Maria Maddalena Filippi

Publications (5)15.47 Total impact

• Article: Imagery-induced cortical excitability changes in stroke: a transcranial magnetic stimulation study.

  Paola Cicinelli, Barbara Marconi, Marina Zaccagnini, Patrizio Pasqualetti, Maria Maddalena Filippi, Paolo Maria Rossini
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  ABSTRACT: Focal transcranial magnetic stimulation (TMS) was employed in a population of hemiparetic stroke patients in a post-acute stage to map out the abductor digiti minimi (ADM) muscle cortical representation of the affected (AH) and unaffected (UH) hemisphere at rest, during motor imagery and during voluntary contraction. Imagery induced an enhancement of the ADM map area and volume in both hemispheres in a way which partly corrected the abnormal asymmetry between AH and UH motor output seen in rest condition. The voluntary contraction was the task provoking maximal facilitation in the UH, whereas a similar degree of facilitation was obtained during voluntary contraction and motor imagery in the AH. We argued that motor imagery could induce a pronounced motor output enhancement in the hemisphere affected by stroke. Further, we demonstrated that imagery-induced excitability changes were specific for the muscle 'prime mover' for the imagined movement, while no differences were observed with respect to the stroke lesion locations. Present findings demonstrated that motor imagery significantly enhanced the cortical excitability of the hemisphere affected by stroke in a post-acute stage. Further studies are needed to correlate these cortical excitability changes with short-term plasticity therefore prompting motor imagery as a 'cortical reservoir' in post-stroke motor rehabilitation.
  Cerebral Cortex 03/2006; 16(2):247-53. · 6.54 Impact Factor
• Article: Specific forms of neural activity associated with tactile space awareness.

  Massimiliano Oliveri, Paolo Maria Rossini, Maria Maddalena Filippi, Raimondo Traversa, Paola Cicinelli, Carlo Caltagirone
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  ABSTRACT: Left tactile extinction, in which a left tactile stimulus fails to access consciousness only when a right stimulus is presented simultaneously, offers a model for studying tactile awareness from its transitory absence. Pairs of transcranial magnetic stimuli (TMS) on the parietal cortex inhibit contralateral tactile perception when separated by an interval of 1 ms. We have applied this technique on the left parietal cortex of right brain damaged (RBD) patients and normal subjects and have shown a selective lack of paired TMS inhibitory effects on right tactile perception of patients during bimanual stimulation. TMS effects were normal during unimanual right stimulation. These results suggest the presence of a specific pattern of inhibitory/excitatory interactions in parietal brain areas as critical for tactile awareness.
  Neuroreport 07/2002; 13(8):997-1001. · 1.66 Impact Factor
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  Available from: Massimiliano Oliveri

  Article: Are autonomic signals influencing cortico-spinal motor excitability?: A study with transcranial magnetic stimulation

  Maria Maddalena Filippi, Massimiliano Oliveri, Fabrizio Vernieri, Patrizio Pasqualetti, Paolo Maria Rossini
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  ABSTRACT: In order to investigate the role of visceral afferent inputs flowing along autonomic fibers on corticospinal tract excitability, the variability of Motor Evoked Potentials (MEPs), elicited by Transcranial Magnetic Stimulation (TMS), was analysed during simultaneous monitoring of electrocardiogram (EKG) phases, breathing phases and sudomotor skin responses (SSRs) in a group of 10 healthy subjects. A cascade of at least 60 consecutive magnetic stimuli, with an interstimulus interval randomly varying between 20 and 40 s, was acquired. At the end of the recording session, the subject was asked to make at random five not consecutive self-paced forced inspirations. TMS was carried out at an intensity 10% above motor threshold excitability via a circular coil placed over the motor area of the right hemisphere. MEPs were recorded from the contralateral abductor digiti minimi muscle (ADM). Sudomotor Skin Responses (SSRs) were recorded on both hand palms. MEPs latency and amplitude did not show significant correlation with any of the EKG and respiratory phases. During forced inspiration, a significant latency shortening was found. TMS elicited SSRs, whose amplitudes were not correlated with MEP parameters. During forced inspiration a significant SSR amplitude increment, not correlated with MEP latency shortening, was also observed. These results assign a minor if any role to the considered autonomic parameters in modulating corticospinal motor excitability.
  Brain Research 11/2000; · 2.73 Impact Factor
• Article: Neurophysiological evaluation of tactile space perception deficits through transcranial magnetic stimulation

