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PubMed1993

Visual projections induced into the auditory pathway of ferrets: II. Corticocortical connections of primary auditory cortex.

Although the development of corticocortical projections has been well studied, less is known about the role of sensory inputs in the specification of these connections. As part of an ongoing series of studies in our laboratory, we have examined the role of thalamic input modality in the development of corticocortical connections. These studies involve making unilateral lesions and inducing retinal inputs into the auditory thalamus (MGN) during early development in ferrets, thereby conferring visual responsiveness on primary auditory cortex (AI). In this way we can examine the role of input identity in cortical specification in general, and connectivity patterns specifically. A previous paper (Pallas et al. [1990] J. Comp. Neurol. 298:50-68) described the pattern of thalamocortical and corticothalamic connections of auditory cortex in normal and lesioned animals. This study compares the pattern of auditory corticocortical connections in normal and lesioned animals. We injected neuroanatomical tracers into AI and mapped out the distribution of retrogradely labelled cells in the cortex. We report that the cortical inputs to ferret AI resembled those in cats, and that the pattern of ipsi- and contralateral corticocortical connections of ferret AI with visual input was similar to the normal pattern. Auditory cortex with visual input did not make ectopic connections with visual cortex, but maintained its connections with other auditory cortical areas. These results suggest that the overall corticocortical connections of an area are not influenced by the modality or activity pattern of its inputs. In particular, altering the input activity to a cortical area does not seem to promote the formation of entirely new connections, although small changes in the strength of existing connections are possible (Sur et al. [1990] Trends Neurosci. 13:227-233).

Animals↗
PubMed2005

Lagrangian frame diffeomorphic image registration: Morphometric comparison of human and chimpanzee cortex.

We develop a novel Lagrangian reference frame diffeomorphic image and landmark registration method. The algorithm uses the fixed Langrangian reference frame to define the map between coordinate systems, but also generates and stores the inverse map from the Eulerian to the Lagrangian frame. Computing both maps allows facile computation of both Eulerian and Langrangian quantities. We apply this algorithm to estimating a putative evolutionary change of coordinates between a population of chimpanzee and human cortices. Inter-species functional homologues fix the map explicitly, where they are known, while image similarities guide the alignment elsewhere. This map allows detailed study of the volumetric change between chimp and human cortex. Instead of basing the inter-species study on a single species atlas, we diffeomorphically connect the mean shape and intensity templates for each group. The human statistics then map diffeomorphically into the space of the chimpanzee cortex providing a comparison between species. The population statistics show a significant doubling of the relative prefrontal lobe size in humans, as compared to chimpanzees.

Algorithms↗
PubMed1997

The pathogenicity of the Pro1148Ala substitution in the FBN1 gene: causing or predisposing to Marfan syndrome and aortic aneurysm, or clinically innocent?

In individuals with the Marfan syndrome (MFS), mutations have been identified in the fibrillin-1 gene (FBN1) at 15q21.1. A proline-to-alanine change at position 1148 in exon 27 (Pro1148Ala) has been reported in probands with MFS, aortic aneurysm or Marfanoid-craniosynostosis. It was suggested that this mutation could be a risk factor for aortic dilatation, since it was rarely observed in control populations. To investigate further the pathogenicity of this substitution, we screened 416 unrelated control individuals by allele-specific oligonucleotide (ASO) hybridization. We found 16 individuals who carried the alanine allele (3.8%), 3 of whom were homozygous. Five were of Latin American and eight were of Asian extraction. We also screened 133 probands with MFS, aortic aneurysm or related connective tissue disorders and found 4 (3%) that were heterozygous for the 1148Ala allele. All positive results were confirmed by DNA sequencing. In 20 individuals with 1148Ala, we confirmed the association with the rarer A allele at the IVS27-5G-->A polymorphism. Our results suggest that the Pro1148Ala change is a polymorphism of ancient evolutionary origin that is more prevalent in Asian and Latin American than in Caucasian or African populations.

Alanine↗
PubMed2005

Cytology and functionally correlated circuits of human posterior cingulate areas.

