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At least 685 records · Page 38Linked to original sources
PubMed1993

Architectonics, somatotopic organization, and ipsilateral cortical connections of the primary motor area (M1) of owl monkeys.

The ipsilateral cortical connections of primary motor cortex (M1) of owl monkeys were revealed by injecting WGA-HRP and fluorescent tracers into M1 sites identified by intracortical microstimulation. In some of the same animals, the extent and somatotopic organization of M1 was determined by making detailed microstimulation movement maps and relating the results to cortical architectonics. Thus, delineation of M1 was based on a combination of physiological and anatomical characteristics. M1 comprised most, but not all, of the cortex rostral to area 3a where movements were evoked at low levels of current (40 microA or less). Analysis of somatotopic patterns and architectonics placed some of the low-threshold sites in a ventral premotor field (PMV) and the dorsomedially situated supplementary motor area (SMA). Movements were also reliably elicited from a dorsal premotor area (PMD) at higher currents. M1 was characterized by a somatotopic global organization, representing hindlimb, trunk, forelimb, and face movements in a mediolateral sequence, and a mosaic local organization, with a given movement typically represented at several different sites. Architectonically, M1 was characterized by the absence of a granular layer IV and the presence of very large layer V pyramidal cells. However, M1 was not uniform in structure: pyramidal cells were larger caudally than rostrally, a feature we used to distinguish caudal (M1c) and rostral (M1r) subdivisions of the area. M1 resembles Brodmann's area 4, although the rostral subdivision has probably been considered as part of area 6 by some workers. Tracer injections of M1 revealed somatotopically distributed connections with motor areas PMD, PMV, and SMA, as well as in somatosensory areas 3a, 1, 2, and S2. Weaker connections were with area 3b, posterior parietal cortex, the parietal ventral area (PV), and cingulate cortex. M1r and M1c differed connectionally as well as architectonically, M1c being connected primarily with somatosensory areas, while M1r was strongly connected with both non-primary motor cortex and somatosensory cortex. These results indicate that M1 interacts directly with at least three non-primary motor areas and at least six somatosensory areas.

Afferent Pathways↗
PubMed1995

Intrinsic connections of the rat amygdaloid complex: projections originating in the basal nucleus.

The amygdaloid complex is involved in associational processes, such as the formation of emotional memories about sensory stimuli. However, the anatomical connections through which the different amygdaloid nuclei process incoming information and communicate with the other amygdaloid nuclei, is poorly understood. As part of an ongoing project aimed at elucidating the intrinsic connections of the rat amygdaloid complex, we injected the anterograde tracer PHA-L (Phaseolus vulgaris-leucoagglutinin) into different rostrocaudal levels of the basal nucleus of the amygdala in 21 rats and analyzed the distribution of labeled fibers and terminals throughout the amygdaloid complex. The connectional analysis, together with cytoarchitectonic observations, suggested that contrary to previous notions the basal nucleus in the rat has three divisions: magnocellular, intermediate, and parvicellular. The magnocellular division has heavy reciprocal connections with the lateral portion of the parvicellular division and the intermediate division projects weakly to the parvicellular division, whereas the projection from the medial portion of the parvicellular division to the intermediate division is heavy and the lateral and medial portions of the parvicellular division are only weakly interconnected, as are the magnocellular and intermediate divisions. The main intraamygdaloid targets of the basal nucleus projections are the nucleus of the lateral olfactory tract, the anterior amygdaloid area, the medial and capsular divisions of the central nucleus, the anterior cortical nucleus, and the amygdalohippocampal area. Our findings provide the most detailed understanding of the intra-amygdala connections of the basal nucleus to date and show that the connections within the basal nucleus and between the basal nucleus and other amygdaloid areas are more widespread and topographically organized than previously recognized.

Amygdala↗
PubMed1995

Overall pattern of callosal connections in visual cortex of normal and enucleated cats.

