Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Connective”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
PubMedDate not supplied

Orientation-specific relationship between populations of excitatory and inhibitory lateral connections in the visual cortex of the cat.

The topography of lateral excitatory and lateral inhibitory connections was studied in relation to orientation maps obtained in areas 17 and 18. Small iontophoretic injections of biocytin were delivered to the superficial layers in regions where orientation selectivity had been mapped using electrode recordings of single- and multi-unit activity from various cortical depths. Biocytin revealed extensive patchy axonal projections of up to 3.5 mm in both areas while labelled somata occurred chiefly at the injection site, indicating that the labelling was primarily anterograde. Two types of boutons could be clearly distinguished: (i) putative excitatory boutons either en passant or having a short stalk and (ii) inhibitory boutons which were invariably of the basket-type. Three-dimensional reconstructions of all labelled boutons showed that the excitatory and the inhibitory networks had a distinctively different relationship to orientation maps. The overall distribution of connections showed that 53-59% of excitatory and 46-48% of inhibitory connections were at iso-orientation, +/-30 degrees; oblique-orientation, +/-(30-60) degrees, was shown by 30% of excitatory and 28-39% of inhibitory connections; cross-orientation was shown by 11-17% of excitatory and 15-24% of inhibitory connections. Although excitatory patches occupied mainly iso-orientation locations, interpatch regions representing chiefly non-iso-orientations (oblique + cross orientation) were also innervated. There was considerable overlap between the excitatory and inhibitory network. Nonetheless, inhibitory connections were more common than excitatory connections with non-iso-orientation locations. There was no significant difference between the orientation topography of area 17 and area 18 projections. The results suggest that in general the lateral connectivity system is not orientation specific, but shows a moderate iso-orientation preference for excitation and an even weaker iso-orientation preference for inhibition. The broad orientation spectrum of lateral connections could provide the basis for mechanisms that requiring different orientations, as for example in detecting orientation discontinuities.

Animals↗
PubMed2005

Spatial patterns of excitation and inhibition evoked by lateral connectivity in layer 2/3 of rat barrel cortex.

In the rat barrel cortex, neurons in layer 4 are topographically arranged in a precise columnar structure, and the excitatory feed-forward input from layer 4 to layer 2/3 projects almost exclusively within the home barrel column. Here we analyzed the lateral connectivity that links neighboring columns in layer 2/3, which is necessary for integrating information across whiskers. We examined the spatial distributions of three different functional types of lateral connections in layer 2/3 of the rat barrel cortex: glutamate receptor-mediated excitatory connections, GABA(A) receptor-mediated inhibitory connections and GABA(B) receptor-mediated inhibitory connections. Synaptic potentials of pyramidal neurons, which are measures of the strength of connections, were evoked by a horizontal array of stimulation electrodes. The synaptic potentials and their decrease with distance from the stimulation site were measured in two types of slices whose planes were parallel to or orthogonal to barrel rows. Excitatory and GABA(B) receptor-mediated inhibitory connections were stronger along barrel rows than across them, whereas GABA(A) receptor-mediated inhibitory connections did not show such a tendency. These results indicate that lateral connectivity in layer 2/3 varies on the basis of not only excitatory polarity but also receptor subtypes.

Animals↗
PubMed1995

Non-metric multidimensional scaling in the analysis of neuroanatomical connection data and the organization of the primate cortical visual system.

Neuroanatomists have established that the various gross structures of the brain are divided into a large number of different processing regions and have catalogued a large number of connections between these regions. The connectional data derived from neuroanatomical studies are complex, and reliable conclusions about the organization of brain systems cannot be drawn from considering them without some supporting analysis. Recognition of this problem has recently led to the application of a variety of techniques to the analysis of connection data. One of the techniques that we previously employed, non-metric multidimensional scaling (NMDS), appears to have revealed important aspects of the organization of the central nervous system, such as the gross organization of the whole cortical network in two species. We present here a detailed treatment of methodological aspects of the application of NMDS to connection data. We first examine in detail the particular properties of neuroanatomical connection data. Second, we consider the details of NMDS and discuss the propriety of different possible NMDS approaches. Third, we present results of the analyses of connection data from the primate visual system, and discuss their interpretation. Fourth, we study independent analyses of the organization of the visual system, and examine the relation between the results of these analyses and those from NMDS. Fifth, we investigate quantitatively the performance of a number of data transformation and conditioning procedures, as well as tied and untied NMDS analysis of untransformed low-level data, to determine how well NMDS can recover known metric parameters from artificial data. We then re-analyse real connectivity data with the most successful methods at removing the effects of sparsity, to ensure that this aspect of data structure does not obscure others. Finally, we summarize the evidence on the connectional organization of the primate visual system, and discuss the reliability of NMDS analyses of neuroanatomical connection data.

