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Y. Uchino - One of the best experts on this subject based on the ideXlab platform.
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Otolith and canal integration on single vestibular neurons in cats
Experimental Brain Research, 2005Co-Authors: Y. Uchino, M. Sasaki, H. Sato, E. KawamotoAbstract:In this review, based primarily on work from our laboratory, but related to previous studies, we summarize what is known about the convergence of vestibular afferent inputs onto single vestibular neurons activated by selective stimulation of individual vestibular nerve branches. Horizontal semicircular canal (HC), anterior semicircular canal (AC), posterior semicircular canal (PC), utricular (UT), and saccular (SAC) nerves were selectively stimulated in decerebrate cats. All recorded neurons were classified as either projection neurons, which consisted of Vestibulospinal (VS), vestibulo-oculospinal (VOS), vestibulo-ocular (VO) neurons, or non-projection neurons, which we simply term “vestibular″ (V) neurons. The first three types could be successfully activated antidromically from oculomotor/trochlear nuclei and/or spinal cord, and the last type could not be activated antidromically from either site. A total of 1228 neurons were activated by stimulation of various nerve pair combinations. Convergent neurons were located in the caudoventral part of the Lateral, the rostral part of the descending, and the medial vestibular nuclei. Otolith-activated vestibular neurons in the superior vestibular nucleus were extremely rare. A high percentage of neurons received excitatory inputs from two nerve pairs, a small percentage received reciprocal convergent inputs and even fewer received inhibitory inputs from both nerves. More than 30% of vestibular neurons received convergent inputs from vertical semicircular canal/otolith nerve pairs. In contrast, only half as many received convergent inputs from HC/otolith-nerve pairs, implying that convergent input from vertical semicircular canal and otolith-nerve pairs may play a more important role than that played by inputs from horizontal semicircular canal and otolith-nerve pairs. Convergent VS neurons projected through the ipsiLateral Lateral Vestibulospinal Tract (i-LVST) and the medial Vestibulospinal Tract (MVST). Almost all the VOS neurons projected through the MVST. Convergent neurons projecting to the oculomotor/trochlear nuclei were much fewer in number than those projecting to the spinal cord. Some of the convergent neurons that receive both canal and otolith input may contribute to the short-latency pathway of the vestibulocollic reflex. The functional significance of these convergences is discussed.
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Convergence of the anterior semicircular canal and otolith afferents on cat single vestibular neurons
Experimental Brain Research, 2002Co-Authors: X. Zhang, M. Sasaki, H. Sato, H. Meng, M. Imagawa, Y. UchinoAbstract:The convergence between the anterior semicircular canal (AC) and utricular (UT) inputs, as well as the convergence between the AC and saccular (SAC) inputs in single vestibular neurons of decerebrated cats were investigated. Postsynaptic potentials were recorded intracellularly after selective stimulation of each pair of vestibular nerves AC/UT or AC/SAC. Neurons were recorded from the central parts of the vestibular nuclei, where the otolith afferents mainly terminate. Of a total of 105 neurons that were activated after stimulation of the AC and UT nerves, 42 received convergent inputs. Thirty-eight of these neurons received excitatory inputs from both afferents. Convergent neurons were further classified into Vestibulospinal ( n =28) and vestibulooculospinal ( n =6) neurons by antidromic activation from the border between the C1 and C2 spinal cord and the oculomotor or trochlear nucleus. Eight neurons that were not antidromically activated from either site were classified as vestibular neurons. Forty three percent of the convergent Vestibulospinal neurons and most of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract. Of a total of 118 neurons that were activated after stimulation of the AC and/or SAC nerves, 51 received convergent inputs (27 Vestibulospinal, 4 vestibulooculospinal, 5 vestibuloocular and 15 vestibular neurons). Forty-two of the convergent neurons received excitatory inputs from both afferents. Thirty seven percent of the convergent Vestibulospinal neurons and all of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract.
