Publications (5)11.78 Total impact
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Article: S1 to S2 hind- and forelimb projections in the agouti somatosensory cortex: axon fragments morphological analysis.
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ABSTRACT: The integration of cutaneous, proprioceptive, and motor information in area S2 seems to be essential for manual object recognition and motor control. Part of the inputs to S2 comes from area S1. However no detailed investigations of the morphology of this projection are available. In the present study we describe and quantify the morphology of axon fragments of S1 to S2 ipsilateral projections in the agouti somatosensory cortex. Two groups of projecting axon arbors in S2 were individually reconstructed in three dimensions using Neurolucida, after a single electrophysiological guided BDA injection in either the forelimb (n=4) or the hindlimb (n=4). Electrophysiological mapping was performed 15 days after injections, allowing the localization of S2. Cluster analysis of 40 fragments after hindlimb and 40 after forelimb distinguished two clusters of terminals designated as type I and type II. On average, Type I fragments had greater surface areas and segment lengths than type II fragments, whereas type II fragments had higher number of terminal boutons, number of segments and branching points/mm than type I fragments. Type I corresponded to 58% of the axons projecting from the hindlimb representation in S1 whereas 63% of the sample originating from the forelimb representation in S1 corresponded to type II axons. The results suggest possible parallel processing by two stereotyped classes of axon terminals in the S1 to S2 projections that may represent at least part of the circuitry groundwork associated with distinct somatomotor skills of these limbs in agoutis.Journal of chemical neuroanatomy 10/2010; 40(4):339-45. · 1.75 Impact Factor -
Article: The organizational variability of the rodent somatosensory cortex.
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ABSTRACT: Rodentia is the largest mammalian order, with more than 2,000 species displaying a great diversity of morphological characteristics and living in different ecological niches (terrestrial, semi-aquatic, arboreal and fossorial). Analysis of the organization of the somatosensory areas in six species of rodents allowed us to demonstrate that although these species share a similar neocortical blueprint with other eutherian mammals, important differences exist between homologous areas across different species, probably as a function of both lifestyle and peripheral sensory specializations typical of each species. We based this generalization on a phylogenetic comparison of the intrinsic organization of the primary somatosensory area (SI) across representatives of different rodent suborders. This analysis revealed considerable structural variability, including the differential expansion of cortical representation of specific body parts (cortical amplification) as well as the parcellation of areas into processing modules.Reviews in the neurosciences 02/2007; 18(3-4):283-94. · 2.41 Impact Factor -
Article: Callosal axon arbors in the limb representations of the somatosensory cortex (SI) in the agouti (Dasyprocta primnolopha).
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ABSTRACT: The present report compares the morphology of callosal axon arbors projecting from and to the hind- or forelimb representations in the primary somatosensory cortex (SI) of the agouti (Dasyprocta primnolopha), a large, lisencephlic Brazilian rodent that uses forelimb coordination for feeding. Callosal axons were labeled after single pressure (n = 6) or iontophoretic injections (n = 2) of the neuronal tracer biotinylated dextran amine (BDA, 10 kD), either into the hind- (n = 4) or forelimb (n = 4) representations of SI, as identified by electrophysiological recording. Sixty-nine labeled axon fragments located across all layers of contralateral SI representations of the hindlimb (n = 35) and forelimb (n = 34) were analyzed. Quantitative morphometric features such as densities of branching points and boutons, segments length, branching angles, and terminal field areas were measured. Cluster analysis of these values revealed the existence of two types of axon terminals: Type I (46.4%), less branched and more widespread, and Type II (53.6%), more branched and compact. Both axon types were asymmetrically distributed; Type I axonal fragments being more frequent in hindlimb (71.9%) vs. forelimb (28.13%) representation, while most of Type II axonal arbors were found in the forelimb representation (67.56%). We concluded that the sets of callosal axon connecting fore- and hindlimb regions in SI are morphometrically distinct from each other. As callosal projections in somatosensory and motor cortices seem to be essential for bimanual interaction, we suggest that the morphological specialization of callosal axons in SI of the agouti may be correlated with this particular function.The Journal of Comparative Neurology 02/2007; 500(2):255-66. · 3.81 Impact Factor -