Human posterior cingulate cortex (PCC) and retrosplenial cortex (RSC) form the posterior cingulate gyrus, however, monkey connection and human imaging studies suggest that PCC area 23 is not uniform and atlases mislocate RSC. We histologically assessed these regions in 6 postmortem cases, plotted a flat map, and characterized differences in dorsal (d) and ventral (v) area 23. Subsequently, functional connectivity of histologically guided regions of interest (ROI) were assessed in 163 [(18)F]fluorodeoxyglucose human cases with PET. Compared to area d23, area v23 had a higher density and larger pyramids in layers II, IIIc, and Vb and more intermediate neurofilament-expressing neurons in layer Va. Coregisrtration of each case to standard coordinates showed that the ventral branch of the splenial sulci coincided with the border between d/v PCC at -5.4 +/- 0.17 cm from the vertical plane and +1.97 +/- 0.08 cm from the bi-commissural line. Correlation analysis of glucose metabolism using histologically guided ROIs suggested important circuit differences including dorsal and ventral visual stream inputs, interactions between the vPCC and subgenual cingulate cortex, and preferential relations between dPCC and the cingulate motor region. The RSC, in contrast, had restricted correlated activity with pericallosal cortex and thalamus. Visual information may be processed with an orbitofrontal link for synthesis of signals to drive premotor activity through dPCC. Review of the literature in terms of a PCC duality suggests that interactions of dPCC, including area 23d, orient the body in space via the cingulate motor areas, while vPCC interacts with subgenual cortex to process self-relevant emotional and non-emotional information and objects and self-reflection.

Adult↗
PubMed1997

Convergence-Zone Episodic Memory: Analysis and Simulations.

Human episodic memory provides a seemingly unlimited storage for everyday experiences, and a retrieval system that allows us to access the experiences with partial activation of their components. The system is believed to consist of a fast, temporary storage in the hippocampus, and a slow, long-term storage within the neocortex. This paper presents a neural network model of the hippocampal episodic memory inspired by Damasio's idea of Convergence Zones. The model consists of a layer of perceptual feature maps and a binding layer. A perceptual feature pattern is coarse coded in the binding layer, and stored on the weights between layers. A partial activation of the stored features activates the binding pattern, which in turn reactivates the entire stored pattern. For many configurations of the model, a theoretical lower bound for the memory capacity can be derived, and it can be an order of magnitude or higher than the number of all units in the model, and several orders of magnitude higher than the number of binding-layer units. Computational simulations further indicate that the average capacity is an order of magnitude larger than the theoretical lower bound, and making the connectivity between layers sparser causes an even further increase in capacity. Simulations also show that if more descriptive binding patterns are used, the errors tend to be more plausible (patterns are confused with other similar patterns), with a slight cost in capacity. The convergence-zone episodic memory therefore accounts for the immediate storage and associative retrieval capability and large capacity of the hippocampal memory, and shows why the memory encoding areas can be much smaller than the perceptual maps, consist of rather coarse computational units, and are only sparsely connected to the perceptual maps. Copyright 1997 Elsevier Science Ltd.

Journal Article↗
PubMed1999

T cell receptor beta-chain third complementarity-determining region gene usage is highly restricted among Sm-B autoantigen-specific human T cell clones derived from patients with connective tissue disease.

OBJECTIVE: To determine the structure of T cell receptors (TCR) used by Sm-B-reactive human T cell clones, to map T cell epitopes on the Sm-B autoantigen, and to determine the HLA restriction element used in the recognition of Sm-B by T cells. METHODS: Sm-B-reactive T cell clones were generated from patients with connective tissue disease by using either a recombinant fusion protein or synthetic peptides. The TCR structure was defined with the use of polymerase chain reaction and DNA sequencing. Synthetic peptides were used to map T cell epitopes on Sm-B. HLA restriction element usage was defined by using monoclonal antibody blocking. RESULTS: Usage of the TCR third complementarity-determining region (CDR3) was highly restricted among Sm-B autoantigen-specific human T cell clones. Only amino acids 48-96 of the Sm-B2 autoantigen were recognized by T cells, and this occurred in the context of HLA-DR. CONCLUSION: TCR CDR3 gene usage is highly conserved by Sm-B autoantigen-specific T cell clones, and this appears to be related to the recognition of a limited number of T cell epitopes on the Sm-B autoantigen presented in the context of HLA-DR.

Amino Acid Sequence↗
PubMed1984

Retinal ganglion cell terminals change their projection sites during larval development of Rana pipiens.