The effect of neonatal bilateral enucleation on the overall distribution of callosal connections in striate and extrastriate visual cortex of the cat was studied using tangential sections from the physically unfolded and flattened cortex. Callosal neurons were labeled by administering the anatomical tracer horseradish peroxidase directly to the transected corpus callosum. The pattern of callosal connections in binocularly enucleated cats showed both consistent differences and consistent similarities with the pattern in normal cats. In agreement with previous studies, it was found that callosal labeling at the 17/18 border of enucleated cats was considerably sparser than in normal cats. Moreover, we found that the strip containing the majority of labeled cells at the 17/18 border was narrower than in normal cats. In both normal and enucleated cats, scattered cells were distributed on either side of the 17/18 callosal strip, well into areas 17 and 18. In much of extrastriate cortex, the pattern of callosal connectivity in enucleated cats looked surprisingly normal. Details of the callosal pattern that were consistently found in normal cats could also be recognized in binocularly enucleated cats, such as two to four bridges of labeling spanning areas 18 and 19. Also, four zones that were free of callosal connectivity in area 7, on the banks of the suprasylvian sulcus, and in the posterior suprasylvian sulcus were found in both normal and enucleated cats. Finally, as in normal cats, dense cell labeling occurred on the crown of the suprasylvian gyrus at its posterior end, from which it extended laterally across both banks of the suprasylvian sulcus and into the fundus of this sulcus. The results of this study suggest that, although the stabilization of callosal connections at the 17/18 border region appears to depend on visual input, this input plays a less prominent role in the stabilization of callosal connections in extrastriate visual cortex.

Animals↗
PubMed1990

Specification of synaptic connections between sensory and motor neurons in the developing spinal cord.

Experimental studies of mechanisms underlying the specification of synaptic connections in the monosynaptic stretch reflex of frogs and chicks are described. Sensory neurons innervating the triceps brachii muscles of bullfrogs are born throughout the period of sensory neurogenesis and do not appear to be related clonally. Instead, the peripheral targets of these sensory neurons play a major role in determining their central connections with motoneurons. Developing thoracic sensory neurons made to project to novel targets in the forelimb project into the brachial spinal cord, which they normally never do. Moreover, these foreign sensory neurons make monosynaptic excitatory connections with the now functionally appropriate brachial motoneurons. Normal patterns of neuronal activity are not necessary for the formation of specific central connections. Neuromuscular blockade of developing chick embryos with curare during the period of synaptogenesis still results in the formation of correct sensory-motor connections. Competitive interactions among the afferent fibers also do not seem to be important in this process. When the number of sensory neurons projecting to the forelimb is drastically reduced during development, each afferent still makes central connections of the same strength and specificity as normal. These results are discussed with reference to the development of retinal ganglion cells and their projections to the brain. Although many aspects of the two systems are similar, patterned neural activity appears to play a much more important role in the development of the visual pathway than in the spinal reflex pathway described here.

Animals↗
PubMed1996

Inhibition synchronizes sparsely connected cortical neurons within and between columns in realistic network models.

Networks of compartmental model neurons were used to investigate the biophysical basis of the synchronization observed between sparsely-connected neurons in neocortex. A model of a single column in layer 5 consisted of 100 model neurons: 80 pyramidal and 20 inhibitory. The pyramidal cells had conductances that caused intrinsic repetitive bursting at different frequencies when driven with the same input. When connected randomly with a connection density of 10%, a single model column displayed synchronous oscillatory action potentials in response to stationary, uncorrelated Poisson spike-train inputs. Synchrony required a high ratio of inhibitory to excitatory synaptic strength; the optimal ratio was 4 : 1, within the range observed in cortex. The synchrony was insensitive to variation in amplitudes of postsynaptic potentials and synaptic delay times, even when the mean synaptic delay times were varied over the range 1 to 7 ms. Synchrony was found to be sensitive to the strength of reciprocal inhibition between the inhibitory neurons in one column: Too weak or too strong reciprocal inhibition degraded intra-columnar synchrony. The only parameter that affected the oscillation frequency of the network was the strength of the external driving input which could shift the frequency between 35 to 60 Hz. The same results were obtained using a model column of 1000 neurons with a connection density of 5%, except that the oscillation became more regular. Synchronization between cortical columns was studied in a model consisting of two columns with 100 model neurons each. When connections were made with a density of 3% between the pyramidal cells of each column there was no inter-columnar synchrony and in some cases the columns oscillated 180 degrees out of phase with each other. Only when connections from the pyramidal cells in each column to the inhibitory cells in the other column were added was synchrony between the columns observed. This synchrony was established within one or two cycles of the oscillation and there was on average less than 1 ms phase difference between the two columns. Unlike the intra-columnar synchronization, the inter-columnar synchronization was found to be sensitive to the synaptic delay: A mean delay of greater than 5 ms virtually abolished synchronization between columns.

