I nfluences on the development of Sensory Integration Theory

Sensory Integration Theory was not unique to Jean Ayres. She is responsible for synthesizing much of the scientific research and making it specific to certain areas of human performance, particularly in the area of reading and learning disabilities. Her research that established clusters of symptoms was a major contribution to the understanding of brain mechanism and neuro-psychology. She stood on some fairly large shoulders and review some of this may help us gain a broader perspective on sensory integration theory and help us consider the multi-disciplinary contributions.

In 1871 Darwin proposed some ideas on human cognitive evolution that suggested the idea of a series of special human adaptations leading to speech. In his book "The Descent of Man" - a chapter called the " Comparison of the Mental Powers of Man and the Lower Animals" , Darwin proposes that "language evolved out of prelinguistic change in primate cognition that raised the level of basic cognitive skills above those of Apes." He also suggested that speech once established interacted with the human capacity for thought, leading to the development of new thinking. It was the beginning of considering phylogony in the development of cognition and it also suggested that interaction of newly acquired capacity with the rest of the brain lead to new and higher level cognitive organization. This was the concept that newer evolutionary skill grew out of older functions and had some dependence upon them.

The neurophysiologist Charles Sherrington stressed the importance of the central nervous system mechanisms for sensory integration in his 1906 book The Integrative Action of the Nervous System. He stressed the emergence of mechanisms enabling intersensory integration as a major phyletic trend. He suggests that this capacity was a major source of man's advanced adaptive ability.

Lassek in his 1957 book "The Human Brain from Primitive to Modern" focused on the rapid evolution of sensory neurons as opposed to motor neurons that lead to enhanced perception of the environment which in turn led to additional new and more complex adaptive responses. Enlarging the scope of information supplied the brain enabled it, in turn to develop increasingly complex adaptive responses.

C. Judson Herrick The Evolution of Human Nature 1956, wrote that higher intellectual functions are just as much a product of the evolutionary development as is the human skeleton. (p5 Ayres) It is not possible to say when Man's brain began to learn how to learn. The function of the human cortex today is still strongly dependent upon brain stem functions. (p9 Ayres) Higher integrative functions operate through the mediation of sensorimotor experience (Ayres 26) It primarily motor reaction to environmental demands which effected the evolution of the mind rather than the mind that make the body into the motor being (Ayres p36) The cerebral cortex never works independently of the more primitive structures from which is was derived (Ayres p119)

The Russian neuropsychologist Lauria, A. R. Higher Cortical Functions in Man. Lauria - higher brain processes, such as perception, cognition and learning are performed by a number of dynamic functional system of neurons involving many CNS structures at many different levels. These systems involve the combined working of parts of the brain which may be remote, each contributing to the integrated functional system. The process of developing higher cortical function is characterized by an early focus on elementary sensorimotor processes. (Ayres p92-93) The greater the opportunity for interaction among parts of the brain, the greater the adaptive capacity. From an evolutionary standpoint, the capacity for interaction among localized area has been increased through the association areas. Each primary sensory area of the cerebral cortex is surrounded by integrating areas which overlap integrating areas of other sensory modalities. (Ayres p14)

Piaget in The Origins of Intelligence in Children, 1952, stressed the importance of early sensorimotor stage in infants as leading to meaningful experiences and the formation of associations which are the source of sensorimotor intelligence. Symbolic action is based on assimilation of prior sensorimotor intelligence.

Paul Schilder was perhaps one of the most interesting writers to influence sensory integration theory. Schilder was one of the first clinicians to recognize the significance of the vestibular system to the whole psychic structure. (Ayres Tx young schiz p321) Paul Schilderexamined the vestibular apparatus in neurosis and psychosis (1933). Conceived the vestibular system as a coordinating apparatus for all sensory functions. The vestibular apparatus is an organ the function of which is directed against the isolation of the diverse functions of the body. (Ayres p 61) Study of the vestibular apparatus may have great importance for the understanding of psychotic and neurotic states. Dysfunction of the vestibular apparatus is very often the expression of two conflicting psychic tendencies. The neurosis may produce organic changes in the vestibular sphere. Organic changes in the vestibular apparatus willbe reflected in the psyche structures. They will not only influence the tone, the vegetative system, and the attitudes of the body, but they must also change our whole perceptive apparatus and even our consciousness. (Feldenkraise p88 ) Schilder 1951 Brain and Personality He stressed the importance of muscle tone and its role in the postural model of the body and in psychic and motor development With reduced muscle tone the body scheme and motor development develop less then optimally. (Ayres p 68) The body scheme which provides the substrate for praxis is a product of intersensory integration. The postural model of the body is not the sum of optic, kinesthetic and tactile sensations. It is an integration (Ayres 165)