Interconnecting neuronal populations in the vertebrate CNS are typically not well matched in their overall topographic patterns of histogenesis and differentiation during development. One striking example of this mismatch is the retinotectal system of the frog, where the retina grows in concentric annuli, while the optic tectum, a major retinal target, adds new neurons at only the caudo-medial border. The retinal ganglion cell (RGC) terminals nevertheless form an organized map in the tectum during the period when the two structures are undergoing such disparate modes of growth. This led Gaze et al. (Gaze, R. M., M. J. Keating, and S. H. Chung (1974) Proc. R. Soc. Lond. (Biol.) 185: 301-330) to propose that the terminals must shift caudally during development. In the present study, we have directly tested the hypothesis of "shifting connections" by selectively labeling an identified population of RGC terminals, those at the optic nerve head (ONH), and determining their tectal projection site relative to a particular group of [3H]thymidine-labeled tectal neurons. With this double-label technique, we have found that RGC terminals from cells at the ONH move from a position rostral to the [3H]thymidine-labeled tectal cells to a position caudal to these same cells during the latter half of larval development. This represents a movement of approximately 1.4 mm across the tectal surface between stages T&K XII and T&K XXV. In addition, we have used electron microscopy and electrophysiology to demonstrate that the RGC terminals make functional synaptic connections during this period. This indicates that RGC terminals continually change the tectal neurons with which they form functional synapses during the development of the retinotectal system. We propose that such moving, but highly ordered connections can best be explained by a two stage mechanism for map formation, in which graded selective adhesions between cells in appropriate regions of retina and tectum provide the overall gross retinotopy of the projection, while competitive interactions between RGC terminals are responsible for the refinement of the precision in this system.

Animals↗
PubMed2006

A parallel approach to STAP implementation for fMRI data.

PURPOSE: To exploit the capabilities of parallel processing in applying the space-time adaptive processing (STAP) algorithm, previously explored on a small scale for functional magnetic resonance imaging (fMRI) applications, to conventional size fMRI data sets. MATERIALS AND METHODS: STAP is a two-dimensional filter that is able to locate fMRI activations in both space and frequency. It is applied here for the construction of brain activation maps in fMRI using Visual Age C, incorporating Engineering and Scientific Subroutine Library (ESSL) functions, compiled in 64-bit, and executed on an IBM SP supercomputer. RESULTS: Computer simulations incorporating actual MRI noise indicate that STAP, incorporated using the method of steepest descent, is feasible on conventional size data sets and exhibits an improvement in detecting activations over the more traditional cross correlation method of fMRI analysis when the response is unknown. CONCLUSION: STAP is feasible on traditional size fMRI data sets and useful in elucidating spatial and temporal connectivity.

Algorithms↗
PubMed2001

Cryoablation of ventricular tachycardia guided by return cycle mapping after entrainment.

BACKGROUND: Although the implantable cardioverter-defibrillator effectively prevents sudden cardiac death, patients are still prone to recurrence of ventricular tachyarrhythmias. Electrophysiologically guided surgery is the most effective modality in abolishing ventricular tachycardia, having a lower recurrence rate than pharmacologic therapy or catheter ablation. Return cycle mapping after entrainment has been shown to localize the central common pathway, which is the target region for ablation, without pacing at the pathway or recording the potentials from the pathway. METHODS: To determine the accuracy and usefulness of return cycle mapping in surgery for ventricular tachycardia, we cryoablated 8 morphologies of ventricular tachycardia induced in postinfarction dogs with the guidance of return cycle mapping. The ventricular tachycardia was entrained from 3 to 5 different epicardial sites at a paced cycle length 10 to 20 ms shorter than the ventricular tachycardia cycle length and the epicardium was mapped with 61 unipolar electrodes during cessation of entrainment to construct return cycle maps. The return cycle was determined by subtracting the first activation time from the second activation time after the last stimulus in each electrode location, and the maps were then displayed on a computer. RESULTS: The total analysis process was completed within 3 minutes by means of a computer with custom-made programs. The activation map during ventricular tachycardia did not localize the central common pathway in any morphology of ventricular tachycardia, because the pattern of activation was concentric and diastolic potentials were not recorded. Cryoablation of the region where the isotemporal lines of the return cycle equal to the ventricular tachycardia cycle length intersected resulted in termination of ventricular tachycardia in all morphologies. The intersection was 26 +/- 9 mm from the earliest activation site. Epicardial mapping with 253 electrodes during cryothermia showed that the region localized by return cycle mapping was the central common pathway sandwiched between the lines of conduction block and that the cryolesion connected the lines of block, blocked the rotating wave front, and resulted in termination of the ventricular tachycardia. CONCLUSION: Return cycle mapping provides an accurate and rapid means of localizing the central common pathway without the need for recording potentials from the pathway or pacing at the pathway in ablation for ventricular tachycardia.

