The Experts below are selected from a list of 46053 Experts worldwide ranked by ideXlab platform
P. Cavallari - One of the best experts on this subject based on the ideXlab platform.
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Postural Control in Children with Cerebellar Ataxia
'MDPI AG', 2020Co-Authors: V. Farinelli, R. Esposti, S M Marchese, C. Palmisano, C.m.m. Strano, S. D’, C. Pantaleoni, A. Ardissone, N. Nardocci, P. CavallariAbstract:Controlling posture, i.e., governing the ensemble of involuntary muscular activities that manage Body Equilibrium, represents a demanding function in which the cerebellum plays a key role. Postural activities are particularly important during gait initiation when passing from quiet standing to locomotion. Indeed, several studies used such motor task for evaluating pathological conditions, including cerebellar disorders. The linkage between cerebellum maturation and the development of postural control has received less attention. Therefore, we evaluated postural control during quiet standing and gait initiation in children affected by a slow progressive generalized cerebellar atrophy (SlowP) or non-progressive vermian hypoplasia (Joubert syndrome, NonP), compared to that of healthy children (H). Despite the similar clinical evaluation of motor impairments in NonP and SlowP, only SlowP showed a less stable quiet standing and a shorter and slower first step than H. Moreover, a descriptive analysis of lower limb and back muscle activities suggested a more severe timing disruption in SlowP. Such differences might stem from the extent of cerebellar damage. However, literature reports that during childhood, neural plasticity of intact brain areas could compensate for cerebellar agenesis. We thus proposed that the difference might stem from disease progression, which contrasts the consolidation of compensatory strategies
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Anodal tDCS on parietal operculum does not affect the programming of intra-limb anticipatory postural adjustments
Società Italiana di Fisiologia, 2018Co-Authors: S M Marchese, F. Bolzoni, R. Esposti, P. CavallariAbstract:Voluntary movements induce postural perturbations which are counteracted by anticipatory postural adjustments (APAs). These actions build up long fixation chains toward the available support points, to grant whole Body Equilibrium, but also develop short chains within the same limb where a distal segment is moved (intra-limb APAs), to stabilize the proximal segments. The neural structures generating intra-limb APAs still need investigations. In this view we tested the involvement of the parietal operculum (PO), which has been suggested to play a key role in motor control (Sepulcre 2014, Neuroscientist). APAs that stabilize the arm when the index-finger is briskly flexed were recorded in 9 healthy subjects, before, during and after anodal transcranial direct current stimulation (tDCS, 20 min at 2 mA) applied over PO, and compared to APAs recorded in 9 healthy subjects who underwent sham tDCS. In agreement with literature, in the sham group the activation of prime mover Flexor Digitorum Superficialis (FDS) was preceded by an inhibitory APA in Biceps Brachii and Anterior Deltoid, and almost simultaneous to an excitatory APA in Triceps Brachii. The same pattern also occurred in the anodal group, where tDCS did not significantly affect neither APAs amplitude nor timing. Index-finger kinematics were also unchanged. These preliminary results seem to exclude PO from intra-limb APA organization, though more experiments are needed to increase the sample size and also test cathodal tDCS
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Temporal disruption of upper-limb anticipatory postural adjustments in cerebellar ataxic patients
'Springer Science and Business Media LLC', 2015Co-Authors: C. Bruttini, F. Bolzoni, R. Esposti, A. Vanotti, C. Mariotti, P. CavallariAbstract:Voluntary movements induce postural perturbations, which are counteracted by anticipatory postural adjustments (APAs) that preserve Body Equilibrium. Little is known about the neural structures generating APAs, but several studies suggested a role of sensory-motor areas, basal ganglia, supplementary motor area and thalamus. However, the role of the cerebellum still remains an open question. The aim of this present paper is to shed further light on the role of cerebellum in APAs organization. Thus, APAs that stabilize the arm when the index finger is briskly flexed were recorded in 13 ataxic subjects (seven sporadic cases, four dominant ataxia type III and two autosomal recessive), presenting a slowly progressive cerebellar syndrome with four-limb dysmetria, and compared with those obtained in 13 healthy subjects. The pattern of postural activity was similar in the two groups [excitation in triceps and inhibition in biceps and anterior deltoid (AD)], but apparent modifications in timing were observed in all ataxic subjects in which, on average, triceps brachii excitation lagged the onset of the prime mover flexor digitorum superficialis by about 27 ms and biceps and AD inhibition were almost synchronous to it. Instead, in normal subjects, triceps onset was synchronous to the prime mover and biceps and AD anticipated it by about 40 ms. The observed disruption of the intra-limb APA organization confirms that the cerebellum is involved in APA control and, considering cerebellar subjects as a model of dysmetria, also supports the view that a proper APA chain may play a crucial role in refining movement metria