Cerebral Cortex↗
PubMed1992

Output connections of a wind sensitive interneurone with motor neurones innervating flight steering muscles in the locust.

The output connections of a bilaterally symmetrical pair of wind-sensitive interneurones (called A4I1) were determined in a non-flying locust (Schistocerca gregaria). Direct inputs from sensory neurones of specific prosternal and head hairs initiate spikes in these interneurones in the prothoracic ganglion. The interneurone with its axon in the right connective makes direct, excitatory connections with the two mesothoracic motor neurones innervating the pleuroaxillary (pleuroalar, M85) muscle of the right forewing, but not with the comparable motor neurones of the left forewing. The connections can evoke motor spikes. The interneurones also exert a powerful, but indirect effect on the homologous metathoracic pleuroaxillary motor neurones (muscle 114), and a weaker, indirect effect on subalar motor neurones of the hindwings. No connections or effects were found with other flight motor neurones, or motor neurones innervating hindleg muscles, including common inhibitor 1 which also innervates the pleuroaxillary muscle. One thoracic interneurone with its cell body in the right half of the mesothoracic ganglion and with its axon projecting ipsilaterally to the metathoracic ganglion receives a direct input from the right A4I1 interneurone. These restricted output connections suggest a role for the A4I1 interneurones in flight steering.

Animals↗
PubMed1992

Intimate apposition of the glomus and smooth muscle cells (g-s connection) in the carotid labyrinth of juvenile bullfrogs.

Intimate apposition of the glomus and smooth muscle cells (g-s connection) was found in almost all glomus cells of the carotid labyrinths in juvenile bullfrogs, Rana catesbeiana. There were three types of g-s connection: between thin processes (0.1-0.2 micron in width) without dense-cored vesicles of glomus cells and smooth muscle cells; between thick processes (1.0-1.5 microns in width) with dense-cored vesicles of glomus cells and smooth muscle cells; and between the tongue-like projections of smooth muscle cells and the flat surface of the glomus cell. In some cases, a single glomus cell made g-s connections with several smooth muscle cells. Exocytosis often occurs at the g-s connection. Afferent and efferent synapses were found on the glomus cells with g-s connections. Reciprocal synapses were also observed. On the basis of these findings, the second and third types of g-s connection are presumed to participate in vascular regulation.

Animals↗
PubMed1996

Spinal connections of ventral-group bulbospinal inspiratory neurons studied with cross-correlation in the decerebrate rat.

