Motor alimentary conditioned reflexes and delayed reactions in dogs following destruction of the caudate nucleus]

The characteristics of formation and achievement of motor conditioned reactions were studied in seventeen dogs before and after the lesion of head or body of the caudate nucleus. It has been shown that the degree of higher nervous activity disturbances depends on the localization of injuries in the nucleus, and on the complexity of the tests used. The caudate nucleus exerts a modulating effect on the parameters of motor conditioned reflexes and takes a direct part in the structure of delayed reflexes. Lesion of the caudate nucleus body is attended with more serious disturbances of higher nervous activity than lesion of its head.     

An EEG-study of participation by the head of the dog caudate nucleus in alimentary conditioned reflex activity]

It was shown during alimentary conditioning in dogs that in the "background" electrocaudatogram there are rhythms typical of the act of eating, which become more clearly pronounced under the action of the conditioned stimulus. The EEG of the caudate nucleus head sharply changed during discordance reactions. It has been assumed that the caudate nucleus head forms a link in the functional system of the alimentary conditioned reflex at stages of afferent synthesis and functioning of the action acceptor.     

Complex alimentary motor conditioned reflex reactions in cats and dogs]

The ability of animals to perform a complex motor task representing a model of compensatory discrete tracing was investigated in dogs and cats. Elongation of a light spot on an oscilloscope screen into a vertical line served as a signal of motor reaction. The reaction consisted in several movements, each of which reduced the initial signal change by 1/2, 1/3, 1/4 or 1/5 of its value. Alimentary reinforcement was given only after a reduction of the signal to its initial level. Signals with a different number of steps of transition to their initial state were presented at random. It was found that learned animals were capable of a stable behaviour of a compensatory discrete tracing type. A hypothesis has been advanced about a probabilistic participation of visual control in the realization of tracing motor behaviour.     

Role of acetylcholinergic structures of the caudate nucleus in mechanisms of inhibition of a conditioned food-getting reflex in the cat

The effect of acetylcholinergic structures stimulation on the acquisition and inhibition of a conditioned food-procuring reflex was studied in cats. Physostigmine injections (0.1 mg/kg) did not facilitate the extinction of the non-reinforced food-procuring reactions of caudatectomized cats in contrast to the intact or lobectomized ones. The conclusion is made that acetylcholinergic structures of the caudate nucleus play an important role in the central inhibitory mechanisms responsible for the extinction of nonreinforced reactions.     

Effect of electric stimulation of the somatosensory cortex and caudate nucleus on extinctive inhibition of a conditioned alimentary reflex to sound]

In experiments performed on 9 dogs with alimentary method, extinctive inhibition was deepened and its elaboration was aceelerated by electrical stimulation of somatosensory and motor cortical areas and ventral segment of the caudate nucleus head. The extinction of the conditioned reflex was slowed down by stimulation of the anterolateral gyrus and the central segment of the caudate nucleus head. General motor excitation of animals during stimulation of the dorsal zone of caudate nucleus head impaired the elaboration of extinctive inhibition.     

Alimentary conditioned reflex behavior in the rat following injection of 6-hydroxydopamine into the caudate nucleus and nucleus accumbens

In Wistar rats with degenerated dopaminergic terminals of the caudate and accumbens nuclei (administration of 6-hydroxydopamine, 30 mcg, bilaterally), an alimentary conditioned reflex was elaborated in a T-maze. Degeneration of the caudate nucleus terminals disturbed the elaboration, while degeneration of N. accumbens terminals did not affect the learning.     

Spatial organization of the caudate nucleus in dogs

The dog caudate nucleus was studied by the Nissl, Kluver-Barrera, and Golgi methods in the usual planes of section. A complex spatial organization of the caudate nucleus was established. Radial bundles of fibers form fibrous layers through which run blood vessels and in which large neurons (long-axon reticular and large short-axon smooth-dendritic) and also two types of small cells are located. In the mesh of the fibrous layers barrel-shaped concentrations of small (17.5 µm, about 2–4%, small short-axon smooth-dendritic) and medium-sized (25 µm, about 96–98%, long-axon densely branching spinous) cells can be observed. These concentrations have the appearance of two or three layers of elongated "barrels," their axis perpendicular to the surface of the internal capsule. The stria periventricularis of the caudate nucleus and certain others of its regions are less differentiated.     

Neuronal correlates of an alimentary instrumental conditioned reflex in rats

Elaboration of an instrumental reaction of getting the food from a narrow tube with a defnite forepaw (handedness) brings about a distinct re-distribution of cellular activity in the motor cortex and in the caudate nucleus, contralateral to the instrumental paw. The changes were observed at a 250 msec. interval before and 512 msec. interval after the beginning of the movement. Two types of cellular discharge changes were recorded: phasic and tonic. The phasic reactions (both inhibitory and activating) were grouped around the beginning of movement, with an average duration of about 100 msec. The tonic reactions lasted a few hundred milliseconds.     

Transfer of conditioned reflex hypoglycemia in dogs

Conditioned hypoglycemia was induced by intravenous injection of a 20% glucose solution to donor dogs. In control tests the dogs were injected the same volume of 0.9% saline. Then 0.5 ml of cerebrospinal fluid from donor animals was injected into suboccipital cisterna of recipient dogs. 24 hours later the recipient animals were exposed to the conditioned signal and injected physiological saline. It has been demonstrated that hypoglycemic response in recipient and donor dogs was identical, the reactions retained in the recipient dogs for 5-7 days after the liquor administration.