The regulatory effect of the functional status of the cat on the perception of an external afferent stimulus]

Experiments were conducted on cats by conditioned food-procuring method. Behavioural, vegetative reactions and a set of electrophysiological characteristics were recorded. It was found that regulatory influence of an extraneous stimulus and of artificial excitation of the brain was expressed in an increase of reactivity to conditioned and unconditioned sensory stimuli and in disinhibition of effector responses. This influence was realized not only during the development of EEG activation reaction but could be preserved over a long period in conditions of the deactivated brain state. Regulatory influence of interceptive factors is characterized by a decrease of reactivity and by inhibition of effector responses. As in the case of external effects, the realization of this influence begins with a period of brain activation and is preserved for a long time in conditions of deactivated state.     

Cellular reactions to elaboration of a backward conditioned connection in Helix lucorum

After 10-15 food stimuli paired with electrical shock in semi-intact snail preparation, responses to strong tactile stimuli identified feeding behaviour neurones were studied. Inhibition evoked by tactile stimulation in these cells before learning procedure disappeared and in some cases noxious stimulus evoked synaptic activation corresponding to feeding reactions in the intact animal. Changes in second-order sensory neurones pre-synaptic to the command neurones of avoidance behaviour are suggested to be the mechanism of forward conditioned connection as well as the mechanism of backward conditioned connection.     

Self-deprivation of paradoxical sleep in cats

The phenomenon of paradoxical sleep (PS) self-deprivation has been detected and described. The self-deprivation is acquired just as a classical conditioned reflex during enforced PS deprivation both by water tank procedure and by the animal's awakenings in response to sensory stimuli or direct electric stimulation of activating structures of the midbrain and diencephalon, following the transition of slow-wave sleep to PS. In this situation the transition of the brain from one physiological state to another is a conditioned signal, and sensory stimulation or brain stimulation, resulting in arousal reaction, serves as an unconditioned stimulus. It is suggested that the detection and analysis of PS self-deprivation are of a great importance, on the one hand, for correct understanding of the functional significance of this physiological brain state, and, on the other hand, for accurate analysis and assessment of the dissociative processes, observed during PS deprivation and postdeprivation period.     

Forming of the visual cognitive structures in the monkey conditioned-reflex behaviour: the dependence on the sensory information

In monkeys, changes in size and shape of figures led to a significant decrease of correct solutions in training and a considerable increase of refusals from solution of tasks as well as the time of their motor response. The invariance of differentiation in this case was achieved after additional training. The data obtained show that, based on the stimulus sensory processing in conditioned-reflex training, in the long-term memory some differentiating signs are formed: the cognitive structures (the functional neurophysiological mechanisms) maintaining the classification of visual images. With these structures, temporary conditioned connection will be established. Their formation will be determined by the type of sensory information and provided for by existence in the long-term memory of separate subsystems for spatial as well as non-spatial information.     

Effect of the preparation baliz-2 on the integrative brain activity and biogenic amine metabolism in rats under stress

Effects of balis-2 on exploratory activity in the open field and elevated plus-maze, attention to sensory stimuli of different modalities, elaboration and retention of conditioned reflexes with food reinforcement, were studied in rats under stress. Prolonged treatment of rats with balis-2 seems to normalise integrative activity and metabolism of serotonine and dopamine in the animal brain.     

Ultrastructural investigation of the nuchal organs ofPygospio elegans (Polychaeta). I. Larval nuchal organs

The structural differentiation of the nuchal organs during the post-embryonic development ofPygospio elegans is described. The sensory organs are composed of two cell types: ciliated cells and bipolar primary sensory cells, constituting the nuchal ganglion, which is associated with both the sensory epithelium and the brain. Since the sensory neurons are largely integrated into posterolateral parts of the cerebral ganglion, the nuchal organs are primary presegmental structures. The microvilli of the ciliated cells form a cover over the cuticle with a presumed protective function. An extracellular space extends between cuticle and sensory epithelium. The distal dendrites of the sensory cells terminate in sensory bulbs, bearing one modified sensory cilium each that projects into the olfactory chamber, embedded within the secretion of the ciliated cells. During development, the nuchal organs increase in size. This is accompanied by a shift in position, an expansion of the sensory area, and secretory activity of the ciliated cells. The nuchal ganglion differentiates into three nuchal centres forming three distinct sensory areas around the ciliated region. Each nuchal complex reveals two short nuchal nerves comprising the sensory axons, which enter the posterior circumesophageal connective. The sensory cells lying in the brain exhibit neurosecretory activity; the sensory cilia enlarge their surface area by dilating and branching. Nuchal organs accomplish the basic structural adaptions of chemoreceptors and show structural analogies to arthropod olfactory sensilla; thus, there is every reason to suppose chemoreceptor function.     