We examined the synaptic connections from ventral-group bulbospinal inspiratory neurons to upper-cervical inspiratory neurons and phrenic and intercostal motoneurons in decerebrate rats using cross-correlation. Inspiratory neurons were recorded in the medulla (n = 28) at the level of the obex and from the upper-cervical segments (C1 and C2) of the spinal cord (n = 29) in 18 vagotomized, paralyzed, ventilated, and decerebrated rats. The neurons were identified by their inspiratory firing pattern and antidromic activation from the spinal cord at C7. Whole-nerve recordings were made using bipolar electrodes from the central cut ends of the C5 phrenic nerve and the external and internal intercostal nerves at various thoracic levels. Cross-correlation histograms were computed between these recordings to detect short time scale synchronizations indicative of synaptic connections. Cross-correlation histograms (n = 20), computed between the activities of ventral-group bulbospinal inspiratory neurons and the phrenic nerve, all showed peaks (mean half-amplitude width +/- SD, 1.1 +/- 0.3 ms) at short latencies (mean latency +/- SD, 2.0 +/- 0.6 ms) suggestive of monosynaptic excitation. Cross-correlation histograms (n = 33), computed between the activities of ventral-group bulbospinal inspiratory neurons and upper-cervical inspiratory neurons, displayed four (12%) peaks (mean half-amplitude width +/- SD, 0.9 +/- 0.1 ms) at short latencies (mean latency +/- SD, 1.8 +/- 0.6 ms) suggestive of monosynaptic excitation, and six (18%) peaks (mean half-amplitude width +/- SD, 1.4 +/- 0.4 ms) at latencies near zero suggestive of excitation from a common source. Cross-correlation histograms (n = 34), computed between the activities of ventral-group bulbospinal inspiratory neurons and the internal and external intercostal nerves at various thoracic levels (T2-8), showed six (18%) peaks (mean half-amplitude width +/- SD, 2.5 +/- 0.5 ms) at short latency (mean latency +/- SD, 4.5 +/- 1.1 ms) suggestive of oligosynaptic connections. Cross-correlation histograms (n = 42) computed between activities of intercostal nerves at various levels of the thoracic spinal cord showed central peaks suggestive of excitation from a common source. Although the size of the peaks decreased with segmental separation, the displacement of the peaks from time zero did not increase with segmental separation (mean displacement +/- SD, 0.6 +/- 0.6 ms) as would be expected if the common excitation resulted from a descending monosynaptic excitation by a source such as the ventral-group bulbospinal inspiratory neurons. We conclude that all ventral-group bulbospinal inspiratory neurons make monosynaptic connections to phrenic motoneurons, a few make monosynaptic connections to upper-cervical, inspiratory neurons, but connections to intercostal motoneurons are made via interneurons.

Animals↗
PubMed1990

Conserved patterns of cortico-cortical connections define areal hierarchy in rat visual cortex.

The prevalence of reciprocal connections in the cerebral cortex indicates that they play a fundamental role in the processing of sensory information. We have investigated the laminar termination patterns of such paired connections between different visual cortical areas of the rat, and have found two basic projection types: one which includes layer 4 and a second which includes layer 1 and avoids layer 4. The projections from primary visual cortex (area 17) to extrastriate visual cortical targets in the cytoarchitectonical areas 18a and 18b, and from 18a to a site in 18b, are of the first type. In contrast, the return projections from 18a and 18b to area 17 and from 18b to 18a, are of the second type. Thus each pair of connections has one element of each type, giving every circuit a nearly identical asymmetric structure. These laminar patterns resemble those of forward and feedback connections in primate cortex, indicating that corticocortical connectivity patterns are highly conserved through evolution, and that, as in monkeys, these connections define a hierarchical organization of areas in rat visual cortex.

Animals↗
PubMed1984

Cortical connections of the anteromedial extrastriate visual cortex in the rat.

Efferent and afferent connections of the visually responsive cortex (area anteromedial, AM) located in the anterior portion of area 18b were studied with degeneration and horseradish peroxidase (HRP) methods following small lesions and HRP injections into this area. Degenerating axons, terminals and retrogradely HRP-labeled neurons were observed in a broad region of the cortex including areas located lateral, medial and anterior to the striate cortex. The main finding of this study is that connections of area AM with area 18a are distributed in discrete patches whose arrangement is similar to that of the lateral extrastriate visual areas postulated in previous physiological and anatomical reports. These results thus suggest that visual area AM is reciprocally connected with visual areas in area 18a. Area AM is also connected with other regions within area 18b, thus supporting the notion advanced by recent studies that area 18b contains more than one visual area. A weak afferent connection to area AM from the dorsal lateral geniculate nucleus of the thalamus was noted. Previously described connections of area 18b with areas 8 and 29 as well as with the lateral and latero-posterior thalamic nuclei were confirmed in the present study.

