[Barotherapy in the military medicine].

Barotherapy in the military medicine. The authors present current data on place and role of hyperbaric oxygenation for military and extreme medicine. Main mechanisms of oxygen saturation and its <> to cells and tissues of the organisms is described in the given article. The authors proved advantages of the hyperbaric oxygenation over the normobaric and showed its high efficiency for the trauma and suppurative- septic lesion treatment, and for the combat therapeutic pathology. Main clinical and physiological effects of the hyperbaric oxygenation are showed. Modern indications and contra-indications for the use of the hyperbaric oxygenation as a therapeutic mean are proved.

Differential control of cortical activity by the basal forebrain in rats: a role for both cholinergic and inhibitory influences.

Using microdialysis and high-performance liquid chromatography, we measured acetylcholine (ACh) release simultaneously from two cortical sites in anesthetized rats. One site was always in the somatosensory cortex, and the other was in either the visual or the motor cortex. After baseline measurements were obtained, selected sites in the basal forebrain (BF) were stimulated to increase ACh release. Some BF sites provoked more release in one microdialysis probe than in the other, suggesting some degree of corticotropic organization of the cholinergic projections from the BF. BF sites optimal for release from the visual cortex were separated from optimal sites for release from the somatosensory cortex by greater distances than were the best sites for release from the somatosensory and the motor cortex. Stimulation of a single BF site often provoked similar release from the latter two cortical areas. Electrical stimulation of the BF also modified cortical neuronal activity. Activation of some BF sites provoked an intense discharge of many neurons in the vicinity of the cortical recording electrode, and the same stimulus site in the BF provoked release of large amounts of ACh in the cortex. Stimulation of other BF sites produced strong inhibition of ongoing cortical activity and no increase in cortical ACh release. When other sites were stimulated, they had no effect or they generated stereotyped bursting patterns in the cortex without any observable effect on ACh release. BF sites that generated inhibition of cortical neural activity were generally located near the sites that activated the cortex and provoked release of ACh. These data suggest an elaborate control of the sensory cortex by a mechanism involving both gamma-aminobutyric acid-containing and cholinergic neurons of the BF.

Correlating cytoarchitecture and function in cat primary somatosensory cortex: the challenge of individual differences.

Principles of organization for the primary somatosensory cortex are generalizations derived by examining data obtained in different individuals. The manner in which these data are combined influences the conclusions derived. We found the line representing the widest anteroposterior distance across the sigmoid gyrus to be a useful reference in the cat somatosensory cortex for combining and comparing electrophysiological and cytoarchitectonic data from different individuals when we constructed cytoarchitectonic and functional maps of the bank of the medial ansate sulcus; maps prepared from combined data sets had boundaries similar to those found among individuals. Nevertheless, we argue that, for reasons inherent to the nature of the cerebral hemispheres and cortical maps, such references will never allow combinations of data capable of defining a unique high resolution prototypical map of individual body parts; the somatotopic order of body representations is, as are certain other attributes of somatosensory cortex, idiosyncratic. The genetic, developmental and use-dependent reasons for this situation are discussed.

The effects of peripheral deafferentation on spontaneously bursting neurons in the somatosensory cortex of waking cats.

Single neurons (n = 356) were studied in the forelimb representation of awake, quietly resting cats. Thirty-five spontaneously bursting neurons in a sample of 206 cells recorded before forelimb deafferentation were compared to 39 spontaneously bursting neurons in a sample of 127 neurons studied 1-3 weeks after deafferentation. The probability of encountering bursting neurons increased significantly following deafferentation from 17% to 31% of the sample (P < 0.005). The same 5 classes of bursting cells were observed after deafferentation but there were significant changes in the duration of interspike intervals in some classes, in the probability of observing certain classes, and in the proportion of spikes found in bursts. The probability of encountering class III cells, a class thought to consist primarily of non-inactivating pyramidal burst neurons, nearly doubled and the average interspike interval length within the burst increased from 1.9 to 3.0 ms. The burst structure in the other classes did not change but they were found less frequently. These other classes may include inhibitory interneurons which receive less excitatory drive after deafferentation and therefore provide less inhibition to class III cells. The differential behavior of the different classes of bursting cells may be one reason why the overall level of spontaneous activity does not change after deafferentation and it suggests that there are homeostatic mechanisms in primary somatosensory cortex that maintain a certain level of neural activity.

Recognition of temporally structured activity in spontaneously discharging neurons in the somatosensory cortex in waking cats.

