Papers by Fausto Baldissera
Aim: When sitting on an armchair and rhythmically oscillating one foot, the excitability of flexo... more Aim: When sitting on an armchair and rhythmically oscillating one foot, the excitability of flexor and extensor muscles of the resting ipsilateral forearm is subliminally modulated in a reciprocal way, increasing in each muscle when the \u201cisodirectional\u201d foot mover is activated. In a less stable postural context (upright standing) and using the hand for postural support, those subliminal changes are transformed into overt activities, featured as Anticipatory Postural Adjustments (APAs). We report here evidence for the reverse correlation: oscillations of one hand in the parasagittal plane are accompanied by overt APAs in the foot flexors and extensors. Methods: Ten subjects standing with their right forearm directed forward (arm vertical, elbow at 90\ub0), either prone or supine, performed series of 15-20 impulsive flexions or extensions of the wrist (movement rate 0.2Hz) as well as series of 30 cyclic flexions-extensions at 1Hz. EMG from the prime movers Extensor and Flexo...
European Journal of Neuroscience, 2001
There is growing evidence that observation of actions performed by other individuals activates ob... more There is growing evidence that observation of actions performed by other individuals activates observer's cortical motor areas. This matching of observed actions on the observer's motor repertoire could be at the basis of action recognition. Here we investigated if action observation, in addition to cortical motor areas, involves also low level motor structures mimicking the observed actions as if they were performed by the observer. Spinal cord excitability was tested by eliciting the H-re¯ex in a ®nger exor muscle (¯exor digitorum super®cialis) in humans looking at goal-directed hand actions presented on a TV screen. We found that, in the absence of any detectable muscle activity, there was in the observers a signi®cant modulation of the monosynaptic re¯ex size, speci®cally related to the different phases of the observed movement. The recorded H-re¯ex rapidly increased in size during hand opening, it was depressed during hand closing and quickly recovered during object lifting. This modulation pattern is, however, opposite to that occurring when the recorded muscles are actually executing the observed action [Lemon et al. (1995) J. Neurosci., 15, 6145±56]. Considering that, when investigated at cortical level the modulation pattern of corticospinal excitability replicates the observed movements [Fadiga et al. (1995) J. Neurophysiol., 73, 2608±2611], this spinal inverted mirror' behaviour might be ®nalised to prevent the overt replica of the seen action.
Experimental Brain Research, 2000
(1) Rhythmic flexion-extensions of the hand and foot on one side were performed by ten male and n... more (1) Rhythmic flexion-extensions of the hand and foot on one side were performed by ten male and nine female subjects. Limbs were rotated in the same direction (in-phase) or in opposite directions (anti-phase). Oscillation frequency ranged from 0.6 to 3.2 Hz for inphase and to 2.2 Hz for anti-phase movements. In both genders, movement synchrony was more strictly maintained during anti-phase than during in-phase coupling. (2) EMG recordings showed that, in males, movement synchrony was achieved by activating hand movers in advance of foot movers. This phase advance increased as the oscillation frequency increased. In females, instead, muscles of the two limbs were activated almost simultaneously over most of the frequency range. Since the different timing of muscle activation in the two genders suggests that their limbs have different mechanical characteristics, the frequency response of each limb was estimated in either gender. The frequency response between 0.6 and 3.2 Hz was evaluated in five males and five females by measuring the phase delay between the onset of the EMG activity and the onset of the related movement, both when the limbs were moved in isolation and when they were coupled. (3) In uncoupled conditions, the hand and foot curves were roughly parallel in females, the phase delay being about 45°larger in the hand than in the foot. In males, the curves were also separated by 45°a t the lowest frequencies but they further diverged when the frequency was raised, because of a faster increase in the phase delay in the hand than in the foot. These results indicate that, when the extremities have to be coupled, a nervous compensation is necessary and that it must be different in the two genders. (4) Analysis of the phase-response when limbs were coupled showed that synchrony was approached by two mechanisms: (a) an earlier EMG activation of the hand movers, preferentially utilised by males during in-phase coupling; and (b) a change in the viscoelastic properties of one extremity, which reduces (or eliminates) the difference between their frequency responses as well as between the EMG onsets of hand and foot movers. This second mechanism was utilised by both genders during anti-phase coupling.
The Journal of Physiology
Frontiers in Human Neuroscience, 2017
Experimental Brain Research, Mar 1, 2008
While sitting on a turnable stool, with both shoulder flexed at 90° or, alternatively, with arms ... more While sitting on a turnable stool, with both shoulder flexed at 90° or, alternatively, with arms parallel to the trunk and the elbow flexed at 90°-the hands being semisupine-subjects performed unidirectional and cyclic movements on the horizontal plane of the right arm (adduction and abduction) or hand (flexion-extension). The left arm was still, in a position symmetrical to that of the right limb and with the hand contacting a fixed support by the palmar or dorsal surface. During both unidirectional and cyclic arm or hand movements, activation of the prime mover muscles (right Pectoralis Major for arm adduction and Infraspinatus for abduction; right Flexor Carpi Radialis and Extensor Carpi Radialis for the hand movements) was accompanied by activation of the homologous muscles of the contralateral arm and inhibition of antagonists. The contralateral activities 1) regularly preceded the burst in the movement prime movers and 2) were organised in fixation chains that, exerting forces on the hand fixed support, will counterbalance the rotatory action exerted on the trunk by the primary movement. Based on these features, these activities may be classified as Anticipatory Postural Adjustments (APAs). The observed APAs distribution is such as to favour the preferential (mirror symmetrical) coupling of upper limb movements on the horizontal plane. The possible role of these APAs in determining the different constraints experienced when performing mirror symmetrical versus isodirectional coupling is discussed.