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Convergence of the horizontal semicircular canal and otolith afferents on cat single vestibular neurons
Experimental Brain Research, 2001Co-Authors: X. Zhang, H. Sato, H. Meng, M. Zakir, Y. UchinoAbstract:We studied the convergence of two afferent pairs of single vestibular neurons by selective stimulation of the horizontal semicircular canal (HC) and saccular (SAC) nerves, and the HC and utricular (UT) nerves in decerebrate cats. All recorded neurons were classified as Vestibulospinal (VS), vestibulo-oculospinal (VOS) or vestibulo-ocular (VO), by antidromic stimulation from the oculomotor/trochlear nuclei and the spinal cord: neurons that could not be activated from any test sites were classified as vestibular (V) neurons. Of a total of 125 neurons activated by stimulation of the HC/SAC nerves, 21(17%) received convergent inputs. Twelve of 21 neurons received monosynaptic excitatory inputs from both nerves. About half (9/21, 43%) of the convergent neurons were classified as VS neurons, the majority of which descended through the ipsiLateral Lateral Vestibulospinal Tract (i-LVST). The HC/SAC convergent neurons were located in the rostral part of the descending, the medial and the caudal-ventral part of the Lateral vestibular nucleus. In 80 neurons studied by stimulation of the HC/UT nerves, both inputs converged in 12 (15%) neurons, more than half of which were VS neurons. Eight of 12 convergent neurons received excitatory inputs followed by inhibition from both the HC and UT nerves. A few convergent neurons (3/12) projected to the oculomotor/trochlear nucleus. Half of the convergent and non-convergent VS neurons descended to the spinal cord through the i-LVST, and the only one VOS convergent neuron via the medial Vestibulospinal Tract. Most of the convergent neurons were located in the Lateral, the rostral part of the descending and medial vestibular nucleus. The percentages of HC/SAC and HC/UT convergence were half those of the posterior semicircular canal (PC), PC/SAC (33%) and PC/UT (33%) convergence, respectively. The convergent neurons receiving the HC and otolith inputs may contribute at least partly to the vestibulocollic reflex.
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Convergence patterns of the posterior semicircular canal and utricular inputs in single vestibular neurons in cats
Experimental Brain Research, 2000Co-Authors: M. Zakir, H. Sato, K. Kushiro, Y. Ogawa, Y. UchinoAbstract:The convergence of the posterior semicircular canal (PC) and utricular (UT) inputs in single vestibular nuclei neurons was studied intracellularly in decerebrate cats. A total of 160 vestibular neurons were orthodromically activated by selective stimulation of the PC and the UT nerve and classified according to whether or not they were antidromically activated from the spinal cord and oculomotor nuclei into Vestibulospinal (VS), vestibulooculospinal (VOS), vestibuloocular (VO), and unidentified vestibular neurons. Fifty-three (33%) of 160 vestibular neurons received convergent inputs from both the PC and UT nerves. Seventy-nine (49%) vestibular neurons responded to PC inputs alone, and 28 (18%) neurons received inputs only from the UT nerve. Of 53 convergent neurons, 8 (15%) were monosynaptically excited from both nerves. Thirty-five (66%) received monosynaptic excitatory inputs from the PC nerve and polysynaptic excitatory or inhibitory inputs from the UT nerve, or vice versa. Approximately one-third of VS and VOS neurons received convergent inputs. A majority of the VS neurons descended to the spinal cord through the Lateral Vestibulospinal Tract, while almost all the VOS neurons descended to the spinal cord through the medial Vestibulospinal Tract. The convergent neurons were found in all vestibular nuclei but more in the Lateral nucleus and descending nucleus. The VS neurons were more numerous than VO neurons or VOS neurons.
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Convergence of posterior semicircular canal and saccular inputs in single vestibular nuclei neurons in cats
Experimental Brain Research, 2000Co-Authors: H. Sato, M. Imagawa, K. Kushiro, M. Zakir, Y. UchinoAbstract:Convergence between posterior canal (PC) and saccular (SAC) inputs in single vestibular nuclei neurons was investigated in decerebrated cats. Postsynaptic potentials were recorded intracellularly after selective stimulation of the SAC and PC nerves. Stimulation of either the SAC or PC nerve orthodromically activated 143 vestibular nuclei neurons. Of these, 61 (43%) were antidromically activated by stimulation of the C1–C2 junction, 14 (10%) were antidromically activated by stimulation of the oculomotor or trochlear nucleus, and 14 (10%) were antidromically activated by stimulation of both the oculomotor or trochlear nucleus and the spinal cord. Fifty-four (38%) neurons were not activated by stimulation of either or both. We named these neurons Vestibulospinal (VS), vestibulo-ocular (VO), vestibulo-oculo-spinal (VOS) and vestibular (V) neurons, respectively. Both PC and SAC inputs converged in 47 vestibular nuclei neurons (26 VS, 2 VO, 6 VOS and 13 V neurons). Of these, 19 received monosynaptic excitatory inputs from both nerves. This input pattern was frequently seen in VS neurons. Approximately half of the convergent VS neurons descended to the spinal cord through the Lateral Vestibulospinal Tract. The remaining half and all the convergent VOS neurons descended to the spinal cord through the medial Vestibulospinal Tract. Most of the convergent neurons were located in the Lateral nucleus or descending nucleus.
