L. Parenti

High Hypnotizability Impairs the Cerebellar Control of Pain.

In the general population, transcranial anodal direct current stimulation of the cerebellum (ctDCS) reduces pain intensity and the amplitude of nociceptive laser evoked potentials (LEPs), whereas cathodal ctDCS elicits opposite effects. Since behavioral findings suggest that the cerebellar activity of highly hypnotizable individuals (highs) differs from the general population, we investigated whether hypnotizability-related differences occur in the modulation of pain by ctDCS. Sixteen healthy highs (according to the Stanford Hypnotic Susceptibility Scale, form A) and 16 participants not selected according to hypnotizability (controls) volunteered to undergo laser nociceptive stimulation of the dorsum of the left hand before and after anodal or cathodal ctDCS. LEPs amplitudes and latencies and the subjective pain experience (Numerical Rating Scale) were analyzed. Smaller LEP amplitudes and longer latencies were observed in highs with respect to controls independently of stimulation. After anodal and cathodal cerebellar stimulation, controls reported lower and higher pain than before it, respectively. In contrast, highs did not report significant changes in the perceived pain after both stimulations. They increased significantly their N2/P2 amplitude after anodal ctDCS and did not exhibit any significant change after cathodal tDCS, whereas controls decreased the N1 and N2P2 amplitude and increased their latency after anodal cerebellar stimulation and did the opposite after cathodal ctDCS. In conclusion, the study showed impaired cerebellar pain modulation and suggested altered cerebral cortical representation of pain in subjects with high hypnotizability scores.

Impaired interhemispheric processing in early Huntington’s Disease: A transcranial magnetic stimulation study

Background and Rationale Changes in interhemispheric connectivity in Huntington’s Disease (HD) have been only recently investigated and little is known about their temporal relation with clinical features or grey matter atrophy: callosal disruption could contribute both to cognitive dysfunction and impairment of associative functions (Rosas et al. , 2010) and likely occurs many years before clinical onset, along a posterior-to-anterior direction (Phillips et al. , 2013). Here, we evaluated changes in ipsilateral Silent Period (iSP: onset latency, iSPOL, and duration, iSPD) and Transcallosal Conduction Time (TCT) in HD patients and correlated electrophysiological findings with mutational load and motor score.

Neurophysiological Comparison Among Tonic, High Frequency, and Burst Spinal Cord Stimulation: Novel Insights Into Spinal and Brain Mechanisms of Action: SPINAL AND BRAIN SCS MECHANISMS OF ACTION

Spinal cord stimulation (SCS) is an effective option for neuropathic pain treatment. New technological developments, as high‐frequency (HF) and theta burst stimulation (TBS), have shown promising results, although putative mechanisms of action still remain debated.

Cerebellar direct current stimulation modulates hand blink reflex: implications for defensive behavior in humans

The cerebellum is involved in a wide number of integrative functions. We evaluated the role of cerebellum in peripersonal defensive behavior, as assessed by the so‐called hand blink reflex (HBR), modulating cerebellar activity with transcranial direct current stimulation (tDCS). Healthy subjects underwent cerebellar (sham, anodal, and cathodal tcDCS) and motor cortex tDCS (anodal or cathodal; 20′, 2 mA). For the recording of HBR, electrical stimuli were delivered using a surface bipolar electrode placed on the median nerve at the wrist and EMG activity recorded from the orbicularis oculi muscle bilaterally. Depending on the hand position respective to the face, HBR was assessed in four different conditions: “hand‐far,” “hand‐near” (eyes open), “side hand,” and “hand‐patched” (eyes closed). While sham and cathodal cerebellar stimulation had no significant effect, anodal tcDCS dramatically dampened the magnitude of the HBR, as measured by the area under the curve (AUC), in the “hand‐patched” and “side hand” conditions only, for ipsilateral (F(4,171) = 15.08, P < 0.0001; F(4,171) = 8.95, P < 0.0001) as well as contralateral recordings (F(4,171) = 17.96, P < 0.0001); F4,171) = 5.35, P = 0.0004). Cerebellar polarization did not modify AUC in the “hand‐far” and “hand‐near” sessions. tDCS applied over the motor area did not affect HBR. These results seem to support a role of the cerebellum in the defensive responses within the peripersonal space surrounding the face, thus suggesting a possible cerebellar involvement in visual‐independent defensive behavior.

Holmes’ or functional tremor?

Highlights • We report the case of an Holmes tremor with atypical features.• The association between Holmes and functional tremor has never been reported before.• We propose a fast battery for the differential diagnosis of functional tremor.

5. Cerebellar direct current stimulation modulates pain perception and its neural correlates in humans

Here, we investigated whether level of cortical excitability changes with the distance from the last migraine attack could explain previous inconsistent results. Twenty-six patients with untreated migraine without aura (MO) underwent MEP study between attacks and were compared to a group of 24 healthy volunteers (HV). The TMS figure-of-eight coil was positioned over the left motor area. We first identified the resting motor threshold (RMT) and then amplitude of MEP was evaluated by delivering and averaging 10 single pulses of TMS using a stimulus intensity of 120% RMT at a rate of 0.1 Hz. Mean RMTs (54.2 in MO vs. 55.8 in HV) and MEP amplitudes (3057 microV in MO vs. 3675 microV in HV) were not significantly different between MO and HV. In MO, the RMT negatively correlated with days elapsed since the last migraine attack (r = 0.426, p = 0.03), i.e. RMT was minimal at a long time interval after an attack while it was greater and within the range of normative values approaching to an attack. The dynamic RMT variations found here resemble those we have previously reported for visual and somatosensory evoked potentials, and may represent timedependent plastic changes in brain excitability in relation with the migraine cycle.