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O. Pompeiano - One of the best experts on this subject based on the ideXlab platform.

  • Depression of the vestibulospinal reflex adaptation by intravermal microinjection of GABA-A and GABA-B agonists in the cat.
    Archives Italiennes De Biologie, 1994
    Co-Authors: Diego Manzoni, Paolo Andre, Paola D'ascanio, O. Pompeiano
    Abstract:

    In decerebrate cats the gain of the vestibulospinal reflex (VSR), elicited by sinusoidal Roll tilt of the animal at 0.15 Hz, ± 10 degrees, was tested every 10-15 min during and after a sustained (3 h) Period of Roll tilt of the head at the parameters indicated above, associated with synchronous Roll tilt of the body at 0.15 Hz, ± 12.5 degrees; this stimulus led to 2.5 degrees of neck rotation, which was thus out of phase with respect to head rotation. In this condition the gain of the VSR progressively increased during the first h of neck-vestibular stimulation, to reach a plateau level at the end of the third h of stimulation. This adaptive process was followed for at least 1 h after stimulation. Microinjection into the zone B of the cerebellar anterior vermis of the GABA-A agonist muscimol (0.25 microliter at 8 micrograms/microliter saline) producing only a slight or negligible depression of the VSR gain in non-adaptive conditions, prevented the occurrence of the adapted increase in gain of the VSR following a 3-h Period of sustained head and neck rotation. In addition, intravermal injection of the GABA-A or the GABA-B agonist muscimol or baclofen, respectively, at the same dose indicated above supressed the adapted increase in gain occurring after a 3-h Period of continuous neck-vestibular stimulation. The effective sites were located into the zone B of the cerebellar anterior vermis, from which the direct corticocerebellar projection to the lateral vestibular nucleus originates. In conclusion, the results seem to indicate that the adaptive increase in gain of the VSR which occurs in decerebrate cats depend upon plastic changes which affect the Purkinje cells of the cerebellar anterior vermis. These changes were in fact suppressed by GABAergic inhibition of these neurons. The demonstration that the effects of the GABA agonists occurred suddenly makes unlikely the hypothesis that the cerebellar anterior vermis represents either a relay for adaptive changes occurring before it (for instance in the inferior olive) or else the generator of error signals that elicit plasticity in target structures (as in the vestibular nuclei).

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation
    Pflügers Archiv, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz,±10° produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5° or 7.5°. This additional stimulus led to 2.5° of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5°. In the first experimental condition A, the gain of the VSR (tested every 10–15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i. e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the inphase stimulation.

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation.
    Pflugers Archiv : European journal of physiology, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz, +/- 10 degrees produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5 degrees or 7.5 degrees. This additional stimulus led to 2.5 degrees of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5 degrees. In the first experimental condition A, the gain of the VSR (tested every 10-15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i.e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the in phase stimulation.

P. Andre - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation
    Pflügers Archiv, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz,±10° produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5° or 7.5°. This additional stimulus led to 2.5° of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5°. In the first experimental condition A, the gain of the VSR (tested every 10–15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i. e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the inphase stimulation.

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation.
    Pflugers Archiv : European journal of physiology, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz, +/- 10 degrees produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5 degrees or 7.5 degrees. This additional stimulus led to 2.5 degrees of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5 degrees. In the first experimental condition A, the gain of the VSR (tested every 10-15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i.e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the in phase stimulation.

P. D'ascanio - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation
    Pflügers Archiv, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz,±10° produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5° or 7.5°. This additional stimulus led to 2.5° of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5°. In the first experimental condition A, the gain of the VSR (tested every 10–15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i. e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the inphase stimulation.

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation.
    Pflugers Archiv : European journal of physiology, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz, +/- 10 degrees produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5 degrees or 7.5 degrees. This additional stimulus led to 2.5 degrees of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5 degrees. In the first experimental condition A, the gain of the VSR (tested every 10-15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i.e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the in phase stimulation.

D. Manzoni - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation
    Pflügers Archiv, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz,±10° produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5° or 7.5°. This additional stimulus led to 2.5° of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5°. In the first experimental condition A, the gain of the VSR (tested every 10–15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i. e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the inphase stimulation.

