Corollary Discharge, an important ingredient in Hanna Somatic Education By Eleanor Criswell, Ed.D.
The term corollary discharge first caught my attention in a lecture by Yochanan Rywerant during Wave I of the Hanna Somatic Education training in the early 1990s. Later I read references to it in Vernon Brooks’ The Neural Basis of Motor Control. The concept of corollary discharge, and the related term efference copy, have intrigued me over the years, but they have remained somewhat elusive as I pondered motor mechanisms and worked somatically with myself and others. Later Rywerant wrote a monograph about it. In his monograph, Rywerant gives us a clear understanding of corollary discharge, a neural mechanism that is so important for our effective movements and usually so far below our level of awareness.
Corollary discharge was discovered by H.L.Teuber, a neuroscientist from the Massachusetts Institute of Technology, Cambridge, Massachusetts, in the 1960s. The explorations of other neuroscientists followed. Rywerant used an understanding of corollary discharge in Feldenkrais’s relative conjugate movements (a function named by Rywerant). Corollary discharges play a role in habitual and non-habitual patterns of action. An understanding of corollary discharges can be applied to movements in everyday life. The boundaries of the self can be explored from the perspective of corollary discharge. Part of the recovery from movement impairment includes establishing new corollary discharges. As an Hanna Somatic Educator you can help your client move beyond the restrictions imposed by the corollary discharges created by the impairment to create new corollary discharges. Corollary discharges relate to the link between the mind and body.
What is corollary discharge? Corollary discharge is a discharge from the motor system to sensory systems regarding intended voluntary movement or postural change, “preparing those sensory systems for changes that will occur as a result of the intended movement.” Because corollary discharge is unconscious, subliminal, or below the level of our awareness, it is valuable to be aware of what it is, why it is important, and how it enhances our function. Rywerant says, “The corollary discharge is the mechanism by which a nonhabitual pattern of action changes gradually into being more habitual.”
Corollary discharge and efference copy are related concepts. Efference copy is a special case of corollary discharge. According to Webster’s Ninth New Collegiate Dictionary, corollary refers to “something that incidentally or naturally accompanies or parallels.” Discharge means “to relieve of a charge, load or burden.” Efference is a term for information moving out from the central nervous system to cause muscle contractions or glandular secretions. Efference copy is a copy of the expected sensations that may arise because of motor action that are sent to the sensory cortex to prepare the organism to ignore self-generated sensations. Therefore, Rywerant says, “the consequences of the intended actions are already anticipated.” The example for this that is often given is the observation that you cannot tickle yourself because you will have already anticipated the sensation and controlled for it.
My sense of efference copy is that as a movement plan is created by the brain, information is sent to all parts of the body notifying it of what is to come and preventing interference with the activities. All too often we do not consider this necessity in our motor planning. Frequently, the person interferes with the very action he or she intends. This is very common in the unnecessary co-contractions that people frequently exhibit that interfere with ease of movement.
With the sense of corollary discharge expressed by Rywerant we can see the importance of developing the learned corollary discharge for skilled movement. The athlete or musician has a highly developed capacity for this. This is a huge area of untapped potential for all of us. In the various awareness enhancing disciplines, such as the Feldenkrais Method and Hanna Somatics, the person may be instructed to recover awareness of reafference or to decrease the prior editing effect of the efference copies. This deliberate allowing of awareness of the sensory feedback from one’s own movements permits the person to remain aware of the results of his or her movements. This increases the complexity of the sensory experience and allows the person to appreciate more of the sensory world.
Understanding and becoming aware of corollary discharges brings this sometimes subliminal aspect of our worlds to our conscious awareness both for the appreciation of the function and to begin to make more conscious use of it. The expansion of our awareness of corollary discharge has huge potential for enhancing motor functioning. As an HSE practitioner you will enhance your work with clients and students by being aware of this ever present dimension of movement. Actually, you are already using corollary discharges in your work without your being aware of them.
Adapted from the Criswell’s introduction to Corollary Discharge, the Forgotten Link, a monograph by Yochanan Rywerant, Freeperson Press, 2007.