Animals↗
PubMed2005

Interatrial electrical connections: the precise location and preferential conduction.

BACKGROUND: The atria are assumed to be connected electrically to each other at the level of the Bachmann's bundle, coronary sinus (CS) musculature, and interatrial septum, and these connections may have an important role in the interatrial conduction and perpetuation of various types of atrial tachyarrhythmias. However, the number, location, and preferential connections of the interatrial conduction related to the site of activation have not been examined yet. METHODS: The endocardium of both atria and the CS were mapped during continuous pacing from the left superior and inferior pulmonary veins, right pulmonary veins, upper and lower right atrium, or right atrial septum at various paced cycle lengths in 14 canines. The electrograms were recorded by custom-made form-fitted electrodes mounted on a specially designed device that allowed the septal aspects of the electrode forms to be spatially fixed to each other accurately. RESULTS: Four distinct interatrial electrical connections were identified at the Bachmann's bundle, CS, and antero-superior and postero-inferior septa. Decremental conduction was not seen in any of the connections. Bachmann's bundle was the most preferential connection during pacing from any epicardial site. The transseptal connections were evident only during pacing from the interatrial septum. The preference among the four connections was determined by the site of stimulation and the propagation of the activation related to the myocardial architecture. CONCLUSION: These unique preferential connections may play a significant role in the interatrial conduction and perpetuation of atrial tachyarrhythmias.

Animals↗
PubMed1994

Rearrangements of synaptic connections in visual cortex revealed by laser photostimulation.

Assessing patterns of synaptic connections in the developing mammalian neocortex has relied primarily on anatomical studies. In a physiological approach described here, the patterns of synaptic connections in slices of developing ferret visual cortex were determined with scanning laser photostimulation. Functional synaptic inputs to pyramidal cells in cortical layers 2 and 3 originating from sites close to the neuronal cell body appeared at least 2 weeks before eye opening, prior to the formation of long-range horizontal connections. Extensive long-range horizontal connections appeared in the next 10 days of development. The number of local connections peaked at the time of eye opening; the number of these connections subsequently declined to the level found in the adult while the specificity of long-distance connections increased. Thus, the relative influence of local connections on the activity of layer 2 and layer 3 neurons declines as the cortex matures while the influence of longer range connections increases substantially.

Animals↗
PubMed1995

Comparison by computerized numeric modeling of energy losses in different Fontan connections.

BACKGROUND: Different surgical techniques for creating a Fontan circulation can be used. The option of including an atrium in the circuit, or the technique used for connecting the caval veins to the pulmonary artery in a total cavopulmonary connection, frequently is empirical and is based on personal experience and preference. The hemodynamic and energetic differences between the different circuits are small, and short-term results are comparable. However, small, energetic differences may have significant implications for the long-term follow-up. The finite element method allows a computer-based modeling of the flow dynamics and pressure losses. It permits comparison of different Fontan connections in a single patient with identical geometry and functional conditions. METHODS AND RESULTS: We compared the atriopulmonary connection with different types of cavopulmonary connections, which differed in the degree of symmetry of implantation of both caval veins into the right pulmonary artery. Based on anatomic models and physiological flow dynamics, three-dimensional geometries and finite element meshes were created with PATRAN; flows were calculated with POLYFLOW (B), and results were visualized with DATA VISUALIZER. CONCLUSIONS: The atriopulmonary connection produces higher energy losses than the cavopulmonary connection (+/- 1 mm Hg at rest). The cavopulmonary connection is more efficient when the connection of the caval veins to the pulmonary artery is asymmetrical.

Blood Flow Velocity↗
PubMed2002

Neural connections and receptive field properties in the primary visual cortex.

