe, responsible for conscious thought, Parietal lobe, responsible for visuospatial processing, the Occipital lobe, responsible for the sense of sight, and the temporal lobe, responsible for the senses of smell and sound. From the earliest times of neurology, it has been thought that these lobes are solely responsible for their one sensory modality input.[9] However, newer research has shown that that may not entirely be the case. It is worth noting that in the mid-20th century, Gonzalo conducted research that led him to establish cortical functional gradients where functional specificity would be in gradation throughout the cortex.[10]
Problems
Sometimes there can be a problem with the encoding of the sensory information. This disorder is known as Sensory processing disorder (SPD). This disorder can be further classified into three main types.[11]
- Sensory modulation disorder, in which patients seek sensory stimulation due to an over or under response to sensory stimuli.
- Sensory based motor disorder. Patients have incorrect processing of motor information that leads to poor motor skills.
- Sensory processing disorder or sensory discrimination disorder, which is characterized by postural control problems, lack of attentiveness, and disorganization.
There are several therapies used to treat SPD.
History
In the 1930s, Wilder Penfield was conducting a very bizarre operation at the Montreal Neurological Institute.[12] Penfield "pioneered the incorporation of neurophysiological principles in the practice of neurosurgery.[4][13] Penfield was interested in determining a solution to solve the epileptic seizure problems that his patients were having. He used an electrode to stimulate different regions of the brain's cortex, and would ask his still conscious patient what he or she felt. This process led to the publication of his book, The Cerebral Cortex of Man. The "mapping" of the sensations his patients felt led Penfield to chart out the sensations that were triggered by stimulating different cortical regions.[14] Mrs. H. P. Cantlie was the artist Penfield hired to illustrate his findings. The result was the conception of the first sensory Homunculus.
The Homonculus is a visual representation of the intensity of sensations derived from different parts of the body. Wilder Penfield and his colleague Herbert Jasper developed the Montreal procedure using an electrode to stimulate different parts of the brain to determine which parts were the cause of the epilepsy. This part could then be surgically removed or altered in order to regain optimal brain performance. While performing these tests, they discovered that the functional maps of the sensory and motor cortices were similar in all patients. Because of their novelty at the time, these Homonculi were hailed as the "E=mc² of Neuroscience".[12]
Current research
There are still no definitive answers to the questions regarding the relationship between functional and structural asymmetries in the
Research on sensory processing has much to offer towards understanding the function of the brain as a whole. The primary task of multisensory integration is to figure out and sort out the vast quantities of sensory information in the body through multiple sensory modalities. These modalities not only are not independent, but they are also quite complementary. Where one sensory modality may give information on one part of a situation, another modality can pick up other necessary information. Bringing this information together facilitates the better understanding of the physical world around us.
It may seem redundant that we are being provided with multiple sensory inputs about the same object, but that is not necessarily the case. This so-called "redundant" information is in fact verification that what we are experiencing is in fact happening. Perceptions of the world are based on models that we build of the world. Sensory information informs these models, but this information can also confuse the models. Sensory illusions occur when these models do not match up. For example, where our visual system may fool us in one case, our auditory system can bring us back to a ground reality. This prevents sensory misrepresentations, because through the combination of multiple sensory modalities, the model that we create is much more robust and gives a better assessment of the situation. Thinking about it logically, it is far easier to fool one sense than it is to simultaneously fool two or more senses.
Examples
One of the earliest sensations is the
Audiovisual system
Perhaps one of the most studied sensory integrations is the relationship between vision and audition.[16] These two senses perceive the same objects in the world in different ways, and by combining the two, they help us understand this information better.[17] Vision dominates our perception of the world around us. This is because visual spatial information is one of the most reliable sensory modalities. Visual stimuli are recorded directly onto the retina, and there are few, if any, external distortions that provide incorrect information to the brain about the true location of an object.[18] Other spatial information is not as reliable as visual spatial information. For example, consider auditory spatial input. The location of an object can sometimes be determined solely on its sound, but the sensory input can easily be modified or altered, thus giving a less reliable spatial representation of the object.[19] Auditory information therefore is not spatially represented unlike visual stimuli. But once one has the spatial mapping from the visual information, multisensory integration helps bring the information from both the visual and auditory stimuli together to make a more robust mapping.
There have been studies done that show that a dynamic neural mechanism exists for matching the auditory and visual inputs from an event that stimulates multiple
Sensorimotor system
Hand eye coordination is one example of sensory integration. In this case, we require a tight integration of what we visually perceive about an object, and what we tactilely perceive about that same object. If these two senses were not combined within the brain, then one would have less ability to manipulate an object. Eye–hand coordination is the tactile sensation in the context of the visual system. The visual system is very static, in that it does not move around much, but the hands and other parts used in tactile sensory collection can freely move around. This movement of the hands must be included in the mapping of both the tactile and visual sensations, otherwise one would not be able to comprehend where they were moving their hands, and what they were touching and looking at. An example of this happening is looking at an infant. The infant picks up objects and puts them in his mouth, or touches them to his feet or face. All of these actions are culminating to the formation of spatial maps in the brain and the realization that "Hey, that thing that's moving this object is actually a part of me." Seeing the same thing that they are feeling is a major step in the mapping that is required for infants to begin to realize that they can move their arms and interact with an object. This is the earliest and most explicit way of experiencing sensory integration.
Further research
In the future, research on sensory integration will be used to better understand how different sensory modalities are incorporated within the brain to help us perform even the simplest of tasks. For example, we do not currently have the understanding needed to comprehend how neural circuits transform sensory cues into changes in motor activities. More research done on the
See also
- Anna Jean Ayres
- Environmental sensitivity
- Ideasthesia
- Developmental coordination disorder
- Motor coordination
- Multisensory integration
- Music therapy
- Occupational therapy
- Sensory-motor coupling
- Predictive coding
- Sensory processing sensitivity
- Sensory processing disorder
- Psychopathology
- Sensory deprivation
- Gut–brain axis
- Neuroinflammation
- Neurodegeneration
- Two-alternative forced choice
- Autism
References
- PMID 19345256.
- PMID 21741550.
- S2CID 5685282.
- ^ S2CID 36953396.
- PMID 18621692.
- PMID 19404475.
- S2CID 207141116.
- PMID 18597554.)
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: CS1 maint: multiple names: authors list (link - PMID 18396441.
- ^ Gonzalo, J. (1945, 1950, 1952, 2010, 2023). Dinámica Cerebral, Open Access. Edición facsímil 2010 del Vol. 1 1945, Vol. 2 1950 (Madrid: Inst. S. Ramón y Cajal, CSIC), Suplemento I 1952 (Trab. Inst. Cajal Invest. Biol.) y 1ª ed. Suplemento II. Red Temática en Tecnologías de Computación Artificial/Natural (RTNAC) y Universidad de Santiago de Compostela (USC). ISBN 978-84-9887-458-7. English edition 2023 Brain Dynamics (Vols.1 and 2, Supplements I and II), Ediciones CSIC, Open Access.
- PMID 19826493.
- ^ ISBN 978-1-4000-6469-4.
- PMID 18325826.
- PMID 18606562.
- ^ PMID 15886094.
- PMID 16269365.
- PMID 17027392.
- PMID 18927004.
- S2CID 7420746.
- PMID 15886092.
- S2CID 11042371.
- S2CID 3125842.
- PMID 15886093.