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Disrupt of anticipatory postural adjustments in cerebellar ataxia
2013Co-Authors: F. Bolzoni, R. Esposti, C. Bruttini, A. Vanotti, C. Mariotti, P. CavallariAbstract:Each voluntary movement is known to induce postural perturbations which are counteracted by anticipatory postural adjustments (APAs): i.e. unconscious feed-forward muscular activities, aimed at building up a muscular chain toward an available fixation points (Massion, 1992). The importance of a proper whole-Body stabilisation is apparent when considering standing subjects performing intentional movements involving large masses; in these motor acts, the Equilibrium-perturbing forces would cause a whole-Body Equilibrium disturbance, by displacing both the trunk and the whole-Body CoM (Bouisset and Do, 2008). On the other hand, the importance of an accurate segmental stabilisation may look less obvious in those tasks in which the whole-Body Equilibrium is not threatened, such an index finger flexion. It has been reported that an APA chain also develops in several upper-limb muscles when the index finger is flexed. In this case the prime mover Flexor Digitorum Superficialis (FDS) is preceded by an excitatory burst in Triceps Brachii (TB) and the tonically active Biceps Brachii (BB) and Anterior Deltoid (AD) are carved by inhibitory APAs (Caronni and Cavallari, 2009a). In the present study, APAs and prime mover activation were recorded in seven patients with cerebellar degeneration and on an equal number of healthy subjects. All patients suffered from a slowly progressive cerebellar syndrome, without involvement of the sensory and motor systems. This was witnessed by a standard 1.5-T brain MRIs showing cerebellar atrophy without cerebral cortex, pons, medulla or white matter lesions. Two cases were sporadic, five had a positive family history for autosomal dominant cerebellar ataxia type III. Meann onset age was 31\ub114 years while age at examination was 52 \ub113. All patients presented pure gait ataxia, four-limb dysmetria, mild dysarthria, and occasionally mild increase of deep tendon reflexes, without spasticity. Cognition was normal. Scale for the Assessment and Rating of Ataxia was applied to all patients. The pattern of EMG activities was similar between the two groups, while modifications in the timing of EMG onsets were observed in cerebellar patients, in which no anticipatory activity could be observed in postural muscles. Both inhibition in BB and AD and excitation in TB lagged the onset of the prime mover. Although the role of the cerebellum in the genesis or in the transmission of the APAs still remains open, these data supports the idea that both the prime mover onset and the temporal distribution of the related APAs are set by the \u201ccerebellar timing machine\u201d
Anne Krause - One of the best experts on this subject based on the ideXlab platform.
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Stimulus Prediction and Postural Reaction: Phase-Specific Modulation of Soleus H-Reflexes Is Related to Changes in Joint Kinematics and Segmental Strategy in Perturbed Upright Stance
Frontiers Media S.A., 2018Co-Authors: Ramona Ritzmann, Kyungsoo Lee, Anne Krause, Albert Gollhofer, Kathrin FreylerAbstract:Anticipation determines the timing and efficiency of human motor performance. This study aimed to evaluate the effect of stimulus anticipation on proactive (prior to the event) and reactive (after the event) postural adjustments in response to perturbations. Postural set was manipulated by providing either (i) predictable, (ii) unpredictable, or (iii) cheated perturbations which require balance corrections to maintain postural stability. In 29 subjects, a protocol of anterior and posterior perturbations was applied for the conditions (i–iii). Center of pressure (COP) displacement, ankle, knee, and hip joint kinematics and electromyographic activity (EMG) of the soleus (SOL) and tibialis anterior (TA) muscles were recorded prior (PRE) and after posterior perturbations. SOL H-reflexes at the peak of the short-, medium- ,and long-latency responses (SLR, MLR, LLR) were assessed. For conditions (i to iii) EMG activity and COP differed prior to perturbation onset (p < 0.05). After perturbation, results demonstrated a progressively increased H-reflex amplitude in the MLR and LLR (p < 0.05), delayed muscle activities (p < 0.05), and shifted activation patterns, with muscles of the proximal segment being more