European Journal of Applied Physiology, 2010
When oscillating the upper limbs in the horizontal plane, the effort required to maintain posture... more When oscillating the upper limbs in the horizontal plane, the effort required to maintain posture is higher when the limbs move isodirectionally (ISO coupling) than when they move mirrorsymmetrical, i.e., antidirectionally (ANTI). Movements stability and accuracy are much lower in ISO than in ANTI and the higher postural requests may be one factor contributing to the coordination deficiency of ISO movements. On this background, we measured the metabolic cost of ISO and ANTI movements in order to 1) quantitatively evaluate the supplemental effort required by ISO coupling, 2) establish whether it can be entirely ascribed to postural activities, and 3) compare it with the effort paid for the primary movement. Breath-by-breath metabolic (2 O V & , 2 CO V &) and cardio-respiratory (HR, E V &) parameters were measured in six participants, who performed intermittent exercises (5 minutes long, 12s movement, 12s rest) of cyclic arm adduction-abduction in the horizontal plane with either one arm or both arms in ISO or ANTI coupling, at 1.4 and 2.0 Hz. A force platform recorded the reaction forces to ground and the torque about the trunk vertical axis (Tz). At both frequencies and at metabolic steady-state, the mean values of both 2 O V & and Tz were found to be larger during ISO than ANTI coupling. Moreover, a linear relation was found between metabolic cost and Tz. Lastly, during ANTI coupling virtually all the energy was spent for the primary movement while the large increase in energy expenditure when passing from ANTI to ISO was almost entirely ascribable to postural activities.
Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society, 1989
ABSTRACT A special sensitivity of spinal motoneurones to the rate of rise of input currents devel... more ABSTRACT A special sensitivity of spinal motoneurones to the rate of rise of input currents develops in the same range of the frequency domain (i.e. above 1 Hz) where the mechanical response of the muscle is cut off. The upper limit of the frequency response was found to be about ten times higher in the motor unit (motoneurone plus the innervated muscle fibers) than in the isolated muscle. It is concluded that the dynamic sensitivity of motoneurone compensates for the low-pass filter properties of muscle contraction and improves the motor unit response by elevating the cutoff frequency by around ten times
Interlimb Coordination, 1994
Electroencephalography and clinical neurophysiology, 1995
Changes in motor cortex excitability induced by somatosensory afferences were evaluated in 5 subj... more Changes in motor cortex excitability induced by somatosensory afferences were evaluated in 5 subjects by testing how the short-latency cortico-spinal effects evoked by transcranial magnetic stimulation in flexor carpi radialis (FCR) motoneurones were influenced by volleys in median nerve afferent fibres. Transcranial magnetic stimulation induced two facilitatory peaks on FCR H reflex, the first at a conditioning-test interval of about -3 msec and the second at msec, separated by a phase of inhibition. If an electric shock to the median nerve at the wrist, 0.8-1 x motor threshold (MT) for thenar muscles, preceded the cortical stimulus by 18-25 msec, an increase in size of both facilitatory peaks was observed. The increase was partly due to a direct action of the median nerve volley on motoneurones. When this contribution was subtracted, two peaks of additional facilitation resulted as the effect of combined conditioning. Additional facilitation was present even during the short-lasti...
Electromyography and clinical neurophysiology
The Laryngoscope, 1986
The aim of this work was to reestablish the respiratory function of the paralyzed larynx through ... more The aim of this work was to reestablish the respiratory function of the paralyzed larynx through reinnervation of the posterior cricoarytenoid (PCA) muscle by phrenic motoneurons. In nine adult cats the adductor branch of the recurrent laryngeal nerve (RLN) of one side was cut and ligated, while the abductor branch was left intact. The whole RLN was then transected lower in the neck and its distal stump anastomosed to the upper branch of the phrenic nerve. Periodical laryngoscopies under ketamine anesthesia assessed that the inspiratory abduction of the paralyzed vocal cord recovered within 45 days to 60 days in all cats. Abduction was caused by reinnervation of the PCA muscle from phrenic motoneurons, as demonstrated by electrophysiological and anatomical (retrograde transport of horseradish peroxidase) testings.
Comprehensive Physiology, 2011
... Editors & Contributors. Standard Article. Integration in Spinal Neuronal Systems. Fausto ... more ... Editors & Contributors. Standard Article. Integration in Spinal Neuronal Systems. Fausto Baldissera 1 ,; Hans Hultborn 2 ,; Michael Illert 3. Published Online: 1 JUN 2010. DOI: 10.1002/cphy.cp010212. Copyright © 2010 American Physiological Society. All rights reserved. Book Title ...
