The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform
Shigeo Okoyama - One of the best experts on this subject based on the ideXlab platform.
-
anatomical plasticity of the Tectospinal Tract after unilateral lesion of the superior colliculus in the neonatal rat
1991Co-Authors: Shigeo OkoyamaAbstract:After unilateral ablation of the superior colliculus (SC) in neonatal or adult rats, the reorganization of the Tectospinal Tract (TST) was examined using the technique of anterograde transport of horseradish peroxidase to which wheat germ agglutinin had been conjugated (WGA-HRP). In neonatally lesioned rats, aberrant labeled terminals of TST axons were found on the ipsilateral side of the spinal cord. Postnatal development of the TST was then studied by retrograde transport of HRP to determine whether the aberrant Tectospinal projections resulted from normally transient ipsilateral projections that persisted in operated rats or were due to collateral sprouting of projections to the contralateral projection field. The results failed to show an ipsilateral projection from the SC to spinal cord in normal neonatal rats. However, in neonatally lesioned rats, aberrant labeled fibers were observed recrossing the midline of the cervical spinal cord. Therefore, the increase in labeled terminals on the ipsilateral side following unilateral SC ablation appeared to originate from collateral sprouting at the spinal cord level of TST fibers from the intact pathway.
V C Abrahams - One of the best experts on this subject based on the ideXlab platform.
-
projections of the Tectospinal Tract to the upper cervical spinal cord of the cat a study with the anterograde tracer pha l
1991Co-Authors: P K Rose, J Macdonald, V C AbrahamsAbstract:The goal of the present experiments was to re-examine the spinal projections of neurons in the superior colliculus (SC) of the cat by taking advantage of the high sensitivity of the anterograde tracer, phaseolus vulgaris leucoagglutinin (PHA-L). In seven experiments, multiple injections of PHA-L into different regions of the SC labelled a total of 172 axons in the predorsal bundle; yet only 11 Tectospinal Tract (TST) axons were found in the upper cervical spinal cord. Collaterals emerging from these axons were rare and arose exclusively from TST axons with a diameter of less than 1 micron. Individual collaterals had different termination zones: some terminated in the lateral part of lamina V and VI after taking a dorsolateral course through lamina VII and VIII; others terminated in the medial part of lamina VII. One collateral terminated within lamina IX and the ventral part of lamina VIII. The combined termination of all collaterals was densest in lamina VII and dorsal lamina VIII. A small number of boutons were also found in the lateral parts of laminae V and VI, and in lamina IX and immediately adjacent regions in lamina VIII. Compared to axons belonging to other spinal descending systems, individual TST axons give rise to much simpler intraspinal collaterals with relatively few boutons. This feature, together with the relative paucity of TST axons, suggests that direct connections from the SC to neurons in the upper cervical spinal cord are sparse. Furthermore, our results are consistent with electrophysiological studies that show that few, if any, neck motoneurons receive monosynaptic connections from TST neurons. Projections to neck motoneurons must therefore involve a relay, either through other descending pathways, such as the reticulospinal system, or via local segmental interneurons.
Eric M. Rouiller - One of the best experts on this subject based on the ideXlab platform.
-
Corticotectal Projections From the Premotor or Primary Motor Cortex After Cortical Lesion or Parkinsonian Symptoms in Adult Macaque Monkeys: A Pilot Tracing Study.
2019Co-Authors: Michela Fregosi, Martin E. Schwab, Jocelyne Bloch, Alessandro Contestabile, Simon Badoud, Simon Borgognon, Jérôme Cottet, Jean-françois Brunet, Eric M. RouillerAbstract:: The corticotectal projections, together with the corticobulbar (corticoreticular) projections, work in parallel with the corticospinal Tract (CST) to influence motoneurons in the spinal cord both directly and indirectly via the brainstem descending pathways. The Tectospinal Tract (TST) originates in the deep layers of the superior colliculus. In the present study, we analyzed the corticotectal projections from two motor cortical areas, namely the premotor cortex (PM) and the primary motor cortex (M1) in eight macaque monkeys subjected to either a cortical lesion of the hand area in M1 (n = 4) or Parkinson's disease-like symptoms PD (n = 4). A subgroup of monkeys with cortical lesion was subjected to anti-Nogo-A antibody treatment whereas all PD monkeys were transplanted with Autologous Neural Cell Ecosystems (ANCEs). The anterograde tracer BDA was used to label the axonal boutons both en passant and terminaux in the ipsilateral superior colliculus. Individual axonal boutons were charted in the different layers of the superior colliculus. In intact animals, we previously observed that corticotectal projections were denser when originating from PM than from M1. In the present M1 lesioned monkeys, as compared to intact ones the corticotectal projection originating from PM was decreased when treated with anti-Nogo-A antibody but not in untreated monkeys. In PD-like symptoms' monkeys, on the other hand, there was no consistent change affecting the corticotectal projection as compared to intact monkeys. The present pilot study overall suggests that the corticotectal projection is less affected by M1 lesion or PD symptoms than the corticoreticular projection previously reported in the same animals.