Article: Callosal axon arbors in the limb representations of the somatosensory cortex (SI) in the agouti (Dasyprocta primnolopha)
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ABSTRACT: The present report compares the morphology of callosal axon arbors projecting from and to the hind- or forelimb representations in the primary somatosensory cortex (SI) of the agouti (Dasyprocta primnolopha), a large, lisencephlic Brazilian rodent that uses forelimb coordination for feeding. Callosal axons were labeled after single pressure (n = 6) or iontophoretic injections (n = 2) of the neuronal tracer biotinylated dextran amine (BDA, 10 kD), either into the hind- (n = 4) or forelimb (n = 4) representations of SI, as identified by electrophysiological recording. Sixty-nine labeled axon fragments located across all layers of contralateral SI representations of the hindlimb (n = 35) and forelimb (n = 34) were analyzed. Quantitative morphometric features such as densities of branching points and boutons, segments length, branching angles, and terminal field areas were measured. Cluster analysis of these values revealed the existence of two types of axon terminals: Type I (46.4%), less branched and more widespread, and Type II (53.6%), more branched and compact. Both axon types were asymmetrically distributed; Type I axonal fragments being more frequent in hindlimb (71.9%) vs. forelimb (28.13%) representation, while most of Type II axonal arbors were found in the forelimb representation (67.56%). We concluded that the sets of callosal axon connecting fore- and hindlimb regions in SI are morphometrically distinct from each other. As callosal projections in somatosensory and motor cortices seem to be essential for bimanual interaction, we suggest that the morphological specialization of callosal axons in SI of the agouti may be correlated with this particular function. J. Comp. Neurol. 500:255–266, 2007. © 2006 Wiley-Liss, Inc.The Journal of Comparative Neurology 01/2007; 500(2):255 - 266. · 3.81 Impact Factor -
Article: S1 to S2 hind- and forelimb projections in the agouti somatosensory cortex: Axon fragments morphological analysis
[show abstract] [hide abstract]
ABSTRACT: The integration of cutaneous, proprioceptive, and motor information in area S2 seems to be essential for manual object recognition and motor control. Part of the inputs to S2 comes from area S1. However no detailed investigations of the morphology of this projection are available. In the present study we describe and quantify the morphology of axon fragments of S1 to S2 ipsilateral projections in the agouti somatosensory cortex. Two groups of projecting axon arbors in S2 were individually reconstructed in three dimensions using Neurolucida, after a single electrophysiological guided BDA injection in either the forelimb (n = 4) or the hindlimb (n = 4). Electrophysiological mapping was performed 15 days after injections, allowing the localization of S2. Cluster analysis of 40 fragments after hindlimb and 40 after forelimb distinguished two clusters of terminals designated as type I and type II. On average, Type I fragments had greater surface areas and segment lengths than type II fragments, whereas type II fragments had higher number of terminal boutons, number of segments and branching points/mm than type I fragments. Type I corresponded to 58% of the axons projecting from the hindlimb representation in S1 whereas 63% of the sample originating from the forelimb representation in S1 corresponded to type II axons. The results suggest possible parallel processing by two stereotyped classes of axon terminals in the S1 to S2 projections that may represent at least part of the circuitry groundwork associated with distinct somatomotor skills of these limbs in agoutis.Research highlights▶ Cortical S1 to S2 axon arbors were individually reconstructed. ▶ Cluster analysis of the morphologies distinguished two types of axon terminals. Type II arbors may recruit more neurons and potentially more synapses than type I. ▶ We suggest possible parallel processing by two stereotyped classes of axon terminals. A higher proportion of Type II fragment was found within the forelimb representation. ▶ Bi-lateral sensorimotor behavior in the agouti is restricted to the forelimbs. ▶ Axon morphological differences may contribute to these distinct somatomotor skills.Journal of Chemical Neuroanatomy. 40(4):339-345.
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Institutions
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2010
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Hospital Universitário João de Barros Barreto
Belém, Estado do Para, Brazil
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2007
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Universidade Federal do Pará
- Departamento de Patologia
Belém, Estado do Para, Brazil -
Universidade Federal do Oeste do Pará
Santarém, Estado do Para, Brazil
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