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L. Bello - One of the best experts on this subject based on the ideXlab platform.

  • Anatomo-functional characterisation of the human “hand-knob” : a direct electrophysiological study
    'Elsevier BV', 2019
    Co-Authors: L. Vigano, L. Fornia, M. Rossi, H. Howells, A. Leonetti, G. Puglisi, Conti M. Nibali, A. Bellacicca, M. Grimaldi, L. Bello
    Abstract:

    The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the ‘hand-knob’ and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an Internal Subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional Subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control

  • Anatomo-functional characterisation of the human “hand-knob” : a direct electrophysiological study
    'Elsevier BV', 2019
    Co-Authors: L. Vigano, L. Fornia, M. Rossi, H. Howells, A. Leonetti, G. Puglisi, Conti M. Nibali, A. Bellacicca, M. Grimaldi, L. Bello
    Abstract:

    The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the \u2018hand-knob\u2019 and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an Internal Subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional Subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control

Laurent Excoffier - One of the best experts on this subject based on the ideXlab platform.

  • distinguishing between population bottleneck and population Subdivision by a bayesian model choice procedure
    Molecular Ecology, 2010
    Co-Authors: Benjamin M Peter, Daniel Wegmann, Laurent Excoffier
    Abstract:

    Although most natural populations are genetically subdivided, they are often analysed as if they were panmictic units. In particular, signals of past demographic size changes are often inferred from genetic data by assuming that the analysed sample is drawn from a population without any Internal Subdivision. However, it has been shown that a bottleneck signal can result from the presence of some recent immigrants in a population. It thus appears important to contrast these two alternative scenarios in a model choice procedure to prevent wrong conclusions to be made. We use here an Approximate Bayesian Computation (ABC) approach to infer whether observed patterns of genetic diversity in a given sample are more compatible with it being drawn from a panmictic population having gone through some size change, or from one or several demes belonging to a recent finite island model. Simulations show that we can correctly identify samples drawn from a subdivided population in up to 95% of the cases for a wide range of parameters. We apply our model choice procedure to the case of the chimpanzee (Pan troglodytes) and find conclusive evidence that Western and Eastern chimpanzee samples are drawn from a spatially subdivided population.

L. Vigano - One of the best experts on this subject based on the ideXlab platform.

  • Anatomo-functional characterisation of the human “hand-knob” : a direct electrophysiological study
    'Elsevier BV', 2019
    Co-Authors: L. Vigano, L. Fornia, M. Rossi, H. Howells, A. Leonetti, G. Puglisi, Conti M. Nibali, A. Bellacicca, M. Grimaldi, L. Bello
    Abstract:

    The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the ‘hand-knob’ and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an Internal Subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional Subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control

  • Anatomo-functional characterisation of the human “hand-knob” : a direct electrophysiological study
    'Elsevier BV', 2019
    Co-Authors: L. Vigano, L. Fornia, M. Rossi, H. Howells, A. Leonetti, G. Puglisi, Conti M. Nibali, A. Bellacicca, M. Grimaldi, L. Bello
    Abstract:

    The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the \u2018hand-knob\u2019 and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an Internal Subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional Subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control

Hüneke Heiko - One of the best experts on this subject based on the ideXlab platform.

  • Diagnostic criteria using microfacies for calcareous contourites, turbidites and pelagites in the Eocene–Miocene slope succession, southern Cyprus
    'Wiley', 2020
    Co-Authors: Hüneke Heiko, Rodríguez Tovar, Francisco J
    Abstract:

    Interbedded contourites, turbidites and pelagites are commonplace in many deep-water slope environments. However, the distinction between these different facies remains a source of controversy. This detailed study of calcareous contourites and associated deep-marine facies from an Eocene–Miocene sedimentary succession on Cyprus clearly documents the diagnostic value of microfacies in this debate. In particular, the variability of archetypical bi-gradational contourite sequences and their Internal Subdivision (bedding, layering and lamination) are explored. Contourites can be distinguished from turbidites, pelagites and hemipelagites by means of carbonate microfacies in combination with bed-scale characteristics. Particle composition provides valuable information on sediment provenance. Depositional texture, determined by the ratio between carbonate mud and bioclasts, is crucial for identifying bi-gradational sequences in both muddy and sandy contourites, and normally-graded sequences in turbidite beds. Equally important are the type and preservation of traction structures, as well as the temporality and impact of bioturbation. Shell fragmentation under conditions of increased hydrodynamic agitation (textural inversion) is recognized as a carbonate-specific feature of bioclastic sandy contourites.Spanish Ciencia y Tecnologias Marinas projects CTM 2012-39599C03 CGL2016-80445-R CTM2016-75129-C3-1-RSecretaria de Estado de I+D+I, Spain CGL201566835-P PID2019-104625RB-100PFEDER Andalucía B-RNM-072-UGR18Junta de Andalucía P18-RT-4074Universidad de Granada UCE2016-05Projekt DEAL (University of Greifswald in the Alliance of German Science Organizations

  • Diagnostic criteria using microfacies for calcareous contourites, turbidites and pelagites in the Eocene–Miocene slope succession, southern Cyprus
    'Wiley', 2020
    Co-Authors: Hüneke Heiko, Hernández‐molina F. Javier, Rodríguez‐tovar, Francisco J., Llave Estefanía, Chiarella Domenico, Mena Anxo, Stow, Dorrik A.
    Abstract:

    Abstract Interbedded contourites, turbidites and pelagites are commonplace in many deep‐water slope environments. However, the distinction between these different facies remains a source of controversy. This detailed study of calcareous contourites and associated deep‐marine facies from an Eocene–Miocene sedimentary succession on Cyprus clearly documents the diagnostic value of microfacies in this debate. In particular, the variability of archetypical bi‐gradational contourite sequences and their Internal Subdivision (bedding, layering and lamination) are explored. Contourites can be distinguished from turbidites, pelagites and hemipelagites by means of carbonate microfacies in combination with bed‐scale characteristics. Particle composition provides valuable information on sediment provenance. Depositional texture, determined by the ratio between carbonate mud and bioclasts, is crucial for identifying bi‐gradational sequences in both muddy and sandy contourites, and normally‐graded sequences in turbidite beds. Equally important are the type and preservation of traction structures, as well as the temporality and impact of bioturbation. Shell fragmentation under conditions of increased hydrodynamic agitation (textural inversion) is recognized as a carbonate‐specific feature of bioclastic sandy contourites

H. Howells - One of the best experts on this subject based on the ideXlab platform.

  • Anatomo-functional characterisation of the human “hand-knob” : a direct electrophysiological study
    'Elsevier BV', 2019
    Co-Authors: L. Vigano, L. Fornia, M. Rossi, H. Howells, A. Leonetti, G. Puglisi, Conti M. Nibali, A. Bellacicca, M. Grimaldi, L. Bello
    Abstract:

    The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the ‘hand-knob’ and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an Internal Subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional Subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control

  • Anatomo-functional characterisation of the human “hand-knob” : a direct electrophysiological study
    'Elsevier BV', 2019
    Co-Authors: L. Vigano, L. Fornia, M. Rossi, H. Howells, A. Leonetti, G. Puglisi, Conti M. Nibali, A. Bellacicca, M. Grimaldi, L. Bello
    Abstract:

    The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the \u2018hand-knob\u2019 and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an Internal Subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional Subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control