involved in the compensatory postural response (p < 0.05). COP displacements and ankle, knee, and hip joint deflections progressively increased (p < 0.05). Neuromechanical coupling showed positive correlations for the anticipation-induced changes in EMG activity and H-reflex amplitude with that of COP displacement (p < 0.05). In conclusion, proactive and reactive postural responses indicated setting dependent modulations of segmental and phasic muscle activation. A shift to proximal muscle groups and facilitated late reflex responses compensating for cheated or unpredicted perturbations was found to recover a safe Body Equilibrium. In consideration of the phase-specific adaptation and its interrelationship to the kinematics, it suggested that changes in stimulus prediction challenged the central nervous system to appropriately counteract the higher postural challenges. The outcomes of this experiment are of functional relevance for experimental and training settings involving perturbation stimuli. These findings provide fundamental information of the mechanisms underlying postural adjustments in response to external perturbations
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Neuromuscular and Kinematic Adaptation in Response to Reactive Balance Training – a Randomized Controlled Study Regarding Fall Prevention
Frontiers Media S.A., 2018Co-Authors: Anne Krause, Albert Gollhofer, Kathrin Freyler, Thomas Stocker, Uli Brüderlin, Ralf Colin, Harald Töpfer, Ramona RitzmannAbstract:Slips and stumbles are main causes of falls and result in serious injuries. Balance training is widely applied for preventing falls across the lifespan. Subdivided into two main intervention types, biomechanical characteristics differ amongst balance interventions tailored to counteract falls: conventional balance training (CBT) referring to a balance task with a static ledger pivoting around the ankle joint versus reactive balance training (RBT) using externally applied perturbations to deteriorate Body Equilibrium. This study aimed to evaluate the efficacy of reactive, slip-simulating RBT compared to CBT in regard to fall prevention and to detect neuromuscular and kinematic dependencies. In a randomized controlled trial, 38 participants were randomly allocated either to CBT or RBT. To simulate stumbling scenarios, postural responses were assessed to posterior translations in gait and stance perturbation before and after 4 weeks of training. Surface electromyography during short- (SLR), medium- (MLR), and long-latency response of shank and thigh muscles as well as ankle, knee, and hip joint kinematics (amplitudes and velocities) were recorded. Both training modalities revealed reduced angular velocity in the ankle joint (P < 0.05) accompanied by increased shank muscle activity in SLR (P < 0.05) during marching in place perturbation. During stance perturbation and marching in place perturbation, hip angular velocity was decreased after RBT (P from TTEST, Pt < 0.05) accompanied by enhanced thigh muscle activity (SLR, MLR) after both trainings (P < 0.05). Effect sizes were larger for the RBT-group during stance perturbation. Thus, both interventions revealed modified stabilization strategies for reactive balance recovery after surface translations. Characterized by enhanced reflex activity in the leg muscles antagonizing the surface translations, balance training is associated with improved neuromuscular timing and accuracy being relevant for postural control. This may result in more efficient segmental stabilization during fall risk situations, independent of the intervention modality. More pronounced modulations and higher effect sizes after RBT in stance perturbation point toward specificity of training adaptations, with an emphasis on the proximal Body segment for RBT. Outcomes underline the benefits of balance training with a clear distinction between RBT and CBT being relevant for training application over the lifespan
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Table_2_Neuromuscular and Kinematic Adaptation in Response to Reactive Balance Training – a Randomized Controlled Study Regarding Fall Prevention.docx
2018Co-Authors: Anne Krause, Albert Gollhofer, Kathrin Freyler, Thomas Stocker, Uli Brüderlin, Ralf Colin, Harald Töpfer, Ramona RitzmannAbstract:Slips and stumbles are main causes of falls and result in serious injuries. Balance training is widely applied for preventing falls across the lifespan. Subdivided into two main intervention types, biomechanical characteristics differ amongst balance interventions tailored to counteract falls: conventional balance training (CBT) referring to a balance task with a static ledger pivoting around the ankle joint versus reactive balance training (RBT) using externally applied perturbations to deteriorate Body Equilibrium. This study aimed to evaluate the efficacy of reactive, slip-simulating RBT compared to CBT in regard to fall prevention and to detect neuromuscular and kinematic dependencies. In a randomized controlled