Cerebral hemodynamic changes during motor imagery and passive robot-assisted movement of the lower limbs.

BACKGROUND: Neurovascular Coupling is the cerebral mechanism responsible for linking neuronal activity, cerebral metabolism and regional cerebral blood flow (CBF). The direct relation between functional brain activity during active, passive and motor imagery paradigms and changes in CBF has been widely investigated using different techniques. However, CBF changes have not been investigated beat by beat during robot assisted passive movement (PM) and motor imagery (MI) of lower limb, yet. MATERIALS AND METHODS: We investigated beat-to-beat hemodynamic changes in 8 healthy subjects using TCD during MI and robot-assisted PM of lower limb. RESULTS: The results showed that MI and PM induce a significant CBFv increase and that PM and MI lead to similar hemodynamic changes in healthy subjects. CONCLUSIONS: The findings may be useful to better understand the variation of CBFv in brain pathology and to develop more specific and efficient rehabilitation therapy protocols in neurological diseases, such as stroke.

Dramatic placebo effect of high frequency repetitive TMS in treatment of chronic migraine and medication overuse headache.

Chronic migraine (CM) is often associated with medication overuse headache (MOH). Few small trials have been conducted on Transcranial Magnetic Stimulation for CM treatment, but results are conflicting. Aim of the study was to investigate the effects of high frequency of repetitive Transcranial Magnetic Stimulation (hf-rTMS) in the dorsolateral prefrontal cortex combined with strongly suggesting to avoid medications overuse in patients suffering with CM and MOH. A six-month single-centre perspective randomized double-blinded study was conducted at the Headache Centre of Trieste. Patients suffering with CM and MOH were randomly enrolled in two groups to receive active hf-rTMS in DLPFC or sham hf-rTMS. Headache days (HD), headache hours (HH) and symptomatic drug intake (SDI) were recorded for 30 days before the beginning of stimulation (T0) and during the three following months (T3). Disability (MIDAS score) was evaluated at T0 and at the three-month follow-up visit. The primary outcome was the evaluation of reduction of HD. Reduction of SDI, HH and disability were considered as secondary outcomes. Out of 26 patients enrolled, 14 completed the study, 7 underwent hf-rTMS and 7 sham-TMS. There were no significant differences between groups at T0 in demographic data and headache measures. Mean number of HD, HH, SDI, and MIDAS similarly reduced in the two groups. Our study failed in demonstrating that hf-rTMS with detoxification advice could be better than detoxification advice alone in CM treatment. hf-rTMS carries a high potential of inducing placebo effect and this can be usefully leveraged to enhance patients' coping strategies.

Involvement of ipsilateral parieto-occipital cortex in the planning of reaching movements: evidence by TMS.

Involvement of the ipsilateral hemisphere during planning of reaching movements is still matter of debate. While it has been demonstrated that the contralateral hemisphere is dominant in visuo-motor integration, involvement of the ipsilateral hemisphere has also been proposed. Furthermore, a dominant role for left posterior parietal cortex has been shown in this process, independently of the hand and visual field involved. In this study, the possible involvement of ipsilateral parieto-occipital cortex in planning of reaching movements was investigated by transcranial magnetic stimulation (TMS). TMS was applied on four points of the parietal and occipital cortex at 50% (Time 1), 75% (Time 2) and 90% (Time 3) of reaction time from a go-signal to hand movement. The only effect observed was an increase in reaction time when a region around the parieto-occipital junction was stimulated at Time 2. These results provide further support to the hypothesis that, in the posterior parietal cortex, planning of reaching movements also relies on the ipsilateral hemisphere, in addition to the contralateral or dominant one.

Parieto-occipital cortex and planning of reaching movements: a transcranial magnetic stimulation study.

A large amount of evidence supports a role for the parietal and frontal cortex in the planning of reaching movements. Nevertheless, neither the timing of involvement of these areas nor if and how their activity can be influenced by external stimuli has been clarified. The parieto-occipital cortex has been investigated by applying transcranial magnetic stimulation (TMS) at 25% (Time 1), 50% (Time 2) and 75% (Time 3) of the reaction time from a go signal to hand movement. No local effect was found with Time 1, since pulses were administered before subjects opened their eyes. Reduction of reaction time was observed at Time 2 when stimuli were applied over the anterior occipital lobe, parieto-occipital cortex and posterior parietal cortex. The effect on the posterior parietal cortex reverted when Time 3 was used. The present data confirm the existence, in humans, of a dorso-medial set of areas involved in on-line planning of reaching movements. Moreover, they provide novel evidence on the time course of this involvement. Finally, present data show that it is possible to interact with the flow of activity along this stream by appropriately delivering TMS pulses.

Effect of transcranial magnetic stimulation (TMS) on parietal and premotor cortex during planning of reaching movements.

BACKGROUND: Cerebral activation during planning of reaching movements occurs both in the superior parietal lobule (SPL) and premotor cortex (PM), and their activation seems to take place in parallel. METHODOLOGY: The activation of the SPL and PM has been investigated using transcranial magnetic stimulation (TMS) during planning of reaching movements under visual guidance. PRINCIPAL FINDINGS: A facilitory effect was found when TMS was delivered on the parietal cortex at about half of the time from sight of the target to hand movement, independently of target location in space. Furthermore, at the same stimulation time, a similar facilitory effect was found in PM, which is probably related to movement preparation. CONCLUSIONS: This data contributes to the understanding of cortical dynamics in the parieto-frontal network, and suggests that it is possible to interfere with the planning of reaching movements at different cortical points within a particular time window. Since similar effects may be produced at similar times on both the SPL and PM, parallel processing of visuomotor information is likely to take place in these regions.