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Results for “functional connectivity”

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At least 397 records · Page 22Linked to original sources
PubMed1984

Central representation and functional connections of afferent and efferent pathways of Helix pomatia L. lip nerves.

Localization and distribution of cerebral neurones sending axons into the three pairs of Helix pomatia lip nerves were investigated by the method of retrograde axonal NiCl2 transport. Using electrophysiological technics (extracellular recordings) the dependence of lip nerve's activity on inputs of other lip nerves was studied after application of various types of stimuli to the lip of semi-intact preparations. All lip nerves have neuronal representation in each lobe of the cerebral ganglia but in different proportions. Labelled neurones were located mainly on the ventral surface of the cerebral ganglia, most of them projecting to the medial, the least to the inner lip nerve. Lip nerves differ from each other according to the proportions of neurones of various size. They share in the axons of large (55-70 microns) and medium sized (30-40 microns) neurones in the order inner greater than outer greater than medial and medial greater than outer greater than inner lip nerve, respectively. Most neurones projecting to different nerves are located in discrete groups. According to the electrophysiological results the medial lip nerve has the most prominent afferent, while the inner one has the strongest efferent activity. Both the afferent and efferent activities of the outer lip nerve proved to be the least significant compared to the other lip nerves. Contralateral cerebral connections play an important role in the sensory information processing. The sensory input of a given nerve usually activates the contralateral member of another pair of lip nerves. Mechano- and chemo-afferent pathways have almost the same properties but there are some differences in latencies and other parameters.

Afferent Pathways↗
PubMedDate not supplied

[Certain functional connections of neurons control the walking of the cockroach Periplaneta americana].

On isolated abdominal nervous chain of the cockroach studies have been made of the responses of motoneurones of the thoracic ganglion to electrical stimulation of afferent axons of the leg nerve under normal conditions and during application of an anticholinesterase drug, GD-7. Depending on the type of stimulated axons, monosynaptic response, as well as polysynaptic phasic and tonic responses of motoneurones were recorded. A scheme of activation of motoneurones is suggested which evokes slow contractions of muscles in cockroach extremities.

Action Potentials↗
PubMedDate not supplied

[Electrophysiological study of the functional connections of the hypothalamus with the forebrain in the tortoise Emys orbicularis].

During stimulation of the posterior hypothalamus, the evoked potentials with short latent periods, high amplitude and poor exhaustion by rhythmic stimulation were recorded in the hippocampal cortex. In the piriform cortex, the evoked potentials exhibited longer latent periods and complex configuration. Less readily the evoked potentials appeared in the neocortex, their latency being very large. During stimulation of the anterior hypothalamus, maximum activity was also localized in the hippocampal cortex. The data obtained indicate close connection between hypothalamic structures and the hippocampal cortex. The latter is presumably the main projectional area for the ascending afferentation from the hypothalamus.

Animals↗
PubMedDate not supplied

[Functional connections between the suprapharyngeal ganglion and segmental motor centers of the cockroach Periplaneta americana].

Studies have been made of non-specific influences of supraesophageal ganglion on the excitability of the segmental centers in the cockroach P. americana. It was shown that electrical stimulation of the mushroom bodies decreases the frequency of the background discharges which are observed in the neuropile of the central body, decreasing simultaneously the activity of motor fibers of the Vth nerve. On the contrary, stimulation of the central body increases the frequency of the spontaneous activity in motor output. It is suggested that the inhibitory influences from the mushroom bodies upon the segmental motor apparatus may spread both directly and in a stepwise fashion, i. e. via the intermediate structure of the central body. The latter is involved into the control of muscle tonus in the cockroach.

Animals↗
PubMedDate not supplied

[Statistical analysis of interneuronal functional connections during conditioned reflex elaboration].

A milk conditioned reflex to a low frequency electrical stimulation of the visual pathways was elaborated in cats. Multineuronal activity in the visual and sensorimotor cortical areas was recorded in the chronic experiment. Statistical analysis of interneuronal intraanalyser and interanalyzer connections was made by constructing crosscorrelograms on the "Plurimat-C" computer. Comparison of the results of the interneuronal interaction in untrained and trained cats has shown an increase of one-way and two-way connections of both the intraanalyser and interanalyser types. Neurones with medium amplitude spikes changed their net properties more than other units acquiring ingoing and outgoing connections in both studied areas of the learned animals. Acquisition was achieved in all the neurones mainly due to increased number of connections from the sensorimotor analyser to the visual one. The problems of formation of backward conditioned connections and "local" conditioned reflex are discussed.

Animals↗
PubMed1995

[The functional connection among the "zusanli"-spinal dorsal horn neurons-trigeminal sensory nucleus of rats].

Electrical stimulation of Zusanli (ST36) point and Trigeminal Sensory Nucleus (TSN) as well as microelectrode recording from the laminae II - VI of the lumbar spinal dorsal horn have been used on the pentobarbital anesthetized rats, finding and identifying 142 spinal neurons responding to the stimulation of both ST36 and TSN. Among them, 29 responded antidromically to TSN; the others, responded orthodromically to TSN; These neurons distributed in the L2-S1 segments, the most in the L3-L6 segments, and in the laminae III-V, occasionally in the laminae II and VI in the spinal dorsal horn, the LTM and WDR neurons were 50% respectively of them. The results indicate that (i) single spinal dorsal horn neurons receives ST36 afferent input and then conveys it to the TSN; (ii) some spinal dorsal horn neurons receive, in turn, innervation from TSN; (iii) The convergence and integration between ST36 and TSN inputs might occur in the spinal dorsal horn neurons.

