Conditioned reflexes L.P. PavlovIn men, the highest nervous activity is dependent upon the structural and functional integrity of the cerebral hemispheres. As soon as these parts get damaged and their functions stop from normal behaviour, the man becomes an invalid. The brain is and has been the most challenging part of the human body to be studied. Technology centuries back didnt help the studies to be performed on human brain and behaviour, and the brain had become the domain of psychology, when according to Pavlov, should be the preserve of psysiologists who could determine the facts about the brains physics and chemistry.Three centuries before Pavlov, Descartes thought that the actions of our bodies and those of animals can be understood purely in terms of physical cause and effect. He suggested that stimuli are capable of setting up vibrations in organs. From there, the vibrations is imagined to run through the nerves connecting the sensory organs to the brain and allowing cerebral-spinal fluid to drain down the hollow tubes of nerves running to the muscles. As the fluid entered the muscles , the muscles fattened up and shortened , thus producing movement in the limbs or other structures to which the muscles were attached. This theory is today proved to be wrong but centuries after that, starting from Descartess results on reflex reactions, Pavlov wanted to investigate the creation of saliva and the action of the digestive glands in dogs. Pavlov decided to try a range of stimuli on the dog to see whats the reason that provoks the saliva secretion. Among the stimuli, we can enumerate buzzers, bells, crackling sounds, showing a black square, heat, touching the dog or flashes of a lamp. All these stimuli occurred exactly before the dog receive food thing that made the dog start to salivate even before the hadnt appeared, because for the dog the bell ring or other stimuls started to mean food. The reflexes and responses were then classified into unconditioned reflexes, the ones produces by the body itself, and the conditioned or aquired reflexes, which arose through unconscious learning. Pavlov could also notice some limits in the creation of these conditioned reflexes, as the dog sometimes wouldnt bother to respond and rather fell asleep, concluding that the cerebral cortex cant be overworked or changed too much but must be kept a certain amount of stability in the brain wiring.Some of Pavlovs experiments included the extirpation of the cerebral cortex. The observations were that the unconditionated reflexes were still present, but the dog wasnt now able to respond to his environment he could walk but he wouldnt know what to do if along his path an obstacle would have appeared. In contrast, with a normal dog if there was a change in its environmental stimulus, or anything new, a investigatory reflex would make the animal prick up his ears. But the investigation applied to dogs wont respond to a generalisation of the stimuls and the brain reactions. The more advanced the organism, the greater its ability to multiply the complexity of its contacts with the external world and to achieve a more and more varied and exact adaptation to external conditions. While dogs developed social and territorial knowledge as an optimal response to the environment, humans created civilizations.In applying to man the results of the investigations in the higher animals, even if organs are allied as the humans in structure, great reserve needs to be exercised and the validity of comparisons has beed verified at every step. Pavlov finds obvious that different kinds of habits based on training, education and discipline of any sort are nothing but a long chain of conditioned reflexes. Associations, once established and aquired between stimuli and responses are persistently and automatically reproduced even if sometimes we fight against them. Even if by that time contemporary medicine distinguished nervousand pshychic disturbances , the distinction is only arbitrary. No demarcation line can be drawn between the two, because it is impossible to imagine a deviation of higher activities from normal without a functional or structural disturbance of the cortex. The distinction can only be made, as Pavlov showed its validity, on grounds of greater or smaller complexity and subtlety in the disturbance of the nervous activity. The dog experiments showed that two conditions can produce pathological disturbances by functional interference: an acute clashing of the excitatory and inhibitory processes and the influence of strong stimuli. In man, precisely similar conditions constitute the usual causes of nervous and psychic disturbances. The two variations in the pathological disturbances of the cortical activity excitation and inhibition are comparable to the two forms of neurosis in man neurasthenia and hysteria, the first with exaggeration of the excitatory and weakness of the inhibitory process, the second with a predominance of the inhibitory and weakness of the excitatory process. To eventually return to a state of stability, we have to incorporate what we have experienced. The phenomenon of 'fight or flight' in the face of a challenge is the nervous system's manner of self-protection in the short term. In the longer term, the fact that we have had a reaction ensures that we can eventually return to a state of equilibrium with our environment. The reactions of Pavlovs dogs could not be predicted. Some dogs grew excited, some frightened , some withdrew. The same way, he could not predict how a person would react emotionally to a strong insult or the loss of someone loved. These reactions are mirrored with the two common psychological reactions to shock recongnised and summarized in the above lines. Pavlov saw the cerebral cortex as a complicated switchboard in which groups of cells were responsible for different reflexes. There was always room for more reflexes to be created, but also capacity for existing ones to be altered. His dogs did have an automatic nature to them, but at the same time their reflexes and reactions were changeable. The implication for humans? Although we live for the most part through habit or enculturation, we are in a position to change our behavior patterns. We are as susceptible to conditioning as any animal, yet at the same time we also have the ability to break our own patterns if ultimately they prove not to be in our interest. Via feedback from our environment we learn what are effective responses to life and what are not. He noted that that many of the dogs' reactions werenotpredictable. Even when conditioning had occurred, there was still room for canine personalities to be expressed. Given our much larger cerebral cortexes, appreciate then how much more room for varied expression - or 'responses to environment' we have.The aggregate of reflexes constitutes the foundation of the human nervous activity. It was therefore very important for Pavlov to study in detail all the fundamental reflexes of the organism, since, by that time, unfortunately studies havent been accomplished and reflexes were nothing but instincts. - Conditioned reflexes, I P Pavlov