trial, 38 participants were randomly allocated either to CBT or RBT. To simulate stumbling scenarios, postural responses were assessed to posterior translations in gait and stance perturbation before and after 4 weeks of training. Surface electromyography during short- (SLR), medium- (MLR), and long-latency response of shank and thigh muscles as well as ankle, knee, and hip joint kinematics (amplitudes and velocities) were recorded. Both training modalities revealed reduced angular velocity in the ankle joint (P < 0.05) accompanied by increased shank muscle activity in SLR (P < 0.05) during marching in place perturbation. During stance perturbation and marching in place perturbation, hip angular velocity was decreased after RBT (P from TTEST, Pt < 0.05) accompanied by enhanced thigh muscle activity (SLR, MLR) after both trainings (P < 0.05). Effect sizes were larger for the RBT-group during stance perturbation. Thus, both interventions revealed modified stabilization strategies for reactive balance recovery after surface translations. Characterized by enhanced reflex activity in the leg muscles antagonizing the surface translations, balance training is associated with improved neuromuscular timing and accuracy being relevant for postural control. This may result in more efficient segmental stabilization during fall risk situations, independent of the intervention modality. More pronounced modulations and higher effect sizes after RBT in stance perturbation point toward specificity of training adaptations, with an emphasis on the proximal Body segment for RBT. Outcomes underline the benefits of balance training with a clear distinction between RBT and CBT being relevant for training application over the lifespan.
Ramona Ritzmann - One of the best experts on this subject based on the ideXlab platform.
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Stimulus Prediction and Postural Reaction: Phase-Specific Modulation of Soleus H-Reflexes Is Related to Changes in Joint Kinematics and Segmental Strategy in Perturbed Upright Stance
Frontiers Media S.A., 2018Co-Authors: Ramona Ritzmann, Kyungsoo Lee, Anne Krause, Albert Gollhofer, Kathrin FreylerAbstract:Anticipation determines the timing and efficiency of human motor performance. This study aimed to evaluate the effect of stimulus anticipation on proactive (prior to the event) and reactive (after the event) postural adjustments in response to perturbations. Postural set was manipulated by providing either (i) predictable, (ii) unpredictable, or (iii) cheated perturbations which require balance corrections to maintain postural stability. In 29 subjects, a protocol of anterior and posterior perturbations was applied for the conditions (i–iii). Center of pressure (COP) displacement, ankle, knee, and hip joint kinematics and electromyographic activity (EMG) of the soleus (SOL) and tibialis anterior (TA) muscles were recorded prior (PRE) and after posterior perturbations. SOL H-reflexes at the peak of the short-, medium- ,and long-latency responses (SLR, MLR, LLR) were assessed. For conditions (i to iii) EMG activity and COP differed prior to perturbation onset (p < 0.05). After perturbation, results demonstrated a progressively increased H-reflex amplitude in the MLR and LLR (p < 0.05), delayed muscle activities (p < 0.05), and shifted activation patterns, with muscles of the proximal segment being more involved in the compensatory postural response (p < 0.05). COP displacements and ankle, knee, and hip joint deflections progressively increased (p < 0.05). Neuromechanical coupling showed positive correlations for the anticipation-induced changes in EMG activity and H-reflex amplitude with that of COP displacement (p < 0.05). In conclusion, proactive and reactive postural responses indicated setting dependent modulations of segmental and phasic muscle activation. A shift to proximal muscle groups and facilitated late reflex responses compensating for cheated or unpredicted perturbations was found to recover a safe Body Equilibrium. In consideration of the phase-specific adaptation and its interrelationship to the kinematics, it suggested that changes in stimulus prediction challenged the central nervous system to appropriately counteract the higher postural challenges. The outcomes of this experiment are of functional relevance for experimental and training settings involving perturbation stimuli. These findings provide fundamental information of the mechanisms underlying postural adjustments in response to external perturbations
-
Neuromuscular and Kinematic Adaptation in Response to Reactive Balance Training – a Randomized Controlled Study Regarding Fall Prevention