Morphological and electrophysiological examination of olfactory sensory neurons during the early developmental prolarval stage of the sea lamprey Petromyzon marinus L

This study examined olfactory sensory neuron morphology and physiological responsiveness in newly hatched sea lamprey, Petromyzon marinus L. These prolarvae hatch shortly after neural tube formation, and stay within nests for approximately 18 days, before moving downstream to silty areas where they burrow, feed and pass to the larval stage. To explore the possibility that the olfactory system is functioning during this prolarval stage, morphological and physiological development of olfactory sensory neurons was examined. The nasal cavity contained an olfactory epithelium with ciliated olfactory sensory neurons. Axons formed aggregates in the basal portion of the olfactory epithelium and spanned the narrow distance between the olfactory epithelium and the brain. The presence of asymmetric synapses with agranular vesicles within fibers in the brain, adjacent to the olfactory epithelium suggests that there was synaptic connectivity between olfactory sensory axons and the brain. Neural recordings from the surface of the olfactory epithelium showed responses following the application of L-arginine, taurocholic acid, petromyzonol sulfate (a lamprey migratory pheromone), and water conditioned by conspecifics. These results suggest that lampreys may respond to olfactory sensory input during the prolarval stage.     

History of the mainstream scientific research at the Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences

The classical reflex theory of the higher nervous activity has been developed in the works of E.A. Asratyan, the first director of the Institute, and his scientific school. The novel aspects of the theory have been developed: the principle of system organization; the concept of the nervous center as a set of structures located in different areas of the central nervous system; conditioned switchover, the mechanism of conditioned connection closure; the origin and localization of conditioned inhibition; the two-way, forward and backward conditioned connections. The elaboration of physiological mechanisms of the active goal-directed motivated behavior was begun. V.S. Rusinov and his collaborates have developed the concept of the dominanta and role of the stationary excitation foci in the integrative brain activity. M.N. Livanov has created the concept of the spatio-temporal organization of bioelectric potential and systemic organization of brain activity. P.V. Simonov, beginning from 1964, has developed the need-informational theory of the human and animal higher nervous activity (behavior). As distinct from the theories that originate from a single viewpoint and reject all the others, Simonov's theory is integrative and follows the logic of development of brain science.     

Significance of the relative position in space of associated stimuli for formation and performance of motor conditioned reflexes

In experiments on cats the rate of formation of conditioned reflexes to sound (running to the feeding trough) depended on the spatial interrelations of the paired stimuli: the closer the source of the conditioned signal to the feeding trough, the sooner the formation of the conditioned reflex. It has been assumed that during formation of a conditioned reflex the closing of connection between conditioned and unconditioned stimuli is also attended with the closing of connection between the spatial parameters of the paired stimuli. Experiments with inactivation through cold of the temporal area (cortical representation of the vestibular system) of one hemisphere have shown that such a connection is formed in central parts of the vestibular analyser. When the conditioned reflex is elaborated to one feeding trough, the connection is duplicated by both hemispheres; in reflexes to two feeding troughs (i.e. spatial choice) such connections are lateralized in each hemisphere.     

Thought in a vat: thinking through Annie Cattrell

This essay reflects on some aspects of the brain in a vat problem through a consideration of the work of the sculptor Annie Cattrell. Cattrell’s series of sculptures ‘Sense’ render in three dimensions MRI scans of different sensory functions in the human brain. These objects—which could be said to represent thought itself stilled and suspended in a transparent medium—make dramatically visible the doctrine of the localization of brain function. The essay argues that the brain in a vat problem in philosophy is an outcome of the same neural ‘mapping’ project as made Cattrell’s ‘thought in a vat’ possible. An interview with the artist reveals a moral dimension to her preoccupation with the localization of function. The article therefore goes on to consider the brain in a vat in the context of some of the history and ethics of the localizationist paradigm.     