H. Sato - One of the best experts on this subject based on the ideXlab platform.
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Axonal Pathways and Projection Levels of Vestibulospinal Neurons Activated by Posterior Semicircular Canal
Equilibrium Research, 2020Co-Authors: Akira Hagiwara, H. Sato, H. Meng, Yoshio Uchino, Mamoru SuzukiAbstract:Axonal pathways and the projection levels of posterior-semicircular canal (PC)-ac-tivated Vestibulospinal neurons were studied in decerebrated and anesthetized cats. The PC nerve was selectively stimulated by bipolar silver electrodes. Two monopolar electrodes were inserted into the Lateral Vestibulospinal Tract (LVST) and medial Vestibulospinal Tract (MVST) to determine the pathway of axons. Three pairs of similar electrodes were positioned in the C2-3, C7-T1 and T12-L3 segments to examine projection levels. Another monopolar electrode was placed in the oculomotor nuclei to determine whether PC-nerve-activated Vestibulospinal neurons s have branches ascending to the oculomotor nuclei.Fifty six neurons were activated orthodromically after PC nerve stimulation. Ten PC-nerve-activated Vestibulospinal neurons were also antidromicaly activated from the oculomotor nuclei. All of these vestibulo-oculo-spinal (VOS) neurons descended through the MVST and terminated in the upper cervical segments. Eighteen PC-ner-ve-activated Vestibulospinal neurons descended through the LVST, 45% of which reached upper lumber segments. Fourteen Vestibulospinal neurons descended through the MVST. Most of these terminated in upper cervical segments. These results suggest that VOS neurons convey posterior semicircular canal signals to both the ocular and neck motor centers, linking eye and head movement.
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Otolith and canal integration on single vestibular neurons in cats
Experimental Brain Research, 2005Co-Authors: Y. Uchino, M. Sasaki, H. Sato, E. KawamotoAbstract:In this review, based primarily on work from our laboratory, but related to previous studies, we summarize what is known about the convergence of vestibular afferent inputs onto single vestibular neurons activated by selective stimulation of individual vestibular nerve branches. Horizontal semicircular canal (HC), anterior semicircular canal (AC), posterior semicircular canal (PC), utricular (UT), and saccular (SAC) nerves were selectively stimulated in decerebrate cats. All recorded neurons were classified as either projection neurons, which consisted of Vestibulospinal (VS), vestibulo-oculospinal (VOS), vestibulo-ocular (VO) neurons, or non-projection neurons, which we simply term “vestibular″ (V) neurons. The first three types could be successfully activated antidromically from oculomotor/trochlear nuclei and/or spinal cord, and the last type could not be activated antidromically from either site. A total of 1228 neurons were activated by stimulation of various nerve pair combinations. Convergent neurons were located in the caudoventral part of the Lateral, the rostral part of the descending, and the medial vestibular nuclei. Otolith-activated vestibular neurons in the superior vestibular nucleus were extremely rare. A high percentage of neurons received excitatory inputs from two nerve pairs, a small percentage received reciprocal convergent inputs and even fewer received inhibitory inputs from both nerves. More than 30% of vestibular neurons received convergent inputs from vertical semicircular canal/otolith nerve pairs. In contrast, only half as many received convergent inputs from HC/otolith-nerve pairs, implying that convergent input from vertical semicircular canal and otolith-nerve pairs may play a more important role than that played by inputs from horizontal semicircular canal and otolith-nerve pairs. Convergent VS neurons projected through the ipsiLateral Lateral Vestibulospinal Tract (i-LVST) and the medial Vestibulospinal Tract (MVST). Almost all the VOS neurons projected through the MVST. Convergent neurons projecting to the oculomotor/trochlear nuclei were much fewer in number than those projecting to the spinal cord. Some of the convergent neurons that receive both canal and otolith input may contribute to the short-latency pathway of the vestibulocollic reflex. The functional significance of these convergences is discussed.