  Massimiliano Oliveri, Paolo Maria Rossini, Paola Cicinelli, Raimondo Traversa, Patrizio Pasqualetti, Maria Maddalena Filippi, Carlo Caltagirone
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  ABSTRACT: We describe a procedure useful to investigate the contralateral space perception deficits frequently encountered in patients with unilateral right brain damage. In particular, we focused on the phenomenon of extinction, i.e., the failure to perceive a contralesional stimulus only when a symmetrical contralateral stimulus is simultaneously applied. Fifteen right brain- and 15 left brain-damaged patients were examined. Somatosensory perception was evaluated by using a dedicated electronic device able to provide electrical stimuli of variable intensity to digits of one or both hands. The electrical stimulator was able to trigger a magnetic brain stimulator connected with a focal figure of eight coil. Threshold electrical stimuli were delivered to one or both hands of the patients, who were asked to indicate whether they perceived the stimulus (i) and to localise it (them). The electrical stimulator was connected with a magnetic stimulator with an interstimulus interval (ISI) of 40 msec (electrical stimulation preceding the transcranial one). Focal threshold transcranial magnetic stimulation (TMS) was applied to frontal and parietal scalp sites of the unaffected hemisphere. At each interpulse interval we found that TMS of the unaffected hemisphere was associated to a decrease in the level of contralesional extinction. Our method demonstrates that a basic deficit underlying neglect and extinction of contralateral space in unilaterally brain damaged patients is the interhemispheric imbalance between the two hemispheres in directing contralateral attention. A transient interference with the function of the unaffected hemisphere can improve these deficits, suggesting a possible application of TMS in the daily clinical practice for speeding up recovery from neglect.Themes: Neural basis of behaviourTopic: Cognition
  Brain Research Protocols 03/2000; · 1.82 Impact Factor
• Article: Effect of paired transcranial magnetic stimulation on the cortical silent period

  Toshio Shimizu, Massimiliano Oliveri, Maria Maddalena Filippi, Maria Giuseppina Palmieri, Patrizio Pasqualetti, Paolo Maria Rossini
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  ABSTRACT: Objective. To investigate the behaviour of silent period (SP) during paired magnetic cortical stimulation. Background. Paired cortical magnetic stimulation is known to inhibit or facilitate motor evoked potentials (MEPs), but no attention has been paid to its effect on SP. Methods. SP was measured in the contracted first dorsal interosseus muscle after paired cortical stimuli at given interstimulus intervals (ISIs) in eight healthy subjects. Test stimulus intensity was fixed at 110% of resting threshold (RT), while three levels of conditioning stimulus intensities at 40%, 65% and 90% RT were separately employed. We also examined the effect of progressively increasing the test stimulus intensity (120–150 RT) on SP while maintaining stable conditioning stimulus intensity. Results. 65% RT conditioning stimulus shortened the SP at 1–3 ms ISIs with MEP size reduction, and prolonged the SP at 15–20 ms ISIs without affecting MEP size. 90% RT conditioning stimulus showed only SP prolongation, while 40% RT showed only SP shortening at 1 ms ISI. The SP shortening at 2 ms ISI was the most evident with 120% RT test stimulus, but without correlation with the MEP size. The SP prolongation at 15 ms ISI was maximal with 110% RT test stimulus and then almost abolished with 150% RT. The SP shortening at short intervals might be due not only to spinal but also to suprasegmental mechanisms, conceivably mediating cortical excitatory drive to the corticospinal tract. The SP prolongation at intermediate intervals might be due to activation of slowly conducting, intra- or sub-cortical polysynaptic pathways exerting a facilitatory drive on the cortical inhibitory interneurons.
  Brain Research 08/1999; · 2.73 Impact Factor