Frontiers Media S.A., 2018Co-Authors: Anne Krause, Albert Gollhofer, Kathrin Freyler, Thomas Stocker, Uli Brüderlin, Ralf Colin, Harald Töpfer, Ramona RitzmannAbstract:Slips and stumbles are main causes of falls and result in serious injuries. Balance training is widely applied for preventing falls across the lifespan. Subdivided into two main intervention types, biomechanical characteristics differ amongst balance interventions tailored to counteract falls: conventional balance training (CBT) referring to a balance task with a static ledger pivoting around the ankle joint versus reactive balance training (RBT) using externally applied perturbations to deteriorate Body Equilibrium. This study aimed to evaluate the efficacy of reactive, slip-simulating RBT compared to CBT in regard to fall prevention and to detect neuromuscular and kinematic dependencies. In a randomized controlled trial, 38 participants were randomly allocated either to CBT or RBT. To simulate stumbling scenarios, postural responses were assessed to posterior translations in gait and stance perturbation before and after 4 weeks of training. Surface electromyography during short- (SLR), medium- (MLR), and long-latency response of shank and thigh muscles as well as ankle, knee, and hip joint kinematics (amplitudes and velocities) were recorded. Both training modalities revealed reduced angular velocity in the ankle joint (P < 0.05) accompanied by increased shank muscle activity in SLR (P < 0.05) during marching in place perturbation. During stance perturbation and marching in place perturbation, hip angular velocity was decreased after RBT (P from TTEST, Pt < 0.05) accompanied by enhanced thigh muscle activity (SLR, MLR) after both trainings (P < 0.05). Effect sizes were larger for the RBT-group during stance perturbation. Thus, both interventions revealed modified stabilization strategies for reactive balance recovery after surface translations. Characterized by enhanced reflex activity in the leg muscles antagonizing the surface translations, balance training is associated with improved neuromuscular timing and accuracy being relevant for postural control. This may result in more efficient segmental stabilization during fall risk situations, independent of the intervention modality. More pronounced modulations and higher effect sizes after RBT in stance perturbation point toward specificity of training adaptations, with an emphasis on the proximal Body segment for RBT. Outcomes underline the benefits of balance training with a clear distinction between RBT and CBT being relevant for training application over the lifespan
-
Table_2_Neuromuscular and Kinematic Adaptation in Response to Reactive Balance Training – a Randomized Controlled Study Regarding Fall Prevention.docx
2018Co-Authors: Anne Krause, Albert Gollhofer, Kathrin Freyler, Thomas Stocker, Uli Brüderlin, Ralf Colin, Harald Töpfer, Ramona RitzmannAbstract:Slips and stumbles are main causes of falls and result in serious injuries. Balance training is widely applied for preventing falls across the lifespan. Subdivided into two main intervention types, biomechanical characteristics differ amongst balance interventions tailored to counteract falls: conventional balance training (CBT) referring to a balance task with a static ledger pivoting around the ankle joint versus reactive balance training (RBT) using externally applied perturbations to deteriorate Body Equilibrium. This study aimed to evaluate the efficacy of reactive, slip-simulating RBT compared to CBT in regard to fall prevention and to detect neuromuscular and kinematic dependencies. In a randomized controlled trial, 38 participants were randomly allocated either to CBT or RBT. To simulate stumbling scenarios, postural responses were assessed to posterior translations in gait and stance perturbation before and after 4 weeks of training. Surface electromyography during short- (SLR), medium- (MLR), and long-latency response of shank and thigh muscles as well as ankle, knee, and hip joint kinematics (amplitudes and velocities) were recorded. Both training modalities revealed reduced angular velocity in the ankle joint (P < 0.05) accompanied by increased shank muscle activity in SLR (P < 0.05) during marching in place perturbation. During stance perturbation and marching in place perturbation, hip angular velocity was decreased after RBT (P from TTEST, Pt < 0.05) accompanied by enhanced thigh muscle activity (SLR, MLR) after both trainings (P < 0.05). Effect sizes were larger for the RBT-group during stance perturbation. Thus, both interventions revealed modified stabilization strategies for reactive balance recovery after surface translations. Characterized by enhanced reflex activity in the leg muscles antagonizing the surface translations, balance training is associated with improved neuromuscular timing and accuracy being relevant for postural control. This may result in more efficient segmental stabilization during fall risk situations, independent of the intervention modality. More pronounced modulations and higher effect sizes after RBT in stance perturbation point toward specificity of training adaptations, with an emphasis on the proximal Body segment for RBT. Outcomes underline the benefits of balance training with a clear distinction between RBT and CBT being relevant for training application over the lifespan.