The regulatory effect of dipeptides on cell proliferation in mammalian nerve tissue culture and olfactory associative learning in insects

The study addresses the effects of dipeptides AspPro and AspSer and their constituent amino acids (aspartic acid—Asp, proline—Pro, and serine—Ser) on proliferative activity of rat brain cortical and subcortical tissue explants and functional activity of the honeybee central nervous system. The area index was calculated as a ratio of the total explant area to the area of its central zone. The number of bees which exhibited a conditioned response, namely proboscis extension towards the odorized solution, 1 min (short-term memory) and 180 min (long-term memory) after single trial learning was also measured. Both dipeptides, as well as aspartate itself, stimulated the expansion of the growth zone of rat subcortical tissue explants and increased the number of bees that retained in their short-term/long-term memory the acquired conditioned response, regardless of the effect of the second component of the dipeptide. The similarity of these effects suggests that common mechanisms of reception and signal transduction have evolved in insects and mammals, and this requires further study.     

Regulation of the total functional state of the brain in dogs in the presence of the 1st and repeated increases in total illumination

The influence of the first and repeated increases of total illumination of the experimental chamber on conditioned activity was studied in chronic experiments on six dogs by the secretory alimentary conditioned reflex method. It was found that such repeated functional loads exert a training effect on the mechanism regulating the general functional state of the brain. In preliminarily trained animals different components of the conditioned reflex are rapidly and synchronously reorganized. In non-trained animals the reorganization of the brain general functional state was prolonged and accompanied by development of a pronounced emotional stress. It has been assumed that training of the functions controlling the general functional state of the brain is based on conditioned mechanisms. An important part is played by the mechanism of conditioned inhibition, which prevents a prolonged retention and reproduction of an excessively intensive level of emotional stress.     

Interhemispheric olfactory circuit and the memory beyond

In mammals, olfactory sensory neurons project their axons exclusively to the ipsilateral olfactory bulb. It remains unclear how odor information interacts between the two hemispheres of the brain. In this issue of Neuron, Yan et al. describe the precise interbulbar connection through the anterior olfactory nucleus pars externa (AONpE), which links contralateral isotypic olfactory columns.     

Morphology and Nanomechanics of Sensory Neurons Growth Cones following Peripheral Nerve Injury

A prior peripheral nerve injury in vivo, promotes a rapid elongated mode of sensory neurons neurite regrowth in vitro. This in vitro model of conditioned axotomy allows analysis of the cellular and molecular mechanisms leading to an improved neurite re-growth. Our differential interference contrast microscopy and immunocytochemistry results show that conditioned axotomy, induced by sciatic nerve injury, did not increase somatic size of adult lumbar sensory neurons from mice dorsal root ganglia sensory neurons but promoted the appearance of larger neurites and growth cones. Using atomic force microscopy on live neurons, we investigated whether membrane mechanical properties of growth cones of axotomized neurons were modified following sciatic nerve injury. Our data revealed that neurons having a regenerative growth were characterized by softer growth cones, compared to control neurons. The increase of the growth cone membrane elasticity suggests a modification in the ratio and the inner framework of the main structural proteins.     

Exploring bis-(indolyl)methane moiety as an alternative and innovative CAP group in the design of histone deacetylase (HDAC) inhibitors

In order to gather further knowledge about the structural requirements on histone deacetylase inhibitors (HDACi), starting from the schematic model of the common pharmacophore that characterizes this class of molecules (surface recognition CAP group—connection unit—linker region—Zinc Binding Group), we designed and synthesized a series of hydroxamic acids containing a bis-(indolyl)methane moiety. HDAC inhibition profile and antiproliferative activity were evaluated.     