A cubic millimeter of primary visual cortex contains about 100,000 neurons that are heavily interconnected by intrinsic and extrinsic afferents. The effort of many neuroanatomists over the past has revealed the general outline of these connections; however, their function remains a mystery. Recently, combined physiological and anatomical approaches are beginning to reveal the role of these connections in the generation of cortical receptive fields. A common theme emerges from all these studies: cortical connections are remarkably specific and this specificity is determined in great extent by the type of connection and the neuronal response properties. Feedforward connections follow relatively rigid rules of wiring selectively targeting neurons with receptive fields matched in position and contrast polarity (thalamus --> cortical layer 4) or position and orientation selectivity (layer 4 --> layers 2 + 3). In contrast, horizontal connections follow more flexible rules connecting distant cells that are not retinotopically aligned and neighboring cells with different orientation preferences. These differences in connectivity may give a hint on how visual stimuli are processed in the primary visual cortex. An attractive hypothesis is that local stimuli use the highly selective feedforward inputs to reliably drive cortical neurons while background stimuli modulate their activity through more flexible horizontal (and feedback) connections.

Animals↗
PubMed1997

Connectives and narrative text: the role of continuity.

Connectives are text devices that signal the relation between adjacent sentences. Recently there has been a surge of research interest in the role played by connectives in on-line processing. The present research tested the hypothesis that connectives will impact on-line processing to the extent that they signal a text event that represents a departure from the continuity of the events stated in the text. In Experiment 1, participants generated sentences to follow a stimulus sentence. An additive, causal, or adversative connective (or no connective) was provided to serve as the first word of the participants' sentence. Results showed that sentences generated in response to additive or causal connectives depicted text events that were continuous with the stimulus text. In contrast, sentences generated in response to adversative connectives depicted discontinuous text events. In Experiments 2 and 3, participants read coherent sentence pairs containing inappropriately placed additive, causal, or adversative connectives. Support for the continuity hypothesis was found when it was shown that adversative connectives led to the greatest amount of processing disruption, as measured by longer reading time on the postconnective sentence (Experiment 2) and lower ratings of coherence (Experiment 3). Future research in this area is discussed.

Analysis of Variance↗
PubMed2000

Functional connectivity in the thalamus and hippocampus studied with functional MR imaging.

BACKGROUND AND PURPOSE: With functional connectivity functional MR imaging, co-variance in signal intensity has been shown in functionally related regions of brain in participants instructed to perform no cognitive task. These changes are thought to represent synchronous fluctuations in blood flow, which imply neuronal connections between the regions. The purpose of this study was to map functional connectivity in subcortical nuclei with functional connectivity functional MR imaging. METHODS: Imaging data were acquired with an echo-planar sequence from six volunteers who performed no specific cognitive task. For functional connectivity functional MR imaging, a "seed" voxel or group of voxels was selected from the resting data set in the thalamus or in the hippocampus. Control voxels in gray matter presumed not to be eloquent cortex were also chosen. The correlation coefficient of the seed voxels and the control voxels with every other voxel in the resting data set was calculated. The voxels with correlation coefficients greater than or equal to 0.5 were mapped onto anatomic images for the functional connectivity functional MR images. The anatomic location of these voxels was determined by conventional parcellation methods. RESULTS: For each participant, functional connectivity functional MR imaging maps based on four seed voxels in the thalamus or hippocampus showed clusters of voxels in the ipsilateral and contralateral thalamus or hippocampus. For control voxels, few voxels in the hippocampus or thalamus showed significant correlation. Significantly more pixels in the ipsilateral hippocampus correlated with the seed voxel than in the contralateral hippocampus. The differences between numbers of functionally connected voxels in ipsilateral thalamus and those in contralateral thalamus were not significant. CONCLUSIONS: The thalamus and hippocampus show functional connectivity, presumably representing synchronous changes in blood flow.

Adult↗
PubMed1992

Quantitative analysis of pulmonary vascular disease in total anomalous pulmonary venous connection in sixty infants.