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Convergence of the anterior semicircular canal and otolith afferents on cat single vestibular neurons
Experimental Brain Research, 2002Co-Authors: X. Zhang, M. Sasaki, H. Sato, H. Meng, M. Imagawa, Y. UchinoAbstract:The convergence between the anterior semicircular canal (AC) and utricular (UT) inputs, as well as the convergence between the AC and saccular (SAC) inputs in single vestibular neurons of decerebrated cats were investigated. Postsynaptic potentials were recorded intracellularly after selective stimulation of each pair of vestibular nerves AC/UT or AC/SAC. Neurons were recorded from the central parts of the vestibular nuclei, where the otolith afferents mainly terminate. Of a total of 105 neurons that were activated after stimulation of the AC and UT nerves, 42 received convergent inputs. Thirty-eight of these neurons received excitatory inputs from both afferents. Convergent neurons were further classified into Vestibulospinal ( n =28) and vestibulooculospinal ( n =6) neurons by antidromic activation from the border between the C1 and C2 spinal cord and the oculomotor or trochlear nucleus. Eight neurons that were not antidromically activated from either site were classified as vestibular neurons. Forty three percent of the convergent Vestibulospinal neurons and most of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract. Of a total of 118 neurons that were activated after stimulation of the AC and/or SAC nerves, 51 received convergent inputs (27 Vestibulospinal, 4 vestibulooculospinal, 5 vestibuloocular and 15 vestibular neurons). Forty-two of the convergent neurons received excitatory inputs from both afferents. Thirty seven percent of the convergent Vestibulospinal neurons and all of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract.
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Convergence of the horizontal semicircular canal and otolith afferents on cat single vestibular neurons
Experimental Brain Research, 2001Co-Authors: X. Zhang, H. Sato, H. Meng, M. Zakir, Y. UchinoAbstract:We studied the convergence of two afferent pairs of single vestibular neurons by selective stimulation of the horizontal semicircular canal (HC) and saccular (SAC) nerves, and the HC and utricular (UT) nerves in decerebrate cats. All recorded neurons were classified as Vestibulospinal (VS), vestibulo-oculospinal (VOS) or vestibulo-ocular (VO), by antidromic stimulation from the oculomotor/trochlear nuclei and the spinal cord: neurons that could not be activated from any test sites were classified as vestibular (V) neurons. Of a total of 125 neurons activated by stimulation of the HC/SAC nerves, 21(17%) received convergent inputs. Twelve of 21 neurons received monosynaptic excitatory inputs from both nerves. About half (9/21, 43%) of the convergent neurons were classified as VS neurons, the majority of which descended through the ipsiLateral Lateral Vestibulospinal Tract (i-LVST). The HC/SAC convergent neurons were located in the rostral part of the descending, the medial and the caudal-ventral part of the Lateral vestibular nucleus. In 80 neurons studied by stimulation of the HC/UT nerves, both inputs converged in 12 (15%) neurons, more than half of which were VS neurons. Eight of 12 convergent neurons received excitatory inputs followed by inhibition from both the HC and UT nerves. A few convergent neurons (3/12) projected to the oculomotor/trochlear nucleus. Half of the convergent and non-convergent VS neurons descended to the spinal cord through the i-LVST, and the only one VOS convergent neuron via the medial Vestibulospinal Tract. Most of the convergent neurons were located in the Lateral, the rostral part of the descending and medial vestibular nucleus. The percentages of HC/SAC and HC/UT convergence were half those of the posterior semicircular canal (PC), PC/SAC (33%) and PC/UT (33%) convergence, respectively. The convergent neurons receiving the HC and otolith inputs may contribute at least partly to the vestibulocollic reflex.