Animals↗
PubMed2000

Decreased extracellular-signal-regulated kinase and increased stress-activated MAP kinase activities in aged human skin in vivo.

The ability of human skin to rejuvenate itself diminishes with the passage of time, resulting in increased fragility. This increased fragility reflects both reduced growth of skin cells and loss of collagenous connective tissue. Oxidative damage plays a central role in cellular aging. Cellular responses to growth signals and oxidative stress are mediated, in part, by growth-factor-activated and stress-activated MAP kinases. We report here that the extracellular-signal-regulated MAP kinase pathway is reduced and the stress-activated MAP kinase pathway is increased in old, compared with young, human skin in vivo. Extracellular-signal-regulated kinase activity was 45% lower in old skin (mean age 84.3 y) relative to young skin (mean age 23.8 y). This lower extracellular- signal-regulated kinase activity resulted from reduced activation, since total extracellular-signal-regulated kinase protein levels did not differ between young and old skin, whereas phosphorylated (i.e., activated) extracellular-signal-regulated kinase protein was reduced 60% in old skin. Cyclin D2, which is regulated by extracellular-signal-regulated kinase and functions to promote cell cycle progression, was reduced 50% in old skin compared with young skin. In contrast, stress-activated MAP kinase activity was elevated 3.4-fold in old skin compared with young skin. This increased activity resulted from enhanced activation, since total stress-activated MAP kinase protein levels were similar in old and young skin. Transcription factor c-Jun, which is activated by stress-activated MAP kinases and promotes expression of connective-tissue-degrading matrix metalloproteinases, was elevated 2-fold in old skin compared with young skin. Treatment of old skin with vitamin A (retinol) for 7 d stimulated extracellular-signal-regulated kinase activity, consistent with its demonstrated ability to stimulate cell growth in old human skin. Taken together, these data indicate that alterations in MAP kinase activities play a key role in the pathophysiology of human skin aging.

Adolescent↗
PubMed1995

A simple model of chaotic advection and scattering.

In this work, we study a blinking vortex-uniform stream map. This map arises as an idealized, but essential, model of time-dependent convection past concentrated vorticity in a number of fluid systems. The map exhibits a rich variety of phenomena, yet it is simple enough so as to yield to extensive analytical investigation. The map's dynamics is dominated by the chaotic scattering of fluid particles near the vortex core. Studying the paths of fluid particles, it is seen that quantities such as residence time distributions and exit-vs-entry positions scale in self-similar fashions. A bifurcation is identified in which a saddle fixed point is created upstream at infinity. The homoclinic tangle formed by the transversely intersecting stable and unstable manifolds of this saddle is principally responsible for the observed self-similarity. Also, since the model is simple enough, various other properties are quantified analytically in terms of the circulation strength, stream velocity, and blinking period. These properties include: entire hierarchies of fixed points and periodic points, the parameter values at which these points undergo conservative period-doubling bifurcations, the structure of the unstable manifolds of the saddle fixed and periodic points, and the detailed structure of the resonance zones inside the vortex core region. A connection is made between a weakly dissipative version of our map and the Ikeda map from nonlinear optics. Finally, we discuss the essential ingredients that our model contains for studying how chaotic scattering induced by time-dependent flow past vortical structures produces enhanced diffusivities. (c) 1995 American Institute of Physics.

Journal Article↗
PubMed1999

Interhemispheric effects on map organization following simulated cortical lesions.

During recent years there has been increasing use of neural models to investigate the implications of hypotheses about brain and cognitive disorders. Here we systematically study the effects of sudden simulated lesions on cortical maps in a neural model consisting of left and right hemispheric regions connected by a corpus callosum. The model identifies conditions under which damage to one hemispheric region leads to reorganization of the contralateral, intact hemispheric region. The intact hemisphere's participation in the recovery process is found to be a function of pre-existing map lateralization/symmetry and lesion size, indicating that interpretation of future experimental work should take these factors into account.

Brain Diseases↗
PubMed1996

Characterization and surgical ablation of atrial flutter after the classic Fontan repair.