A quantitative analysis of small pulmonary arteries, pulmonary veins, and lymphatic vessels was conducted in autopsy cases of total anomalous pulmonary venous connection. The materials were obtained from 60 cases of total anomalous pulmonary venous connection without asplenia or pulmonary stenosis, ages ranging from 2 days to 19 months at the time of death (mean age 2.2 months). Pulmonary arterial pressure had been measured in 32 of these patients before death. Twenty cases of ventricular septal defect with pulmonary hypertension and 15 normal individuals were used as the control group. The mean thickness of the media of small pulmonary arteries and veins was 12.7 and 7.6 microns, respectively, in the total anomalous pulmonary venous connection cases, both values being significantly larger than those for normal and ventricular septal defect cases. No changes in thickness with aging were found. Medial thickness in the arteries and veins was greater in the cases of pulmonary venous obstruction than in those without such obstruction. The medial thickness of small pulmonary arteries in total anomalous pulmonary venous connection cases correlated with increased pulmonary arterial pressure. When the patients with the same pulmonary arterial pressure levels were compared, the medial thickness was always greater in those who had total anomalous pulmonary venous connection than in those who had ventricular septal defect. The medial thickness of pulmonary veins was also highly correlated with increased pulmonary arterial pressure in total anomalous pulmonary venous connection. The severity of the intimal lesions was milder in those who had total anomalous pulmonary venous connection than in those who had ventricular septal defect, suggesting the protective role of the thickened pulmonary arterial media against development of intimal lesions. Intimal fibrous thickening of pulmonary veins was not seen in the cases of ventricular septal defect, but it was present in 45% of the total anomalous pulmonary venous connection cases. Lymphangiectasia was characteristically present in 62% of the total anomalous pulmonary venous connection cases. Interstitial emphysema was often a complication of lymphangiectasia, and it led to eight postoperative deaths.

Age Factors↗
PubMed1986

Comparison of atriopulmonary versus atrioventricular connections for modified Fontan/Kreutzer repair of tricuspid valve atresia.

This study compares the clinical results of two basic variations of the modified Fontan/Kreutzer operation, direct atriopulmonary connection without an interposed valve versus atrioventricular connection using the native pulmonary valve and the potential pumping capability of the subpulmonary ventricular chamber. From January 1979 through June 1985, 84 patients with tricuspid atresia and ventriculoarterial concordance underwent the modified Fontan/Kreutzer operation at the Mayo Clinic. Sixty patients had atriopulmonary connection and 24 patients had atrioventricular connections. Preoperative characteristics of the two patient groups were similar, but there was a greater frequency of Waterston shunts in the atriopulmonary group (38% versus 17%) and greater frequency of Glenn shunts in the atrioventricular group (46% versus 15%). Mean pulmonary arteriolar resistance was 1.9 +/- 0.7 units in the atriopulmonary group and 1.1 +/- 0.8 units in the atrioventricular group (p less than 0.01). Early postoperatively, mean right atrial pressure was slightly higher in the atriopulmonary group than in the atrioventricular group (18 +/- 3 versus 16 +/- 3 mm Hg, p less than 0.01), but this difference was not reflected in the early or late results. Operative mortality was 5% for patients with atriopulmonary connections and 4% for patients with atrioventricular connections. At 3.5 years postoperatively, the overall survival rate was 89% +/- 4% for patients with atriopulmonary connection and 88% +/- 7% for patients with atrioventricular connections. We conclude that there is no important difference in the clinical outcome of patients undergoing modified Fontan/Kreutzer repair for tricuspid atresia with atrioventricular concordance with either of the two operative methods. The choice of the connection should be dictated by the anatomy, such as presence of pulmonary valve or arterial stenoses, size of outlet chamber, and the presence of anomalous coronary arteries.

Adolescent↗
PubMed1988

Thalamic connections of the ground squirrel superior colliculus and their topographic relations.

The connections of the superior colliculus (SC) of the ground squirrel Spermophilus tridecemlineatus were studied with the horseradish peroxidase (HRP) method. Multiple pressure injections of HRP served to define the total pattern of SC projections while iontophoretic injections allowed differentiation of connections of the deep and superficial layers and determination of topographic relations of SC with its associated nuclei. The deep laminae were mainly connected with auditory, somatosensory and reticular regions of the brain, including the inferior colliculus, zona incerta, substantia nigra, mesencephalic central grey, pontine nuclei, spinal trigeminal nucleus, nucleus of the posterior commissure, thalamic reticular nucleus, raphe nuclei, lateral vestibular nucleus, the lateral superficial reticular formation of the medulla, the mesencephalic reticular formation, nucleus gracilis and the cervical spinal cord. The superficial laminae were connected with visual system structures. They were reciprocally connected with the dorsal and ventral lateral geniculate nuclei, the pretectum, nucleus lateralis posterior (LP), the parabigeminal nucleus and the contralateral SC. Connections between the SC and the dorsal lateral geniculate were topologic. LP was found to consist of three divisions: rostrolateral, rostromedial and caudal. SC was interconnected with the rostrolateral and caudal divisions. The connections between the SC and the rostrolateral division were topologic; those with the caudal division were not. The connections of the deep collicular layers in ground squirrels were similar to those which have been reported for cats and monkeys. The connections of the superficial laminae were more extensive than has been reported in other species. These elaborate interconnections indicate extensive interaction between primary retinal projection nuclei in the processing of visual information.

