Using eight-channel metal microelectrodes (diameter of a separate channel 12 µm), we extracellularly recorded the impulse activity of 186 single neurons or their small groups (usually, pairs) localized in the motor cortex of rats anesthetized with ketamine. In 60 cases (32.3%), action potentials (APs) of two single neurons were generated in a parallel manner and demonstrated fixed time relations with each other. This is interpreted as being a result of excitation of two neighboring functionally connected (coupled) cells. These AP pairs could be recorded via one and the same or two neighboring microelectrode channels. Second APs in the pair were elicited exclusively in the case where an AP was preliminarily generated by another neuron, while APs of the latter in some cases could arrive independently. Therefore, "leading" and "accompanying" cells could be identified in such neuronal pairs. The coupling coefficient in the generation of APs by an accompanying unit with respect to APs generated by a leading cell was close to 100%, with no dependence on the discharge frequency in the latter. Intervals between APs of two neurons in different coupled pairs varied from about 1.0 to 22-23 msec. In the case of minimum values of these interspike intervals, APs generated by coupled neurons overlapped each other; this resulted in the formation of spikes looking like "complex APs." Within some time intervals, interspike intervals could increase, and such APs began to be decomposed. The above-described data are considered electrophysiological proof of the existence of tight functional coupling between a significant part of cortical neurons spatially close to each other, i.e., members of a micropopulation, which was obtained in an in vivo experiment.

The organization of walking and its disorders remain one of the most difficult sections of the physiology of the nervous system and neurology. The purpose of the work is to analyze the sexual features of the spatio-temporal parameters of the person walking and the directions of their changes in the conditions of performing additional cognitive tasks. Sex-related features of human walking with cognitive tasks are investigated. 608 individuals of both sexes aged 12-43 years were examined by GAITRite®. Consistent naming of animals and consistent subtraction of 7 starting at 100 were used as cognitive tasks. Statistical processing of the obtained results was performed in the license package “STATISTICA 5.5” using parametric estimation methods. At performing the first (simpler) cognitive task in all age groups of men step length, stride length, step extremity ratio, support base, toe-in-out were increased. Temporal parameters in adolescents of both genders did not differ. Girls have longer step time, cycle time, single support, swing time and a slower velocity. The integral index of walking quality (FAP) tended to decrease in all examined groups: in adolescent males by 13.3±3.9 %; in young men by 14.6±2.2 %; in adolescent women by 15.3±1.8 %; in young women by 14.4±1.1 %; in middle-aged women 7.3±4.8 %. Boys and girls performed more complex cognitive tasks with reduced spatial and temporal parameters (primarily by increasing the double support and swing time), the support base and toe-in-out were stable. The step cycle was rebuilt. The support base and toe-in-out remained unchanged both in boys and girls. The boys were moving at a faster velocity, taking more steps per minute. The step time right, cycle time for each leg, single support time and double support time in girls lasted much longer. FAP declined sharply by 30.4 % in boys and by 33.4 % in girls, indicating a major reorganization of basic mechanisms for regulating walking stability. Such a decrease in FAP leads to a decrease in the level of the balance maintaining and a decrease in body stability during movement, which means that it increases the risk of falls. A complex cognitive task led to a decrease in walking performance and a more critical decrease in the quality of walking in favor of moving forward and maintaining the balance. Thus, walking is not an automated process, but requires the use of a variety of additional CNS resources, primarily attention and cognitive resources.

Human walking is considered as a complex cognitive act. The research purpose is an analysis of age-related features of spatio-temporal parameters of human walking and directions of their changes at walking with dual (cognitive) tasks. The walking spatio-temporal indexes were studied in 608 individuals of both sexes aged 12-43 years by GAITRite® (CIR Systems Inc.,Clifton, NJ) under normal walking at individually comfortable velocity and under additional cognitive tasks: 1) sequentially pronounce aloud any known animals; 2) starting from a number 100, subtract 7 and pronounce the result aloud. The statistical processing of the got results was carried out in the licensed software “STATISTICA 5.5”. At performing the first, simpler, task, the spatial parameters had no significant changes in all age groups. Most of the temporal parameters changed: cycle time, swing time, single support time, and double support time increased. Therefore, equilibrium maintaining at walking with naming animals is realized with a longer overall support period, reducing the walking cadence and velocity. The constant width of the support base and the angle of the feet turn indicate that the magnitudes of the functional support base and angle of the feet turn at normal walking is sufficient to maintain posture and balance at walking with simultaneous performance of the cognitive task, as well as more rigid mechanisms of regulation of these two parameters. The walking temporal parameters are more labile than spatial parameters. With age, the percentage of the integral index of walking quality (FAP) decreases especially in females: in girls by 15.3 %, in young women by 14.4 %, in middle-aged women by 7.4 %. At performing the second, more complex, arithmetic task, in young men and young girls support base, toe-in-out, step length difference had no significant changes only. The mean velocity, cadence, step length, stride length, step extremity ratio decreased. The count of steps, all temporal parameters, and stance percentage increased. FAP declined critically by 30.4 % in young men and 33.4 % in young women, indicating a decrease in balance and body stability under walking with cognitive task and increasing the risk of falls. Therefore, a significant reduction in FAP can be used as a diagnostic criterion in neurological practice.

Technologies for multichannel electrophysiology are experiencing astounding growth. Numbers of channels reach thousands of recording sites, systems are often combined with electrostimulations and optic stimulations. However, the task of design the cheap, flexible system for freely behaving animals without tethered cable are not solved completely. We propose the system for multichannel electrophysiology for both rats and mice. The system allows to record unit activity and local field potential (LFP) up to 32 channels with different types of electrodes. The system was constructed using Intan technologies RHD 2132 chip. Data acquisition and recordings take place on the DAQ-card, which is placed as a back-pack on the animal. The signal is amplified with amplifier cascade and digitalized with 16-bit ADC. Instrumental filters allow to filter the signal in 0.1–20000 Hz bandwidth. The system is powered from the mini-battery with capacity 340 mA/hr. The system was validated with generated signals, in anaesthetized rat and showed a high quality of recordings.

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