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A A Moskvitin

Publications and source records attributed to A A Moskvitin.

At least 19 recordsLinked to original sources
PubMed2006

Methiothepin-sensitive serotonin receptors are involved in the postsynaptic mechanism of sensitization of the defensive response in the common snail.

Rhythmic electrical stimulation of the snail foot leads to sensitization of the defensive reflex. This sensitization has dynamics similar to those of posttetanic potentiation of the amplitude of the acetylcholine-evoked influx current of defensive behavior command neurons in the common snail. It is likely that an increase in the cholinosensitivity of the somatic membrane of defensive behavior command neurons in the common snail may be involved in the mechanism of sensitization of the animal's defensive response. Methiothepin, an antagonist of serotonin receptors, prevented the posttetanic potentiation of the acetylcholine-evoked influx current as well as behavioral sensitization. Serotonin, like methiothepin, also impaired posttetanic potentiation of the acetylcholine-evoked influx current. It is suggested that methiothepin-sensitive serotonin receptors are involved in the postsynaptic mechanism of behavioral sensitization.

Acetylcholine↗
PubMed2004

An apparatus for recording defensive responses to tactile stimulation in the ground snail.

We describe here an original working experimental apparatus for non-invasive objective recording of the magnitudes of defensive responses to tactile stimulation in the ground snail. The apparatus includes a tracking device that ensures that the snail's position relative to a light and photodiode remains constant as it ascends a cylinder rotating about a horizontal axis. The device providing tactile stimulation is based on a loudspeaker circuit and provides blows of dosed energy. The snail responds to the tactile stimulation by retracting the antennae, head, and foot, which decreases the area of its shadow; this is recorded by a photodiode.

Animals↗
PubMed1988

[The hypothesis of the "efferent copy" in saccade programming in cats].

Horizontal eye movements in cats were recorded using the magnetic search coil method. Saccadic eye movements were linearly approximated. For combined eye and head movements the slope of lines was independent of maximal head velocity within the studied range (up to 250 degree/s). Saccades slowed down with a restrained head. The duration of the gaze shift grew with an increase of its amplitude. The amplitude of gaze was found to depend on the head velocity. Experimental data on the interaction of eye and head movements during the coordinated goal displacements are interpreted from standpoint of the saccadic signal suppression by the "efferent copy" signal for head movements.

Animals↗
PubMed1977

[Sensory input to neurons of the motor area of the biceps in cat cortex].

Correlation between activity of cortical neurons in the biceps motor area and a conditioning movement of the contralateral forelimb was studied in chronic experiments of two male cats. In the group of neurons related to the movement sensory inputs were not found in 68.1% of neurons, in the group not related to the movement in 97.9% of neurons. 24.2% of neurons from the first group had cutaneous receptive fields on the dorsal surface of the distal part of the moving forelimb, in this group 5 neurons had inputs from the forelimb joints.

Animals↗
PubMed1976

[Properties of rhythmic discharge by cat motor cortex neurons evoked by a continuous current through their membranes].

The properties of rhythmic discharge of motor cortex neurons evoked by dc depolarizing current through the membrane were studied in acute experiments on immobilized cats. Linear relation between the rate of rhythmic discharge and the strength of current was revealed, the slope of this relation being 18-10.7 imp/s nA. Correlation between input resistance and the slope of the discharge frequency current curve was demonstrated. Two types of adaptation to current were observed: exponential and undamped oscillations. The relation of the latency of the first spike and first interspike interval to current was hyperbolic. The role of dendrites in the observed phenomena is discussed.

Action Potentials↗
PubMed1975

[Electrical characteristics of neurons in the motor region of the cat cerebral cortex].

Electrical parameters of motor cortex neurons were studied in acute experiments on cats. Input resistance of cortical neurons varied from few to some tens of Momega (mean value 11.11 +/- 3.93 Momega). A hyperbolic relation between threshold current and input resistance for cortical neurons was found. Velocity of axon conduction and input resistance are negatively correlated. Time constant of the membrane (to) was 7.1 +/- 3.46 ms. In some neutrons a second time constant t1= 1.65 +/- 0.36 ms was also found. Using result of Rall's model, the electronic length of the dendrite was computed, it was found to be 3.66-0.94 in units of length constant. These data are compared with those obtained on motoneurons. Functional significance of electrical parameters of cortical neurons is discussed.

