Pavlov's conceptualization of unconditional reflexes, or instincts, within the framework of the theory of higher nervous activity

According to I. P. Pavlov's theory of higher nervous activity, the establishment and dissolution of conditional reflexes enhances the higher organism's adaptation to the external environment. Pavlov asserted that, ontogenetically, conditional reflexes are based upon innate, unconditional reflexes (UR) or instincts. Pavlov did not distinguish between URs and instincts, but he preferred the former term. Phylogenetically the URs emerged out of well-established conditional reflexes during the development of higher organisms. An outgrowth of the experimental conditioning procedure, developed during the second decade of this century, was the observation and delineation of new URs. While studying human nervous and psychiatric disorders in the 1930s, Pavlov elucidated other URs. Pavlov identified 13 major URs, but he failed to formulate an exhaustive classification scheme of URs.     

From physiological theory to psychological facts (on the centenary of I. P. Pavlov's speech in Madrid)

Pavlovian theory of conditioned reflexes and Ukhtomsky's theory of dominanta are considered as the most important biological concepts of the XX century. They have laid the foundation of the modern views of the adaptive and active character of the nervous activity underlying the integral behavior in the environment. Approach to a burning problem of neurophysiological mechanisms of goaldirected behavior is impossible without a comprehensive study of works of both these schools. They have formed not only the methodological basis of modern investigations but opened a new avenue of attack.     

The contribution of Academician L. A. Orbeli to the theory of higher nervous activity]

In the paper are discussed the main directions of the investigation of the higher nervous activity, fruitfully developed by academician L. A. Orbeli and his school. These directions are the following: the evolutionary approach, the study of the influence of the sympathetic nervous and endocrine systems, of the role of the extracortical brain structures, especially the hypothalamus and the cerebellum, and the significance of pain and efferent systems for the higher nervous activity.     

Studies of higher nervous activity in functional phychoses.

Psychiatric illnesses can be conceived of as experiments of nature, providing a variety of pathopsychological mechanisms which may elucidate normal psychological processes. Clinically the reactive psychoses are predominantly psychogenic reaction types. They present disturbances of higher nervous activity, similar to those of the neuroses. The unconditional reflex activity is practically as in normal controls, and the most outstanding finding was the large effect of psychodynamic complex structures. This is a physiological parallel to the clinical manifestations with great concern over experienced mental trauma. In the manic-depressive psychoses the most characteristic feature is a marked disturbance of unconditional reflex activity. This factor may be an important physiological mechanism underlying the more biological than psychodynamic reaction type and partly explain the changes of mood and associated interferences with sleep, body weight, sexual activity, aggression and other instinctual and vegetative functions. Schizophrenic psychoses also present changes of unconditional reflex activity, predominantly in the direction of inhibition of response. In addition there are severe dissociations within and between the three levels of unconditional reflexes and the two signaling systems. It is suggested that schizophrenia represents a functional maladaptation, which can be explained from the principles of autokinesis and schizokinesis established by Gantt in animal experiments. Prognostic models based on experimentally established impairment of performances were shown to predict long-term risks of schizophrenic defects just as well as models based on constellations of clinical symptoms. I would predict that psychophysiology and experimental psychology will become increasingly more important for establishing diagnosis and prognosis in the functional psychoses. The data of this article point toward a basis for a prophylactic psychiatry.