P K Rose - One of the best experts on this subject based on the ideXlab platform.
-
projections of the Tectospinal Tract to the upper cervical spinal cord of the cat a study with the anterograde tracer pha l
1991Co-Authors: P K Rose, J Macdonald, V C AbrahamsAbstract:The goal of the present experiments was to re-examine the spinal projections of neurons in the superior colliculus (SC) of the cat by taking advantage of the high sensitivity of the anterograde tracer, phaseolus vulgaris leucoagglutinin (PHA-L). In seven experiments, multiple injections of PHA-L into different regions of the SC labelled a total of 172 axons in the predorsal bundle; yet only 11 Tectospinal Tract (TST) axons were found in the upper cervical spinal cord. Collaterals emerging from these axons were rare and arose exclusively from TST axons with a diameter of less than 1 micron. Individual collaterals had different termination zones: some terminated in the lateral part of lamina V and VI after taking a dorsolateral course through lamina VII and VIII; others terminated in the medial part of lamina VII. One collateral terminated within lamina IX and the ventral part of lamina VIII. The combined termination of all collaterals was densest in lamina VII and dorsal lamina VIII. A small number of boutons were also found in the lateral parts of laminae V and VI, and in lamina IX and immediately adjacent regions in lamina VIII. Compared to axons belonging to other spinal descending systems, individual TST axons give rise to much simpler intraspinal collaterals with relatively few boutons. This feature, together with the relative paucity of TST axons, suggests that direct connections from the SC to neurons in the upper cervical spinal cord are sparse. Furthermore, our results are consistent with electrophysiological studies that show that few, if any, neck motoneurons receive monosynaptic connections from TST neurons. Projections to neck motoneurons must therefore involve a relay, either through other descending pathways, such as the reticulospinal system, or via local segmental interneurons.
Michela Fregosi - One of the best experts on this subject based on the ideXlab platform.
-
Corticotectal Projections From the Premotor or Primary Motor Cortex After Cortical Lesion or Parkinsonian Symptoms in Adult Macaque Monkeys: A Pilot Tracing Study.
2019Co-Authors: Michela Fregosi, Martin E. Schwab, Jocelyne Bloch, Alessandro Contestabile, Simon Badoud, Simon Borgognon, Jérôme Cottet, Jean-françois Brunet, Eric M. RouillerAbstract:: The corticotectal projections, together with the corticobulbar (corticoreticular) projections, work in parallel with the corticospinal Tract (CST) to influence motoneurons in the spinal cord both directly and indirectly via the brainstem descending pathways. The Tectospinal Tract (TST) originates in the deep layers of the superior colliculus. In the present study, we analyzed the corticotectal projections from two motor cortical areas, namely the premotor cortex (PM) and the primary motor cortex (M1) in eight macaque monkeys subjected to either a cortical lesion of the hand area in M1 (n = 4) or Parkinson's disease-like symptoms PD (n = 4). A subgroup of monkeys with cortical lesion was subjected to anti-Nogo-A antibody treatment whereas all PD monkeys were transplanted with Autologous Neural Cell Ecosystems (ANCEs). The anterograde tracer BDA was used to label the axonal boutons both en passant and terminaux in the ipsilateral superior colliculus. Individual axonal boutons were charted in the different layers of the superior colliculus. In intact animals, we previously observed that corticotectal projections were denser when originating from PM than from M1. In the present M1 lesioned monkeys, as compared to intact ones the corticotectal projection originating from PM was decreased when treated with anti-Nogo-A antibody but not in untreated monkeys. In PD-like symptoms' monkeys, on the other hand, there was no consistent change affecting the corticotectal projection as compared to intact monkeys. The present pilot study overall suggests that the corticotectal projection is less affected by M1 lesion or PD symptoms than the corticoreticular projection previously reported in the same animals.
