Normal Table of Xenopus Laevis

havioral performance, and Konorski proposes that the mental experience depends on the occurrence of particular nervous processes in a similar way as overt behavior is correlated with the activity of specific cerebral structures. In Konorski's words, "In this way, the ultimate goal of brain physiology, consisting in conclusions about the mental experiences of a subject from the electrical activity of his brain, ceases to be mere fantasy and begins to be real possibility." If a psychic experience in man is related to definite evoked potentials in the brain, Konorski assumes that a similar experience may be felt by the animals when the stimulus object produces exactly the same set of electrophysiological responses in the brain. This assumption is difficult to prove-or disprove-because sensory inputs produce such a complex spatio-temporal distribution of electrical patterns that their precise recording and analysis is very difficult to achieve. In the opinion of this reviewer, mental activity depends not only on sensory perception but also on past experience, which cannot be detected at the level of sensory inputs. Neurophysiological techniques may inform us about the material carrier (for example, the image of a pencil transduced into a barrage of spikes in the optic pathways) which may be similar in a man or in a cat, but the symbolic meaning is related to previous experience and cultural values which today are still beyond the reach of the neurophysiologist. In spite of possible disagreements in interpretation, experimentation on perceptions and neurophysiological responses in animals are essential for the investigation of psycho-physical correlations. The first part of the book places great emphasis on classical and instrumental conditioned reflexes, the second part concentrates on physiological mechanisms of perceptions and associations based on psychological and neuropathological data collected in human patients. Altogether this is an exceptional book, lucidly written and well documented, which should have a powerful impact on modern thinking about cerebral mechanisms of behavioral and mental activities in animals and man.