R. Esposti - One of the best experts on this subject based on the ideXlab platform.
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Postural Control in Children with Cerebellar Ataxia
'MDPI AG', 2020Co-Authors: V. Farinelli, R. Esposti, S M Marchese, C. Palmisano, C.m.m. Strano, S. D’, C. Pantaleoni, A. Ardissone, N. Nardocci, P. CavallariAbstract:Controlling posture, i.e., governing the ensemble of involuntary muscular activities that manage Body Equilibrium, represents a demanding function in which the cerebellum plays a key role. Postural activities are particularly important during gait initiation when passing from quiet standing to locomotion. Indeed, several studies used such motor task for evaluating pathological conditions, including cerebellar disorders. The linkage between cerebellum maturation and the development of postural control has received less attention. Therefore, we evaluated postural control during quiet standing and gait initiation in children affected by a slow progressive generalized cerebellar atrophy (SlowP) or non-progressive vermian hypoplasia (Joubert syndrome, NonP), compared to that of healthy children (H). Despite the similar clinical evaluation of motor impairments in NonP and SlowP, only SlowP showed a less stable quiet standing and a shorter and slower first step than H. Moreover, a descriptive analysis of lower limb and back muscle activities suggested a more severe timing disruption in SlowP. Such differences might stem from the extent of cerebellar damage. However, literature reports that during childhood, neural plasticity of intact brain areas could compensate for cerebellar agenesis. We thus proposed that the difference might stem from disease progression, which contrasts the consolidation of compensatory strategies
-
Anodal tDCS on parietal operculum does not affect the programming of intra-limb anticipatory postural adjustments
Società Italiana di Fisiologia, 2018Co-Authors: S M Marchese, F. Bolzoni, R. Esposti, P. CavallariAbstract:Voluntary movements induce postural perturbations which are counteracted by anticipatory postural adjustments (APAs). These actions build up long fixation chains toward the available support points, to grant whole Body Equilibrium, but also develop short chains within the same limb where a distal segment is moved (intra-limb APAs), to stabilize the proximal segments. The neural structures generating intra-limb APAs still need investigations. In this view we tested the involvement of the parietal operculum (PO), which has been suggested to play a key role in motor control (Sepulcre 2014, Neuroscientist). APAs that stabilize the arm when the index-finger is briskly flexed were recorded in 9 healthy subjects, before, during and after anodal transcranial direct current stimulation (tDCS, 20 min at 2 mA) applied over PO, and compared to APAs recorded in 9 healthy subjects who underwent sham tDCS. In agreement with literature, in the sham group the activation of prime mover Flexor Digitorum Superficialis (FDS) was preceded by an inhibitory APA in Biceps Brachii and Anterior Deltoid, and almost simultaneous to an excitatory APA in Triceps Brachii. The same pattern also occurred in the anodal group, where tDCS did not significantly affect neither APAs amplitude nor timing. Index-finger kinematics were also unchanged. These preliminary results seem to exclude PO from intra-limb APA organization, though more experiments are needed to increase the sample size and also test cathodal tDCS
-
Temporal disruption of upper-limb anticipatory postural adjustments in cerebellar ataxic patients
'Springer Science and Business Media LLC', 2015Co-Authors: C. Bruttini, F. Bolzoni, R. Esposti, A. Vanotti, C. Mariotti, P. CavallariAbstract:Voluntary movements induce postural perturbations, which are counteracted by anticipatory postural adjustments (APAs) that preserve Body Equilibrium. Little is known about the neural structures generating APAs, but several studies suggested a role of sensory-motor areas, basal ganglia, supplementary motor area and thalamus. However, the role of the cerebellum still remains an open question. The aim of this present paper is to shed further light on the role of cerebellum in APAs organization. Thus, APAs that stabilize the arm when the index finger is briskly flexed were recorded in 13 ataxic subjects (seven sporadic cases, four dominant ataxia type III and two autosomal recessive), presenting a slowly progressive cerebellar syndrome with four-limb dysmetria, and compared with those obtained in 13 healthy subjects. The pattern of postural activity was similar in the two groups [excitation in triceps and inhibition in biceps and anterior deltoid (AD)], but apparent modifications in timing were observed in all ataxic subjects in which, on average, triceps brachii excitation lagged the onset of the prime mover flexor digitorum superficialis by about 27 ms and biceps and AD inhibition were almost synchronous to it. Instead, in normal subjects, triceps onset was synchronous to the prime mover and biceps and AD anticipated it by about 40 ms. The observed disruption of the intra-limb APA organization confirms that the cerebellum is involved in APA control and, considering cerebellar subjects as a model of dysmetria, also supports the view that a proper APA chain may play a crucial role in refining movement metria
