Effects of intra-VTA injection of neurotensin on local cerebral glucose utilization in the rat.

The [14C]2-deoxyglucose method was applied to measure the effects of the injection of neurotensin (7 microg) in the ventral tegmental area on local cerebral glucose utilization in the rat. Injection of neurotensin produced significant increases of glucose utilization in the shell of the nucleus accumbens and in the olfactory tubercle. These results indicate that stimulation of neurotensin receptors in the ventral tegmental area produces functional changes that are confined to the regions receiving mesolimbic projections within the rostral extended amygdaloid complex. These findings extend our understanding on the effects of neurotensin in the limbic system, with particular regard to reward pathways

Theta-Burst Stimulation-Induced Plasticity over Primary Somatosensory Cortex Changes Somatosensory Temporal Discrimination in Healthy Humans

BACKGROUND: The somatosensory temporal discrimination threshold (STDT) measures the ability to perceive two stimuli as being sequential. Precisely how the single cerebral structures contribute in controlling the STDT is partially known and no information is available about whether STDT can be modulated by plasticity-inducing protocols. METHODOLOGY/PRINCIPAL FINDINGS: To investigate how the cortical and cerebellar areas contribute to the STDT we used transcranial magnetic stimulation and a neuronavigation system. We enrolled 18 healthy volunteers and 10 of these completed all the experimental sessions, including the control experiments. STDT was measured on the left hand before and after applying continuous theta-burst stimulation (cTBS) on the right primary somatosensory area (S1), pre-supplementary motor area (pre-SMA), right dorsolateral prefrontal cortex (DLPFC) and left cerebellar hemisphere. We then investigated whether intermittent theta-burst stimulation (iTBS) on the right S1 improved the STDT. After right S1 cTBS, STDT values increased whereas after iTBS to the same cortical site they decreased. cTBS over the DLPFC and left lateral cerebellum left the STDT statistically unchanged. cTBS over the pre-SMA also left the STDT statistically unchanged, but it increased the number of errors subjects made in distinguishing trials testing a single stimulus and those testing paired stimuli. CONCLUSIONS/SIGNIFICANCE: Our findings obtained by applying TBS to the cortical areas involved in processing sensory discrimination show that the STDT is encoded in S1, possibly depends on intrinsic S1 neural circuit properties, and can be modulated by plasticity-inducing TBS protocols delivered over S1. Our findings, giving further insight into mechanisms involved in somatosensory temporal discrimination, help interpret STDT abnormalities in movement disorders including dystonia and Parkinson's disease

Thalidomide sensory neurotoxicity: A prospective study in patients with multiple myeloma

Background: Peripheral neuropathy (PN), the most common complication during thalidomide (TD) treatment, remains incompletely characterized with regard to incidence, anatomic features, risk factors and optimum management Aim of tiffs study is to characterize TD-neuropathy and to assess correlations between PN and TD dose in a series of patients treated for multiple myeloma (MM). Method: We followed for up to 19 months, 25 patients (M/F -- 11/14, mean age 58 ± 10.8 yrs) without evidence of PN at baseline, with onemonthly neurological exanffnations (Neurologic Symptom Score, MRC score, Reflex score) and neurophysiological studies (NCW and SNAP amplitude of sural and ulnar nerves). Patients received a 298 ± 86 mg mean daily TD dose. Median time to PN was calculated with Kaplan-Meier method. Multiple logistic-regression analysis was used for statistics. Significance level < 0.05. Results: Eighteen patients (M/F -- 5/13, mean age 58,17 ± 10.5 yrs) developed a sensory axonal PN. Median time to PN was 8 months (95%CI 6,3-9,7 months). 95% of patients developed PN after 3 months. Twelve patients (48%) showed a SNAP reduction > 50% at PN onset. TD daily mean dose was 295 ± 85 mg, mean cumulative dose was 61.44 ± 29.5 g and mean cumulative dose/body mass index was 2.56 ± 1.2 g. Clinical characteristics and TD doses were similar to those of patients without PN. Demograplffc characteristics were not correlated with PN. Conclusion: 72% of our patients on TD for MM developed a sensory mxonal PN, which occurred in the majority of cases after 3 months. Both cumulative and daily dose of TD did not influence the occurrence of PN

Somatosensory temporal discrimination in patients with primary focal dystonia

Purposes: To determine whether somatosensory temporal discrimination will reliably detect subclinical sensory impairment in patients with various forms of primary focal dystonia. Methods: The somatosensory temporal discrimination threshold (STDT) was tested in 82 outpatients affected by cranial, cervical, laryngeal and hand dystonia. Results were compared with those for 61 healthy subjects and 26 patients with hemifacial spasm, a non-dystonic disorder. STDT was tested by delivering paired stimuli starting with an interstimulus interval of 0 ms followed by a progressively increasing interstimulus interval. Results: STDT was abnormal in all the different forms of primary focal dystonias in all three body regions (eye, hand and neck), regardless of the distribution and severity of motor symptoms. Receiver operating characteristic curve analysis calculated in the three body regions yielded high diagnostic sensitivity and specificity for STDT abnormalities. Conclusions: These results provide definitive evidence that STDT abnormalities are a generalised feature of patients with primary focal dystonias and are a valid tool for screening subclinical sensory abnormalities

Somatosensory temporal discrimination in patients with primary focal dystonia.

Purposes: To determine whether somatosensory temporal discrimination will reliably detect subclinical sensory impairment in patients with various forms of primary focal dystonia. METHODS: We tested the somatosensory temporal discrimination threshold (STDT) in 82 outpatients affected by cranial, cervical, laryngeal and hand dystonia. Results were compared with those for 61 healthy subjects and 26 patients with hemifacial spasm, a non-dystonic disorder. The STDT was tested by delivering paired stimuli starting with an interstimulus interval of 0 msec followed by a progressively increasing interstimulus interval. RESULTS: STDT was abnormal in all the different forms of primary focal dystonias in all three body regions (eye, hand and neck), regardless of the distribution and severity of motor symptoms. Receiver operating characteristic curve analysis calculated in the three body regions yielded high diagnostic sensitivity and specificity for STDT abnormalities. CONCLUSIONS: these results provide definitive evidence that STDT abnormalities are a generalized feature of patients with primary focal dystonias and are a valid tool for screening subclinical sensory abnormalities