  • Adaptive modification of the cat's vestibulospinal reflex during sustained vestibular and neck stimulation.
    Pflugers Archiv : European journal of physiology, 1993
    Co-Authors: P. Andre, P. D'ascanio, D. Manzoni, O. Pompeiano
    Abstract:

    In decerebrate cats, rotation about the longitudinal axis of the whole animal at 0.15 Hz, +/- 10 degrees produced an increased electromyogram (EMG) activity of the triceps brachii during side-down tilt and a decreased activity during side-up tilt. This vestibulospinal reflex (VSR) was tested before, during and after a sustained (3-h) Period of Roll tilt of the head at the parameters indicated above, associated with a synchronous Roll tilt of the body at 0.15 Hz, but at the peak amplitude of either 12.5 degrees or 7.5 degrees. This additional stimulus led to 2.5 degrees of neck rotation, which was respectively out of phase (condition A) or in-phase (condition B) with head rotation. In a few instances the peak amplitude of neck rotation was increased to 5 degrees. In the first experimental condition A, the gain of the VSR (tested every 10-15 min) progressively increased, starting from the first hour of out of phase neck-vestibular stimulation to reach, on average, 241% of the control value at the end of the third hour of stimulation. On the other hand, in the second experimental condition B, the mean gain of the VSR first decreased to 82% during the first hour of in-phase neck-vestibular stimulation, but then increased to 165% of the corresponding control during the last hour of recording. In other experiments an adaptive increase in gain of the pure VSR occurred during a sustained (3-h) Period of selective Roll tilt of the whole animal, but it was less consistent and, on average, smaller in amplitude than that obtained during out of phase neck-vestibular stimulation. The adaptive changes in gain of the VSR described above were not associated with changes in the phase angle of the responses, and were also observed during the post-adaptation Period. Further experiments indicated that the gain of the N-VSR, i.e. of the EMG responses to combined neck-vestibular stimulation, displayed a prominent adaptive increase during the sustained out of phase stimulation, but not during the in phase stimulation.

Diego Manzoni - One of the best experts on this subject based on the ideXlab platform.

  • Depression of the vestibulospinal reflex adaptation by intravermal microinjection of GABA-A and GABA-B agonists in the cat.
    Archives Italiennes De Biologie, 1994
    Co-Authors: Diego Manzoni, Paolo Andre, Paola D'ascanio, O. Pompeiano
    Abstract:

    In decerebrate cats the gain of the vestibulospinal reflex (VSR), elicited by sinusoidal Roll tilt of the animal at 0.15 Hz, ± 10 degrees, was tested every 10-15 min during and after a sustained (3 h) Period of Roll tilt of the head at the parameters indicated above, associated with synchronous Roll tilt of the body at 0.15 Hz, ± 12.5 degrees; this stimulus led to 2.5 degrees of neck rotation, which was thus out of phase with respect to head rotation. In this condition the gain of the VSR progressively increased during the first h of neck-vestibular stimulation, to reach a plateau level at the end of the third h of stimulation. This adaptive process was followed for at least 1 h after stimulation. Microinjection into the zone B of the cerebellar anterior vermis of the GABA-A agonist muscimol (0.25 microliter at 8 micrograms/microliter saline) producing only a slight or negligible depression of the VSR gain in non-adaptive conditions, prevented the occurrence of the adapted increase in gain of the VSR following a 3-h Period of sustained head and neck rotation. In addition, intravermal injection of the GABA-A or the GABA-B agonist muscimol or baclofen, respectively, at the same dose indicated above supressed the adapted increase in gain occurring after a 3-h Period of continuous neck-vestibular stimulation. The effective sites were located into the zone B of the cerebellar anterior vermis, from which the direct corticocerebellar projection to the lateral vestibular nucleus originates. In conclusion, the results seem to indicate that the adaptive increase in gain of the VSR which occurs in decerebrate cats depend upon plastic changes which affect the Purkinje cells of the cerebellar anterior vermis. These changes were in fact suppressed by GABAergic inhibition of these neurons. The demonstration that the effects of the GABA agonists occurred suddenly makes unlikely the hypothesis that the cerebellar anterior vermis represents either a relay for adaptive changes occurring before it (for instance in the inferior olive) or else the generator of error signals that elicit plasticity in target structures (as in the vestibular nuclei).