-
Disrupt of anticipatory postural adjustments in cerebellar ataxia
2013Co-Authors: F. Bolzoni, R. Esposti, C. Bruttini, A. Vanotti, C. Mariotti, P. CavallariAbstract:Each voluntary movement is known to induce postural perturbations which are counteracted by anticipatory postural adjustments (APAs): i.e. unconscious feed-forward muscular activities, aimed at building up a muscular chain toward an available fixation points (Massion, 1992). The importance of a proper whole-Body stabilisation is apparent when considering standing subjects performing intentional movements involving large masses; in these motor acts, the Equilibrium-perturbing forces would cause a whole-Body Equilibrium disturbance, by displacing both the trunk and the whole-Body CoM (Bouisset and Do, 2008). On the other hand, the importance of an accurate segmental stabilisation may look less obvious in those tasks in which the whole-Body Equilibrium is not threatened, such an index finger flexion. It has been reported that an APA chain also develops in several upper-limb muscles when the index finger is flexed. In this case the prime mover Flexor Digitorum Superficialis (FDS) is preceded by an excitatory burst in Triceps Brachii (TB) and the tonically active Biceps Brachii (BB) and Anterior Deltoid (AD) are carved by inhibitory APAs (Caronni and Cavallari, 2009a). In the present study, APAs and prime mover activation were recorded in seven patients with cerebellar degeneration and on an equal number of healthy subjects. All patients suffered from a slowly progressive cerebellar syndrome, without involvement of the sensory and motor systems. This was witnessed by a standard 1.5-T brain MRIs showing cerebellar atrophy without cerebral cortex, pons, medulla or white matter lesions. Two cases were sporadic, five had a positive family history for autosomal dominant cerebellar ataxia type III. Meann onset age was 31\ub114 years while age at examination was 52 \ub113. All patients presented pure gait ataxia, four-limb dysmetria, mild dysarthria, and occasionally mild increase of deep tendon reflexes, without spasticity. Cognition was normal. Scale for the Assessment and Rating of Ataxia was applied to all patients. The pattern of EMG activities was similar between the two groups, while modifications in the timing of EMG onsets were observed in cerebellar patients, in which no anticipatory activity could be observed in postural muscles. Both inhibition in BB and AD and excitation in TB lagged the onset of the prime mover. Although the role of the cerebellum in the genesis or in the transmission of the APAs still remains open, these data supports the idea that both the prime mover onset and the temporal distribution of the related APAs are set by the \u201ccerebellar timing machine\u201d
F. Bolzoni - One of the best experts on this subject based on the ideXlab platform.
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Anodal tDCS on parietal operculum does not affect the programming of intra-limb anticipatory postural adjustments
Società Italiana di Fisiologia, 2018Co-Authors: S M Marchese, F. Bolzoni, R. Esposti, P. CavallariAbstract:Voluntary movements induce postural perturbations which are counteracted by anticipatory postural adjustments (APAs). These actions build up long fixation chains toward the available support points, to grant whole Body Equilibrium, but also develop short chains within the same limb where a distal segment is moved (intra-limb APAs), to stabilize the proximal segments. The neural structures generating intra-limb APAs still need investigations. In this view we tested the involvement of the parietal operculum (PO), which has been suggested to play a key role in motor control (Sepulcre 2014, Neuroscientist). APAs that stabilize the arm when the index-finger is briskly flexed were recorded in 9 healthy subjects, before, during and after anodal transcranial direct current stimulation (tDCS, 20 min at 2 mA) applied over PO, and compared to APAs recorded in 9 healthy subjects who underwent sham tDCS. In agreement with literature, in the sham group the activation of prime mover Flexor Digitorum Superficialis (FDS) was preceded by an inhibitory APA in Biceps Brachii and Anterior Deltoid, and almost simultaneous to an excitatory APA in Triceps Brachii. The same pattern also occurred in the anodal group, where tDCS did not significantly affect neither APAs amplitude nor timing. Index-finger kinematics were also unchanged. These preliminary results seem to exclude PO from intra-limb APA organization, though more experiments are needed to increase the sample size and also test cathodal tDCS