BACKGROUND: Atrial flutter (AFL) is a frequent postoperative complication of the classic Fontan operation, which uses an atriopulmonary connection. We hypothesized that the suture lines alone, in the absence of any hemodynamic alterations, provide the necessary electrophysiologic substrates for AFL. The objectives of this study were to determine if the Fontan suture lines alone are sufficient to permit sustained AFL in an acute canine model and to characterize any resulting reentrant circuits to surgically ablate the AFL. METHODS: After cardiopulmonary bypass, adult dogs (n = 18) underwent a simulated classic Fontan operation. This included a longitudinal right atriotomy and an incision from the base of the right atrial appendage toward the dome of the left atrium, representing the atriopulmonary connection. In 6 of 18 dogs, an atrial septal defect was created at the level of the fossa ovalis. Unipolar 253-point biatrial endocardial mapping electrodes were placed via bilateral ventriculotomies. Induction of AFL was attempted by atrial burst pacing. If AFL could not be induced, isoproterenol was administered and pacing repeated. Activation sequence maps of the pathways of atrial reentry were generated. In 8 dogs with inducible AFL, an incision was made from the atriotomy to the atriopulmonary connection and burst pacing repeated. RESULTS: Sustained AFL could not be induced after bypass alone in any case. After the simulated Fontan operation, sustained AFL was reproducibly induced in all 18 dogs, 6 of which required isoproterenol. The mean cycle length of all cases was 177 +/- 20 ms. During AFL, atrial activation sequence maps demonstrated lines of conduction block created by both the atriotomy and the atriopulmonary connection. The isthmus of tissue between these two lines of block was essential for propagation of the reentrant wavefront. Interruption of this isthmus with an incision successfully terminated AFL in 8 of 8 dogs. CONCLUSIONS: In an acute canine model, the Fontan suture lines alone, in the absence of atrial hypertension or stretch, permit the induction of AFL. An essential electrophysiologic substrate is an isthmus of myocardium between the atriotomy and the atriopulmonary connection. Interruption of conduction through this isthmus terminates the AFL in this model and suggests a technique for ablation of AFL in patients who have undergone a classic Fontan operation.

Animals↗
PubMed2026

Nuclear exosome targeting complexes modulate cohesin binding and enhancer-promoter interactions in 3D.

Three-dimensional long-range contacts between enhancers and promoters are thought to be largely determined by loop extrusion driven by the cohesin complex and insulator factors. However, recent evidence also suggests a role for noncoding RNAs, such as enhancer-associated RNAs and promoter upstream transcripts, in shaping enhancer-promoter connectivity. While the nuclear RNA exosome, together with targeting complexes, poly(A) tail exosome targeting connection and nuclear exosome targeting complex, controls the decay of noncoding RNAs, it remains unclear whether these complexes regulate three-dimensional chromatin contacts. Chromatin recruitment maps of the nuclear exosome targeting complex subunit ZCCHC8, the poly(A) tail exosome targeting connection subunit ZFC3H1, and the RNA helicase MTR4 in human cells reveal that these factors associate with sites of enhancer-promoter interactions. Depletion of these factors leads to the accumulation of ncRNAs, notably enhancer-associated RNAs and promoter upstream transcripts, and increases cohesin occupancy at these sites. Chromatin conformation capture analysis reveals that MTR4 modulates long-range enhancer-promoter contacts. Upon loss of MTR4, enhancer-promoter contacts increase while intraloop contacts decrease, suggesting that MTR4 facilitates loop extrusion. These data highlight a key interplay between cohesin-mediated enhancer-promoter interactions and the regulation of noncoding RNAs by nuclear RNA exosome targeting complexes that is consistent with a role for RNA in genome folding.

Cohesins↗
PubMed1984

Inferior parietal lobule. Divergent architectonic asymmetries in the human brain.

Architectonic parcellation of the parietal lobes of eight human brains, with special attention paid to the inferior parietal lobule, resulted in a map that bore a close relationship to previous maps and took into consideration modern data on physiology and connections. Two general parietal zones were distinguished, one above and the other below the intraparietal sulcus, similar to the dorsal-ventral distinction suggested for the frontal lobe. Five areas were recognized in the inferior parietal lobule, of which areas parietal areas EG (PEG), G (PG), and occipitoparietal G (OPG) were in the angular gyrus. A lateralization toward the right was found for area PEG, an area structurally similar to the visually related cortices of the posterior superior parietal region. A lateralization toward the left was found for area PG, but only in brains with a larger left planum temporale. The asymmetry in area PG seemed to be linked to other asymmetries present in language areas, whereas the right-sided area PEG preponderance showed no relation to the language asymmetries.

