The effect of conditioned stimuli signalling food upon the autochthonous instrumental responses in dogs.

Food CSs, presented (i) concomitantly with SD controlling bar pressing for food, or (ii) on the background of non-discriminated bar pressing (FR 1/15), suppress instrumental performance but elicit undiminished conditioned salivation. This result supports Soltysik-Konorski's model of CNS mechanism controlling food-oriented behavior which postulates drive inhibition by taste-consummatory neurons.

Visual discrimination learning in cats with different early visual experiences.

Simultaneous object discrimination learning in an alimentary situation was strongly impaired in cats deprived from birth of patterned visual experience. The same impairment was observed in cats with experience limited to those objects that were used later in the discrimination task. Some impairment was also present in cats which were reared with opened eyes in the laboratory as compared with normal cats, that spent the early period of life outside of the laboratory. It is concluded that the deprived cats were impaired mainly because of the lack of opportunity during early development to use visual cues in alimentary tasks.

Classical and instrumental conditioning: the general laws of connections between "centers".

This is a synopsis of the author's concept of the physiological mechanisms of classical and instrumental conditioning. In the classical conditioned reflex the connection is established between the central representations of the conditioned and unconditioned stimuli while in the instrumental reflex it is established between the representation of the former stimulus and the kinesthetic representation of the instrumental response. Drives play an important role in both types of conditioning by providing aroma1 in the corresponding neural centers.

The effect of dissection of corpus callosum on differentiation of instrumental reflexes to symmetrical tactile stimuli in dogs.

In normal dogs a differentiation task consisting of lifting the left or right foreleg in response to the tactile stimuli administered to the left or right side of the body respectively is very difficult, requiring from 500 to 1,000 trials. On the contrary the same task presented to other dogs after transection of the corpus callosum is mastered immediately after the animals have learned to perform the instrumental movements. These results are explained as being due to the role played by callosal connections in the transfer of the afferent information from one side of the body to the other side.

Analysis of perception of complex visual stimulus-patterns.

This paper deals with the analysis of visual perceptions of complex patterns consisting of two simple patterns placed one above the other in one frame (united pattern) or in two separate frames each (divided pattern). The upper pattern consisted of a configuration of lines, the lower one of a configuration of dots. There were one positive pattern which a subject had to recognize in tachistoscopic exposure and a number of negative patterns which a subject had to reject. When the dot component of the positive pattern consisted of two dots situated near its left edge, the subjects committed a great number of errors in recognition of the positive pattern and also the negative patterns with dot-negative components. Errors in recognition of negative patterns with line-negative components were much less numerous. Generally less errors were committed with divided patterns than with united patterns. When in the dot component of the positive pattern the distance between the dots was increased and they were placed symmetrically, the number of errors in recognition of this pattern decreased considerably; errors made in rejecting the negative patterns were, however, the same as in the previous test. Contrary to the previous test, errors with united patterns were less numerous than with divided patterns. The data obtained are discussed with reference to the concept of lateral inhibition between components of the complex unknown patterns. It is postulated that this inhibition can be partially overcome if the components of the complex pattern are easy integrated as is the case with symmetric united patterns.

The effects of the removal of the somatosensory areas I and II on left leg-right leg differentiation to tactile stimuli in dogs.

Dogs were trained to lift the right forelegs to a rhythmic tactile stimulus applied to the right side of the trunk, and to lift the left forelegs to a tactile stimulus applied to the left side of the trunk. After training was completed various ablations of sensory I area and sensory II area were made. It was found that the task was impaired after unilateral or bilateral SII lesions, but was virtually preserved after SI lesions.

The effects of cerebellar lesions upon skilled movements and instrumental conditioned reflexes.

Eight cats were trained in reaching for food with their forelegs in cylinders 19-21.6 cm long of various diameters (3.9-10.1 cm). When the pre-operative training was completed, in six cats the interposite and dentate intracerebellar nuclei were destroyed, whereas in two cats the paravermal cortex was ablated. Interposite animals displayed big oscillatory movements around the entrance to the cylinder and overshooting in reaching for food with occasional forced grasping. Paravermal cats displayed overflexion leading to missing the entrance of the cylinder and wild batting movements observed in the large cylinder. The physiological mechanism of these disorders is discussed.

Some hypotheses concerning the functional organization of prefrontal cortex.

The paper deals with systematization of the behavioral disorders after partial prefrontal lesions. It is assumed that depending on the localization of lesions two disorders may be discerned: impairment of drive inhibition (meaning by this only preservative but not protective drives) land of motor-act inhibition. The first deficit leads to the disinhibition of no-go responses in Pavlovian differentiation, the second one to the disorder of R1-R2 differentiation due to the difficulty of switching from one response to the other. Different parts of the prefrontal cortex are engaged in directional response and nondirectional response differentiation. It is posltulated that drive inhibition depends on the limbo-prefrontal system, whereas motor-act inhibition depends on the premotor-prefrontal system for manipulatory responses and the caudate-prefrontal system for locomotor responses.

Purkinje cells in the cerebellum: their responses to postural stimuli in cats.

The responses of Purkinje cells in the cerebellum produced by various positions of the limbs were studied in decerebrated unanesthetized cats. The majority of units located in the intermediate zone of the anterior lobe selectively reacted to definite postures of the limbs: some of them were active when a given limb was in an extended position and were silent when it was in flexion; the other ones, on the contrary, were active when the limb was flexed and silent when it was extended. The rate of discharges was in both cases the same and amounted to 40 to 80 per second. It did not change with the lapse of time, and remained the same when flaxedil was administered. These results, in connection with some other data, seem to explain the problem of how the cerebellum transforms the information about the tensions of tendons and muscles, delivered by the tendon organs and muscle spindles, respectively, into the information about movements.