Transmastoid galvanic stimulation was applied to five subjects while records were taken of the re... more Transmastoid galvanic stimulation was applied to five subjects while records were taken of the rectified and averaged EMG from the triceps brachii of both sides. In four subjects current pulses of 1.6 mA, lasting 10-100 ms, evoked an excitatory response with a latency of 30-35 ms from the side ipsilateral to the anode and inhibition appeared at 40 ms on the side ipsilateral to the cathode. In the fifth subject the stimulus evoked inhibition at 40 ms on both sides. Thresholds for both excitatory and inhibitory responses were between 0.6 and 1 mA. Control experiments excluded a possible cutaneous origin. These actions might therefore represent reflex responses elicited by activation of the vestibular systems.
Background: Synchrony of coupled oscillations of ipsilateral hand and foot may be achieved by con... more Background: Synchrony of coupled oscillations of ipsilateral hand and foot may be achieved by controlling the interlimb phase difference through a crossed kinaesthetic feedback between the two limbs, or by an independent linkage of each limb cycle to a common clock signal. These alternative models may be experimentally challenged by comparing the behaviour of the two limbs when they oscillate following an external time giver, either alone or coupled together. Results: Ten subjects oscillated their right hand and foot both alone and coupled (iso-or antidirectionally), paced by a metronome. Wrist and ankle angular position and Electromyograms (EMG) from the respective flexor and extensor muscles were recorded. Three phase delays were measured: i) the clk-mov delay, between the clock (metronome beat) and the oscillation peak; ii) the neur (neural) delay, between the clock and the motoneurone excitatory input, as inferred from the EMG onset; and iii) the mech (mechanical) delay between the EMG onset and the corresponding point of the limb oscillation. During uncoupled oscillations (0.4 Hz to 3.0 Hz), the mech delay increased from-7° to-111° (hand) and from-4° to-83° (foot). In contrast, the clk-mov delay remained constant and close to zero in either limb since a progressive advance of the motoneurone activation on the pacing beat (neur advance) compensated for the increasing mech delay. Adding an inertial load to either extremity induced a frequency dependent increase of the limb mechanical delay that could not be completely compensated by the increase of the neural phase advance, resulting in a frequency dependent increment of clk-mov delay of the hampered limb. When limb oscillations were iso-or antidirectionally coupled, either in the loaded or unloaded condition, the three delays did not significantly change with respect to values measured when limbs were moved separately. Conclusion: The absence of any significant effect of limb coupling on the measured delays suggests that during hand-foot oscillations, both iso-and antidirectionally coupled, each limb is synchronised to the common rhythm generator by a "private" position control, with no need for a crossed feedback interaction between limbs.
The Journal of Physiology, 1998
Sherrington's motor unit (the motoneurone and the muscle fibres innervated thereby) may be descri... more Sherrington's motor unit (the motoneurone and the muscle fibres innervated thereby) may be described as the elementary interface between the central nervous system and the environment: the motoneurone encodes supraliminal synaptic currents into firing rates and these impulse trains are converted into levels of force by the innervated muscle fibres (the muscle unit). In response to steady inputs, the motoneurone current-torate relation is linear over an extension ('primary range', Kernell, 1965) which covers the straight portion of the rate
Social Neuroscience, 2008
Some neural properties of ''motor resonance''*the subliminal activation of the motor system when ... more Some neural properties of ''motor resonance''*the subliminal activation of the motor system when observing actions performed by others*are investigated in humans. Two actions performed with the right hand are observed by experimental subjects: a finalized (transitive) action (reaching for and grasping a ball) and an intransitive action (cyclic up-and-down oscillation of the hand), while the H-reflex and Transcranial Magnetic Stimulation techniques are utilized to test the excitability of the observer's motor pathways to hand and forearm muscles (first dorsal interosseus, flexor digitorum superficialis, flexor carpi radialis). Results indicate that motor resonance: (1) is mainly mediated by the primary motor cortex; (2) involves the same forearm muscles as used in the execution of the observed movement; (3) is also recorded in the homologous muscles of the arm contralateral to the one observed; and (4) is evoked by both transitive and intransitive movements of the human hand, but not by similar movements of inanimate objects. The similarities and discrepancies between the resonant response in humans and the properties of monkey ''mirror neurons'' are discussed.
Neuroscience Letters, 2000
The effect of the forearm position, prone vs. supine, on the excitability of the H-re¯ex in¯exor ... more The effect of the forearm position, prone vs. supine, on the excitability of the H-re¯ex in¯exor carpi radialis (FCR) muscle was tested in nine adult volunteers by comparing the recruitment pro®les of the H and M waves. The H-re¯ex size, normalized to the maximal M response, was lower when the forearm was supine than when it was prone, with an average reduction of about 50% over most of the H-recruitment curve. In three wrist positions, intermediate between prone and supine, the amount of re¯ex attenuation was related to the prono-supination angle. Control experiments excluded that the changes in the H re¯ex excitability were due to displacements of the stimulating or recording electrodes.
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Papers by Fausto Baldissera