Acupuncture Points↗
PubMed2005

Linking disease-associated genes to regulatory networks via promoter organization.

Pathway- or disease-associated genes may participate in more than one transcriptional co-regulation network. Such gene groups can be readily obtained by literature analysis or by high-throughput techniques such as microarrays or protein-interaction mapping. We developed a strategy that defines regulatory networks by in silico promoter analysis, finding potentially co-regulated subgroups without a priori knowledge. Pairs of transcription factor binding sites conserved in orthologous genes (vertically) as well as in promoter sequences of co-regulated genes (horizontally) were used as seeds for the development of promoter models representing potential co-regulation. This approach was applied to a Maturity Onset Diabetes of the Young (MODY)-associated gene list, which yielded two models connecting functionally interacting genes within MODY-related insulin/glucose signaling pathways. Additional genes functionally connected to our initial gene list were identified by database searches with these promoter models. Thus, data-driven in silico promoter analysis allowed integrating molecular mechanisms with biological functions of the cell.

Binding Sites↗
PubMed1996

Spatially non-uniform Ca2+ signals induced by the reduction of transverse tubules in citrate-loaded guinea-pig ventricular myocytes in culture.

1. Ratiometric confocal microscopy and the whole-cell patch clamp technique were used to simultaneously record intracellular Ca2+ transients and membrane currents from guinea-pig ventricular myocytes. Intracellular dialysis with the low-affinity Ca2+ buffer citrate enabled us to record and analyse Ca2+ transients caused by Ca2+ influx alone and by additional Ca2+ release from the sarcoplasmic reticulum (SR) in the same cell. 2. In freshly isolated adult myocytes (used within 1-4 h of isolation) both types of Ca2+ transients ('Ca2+ entry' and 'Ca2+ release' transients) were spatially uniform regardless of the Ca2+ current (ICa) duration. In contrast, Ca2+ transients in short-term cultured (1-2 days) myocytes exhibited marked spatial inhomogeneities. ICa frequently evoked Ca2+ waves that propagated from either or both ends of the cardiac myocyte. Reduction of the ICa duration caused Ca2+ release that was restricted to one of the two halves of the cell. 3. Analysis of the Ca2+ entry signals in freshly isolated and short-term cultured myocytes indicated that the spatial properties of the Ca2+ influx signal were responsible for the spatial properties of the triggered Ca2+ release from the SR. In freshly isolated ventricular myocytes Ca2+ influx was homogeneous while in short-term cultured cells pronounced Ca2+ gradients could be found during Ca2+ influx. Spatial non-uniformities in the amplitude of local Ca2+ entry transients were likely to cause subcellularly restricted Ca2+ release. 4. The changes in the spatial properties of depolarization-induced Cai2+ signals during short-term culture were paralleled by a decrease (to 65%) in the total cell capacitance. In addition, staining the sarcolemma with the membrane-selective dye Di-8-ANEPPS revealed that, in cultured myocytes, t-tubular membrane connected functionally to the surface membrane was reduced or absent. 5. These results demonstrate that the short-term culture of adult ventricular myocytes results in the concomitant loss of functionally connected t-tubular membrane. The lack of the t-tubular system subsequently caused spatially non-uniform SR Ca2+ release. Evidence is presented to show that in ventricular myocytes lacking t-tubules non-uniform SR Ca2+ release was, most probably, the result of inhomogeneous Ca2+ entry during ICa. These findings directly demonstrate the functional importance of the t-tubular network for uniform ventricular Ca2+ signalling.

Animals↗
PubMed2002

Role of the Rab GTP-binding protein Ypt3 in the fission yeast exocytic pathway and its connection to calcineurin function.

A genetic screen for mutations synthetically lethal with fission yeast calcineurin deletion led to the identification of Ypt3, a homolog of mammalian Rab11 GTP-binding protein. A mutant with the temperature-sensitive ypt3-i5 allele showed pleiotropic phenotypes such as defects in cytokinesis, cell wall integrity, and vacuole fusion, and these were exacerbated by FK506-treatment, a specific inhibitor of calcineurin. Green fluorescent protein (GFP)-tagged Ypt3 showed cytoplasmic staining that was concentrated at growth sites, and this polarized localization required the actin cytoskeleton. It was also detected as a punctate staining in an actin-independent manner. Electron microscopy revealed that ypt3-i5 mutants accumulated aberrant Golgi-like structures and putative post-Golgi vesicles, which increased remarkably at the restrictive temperature. Consistently, the secretion of GFP fused with the pho1(+) leader peptide (SPL-GFP) was abolished at the restrictive temperature in ypt3-i5 mutants. FK506-treatment accentuated the accumulation of aberrant Golgi-like structures and caused a significant decrease of SPL-GFP secretion at a permissive temperature. These results suggest that Ypt3 is required at multiple steps of the exocytic pathway and its mutation affects diverse cellular processes and that calcineurin is functionally connected to these cellular processes.

Actins↗