Adult↗
PubMed1997

Localization of the C terminus of the assembly domain of hepatitis B virus capsid protein: implications for morphogenesis and organization of encapsidated RNA.

The capsid protein of hepatitis B virus, consisting of an "assembly" domain (residues 1-149) and an RNA-binding "protamine" domain (residues 150-183), assembles from dimers into icosahedral capsids of two different sizes. The C terminus of the assembly domain (residues 140-149) functions as a morphogenetic switch, longer C termini favoring a higher proportion of the larger capsids, it also connects the protamine domain to the capsid shell. We now have defined the location of this peptide in capsids assembled in vitro by engineering a mutant assembly domain with a single cysteine at its C terminus (residue 150), labeling it with a gold cluster and visualizing the cluster by cryo-electron microscopy. The labeled protein is unimpaired in its ability to form capsids. Our density map reveals a single undecagold cluster under each fivefold and quasi-sixfold vertex, connected to sites at either end of the undersides of the dimers. Considering the geometry of the vertices, the C termini must be more crowded at the fivefolds. Thus, a bulky C terminus would be expected to favor formation of the larger (T = 4) capsids, which have a greater proportion of quasi-sixfolds. Capsids assembled by expressing the full-length protein in Escherichia coli package bacterial RNAs in amounts equivalent to the viral pregenome. Our density map of these capsids reveals a distinct inner shell of density-the RNA. The RNA is connected to the protein shell via the C-terminal linkers and also makes contact around the dimer axes.

Capsid↗
PubMed2005

Do cortical maps depend on the timing of sensory input? Experimental evidence and computational model.

Fast adaptations in the functional organization of primary sensory cortex are generally assumed to result from changes of network connectivity. However, the effects of intrinsic neuronal excitability alterations due to the activation of neighboring cortical representational zones, which might as well account for the changes of cortical representative maps, have been paid little attention to. In a recent experiment (Braun et al. 2000b) we showed by neuromagnetic source imaging that random or fixed sequence stimulation of three digits of both hands led to stimulation-timing-induced changes in primary somatosensory (SI) cortical maps. The distance between the cortical representation of thumb and middle finger became significantly shorter during the fixed sequence stimulation. The analysis on the time course of the cortical map changes revealed that these reorganizations occurred within minutes and were fully reversible. The previously reported results were interpreted as the involvement of a superordinate center responsible for detecting and activating the appropriate maps. Here we present an alternative parsimonious explanation that is supported by a computational model. Based on the experimental evidence, we developed a simple model that took intrinsic neuronal excitability together with subthreshold activation into account and assumed partial cortical overlap of the representational zones of neighboring digits. Furthermore, in the model the neuronal excitability decayed slowly with respect to the stimulation frequency. The observed cortical map changes in the experiment could be reproduced by the two-layer feed-forward computational network. Our model thus suggests that the dynamic shifts of cortical maps can be explained by the state and time course of intrinsic neuronal excitability and subthreshold activation, without involving changes in network connectivity.

Adult↗
PubMed2001

Advanced database methodology for the Collation of Connectivity data on the Macaque brain (CoCoMac).

The need to integrate massively increasing amounts of data on the mammalian brain has driven several ambitious neuroscientific database projects that were started during the last decade. Databasing the brain's anatomical connectivity as delivered by tracing studies is of particular importance as these data characterize fundamental structural constraints of the complex and poorly understood functional interactions between the components of real neural systems. Previous connectivity databases have been crucial for analysing anatomical brain circuitry in various species and have opened exciting new ways to interpret functional data, both from electrophysiological and from functional imaging studies. The eventual impact and success of connectivity databases, however, will require the resolution of several methodological problems that currently limit their use. These problems comprise four main points: (i) objective representation of coordinate-free, parcellation-based data, (ii) assessment of the reliability and precision of individual data, especially in the presence of contradictory reports, (iii) data mining and integration of large sets of partially redundant and contradictory data, and (iv) automatic and reproducible transformation of data between incongruent brain maps. Here, we present the specific implementation of the 'collation of connectivity data on the macaque brain' (CoCoMac) database (http://www.cocomac.org). The design of this database addresses the methodological challenges listed above, and focuses on experimental and computational neuroscientists' needs to flexibly analyse and process the large amount of published experimental data from tracing studies. In this article, we explain step-by-step the conceptual rationale and methodology of CoCoMac and demonstrate its practical use by an analysis of connectivity in the prefrontal cortex.

Animals↗