-
Temporal disruption of upper-limb anticipatory postural adjustments in cerebellar ataxic patients
'Springer Science and Business Media LLC', 2015Co-Authors: C. Bruttini, F. Bolzoni, R. Esposti, A. Vanotti, C. Mariotti, P. CavallariAbstract:Voluntary movements induce postural perturbations, which are counteracted by anticipatory postural adjustments (APAs) that preserve Body Equilibrium. Little is known about the neural structures generating APAs, but several studies suggested a role of sensory-motor areas, basal ganglia, supplementary motor area and thalamus. However, the role of the cerebellum still remains an open question. The aim of this present paper is to shed further light on the role of cerebellum in APAs organization. Thus, APAs that stabilize the arm when the index finger is briskly flexed were recorded in 13 ataxic subjects (seven sporadic cases, four dominant ataxia type III and two autosomal recessive), presenting a slowly progressive cerebellar syndrome with four-limb dysmetria, and compared with those obtained in 13 healthy subjects. The pattern of postural activity was similar in the two groups [excitation in triceps and inhibition in biceps and anterior deltoid (AD)], but apparent modifications in timing were observed in all ataxic subjects in which, on average, triceps brachii excitation lagged the onset of the prime mover flexor digitorum superficialis by about 27 ms and biceps and AD inhibition were almost synchronous to it. Instead, in normal subjects, triceps onset was synchronous to the prime mover and biceps and AD anticipated it by about 40 ms. The observed disruption of the intra-limb APA organization confirms that the cerebellum is involved in APA control and, considering cerebellar subjects as a model of dysmetria, also supports the view that a proper APA chain may play a crucial role in refining movement metria
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Disrupt of anticipatory postural adjustments in cerebellar ataxia
2013Co-Authors: F. Bolzoni, R. Esposti, C. Bruttini, A. Vanotti, C. Mariotti, P. CavallariAbstract:Each voluntary movement is known to induce postural perturbations which are counteracted by anticipatory postural adjustments (APAs): i.e. unconscious feed-forward muscular activities, aimed at building up a muscular chain toward an available fixation points (Massion, 1992). The importance of a proper whole-Body stabilisation is apparent when considering standing subjects performing intentional movements involving large masses; in these motor acts, the Equilibrium-perturbing forces would cause a whole-Body Equilibrium disturbance, by displacing both the trunk and the whole-Body CoM (Bouisset and Do, 2008). On the other hand, the importance of an accurate segmental stabilisation may look less obvious in those tasks in which the whole-Body Equilibrium is not threatened, such an index finger flexion. It has been reported that an APA chain also develops in several upper-limb muscles when the index finger is flexed. In this case the prime mover Flexor Digitorum Superficialis (FDS) is preceded by an excitatory burst in Triceps Brachii (TB) and the tonically active Biceps Brachii (BB) and Anterior Deltoid (AD) are carved by inhibitory APAs (Caronni and Cavallari, 2009a). In the present study, APAs and prime mover activation were recorded in seven patients with cerebellar degeneration and on an equal number of healthy subjects. All patients suffered from a slowly progressive cerebellar syndrome, without involvement of the sensory and motor systems. This was witnessed by a standard 1.5-T brain MRIs showing cerebellar atrophy without cerebral cortex, pons, medulla or white matter lesions. Two cases were sporadic, five had a positive family history for autosomal dominant cerebellar ataxia type III. Meann onset age was 31\ub114 years while age at examination was 52 \ub113. All patients presented pure gait ataxia, four-limb dysmetria, mild dysarthria, and occasionally mild increase of deep tendon reflexes, without spasticity. Cognition was normal. Scale for the Assessment and Rating of Ataxia was applied to all patients. The pattern of EMG activities was similar between the two groups, while modifications in the timing of EMG onsets were observed in cerebellar patients, in which no anticipatory activity could be observed in postural muscles. Both inhibition in BB and AD and excitation in TB lagged the onset of the prime mover. Although the role of the cerebellum in the genesis or in the transmission of the APAs still remains open, these data supports the idea that both the prime mover onset and the temporal distribution of the related APAs are set by the \u201ccerebellar timing machine\u201d