by Bette Lamont
Sensory processing disorder is a common diagnosis among our clients. Many clients have gone through years of sensory integration without finding full resolution. Often our clients also have social anxiety disorder or generalized anxiety disorder due to the stresses of dealing with an overwhelming sensory environment, including sounds that are loud, annoying, or repetitive; lights that are too bright, colors that annoy, multiple and chaotic visual inputs, or too much movement; touch that annoys – from clothing, tags, food textures, loving touch, water on the skin, etc.
This distress that leads to these various DSM labels is what I would term “environmental anxiety” (as opposed to existential anxiety, which I have discussed previously as a pons level issue). This can be treated effectively with NeuroDevelopmental Movement® programs. You will generally see a group of challenges at the midbrain level of development, including, but not exclusively – visual, auditory, and tactile overwhelm. As well, taste and smell are filtered through the midbrain, but we don’t have specific tests for these. They are generally included on our symptoms list by parent report.
The thalamus here is a main culprit. An immature thalamus may be the major and sometimes the only source of a sensory processing disorder. Herein I will outline the role of the thalamus, to give you more ways to communicate the source of sensory processing disorder to your clients.
The thalamus plays a crucial role in processing and relaying sensory information to different areas of the brain. It acts as a sensory gateway or a “switchboard” that filters and modulates sensory experiences before they reach higher cortical regions for further processing.
The thalamus receives sensory input from various sensory modalities, including vision, hearing, touch, taste, and smell. These sensory inputs arrive in the thalamus from specific sensory organs or relay nuclei in the brainstem. For example, visual information reaches the thalamus through the optic nerves, auditory information through the auditory pathway, and so on.
Once the sensory information arrives in the thalamus, it undergoes several important processes:
Sensory Relay: The thalamus relays sensory information to the appropriate areas in the cerebral cortex. Different regions of the thalamus correspond to specific sensory modalities and project the information to the corresponding cortical areas. For instance, visual information is relayed to the primary visual cortex in the occipital lobe, auditory information to the primary auditory cortex in the temporal lobe, and so on.
Sensory Filtering: The thalamus acts as a filter, selectively amplifying or suppressing certain sensory inputs based on their relevance or importance. This filtering process helps prioritize sensory information and prevents the brain from being overwhelmed by irrelevant or excessive sensory inputs. It allows us to focus on the most relevant stimuli while ignoring background noise or unimportant sensory signals.
Sensory Integration: The thalamus integrates different sensory inputs from various modalities and combines them to create a unified perception of the external world. This integration enables us to form a coherent and multi-dimensional representation of our surroundings. For example, when we see an object and simultaneously hear a sound associated with it, the thalamus helps integrate these sensory inputs to create a meaningful perception of the object.
Sensory Modulation: The thalamus can modulate sensory information by adjusting the strength or timing of the signals sent to the cortex. This modulation can influence the level of alertness, attention, or arousal in response to specific sensory stimuli. For example, the thalamus can enhance or suppress sensory signals depending on the individual’s state of consciousness or attentional focus.
Overall, the thalamus acts as a critical intermediate station in the sensory processing pathway, buffering sensory experiences by relaying, filtering, integrating, and modulating sensory information before it reaches the higher-order cortical regions responsible for perception, cognition, and conscious awareness.
The story that Florence Scott relayed to practitioners that I have not substantiated through research, is that when she was the head of the Sensory department at the Institutes for the Achievement of Human Potential, a woman came to Philadelphia from California who had a great many sensory issues. She worked with the new techniques that Florence was developing and they made a difference for her. She took this information back to the University of California system and decided that parents would not want to do such a difficult program, but that she could work with the sensory components of the program. The name she gave her work was Sensory Integration. Her name was Jean Ayers, the ‘mother’ of Sensory Integration.
However, without the motor components of the program, the sensory work does not change due to lack of stimulation to the midbrain and the thalamus that is considered a midbrain organ.
Bette Lamont© 2023