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Convergence patterns of the posterior semicircular canal and utricular inputs in single vestibular neurons in cats
Experimental Brain Research, 2000Co-Authors: M. Zakir, H. Sato, K. Kushiro, Y. Ogawa, Y. UchinoAbstract:The convergence of the posterior semicircular canal (PC) and utricular (UT) inputs in single vestibular nuclei neurons was studied intracellularly in decerebrate cats. A total of 160 vestibular neurons were orthodromically activated by selective stimulation of the PC and the UT nerve and classified according to whether or not they were antidromically activated from the spinal cord and oculomotor nuclei into Vestibulospinal (VS), vestibulooculospinal (VOS), vestibuloocular (VO), and unidentified vestibular neurons. Fifty-three (33%) of 160 vestibular neurons received convergent inputs from both the PC and UT nerves. Seventy-nine (49%) vestibular neurons responded to PC inputs alone, and 28 (18%) neurons received inputs only from the UT nerve. Of 53 convergent neurons, 8 (15%) were monosynaptically excited from both nerves. Thirty-five (66%) received monosynaptic excitatory inputs from the PC nerve and polysynaptic excitatory or inhibitory inputs from the UT nerve, or vice versa. Approximately one-third of VS and VOS neurons received convergent inputs. A majority of the VS neurons descended to the spinal cord through the Lateral Vestibulospinal Tract, while almost all the VOS neurons descended to the spinal cord through the medial Vestibulospinal Tract. The convergent neurons were found in all vestibular nuclei but more in the Lateral nucleus and descending nucleus. The VS neurons were more numerous than VO neurons or VOS neurons.
M. Zakir - One of the best experts on this subject based on the ideXlab platform.
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Convergence of the horizontal semicircular canal and otolith afferents on cat single vestibular neurons
Experimental Brain Research, 2001Co-Authors: X. Zhang, H. Sato, H. Meng, M. Zakir, Y. UchinoAbstract:We studied the convergence of two afferent pairs of single vestibular neurons by selective stimulation of the horizontal semicircular canal (HC) and saccular (SAC) nerves, and the HC and utricular (UT) nerves in decerebrate cats. All recorded neurons were classified as Vestibulospinal (VS), vestibulo-oculospinal (VOS) or vestibulo-ocular (VO), by antidromic stimulation from the oculomotor/trochlear nuclei and the spinal cord: neurons that could not be activated from any test sites were classified as vestibular (V) neurons. Of a total of 125 neurons activated by stimulation of the HC/SAC nerves, 21(17%) received convergent inputs. Twelve of 21 neurons received monosynaptic excitatory inputs from both nerves. About half (9/21, 43%) of the convergent neurons were classified as VS neurons, the majority of which descended through the ipsiLateral Lateral Vestibulospinal Tract (i-LVST). The HC/SAC convergent neurons were located in the rostral part of the descending, the medial and the caudal-ventral part of the Lateral vestibular nucleus. In 80 neurons studied by stimulation of the HC/UT nerves, both inputs converged in 12 (15%) neurons, more than half of which were VS neurons. Eight of 12 convergent neurons received excitatory inputs followed by inhibition from both the HC and UT nerves. A few convergent neurons (3/12) projected to the oculomotor/trochlear nucleus. Half of the convergent and non-convergent VS neurons descended to the spinal cord through the i-LVST, and the only one VOS convergent neuron via the medial Vestibulospinal Tract. Most of the convergent neurons were located in the Lateral, the rostral part of the descending and medial vestibular nucleus. The percentages of HC/SAC and HC/UT convergence were half those of the posterior semicircular canal (PC), PC/SAC (33%) and PC/UT (33%) convergence, respectively. The convergent neurons receiving the HC and otolith inputs may contribute at least partly to the vestibulocollic reflex.
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Convergence patterns of the posterior semicircular canal and utricular inputs in single vestibular neurons in cats
Experimental Brain Research, 2000Co-Authors: M. Zakir, H. Sato, K. Kushiro, Y. Ogawa, Y. UchinoAbstract:The convergence of the posterior semicircular canal (PC) and utricular (UT) inputs in single vestibular nuclei neurons was studied intracellularly in decerebrate cats. A total of 160 vestibular neurons were orthodromically activated by selective stimulation of the PC and the UT nerve and classified according to whether or not they were antidromically activated from the spinal cord and oculomotor nuclei into Vestibulospinal (VS), vestibulooculospinal (VOS), vestibuloocular (VO), and unidentified vestibular neurons. Fifty-three (33%) of 160 vestibular neurons received convergent inputs from both the PC and UT nerves. Seventy-nine (49%) vestibular neurons responded to PC inputs alone, and 28 (18%) neurons received inputs only from the UT nerve. Of 53 convergent neurons, 8 (15%) were monosynaptically excited from both nerves. Thirty-five (66%) received monosynaptic excitatory inputs from the PC nerve and polysynaptic excitatory or inhibitory inputs from the UT nerve, or vice versa. Approximately one-third of VS and VOS neurons received convergent inputs. A majority of the VS neurons descended to the spinal cord through the Lateral Vestibulospinal Tract, while almost all the VOS neurons descended to the spinal cord through the medial Vestibulospinal Tract. The convergent neurons were found in all vestibular nuclei but more in the Lateral nucleus and descending nucleus. The VS neurons were more numerous than VO neurons or VOS neurons.