Artificial feedback for invasive brain–computer interfaces

During the last two decades, considerable progress has been made in the studies of brain–computer interfaces (BCIs)—devices in which motor signals from the brain are registered by multi-electrode arrays and transformed into commands for artificial actuators such as cursors and robotic devices. This review is focused on one problem. Voluntary motor control is based on neurophysiological processes, which strongly depend on the afferent innervation of skin, muscles, and joints. Thus, invasive BCI has to be based on a bidirectional system in which motor control signals are registered by multichannel microelectrodes implanted in motor areas, whereas tactile, proprioceptive, and other useful signals are transported back to the brain through spatiotemporal patterns of intracortical microstimulation (ICMS) delivered to sensory areas. In general, the studies of invasive BCIs have advanced in several directions. The progress of BCIs with artificial sensory feedback will not only help patients, but will also expand base knowledge in the field of human cortical functions.     

Analysis of the influence of Piyavit®—a biologically active compound of natural origin—on conditioned memory,on neuron-glia interactions of hippocampus,and on neocortex of rat brain

Mnemotropic effect of Piyavit®-a biologically active compound of natural origin—was studied on conditioned avoidance in rats. Morphological changes in neocortex and hippocampus (neuron-glia complex and brain capillaries) were significant and oppositely oriented. We assume that the improvement of rats’ memory under the Piyavitis associated with metabolic changes in the nervous tissues.     

Plasticity of neuroendocrine transducers under the combined influence of the radiation and light exposure

The structural changes of neurons of the rat hypothalamic supraoptic (SON) and of paraventricular (PVN) nucleus after 48 h of bright light exposure, of 5 Gy whole-body X-irradiation and of their combination subjected to the analysis by means of light-optic and of electron microscopy for the estimation of radimodificated effect of light exposure lasted 24 h a day and plasticity of neuroendocrine transducers interacted with the optic sensory system. The structural changes of neurons of the SON after combined action are less considerable and more prolonged in comparison with the PVN that loas defermined by their direct connection with the optic sensory system via the retinohypothalamic tract.     

The possibility of elaborating conditioned reflexes on the basis of emotional reactions evoked by electrical stimulation of limbic structures]

In experiments on cats with chronically implanted electrodes a conditioned stimulus (200 c/s tone) was paired with electrical stimulation of limbic structures, which produces pronounced emotional behaviour: defensive, aggressive, alimentary or drinking reactions. It has been shown that conditioned reactions are not elaborated on the basis of electrical stimulation, which activates alimentary, drinking or aggressive behaviour. Neither is a conditioned reflex formed to the combination of sound and stimulation of the brain structures, which inhibits alimentary behaviour. A distinct conditioned fear reaction sets in as a result of combination of sound and electrical stimulation of brain structures, which evoke defensive behaviour. The data obtained are analyzed in the light of the significance of natural requirements of the organism for the elaboration of conditioned reflexes.     

A contribution to the nomenclature of peripheral sensory structures (sensory nerve endings)

The author has shown the variety in denominating peripheral sensory structures serving for mechanoreception, nociception, thermoreception and chemoreception. To term peripheral sensory structures as nerve endings is considered particularly unsuitable because this denomination is based only on morphogenesis of the ending. From the view of system approach, the peripheral sensory structures forms one unit formed by two or more structural subsystems. Even though the axon or its dendritic zone has the leading role in this unit, the function of the whole formation is influenced (modulated) by further non-nervous components. Although the causes of velocity of adaptation in some sensory structures have been already explained (e.g. in lamellar corpuscles with a thick capsule), different adaptation velocity of Merkel complexes in reptiles and birds on one side, and in mammals on the other, with the same structure has not been clear up to now. From the view of system approach as well as of the share of non-nervous components in the activity of the whole sensory structure, the author has suggested to introduce the term "sensory nerve formation" for peripheral sensory structures serving for mechanoreception, nociception, thermoreception and chemoreception. The term "complex sensory nerve formation" is suggested for more complex sensory structures in which either more sensory nerve formations of the same kind (Pinkus tactile dics) or different kinds of sensory formations (Eimer organ of a mole) are connected constantly or in which the connection of sensory nerve formations with other supporting structures (hairs, feathers) occurs.