Animals↗
PubMed1989

An EM study of the dorsal nucleus of the lateral lemniscus: inhibitory, commissural, synaptic connections between ascending auditory pathways.

The dorsal nucleus of the lateral lemniscus (DNLL) and its connections constitute one of the ascending auditory pathways to the inferior colliculus. One notable feature of this nucleus is the heavy commissural connections between DNLL on opposite sides of the midbrain. These commissural connections may have a significant impact on the ascending pathway. In this study, the fine structure of DNLL in the cat and its commissural connections were examined. Both anterograde and retrograde transport methods were used simultaneously at the EM level. Injections of 3H-leucine mixed with WGA-HRP were made in one DNLL. After axonal transport, EM autoradiographic methods were used to identify the anterogradely labeled axonal endings from the opposite DNLL. In the same location, retrogradely labeled neurons with crossed connections were identified with HRP histochemistry. Two types of axonal endings were found in DNLL, those with round synaptic vesicles forming asymmetrical synaptic junctions and those with pleomorphic vesicles and symmetrical synapses. Both types were equally common. However, only endings with pleomorphic vesicles were labeled after injections in the contralateral DNLL. The labeled endings from the opposite DNLL appeared to represent a homogeneous population, even though a number of variations in the 2 types of endings were found. Labeled endings were presynaptic to all parts of neurons in DNLL, but a large proportion of the synapses were on cell bodies and large dendrites. Two patterns of nuclear morphology and distribution of rough endoplasmic reticulum were identified and may represent different cell types. Examples of both cell types were observed to project to the contralateral side and received labeled synaptic endings. The major finding of this study is that the crossed connections between DNLL exhibit the morphology associated with inhibitory function. Since neurons in DNLL are thought to use GABA as a neurotransmitter, the crossed connections could provide inhibitory inputs to DNLL on each side. Since some neurons receive numerous axosomatic inputs from the contralateral DNLL and also project to the opposite side, they may participate in direct reciprocal, inhibitory connections between the nuclei. Crossed inhibitory connections in the DNLL pathway may be important in regulating the flow of ascending auditory information.

Animals↗
PubMed1982

The afferent and efferent callosal connections of retinotopically defined areas in cat cortex.

We compared the callosal afferent and efferent connections of different retinotopic loci within a given visual cortical area as well as the connectivity patterns among similar retinotopic loci in different visual areas. Small injections (75 nl) of a mixture of horseradish peroxidase and [3H]leucine were made through a recording pipette at injection sites identified by retinotopic mapping. A small locus of cortex within a callosally connected region had precise reciprocal connections with the homotopic locus in the contralateral hemisphere. This small locus also was callosally connected with a variable number of heterotopic loci. Both reciprocal and nonreciprocal heterotopic callosal connections were found. Homotopic and heterotopic connections appeared to have a high degree of retinotopic fidelity. Precisely homotopic connections were present not only between locations on the vertical meridian representations at the left and right area 17/18 borders but also, for example, between mirror-symmetrical points on the peripheral horizontal meridian representation in the left and right posteromedial lateral suprasylvian areas. In several experiments, we found that both callosal neurons and terminals in the homotopic cortex were grouped into two to three distinct clusters ranging from 600 to 900 micrometers in width. Callosal neurons with homotopic connections were primarily pyramidal cells in lower layer III and upper layer IV. Outside of areas 17 and 18, there was a significant number of pyramidal and fusiform-shaped callosal neurons in layers V and VI. The majority of callosal terminals were located in layers II, III, and IV.

Afferent Pathways↗
PubMed1983

Competence to form electrical connections is restricted to growing neurites in the snail, Helisoma.