Animals↗
PubMed1986

Connections of the anterior ectosylvian visual area (AEV).

We have previously described a visual area situated in the cortex surrounding the deep infolding of the anterior ectosylvian sulcus of the cat (Mucke et al. 1982). Using orthograde and retrograde transport methods we now report anatomical evidence that this anterior ectosylvian visual area (AEV) is connected with a substantial number of both cortical and subcortical regions. The connections between AEV and other cortical areas are reciprocal and, at least in part, topographically organized: the rostral AEV is connected with the bottom region of the presylvian sulcus, the lower bank of the cruciate sulcus, the rostral part of the ventral bank of the splenial sulcus, the rostral portion of the lateral suprasylvian visual area (LS) and the lateral bank of the posterior rhinal sulcus; the caudal AEV is connected with the bottom region of the presylvian sulcus, the caudal part of LS, the ventral part of area 20 and the lateral bank of the posterior rhinal sulcus. Subcortically, AEV has reciprocal connections with the ventral medial thalamic nucleus (VM), with the medial part of the lateralis posterior nucleus (LPm), as well as with the lateralis medialis-suprageniculate nuclear (LM-Sg) complex. These connections are also topographically organized with more rostral parts of AEV being related to more ventral portions of the LPm and LM-Sg complex. AEV also projects to the caudate nucleus, the putamen, the lateral amygdaloid nucleus, the superior colliculus, and the pontine nuclei. It is concluded that AEV is a visual association area which functionally relates the visual with both the motor and the limbic system and that it might play a role in the animal's orienting and alerting behavior.

Afferent Pathways↗
PubMed1993

Project CONNECT: an interagency partnership to confront new challenges facing at-risk women and children in New York City.

Project CONNECT is a New York State--New York City collaborative venture to facilitate access to, coordinate and expand the delivery of health and human services, during the perinatal period to women and children in the three areas of New York City with the highest rates of morbidity and mortality. Based on the concept of comprehensive case management, CONNECT coordinates diverse providers around existing resources. Services implemented by community-based case managers for families in need include: medical care, substance/alcohol abuse treatment, foster care preventive services, parent education, developmental assessment, screening and child care. The initial points of entry to CONNECT are specific hospitals within the three targeted neighborhoods. Additional points of entry, including other hospitals and prenatal care sites, are being added on an incremental basis. Enrollment in CONNECT is also enrollment in Medicaid and participants are eligible for Medicaid services. It is expected that the CONNECT program will result in improved birth and health outcomes for women and their children, reduction in chemical dependency and improved family preservation. The state and city agencies that created CONNECT hope that by working together, through a very specific interagency agreement monitored by the offices of the Governor and the Mayor, they will be able to reach those families who have many needs, but traditionally have been difficult to engage and keep involved in the service delivery system. The ultimate benefit will go to the family as a whole, particularly the children, both the newborns and their siblings.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMedDate not supplied

Effects of iontophoretic administration of acetylcholine to rabbit motor cortex neurons on the functioning of intracortical connections.

Experiments were performed on eight rabbits to study the effects of acetylcholine on interneuronal intracortical interactions. Multineuronal activity was recorded in the motor cortex during local iontophoretic administration of acetylcholine and physiological saline. Interneuronal connections were identified by cross-correlation analysis. A role for acetylcholine in intracortical connection reorganization processes is proposed. These studies demonstrated that acetylcholine has an activating effect on intracortical connections; application of acetylcholine leads to increases in the intensity of short-latency, constantly functioning (stable) connections. Acetylcholine application also resulted in the formation of unstable, long-latency connections. Additionally, the data suggest that iontophoretic application of acetylcholine does not lead to the formation of new short-latency interneuronal connections. The modulatory effects of acetylcholine on the network activity of cortical neurons are discussed.