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Convergence of posterior semicircular canal and saccular inputs in single vestibular nuclei neurons in cats
Experimental Brain Research, 2000Co-Authors: H. Sato, M. Imagawa, K. Kushiro, M. Zakir, Y. UchinoAbstract:Convergence between posterior canal (PC) and saccular (SAC) inputs in single vestibular nuclei neurons was investigated in decerebrated cats. Postsynaptic potentials were recorded intracellularly after selective stimulation of the SAC and PC nerves. Stimulation of either the SAC or PC nerve orthodromically activated 143 vestibular nuclei neurons. Of these, 61 (43%) were antidromically activated by stimulation of the C1–C2 junction, 14 (10%) were antidromically activated by stimulation of the oculomotor or trochlear nucleus, and 14 (10%) were antidromically activated by stimulation of both the oculomotor or trochlear nucleus and the spinal cord. Fifty-four (38%) neurons were not activated by stimulation of either or both. We named these neurons Vestibulospinal (VS), vestibulo-ocular (VO), vestibulo-oculo-spinal (VOS) and vestibular (V) neurons, respectively. Both PC and SAC inputs converged in 47 vestibular nuclei neurons (26 VS, 2 VO, 6 VOS and 13 V neurons). Of these, 19 received monosynaptic excitatory inputs from both nerves. This input pattern was frequently seen in VS neurons. Approximately half of the convergent VS neurons descended to the spinal cord through the Lateral Vestibulospinal Tract. The remaining half and all the convergent VOS neurons descended to the spinal cord through the medial Vestibulospinal Tract. Most of the convergent neurons were located in the Lateral nucleus or descending nucleus.
M. Sasaki - One of the best experts on this subject based on the ideXlab platform.
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Otolith and canal integration on single vestibular neurons in cats
Experimental Brain Research, 2005Co-Authors: Y. Uchino, M. Sasaki, H. Sato, E. KawamotoAbstract:In this review, based primarily on work from our laboratory, but related to previous studies, we summarize what is known about the convergence of vestibular afferent inputs onto single vestibular neurons activated by selective stimulation of individual vestibular nerve branches. Horizontal semicircular canal (HC), anterior semicircular canal (AC), posterior semicircular canal (PC), utricular (UT), and saccular (SAC) nerves were selectively stimulated in decerebrate cats. All recorded neurons were classified as either projection neurons, which consisted of Vestibulospinal (VS), vestibulo-oculospinal (VOS), vestibulo-ocular (VO) neurons, or non-projection neurons, which we simply term “vestibular″ (V) neurons. The first three types could be successfully activated antidromically from oculomotor/trochlear nuclei and/or spinal cord, and the last type could not be activated antidromically from either site. A total of 1228 neurons were activated by stimulation of various nerve pair combinations. Convergent neurons were located in the caudoventral part of the Lateral, the rostral part of the descending, and the medial vestibular nuclei. Otolith-activated vestibular neurons in the superior vestibular nucleus were extremely rare. A high percentage of neurons received excitatory inputs from two nerve pairs, a small percentage received reciprocal convergent inputs and even fewer received inhibitory inputs from both nerves. More than 30% of vestibular neurons received convergent inputs from vertical semicircular canal/otolith nerve pairs. In contrast, only half as many received convergent inputs from HC/otolith-nerve pairs, implying that convergent input from vertical semicircular canal and otolith-nerve pairs may play a more important role than that played by inputs from horizontal semicircular canal and otolith-nerve pairs. Convergent VS neurons projected through the ipsiLateral Lateral Vestibulospinal Tract (i-LVST) and the medial Vestibulospinal Tract (MVST). Almost all the VOS neurons projected through the MVST. Convergent neurons projecting to the oculomotor/trochlear nuclei were much fewer in number than those projecting to the spinal cord. Some of the convergent neurons that receive both canal and otolith input may contribute to the short-latency pathway of the vestibulocollic reflex. The functional significance of these convergences is discussed.