Identified neurons of the snail, Helisoma, undergo extensive remodeling in response to axotomy, including the formation of specific sets of novel electrical connections. This communication addresses the question of why, under the conditions employed, some neurons readily form new connections with a single "test" neurons, whereas others do not. The present experiments are a test of the hypothesis that, for these adult neurons, competence to form electrical connections is restricted to pairs of neurons with interacting regions of active outgrowth. Morphological observations demonstrated profuse overlapping outgrowth from neurons which formed electrical connections, whereas neurons which did not connect displayed no simultaneous new outgrowth, although there could be regions of physical overlap or proximity. The causal relationship between growth and the ability to form new connections was tested more directly by two means: (1) Previously nonconnecting neurons were recruited into the connectivity pattern by axotomy-induced growth. (2) Previously connecting neurons did not connect when they were not induced to grow. Thus, growth or lack of growth is an effective discriminator for determining specific sets of interconnected neurons.

Animals↗
PubMed1982

[Formation of connections between the raphe and hippocampal nuclei in tissue culture (intravital functional and morphological studies)].

A combined cultivation in vitro of the hippocampal and raphe nuclei explants have been performed. Certain conditions and mechanisms on connections formed between them have been analysed. Vital observations by means of a phase-contrast microscope makes it possible to reveal three types of connections between the explants which differ by the degree of development and differentiation. The base of the earliest diffuse type of connection is presented by a fine network of flat multipressed and intercontacting gliocytes. The intermediate type of connection is characterized by aggregation of glial elements and formation of loose cords with anastomoses. Reduction of the fine network results from reduction of the glyocytic processes. The most differentiated type of connections is presented by raphe-hippocampal tracts. They are always rectilinear and develop along the shortest way between the explants. When the explants from the hippocamp and cerebellum, which have no natural intercerebral connections, are cultivated together, no formation of any magistral or intermediate types of connection is observed. An important factor in differentiation of the magistral tracts is the reactive kinetics of the glial cells. Strict straightness of the tracts and selectivity in formation of connections between various explants demonstrate also an important role of the neuro-neuronal mechanisms of chemotaxis. The direction of the connections formed can be correlated by means of some artificial guides-threads.

Animals↗
PubMed1981

Connections between the hexon polypeptides in the two-dimensional hexon crystalline array.

Fine interhexonal connections were observed in high resolution electron micrographs of tight two-dimensional hexagonal crystalline arrays. Intrahexonal connections were found among the three polypeptides constituting the hexons. The length of the interhexonal connections was 2.73 mm, and their diameter 1.2 nm; that of the intrahexonal connections were 1.05 nm and 0.75 nm, respectively. The orientation of the hexons in a two-dimensional crystalline array corresponded to a corner to edge conjunction. One side of each of the three polypeptides, constituting a triangular hexon, corresponded to the sides of that hexon; their points of contact were the corners. A tentative diagram of the molecular arrangement of hexon polypeptides and of interhexonal connections was drawn up following analysis of the electron micrographs. It showed that parallel connections run to both ends of each polypeptide of a hexon, connected to one of the end parts of the two nearest polypeptides of the next hexon, as follows from the threefold symmetry. Thus, every hexon is joined to its six neighbours by six times two parallel connections. Two pairs of parallel connections enclose an angle of approximately 60 degrees.

Capsid↗
PubMed1981

Intraanalyzer conditioned reflex properties of two-way connections of cortical neurons in cats.

One of the principles in the formation of integrating activity of the brain appears to be a two-way character of neuronal connections. Forward and backward conditioned connections demonstrate the acquired properties of two-way relations in the cerebral cortex. Interneuronal cortical connections and their modification in conditioned reflex activity were studied in a alert cats with chronically implanted electrodes using a statistical method for analysis of two impulse flows. Multineuronal activity was recorded in the auditory cortex. All of the investigated neurons were divided into pairs according to their functional relations: (1) with two-way connections, (2) with one-way connections and (3) completely independent pairs. The functional interrelation in the cortical microarea, and between cortical microareas, were defined according to the space distribution of neuronal pairs. Elaboration of the motor conditioned reflex led to an intensification of two-way connections both in the cortical microarea and between remote neurons. Extinction of the conditioned reflex exerted almost no effect on the intensity of two-way connections, but considerably decreased the number of independent neuronal pairs at the expense of reduction in the number of one-way connections between cortical microareas. Thus, acquisition and extinction of the conditioned reflex were accompanied by intensive interconnected neuronal activity. The features of interneuronal connection properties during extinction inhibition were the attenuation of successive information transfer in cortical cells, which prevented the impulse activity from passing to effector pathways.

Animals↗