We describe a method to automate the detection and analysis of structured neuronal activity obtained in relatively non-restrictive experiments in awake animals. Several different, regularly occurring, discharge patterns consisting of groups of spikes were identified in extracellular recordings from the somatosensory cortex of awake cats. The introduction of an interspike interval threshold made it possible to segregate these bursts from single spikes. The threshold interval was obtained from the modal interval in high-resolution autocorrelograms (up to 0.1 ms/bin) of the spontaneous neural activity. Single spikes were those separated by intervals greater than the threshold, while those within the group were of less than threshold value. When intervals were arranged and averaged according to their order of occurrence within the burst, four distinctive burst patterns were observed. These four patterns occurred in both normal and deafferented cortex and we believe them to be characteristic of particular cell types, a feature that will be useful for studying such cells in intact cellular networks.

Significance of the interstimulus time interval in repeating combined presentations of L-glutamate and acetylcholine for change in the reactivity of cortical neurons.

A comparative study of the probability, directionally, and intensity of the changes in the baseline and L-glutamate (Gl)- and acetylcholine(ACh)-induced average frequency of the impulse activity (BIA, GlIA, and AChIA, respectively) of individual neurons of the sensorimotor cortex of unanesthetized rats in the course of repeated isolated and combined presentations of Gl and ACh showed that the process of reduction in reactivity to Gl is slowed in the population of cells which experienced the combined action of Gl and ACh with a 1.5 second postponement of applications of ACh in comparison with the situation of its isolated and combined presentation with a 3 second postponement of ACh. The AChIA decreases to a greater degree in the case of a 3 second postponement of ACh, and the probability of an increase in BIA is less than with the isolated application of ACh. It is concluded that the character of the dynamics of the reactivity of neurons is determine by the temporal relationships of local neurochemical stimuli.

Cytoarchitecture and responsiveness of the medial ansate region of the cat primary somatosensory cortex.

To understand its relationship to somatosensory areas in other species, we studied the rostral bank of the medial ansate sulcus in adult cats. Neurons in the shoulder and upper part of the sulcal wall responded to low-threshold cutaneous stimuli much like neurons on the crown of the gyrus, whereas neurons in some deeper portions of the sulcus required more intense but innocuous somatic stimuli. Because we found much of the body surface re-represented in this area, we suggest that, besides the representation in area 3b, there is another cutaneous representation of the hindlimb and trunk located on the gyral crown near the medial end of the medial ansate sulcus and of the forelimb and trunk within the medial ansate sulcus. Posterior to this second cutaneous representation, many parts of the body were also represented in regions activated by more intense stimuli and having a different cytoarchitecture, suggesting that they were part of another body representation. Area 3b and the shoulder of the gyrus were distinguished by relatively intense acetylcholinesterase staining of layers III and IV. In the wall of the sulcus, all layers except layer I were uniformly stained to a point where electrophysiological recordings showed the cortex to be unresponsive, whereupon the outer two-thirds of layer I became very pale. Neurons activated by afferents from knee joints were found only in a small area; we did not find a mediolateral band serving joint afferents as is reported in primates. These data suggest that cat somatosensory cortex differs in some ways from primates but that it contains multiple representations of the body, as do most other mammals.

The reactivity and interaction of neurons of the cerebral cortex of rats in the presence of the microiontophoretic action of acetylcholine in a model negative learning situation.

The activity of 46 pairs of neurons in the sensorimotor cortex of the brain of rats during multiple (up to 60) brief microiontophoretic applications of acetylcholine (ACh) was investigated by means of the method of multicellular recording, with subsequent division into separate impulse streams. It was demonstrated that neurons with high-amplitude spikes have a lower average frequency of discharges in comparison with low-amplitude [neurons]. It was established that cells located adjacent to one another exhibit responses in 63% of cases which are similar in their component makeup; the majority of these responses are inhibitory-excitatory and excitatory. Analysis of the dynamics of the structure of the cross-interval histograms plotted for pairs of cells on the basis of the data of their initial activity, as well as activity in the baseline, and upon termination of the action of ACh, attest to the relative invariability of the excitatory connections between the cells and a possibility of some increase in the efficiency of the inhibitory connections under the conditions of the manifestation of the dynamics of responses to ACh of habituation type by one of the cells.

Temporal specificity in the action of stimuli during the formation of associative ultrastructural reorganizations in neurons of the cerebral cortex.

A morphometric investigation of various components of the synapses of neurons of the sensorimotor region of the cerebral cortex of rats with different variants of combined and uncombined repeated microiontophoretic application of glutamate and acetylcholine has been carried out. A substantial dependence of the character and expressivity of the reorganizations of the thickness of the postsynaptic density (PSD), of the width of the synaptic cleft, and the length of the active zone of the synapses, on the temporal relationships in the action of mediators has been identified: significant changes in the thickness of the PSD appeared only with the combined applications of the stimuli (neuromediators); the maximum thickening of the PSD was induced by the combined action of glutamate and acetylcholine with a 3-second delay in the latter. A hypothesis is presented according to which the temporal specificity in the integration of associable signals arriving at neurons is determined by the kinetics of the various interacting biochemical regulator mechanisms.