Acetylcholine↗
PubMed2000

A quantitative analysis of the local connectivity between pyramidal neurons in layers 2/3 of the rat visual cortex.

This study provides a detailed quantitative estimate for local synaptic connectivity between neocortical pyramidal neurons. A new way of obtaining such an estimate is presented. In acute slices of the rat visual cortex, four layer 2 and four layer 3 pyramidal neurons were intracellularly injected with biocytin. Axonal and dendritic arborizations were three-dimensionally reconstructed with the aid of a computer-based camera lucida system. In a computer experiment, pairs of pre- and postsynaptic neurons were formed and potential synaptic contacts were calculated. For each pair, the calculations were carried out for a whole range of distances (0 to 500 microm) between the presynaptic and the postsynaptic neuron, in order to estimate cortical connectivity as a function of the spatial separation of neurons. It was also differentiated whether neurons were situated in the same or in different cortical layers. The data thus obtained was used to compute connection probabilities, the average number of contacts between neurons, the frequency of specific numbers of contacts and the total number of contacts a dendritic tree receives from the surrounding cortical volume. Connection probabilities ranged from 50% to 80% for directly adjacent neurons and from 0% to 15% for neurons 500 microm apart. In many cases, connections were mediated by one contact only. However, close neighbors made on average up to 3 contacts with each other. The question as to whether the method employed in this study yields a realistic estimate of synaptic connectivity is discussed. It is argued that the results can be used as a detailed blueprint for building artificial neural networks with a cortex-like architecture.

Animals↗
PubMed2003

Basic fibroblast growth factor forms new trabeculae that physically connect with pre-existing trabeculae, and this new bone is maintained with an anti-resorptive agent and enhanced with an anabolic agent in an osteopenic rat model.

Osteoporosis is a disease of excess bone fragility that results from both the loss of bone mass and trabecular bone microarchitecture, thereby creating a very fragile skeleton. The purpose of this study was to determine whether treatment of ovariectomized (OVX) osteopenic rats with basic fibroblast growth factor (bFGF) would stimulate the production of new trabeculae, and whether the newly formed trabeculae would make physical connections with the pre-existing trabeculae after prolonged estrogen deficiency. Six-month-old Sprague Dawley rats were OVXed or sham-operated and were left untreated until day 60 post-OVX. A high resolution microscopic scan (XTM) of the right proximal tibia was performed on groups 1 and 2 on day 1 post-OVX, and was repeated in all animals on day 60 post-OVX. At day 60 groups 1 and 2 were treated with vehicle and groups 3 to 6 were injected with bFGF 200 microg/kg/d intravenously for 15 days. At day 82, all animals obtained another in vivo XTM scan of the right tibia; then group 4 were treated with 17B estradiol 10 microg/kg/3x a week, group 5 were treated with hPTH (1-34) at 80 microg/kg/d for 35 days, group 6 were sacrificed, and groups 1 and 2 were treated with vehicle injections for 35 days. At day 110, all remaining animals were sacrificed, and repeat ex vivo XTM scans of the right proximal tibia were performed. Trabecular bone structural variables-including trabecular bone volume, connectivity, number, and thickness-were obtained from all XTM scans. Biochemical markers of bone turnover were also obtained 24 hours before each XTM scan (osteocalcin and deoxypyridinoline), and analyzed by ELISA. Animals OVXed and treated with vehicle had decreased trabecular bone volume, connectivity and number compared to sham-operated animals at both day 60 and day 110. Animals treated with bFGF from day 60-75 post-OVX had evidence of new trabeculae that physically connected with pre-existing trabeculae and also of increased trabecular bone volume seven days after the injections were discontinued. Biochemical markers of bone formation had a small and insignificant increase over baseline levels during the bFGF injections. Bone resorption markers were significantly reduced during the injection period, but returned to baseline levels after the injections were stopped. In addition, we also demonstrated that these newly formed trabecular connections could be maintained or added to with either estrogen or hPTH (1-34) treatments. Thirty-five days after ending the bFGF treatment, trabecular bone volume and connectivity was 25-80% higher in the estrogen and hPTH (1-34) treated animals compared to the untreated animals ( p<0.01). These results support continued development of bFGF as a potential treatment for severely osteoporotic individuals.