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Convergence of the anterior semicircular canal and otolith afferents on cat single vestibular neurons
Experimental Brain Research, 2002Co-Authors: X. Zhang, M. Sasaki, H. Sato, H. Meng, M. Imagawa, Y. UchinoAbstract:The convergence between the anterior semicircular canal (AC) and utricular (UT) inputs, as well as the convergence between the AC and saccular (SAC) inputs in single vestibular neurons of decerebrated cats were investigated. Postsynaptic potentials were recorded intracellularly after selective stimulation of each pair of vestibular nerves AC/UT or AC/SAC. Neurons were recorded from the central parts of the vestibular nuclei, where the otolith afferents mainly terminate. Of a total of 105 neurons that were activated after stimulation of the AC and UT nerves, 42 received convergent inputs. Thirty-eight of these neurons received excitatory inputs from both afferents. Convergent neurons were further classified into Vestibulospinal ( n =28) and vestibulooculospinal ( n =6) neurons by antidromic activation from the border between the C1 and C2 spinal cord and the oculomotor or trochlear nucleus. Eight neurons that were not antidromically activated from either site were classified as vestibular neurons. Forty three percent of the convergent Vestibulospinal neurons and most of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract. Of a total of 118 neurons that were activated after stimulation of the AC and/or SAC nerves, 51 received convergent inputs (27 Vestibulospinal, 4 vestibulooculospinal, 5 vestibuloocular and 15 vestibular neurons). Forty-two of the convergent neurons received excitatory inputs from both afferents. Thirty seven percent of the convergent Vestibulospinal neurons and all of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract.
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Properties of utricular nerve-activated Vestibulospinal neurons in cats
Experimental Brain Research, 1996Co-Authors: H. Sato, M. Sasaki, M. Imagawa, H. Ikegami, K. Endo, Y. UchinoAbstract:The axonal pathway, conduction velocities, and locations of the cell bodies of utricular nerve-activated Vestibulospinal neurons were studied in decerebrated or anesthetized cats using the collision test of orthodromic and antidromic spikes. For orthodromic stimulation, bipolar tungsten electrodes were placed on the utricular nerve and the other vestibular nerve branches were transected. Monopolar tungsten electrodes were positioned on both sides of the upper cervical segments (C2–4), caudal end of the cervical enlargement (C7-T1), and from the lower thoracic to the upper lumbar segments (T12-L3) and were used for antidromic stimulation of the spinal cord. Another monopolar electrode was also placed in the oculomotor nucleus to study whether utricular nerve-activated Vestibulospinal neurons have ascending branches to the oculomotor nucleus. Of the 173 vestibular neurons orthodromically activated by the stimulation of the utricular nerve, 46 were second-order Vestibulospinal neurons and 5 were third-order neurons. The majority of the utricular nerve-activated Vestibulospinal neurons were located in the rostral part of the descending vestibular nucleus and the caudal part of the ventral Lateral nucleus. Seventy-three percent of the utricular nerve-activated Vestibulospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract. Approximately 80% of these neurons reached the cervicothoracic junction, but a few reached the upper lumbar spinal cord. Twenty-seven percent of the utricular nerve-activated Vestibulospinal neurons descended through the medial Vestibulospinal Tract or the contraLateral Vestibulospinal Tracts. Those axons terminated mainly in the upper cervical segments. Almost none of the utricular nerve-activated vestibular neurons had ascending branches to the oculomotor nucleus.
M. Imagawa - One of the best experts on this subject based on the ideXlab platform.
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Convergence of the anterior semicircular canal and otolith afferents on cat single vestibular neurons
Experimental Brain Research, 2002Co-Authors: X. Zhang, M. Sasaki, H. Sato, H. Meng, M. Imagawa, Y. UchinoAbstract:The convergence between the anterior semicircular canal (AC) and utricular (UT) inputs, as well as the convergence between the AC and saccular (SAC) inputs in single vestibular neurons of decerebrated cats were investigated. Postsynaptic potentials were recorded intracellularly after selective stimulation of each pair of vestibular nerves AC/UT or AC/SAC. Neurons were recorded from the central parts of the vestibular nuclei, where the otolith afferents mainly terminate. Of a total of 105 neurons that were activated after stimulation of the AC and UT nerves, 42 received convergent inputs. Thirty-eight of these neurons received excitatory inputs from both afferents. Convergent neurons were further classified into Vestibulospinal ( n =28) and vestibulooculospinal ( n =6) neurons by antidromic activation from the border between the C1 and C2 spinal cord and the oculomotor or trochlear nucleus. Eight neurons that were not antidromically activated from either site were classified as vestibular neurons. Forty three percent of the convergent Vestibulospinal neurons and most of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract. Of a total of 118 neurons that were activated after stimulation of the AC and/or SAC nerves, 51 received convergent inputs (27 Vestibulospinal, 4 vestibulooculospinal, 5 vestibuloocular and 15 vestibular neurons). Forty-two of the convergent neurons received excitatory inputs from both afferents. Thirty seven percent of the convergent Vestibulospinal neurons and all of the convergent vestibulooculospinal neurons projected to the spinal cord through the medial Vestibulospinal Tract. The remaining Vestibulospinal and vestibulooculospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract.
