Showing papers by "Pavel M. Balaban published in 2014"

Nitric oxide is necessary for labilization of a consolidated context memory during reconsolidation in terrestrial snails.

Abstract: Nitric oxide (NO) is known to be involved in associative memory formation. We investigated the influence of blocking NO function on the reconsolidation of context memory in terrestrial snails (Helix lucorum L.). After a 10 day session of electric shocks in one context only, context memory in snails was observed in test sessions as the significant difference of amplitudes of withdrawal responses to tactile stimuli in two different contexts. After a 1 day rest, a session of 'reminding' was performed, preceded by injection in different groups of the snails with either vehicle or combination of the protein synthesis blocker anisomycin (ANI) with one of the following drugs: the NO scavenger carboxy-PTIO, the NO-synthase inhibitors N-omega-nitro-L-arginin, nitroindazole and NG-nitro-L-arginine methyl ester hydrochloride, or the NO donor S-nitroso-N-acetyl-DL-penicillamine. Testing the context memory at different time intervals after the reminder under ANI injection showed that the context memory was impaired at 24 h and later, whereas the reminder under combined injection of ANI and each of the NO-synthase inhibitors used or the NO scavenger showed no impairment of long-term context memory. Injection of the NO donor S-nitroso-N-acetyl-DL-penicillamine with or without reminder had no effect on context memory. The results obtained demonstrated that NO is necessary for labilization of a consolidated context memory.

Compartmentalization of Non-Synaptic Plasticity in Neurons at the Subcellular Level

Abstract: One efficient by which the nervous system responds to a diversity of external and internal signals consists of increases in the excitability of individual neurons acquired, for example, during the learning process. It is now well established that persistent non-synaptic neuronal plasticity arises after learning and, like synaptic plasticity, can serve as a substrate for long-term memory. However, it remains unknown how nonsynaptic plasticity contributes to changes in the state of the neural networks on which memory is directly dependent. Attempts to find an explanation of how non-synaptic plasticity is translated into a modified state of the neural network and altered behavior constitute one of the most important tasks in contemporary studies of learning and memory. There is also little information on the specific neuronal compartments undergoing plastic changes in the context of the morphological characteristics of a given neuron and the mechanisms regulating the efficiency of its input and output synapses when non-synaptic changes occur in cells. The present review addresses the most important questions of compartmentalization of nonsynaptic plasticity and the effects of non-synaptic plastic changes on the efficiency of the synapses of the neuron concerned.

Changes in Intracellular Calcium Ion Concentrations during Generation of High-Amplitude EPSP in Neurons in the Common Snail

Abstract: Changes in intracellular calcium ion concentrations are the main trigger for most physiological processes in neurons, including changes in gene expression and the processes of synaptic plasticity. Our experiments showed that high-amplitude EPSP in common snail command neurons, like action potentials, are accompanied by marked increases in intracellular calcium ion concentrations. The amplitude of calcium signals accompanying high-amplitude EPSP in command neurons was found to depend linearly on the strength of synaptic stimulation, while the dynamics of changes in the amplitude of EPSP themselves showed marked saturation as stimulus strength increased. This means that over a certain range of changes of membrane potential, calcium signals transmit stimulus strength more adequately than the level of depolarization of the postsynaptic neuron. We suggest that calcium signals evoked by high-amplitude EPSP can induce biochemical changes in neurons, thus mediating cellular responses in the range subthreshold for action potentials.

Mismatch negativity and its hemodynamic equivalent (based on fMRI) in research of speech perception in healthy and in speech disorders

Abstract: The review is devoted to the use of electrophysiological index of auditory discrimination, known as "mismatch negativity" (MMN), and its hemodynamic equivalent obtained by functional magnetic resonamce imaging (fMRI) to study speech perception in normal and pathological conditions. Most attention is paid to works with using MMN as a neurophysiological index of the phonemic hearing impairment in patients with sensory aphasia. The MMN applicability for examination of speech compensation degree is substantiated. Also the perspectives of simultaneous EEG-fMRI registration in exploring speech pathologe are considered.