Animals↗
PubMed2006

Increased local and decreased remote functional connectivity at EEG alpha and beta frequency bands in opioid-dependent patients.

RATIONALE: Although researchers now have a working knowledge of key brain structures involved in realization of actions of substance abuse and addiction, deeper understanding will require examination of network interactions between cortical neuronal assemblies and their subcortical tails in the effects of opioid dependence. OBJECTIVES: Given that repeated exposure to opiates initiates a widespread reorganization of cortical regions, we predict that opioid dependence would result in a considerable reorganization of local and remote functional connectivity in the neocortex. METHODS: We applied the novel operational architectonics approach that enables us to estimate two local and remote functional cortex connectivities by means of electroencephalogram structural synchrony measure. RESULTS: In 22 opioid-dependent patients, we found the evidence that brain functional connectivity was indeed disrupted by chronic opioid abuse (i.e., the local functional connectivity increased and remote functional connectivity decreased in opioid abusers). This significant difference between "opioid" and "control" populations was the same for alpha and beta frequency bands. Additionally, significant negative relations between duration (years) of daily opioid abuse and the number/strength of functional connections in the posterior section of the cortex were found.

Adult↗
PubMedDate not supplied

Modified Fontan operation in patients with anomalies of systemic and pulmonary venous connection.

The presence of anomalies of the systemic and pulmonary venous connection associated with single ventricle anomalies has been considered a contraindication for the Fontan operation (FO). The aim of this study is to outline the technical considerations associated with the presence of anomalies of systemic and/or pulmonary venous connections and to identify the risk factors for mortality in this group of patients undergoing the modified FO. Between 1989 and 2004, 63 patients (median age, 3.2 years) with anomalous systemic or pulmonary venous connection underwent a Fontan procedure at our institution. Nine patients had a combination of anomalous systemic and pulmonary venous connection, 49 patients had anomalous drainage only from the systemic circulation, and 5 patients had isolated anomalies of pulmonary venous return. Visceral heterotaxy syndrome was diagnosed in 25 patients. Previous palliative operations had been performed in 51 patients (81%). There was 1 early death, and 2 patients required take down of Fontan procedures. Two patients required reoperation for revision of the atrial baffle. At a mean follow-up of 4.6 +/- 3.4 years, there have been 5 late deaths (8%) and 45 patients (71%) have undergone Fontan completion. Actuarial survival was 92% at 1 year and 91% at 5 and 10 years-not significantly different from the overall survival of the Fontan patients. We conclude that the modified FO can be successfully performed in patients with anomalous systemic or pulmonary venous connections, including those with visceral heterotaxy syndrome, with morbidity and mortality rates that do not differ significantly from those achieved in all patients with normal connections.

Adolescent↗
PubMed2003

Partial correlation analysis for the identification of synaptic connections.

In this paper, we investigate the use of partial correlation analysis for the identification of functional neural connectivity from simultaneously recorded neural spike trains. Partial correlation analysis allows one to distinguish between direct and indirect connectivities by removing the portion of the relationship between two neural spike trains that can be attributed to linear relationships with recorded spike trains from other neurons. As an alternative to the common frequency domain approach based on the partial spectral coherence we propose a new statistic in the time domain. The new scaled partial covariance density provides additional information on the direction and the type, excitatory or inhibitory, of the connectivities. In simulation studies, we investigated the power and limitations of the new statistic. The simulations show that the detectability of various connectivity patterns depends on various parameters such as connectivity strength and background activity. In particular, the detectability decreases with the number of neurons included in the analysis and increases with the recording time. Further, we show that the method can also be used to detect multiple direct connectivities between two neurons. Finally, the methods of this paper are illustrated by an application to neurophysiological data from spinal dorsal horn neurons.

Action Potentials↗