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Convergence of posterior semicircular canal and saccular inputs in single vestibular nuclei neurons in cats
Experimental Brain Research, 2000Co-Authors: H. Sato, M. Imagawa, K. Kushiro, M. Zakir, Y. UchinoAbstract:Convergence between posterior canal (PC) and saccular (SAC) inputs in single vestibular nuclei neurons was investigated in decerebrated cats. Postsynaptic potentials were recorded intracellularly after selective stimulation of the SAC and PC nerves. Stimulation of either the SAC or PC nerve orthodromically activated 143 vestibular nuclei neurons. Of these, 61 (43%) were antidromically activated by stimulation of the C1–C2 junction, 14 (10%) were antidromically activated by stimulation of the oculomotor or trochlear nucleus, and 14 (10%) were antidromically activated by stimulation of both the oculomotor or trochlear nucleus and the spinal cord. Fifty-four (38%) neurons were not activated by stimulation of either or both. We named these neurons Vestibulospinal (VS), vestibulo-ocular (VO), vestibulo-oculo-spinal (VOS) and vestibular (V) neurons, respectively. Both PC and SAC inputs converged in 47 vestibular nuclei neurons (26 VS, 2 VO, 6 VOS and 13 V neurons). Of these, 19 received monosynaptic excitatory inputs from both nerves. This input pattern was frequently seen in VS neurons. Approximately half of the convergent VS neurons descended to the spinal cord through the Lateral Vestibulospinal Tract. The remaining half and all the convergent VOS neurons descended to the spinal cord through the medial Vestibulospinal Tract. Most of the convergent neurons were located in the Lateral nucleus or descending nucleus.
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Properties of utricular nerve-activated Vestibulospinal neurons in cats
Experimental Brain Research, 1996Co-Authors: H. Sato, M. Sasaki, M. Imagawa, H. Ikegami, K. Endo, Y. UchinoAbstract:The axonal pathway, conduction velocities, and locations of the cell bodies of utricular nerve-activated Vestibulospinal neurons were studied in decerebrated or anesthetized cats using the collision test of orthodromic and antidromic spikes. For orthodromic stimulation, bipolar tungsten electrodes were placed on the utricular nerve and the other vestibular nerve branches were transected. Monopolar tungsten electrodes were positioned on both sides of the upper cervical segments (C2–4), caudal end of the cervical enlargement (C7-T1), and from the lower thoracic to the upper lumbar segments (T12-L3) and were used for antidromic stimulation of the spinal cord. Another monopolar electrode was also placed in the oculomotor nucleus to study whether utricular nerve-activated Vestibulospinal neurons have ascending branches to the oculomotor nucleus. Of the 173 vestibular neurons orthodromically activated by the stimulation of the utricular nerve, 46 were second-order Vestibulospinal neurons and 5 were third-order neurons. The majority of the utricular nerve-activated Vestibulospinal neurons were located in the rostral part of the descending vestibular nucleus and the caudal part of the ventral Lateral nucleus. Seventy-three percent of the utricular nerve-activated Vestibulospinal neurons descended through the ipsiLateral Lateral Vestibulospinal Tract. Approximately 80% of these neurons reached the cervicothoracic junction, but a few reached the upper lumbar spinal cord. Twenty-seven percent of the utricular nerve-activated Vestibulospinal neurons descended through the medial Vestibulospinal Tract or the contraLateral Vestibulospinal Tracts. Those axons terminated mainly in the upper cervical segments. Almost none of the utricular nerve-activated vestibular neurons had ascending branches to the oculomotor nucleus.