Action Potentials↗
PubMedDate not supplied

Effect of 2-amino-5-phosphopentanoic acid (AP5), a glutamate NMDA receptor blocker, on neuron activity in the cat motor cortex during performance of a paw placement conditioned reflex.

Two types of stimulus-associated response were recorded in the contralateral motor cortex during performance of a condition reflex consisting of placing the forepaw on a support in response to a short electrical stimulus (4 msec, 500 Hz) applied to the contralateral parietal cortex (field 5). Primary short-latency responses (peak latent period about 10 msec, duration 30-50 msec) showed little sensitivity to the application of AP5, a blocker of glutamate NMDA receptors; secondary long-latency responses (peak latent period 65 msec, duration 150-200 msec) were inhibited in 44% of cases. Excitatory neuron responses associated with movement were inhibited by AP5 in 18% of cases. Increases in the latent period of the movement itself were seen in 19% of cases. AP5 decreased background activity in 46% of background-active neurons. The number of cases in which individual components of the response and neuron background activity were increased and latent periods of movement were decreased after application of AP5 was no more than expected from a random spread of data.

2-Amino-5-phosphonovalerate↗
PubMedDate not supplied

Long-term potentiation of the late NMDA-dependent components of neuron responses in the cat motor cortex to stimulation of the direct cortical input from field 5 of the parietal cortex.

Bicuculline-filled microelectrodes were used to record responses to weak stimulation of the parietal cortex in field 5 of the motor cortex of anesthetized cats, and revealed late excitatory responses of neurons similar to those seen in the motor cortex of conscious cats in response to conditioned stimulation of the parietal cortex triggering a conditioned reflex consisting of placing the paw on a support. Tetanic stimulation of the parietal cortex (10-20 sec, 100 Hz) in the same conditions evoked long-term potentiation of late responses, resulting in the formation and enhancement of responses, along with decreases in the latent period of responses.

Afferent Pathways↗
PubMedDate not supplied

The facilitatory and depressive effects of iontophoretically applied acetylcholine on different components of neuron responses in the motor cortex of the cat during performance of a conditioned paw positioning reflex.

Iontophoretic application of acetylcholine to neurons in the motor cortex of cats during performance of a conditioned reflex consisting of placing the paw on a support increased neuron excitability and facilitated "extrinsic" connections, resulting in increases in primary responses to electrical stimulation of the parietal region of the cortex, and which was independent of the first effect of suppression, which was seen only in relation to the long-latency components of the response. The functional significance of the differently directed effects of acetylcholine application is indicated by the statistically significant changes in motor reaction times seen in some experiments, which were in the same direction as changes in neuronal responses in the same experiments.

Acetylcholine↗
PubMedDate not supplied

Generalized post-tetanic changes in excitatory postsynaptic and acetylcholine-evoked currents in neurons in the common snail.

Changes in excitatory postsynaptic currents (EPSC) and influx currents induced by local iontophoretic application of acetylcholine (ACh currents) to the surfaces of the bodies of identified neurons LPa3 and RPa3 in the common snail after heteroreceptor tetanic stimulation were studied. The effects of rhythmic application of acetylcholine (0.5-1.0 times per sec for 10-40 sec) on the magnitude of EPSC were analyzed, along with the effects of tetanic stimulation of the nerves (n. intestinalis, n. pallialis dexter, n. pallialis sinister; 1-5 Hz for 1-2 min) on the amplitudes of the ACh current and the magnitudes of EPSC evoked by stimulation of another nerve. The following changes in conditioning responses were found over 1-1.5 h after tetanization: rhythmic application of ACh to the dorsal surface of the cell body resulted in potentiation of EPSC, and tetanic orthodromic stimulation potentiated the ACh current and induced heterosynaptic depression of EPSC. These post-tetanic changes were not local--they developed in those chemoreceptor zones of the membrane which were not activated by the preceding conditioning rhythmic stimulation. It is concluded that generalized post-tetanic changes in neuron responses are induced by activation of its subsynaptic and extrasynaptic mediator chemoreceptors.

Acetylcholine↗