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Biomedical subjects

Simone Rossi

Publications and source records attributed to Simone Rossi.

At least 19 recordsLinked to original sources
PubMed2007

Repetitive Transcranial Magnetic Stimulation (rTMS) in the treatment of panic disorder (PD) with comorbid major depression.

BACKGROUND: Studies suggest that the dorsolateral prefrontal cortex (DLPFC) participates in neural circuitry that is dysregulated in Panic Disorder (PD) and Major Depressive Disorder (MDD). We tested whether low-frequency repetitive Transcranial Magnetic Stimulation (rTMS) could normalize the overactivity of right frontal regions and thereby improve symptoms. METHODS: Six patients with PD and comorbid MDD were treated with daily active 1-Hz rTMS to the right DLPFC for 2 weeks in this open-label trial. RESULTS: Clinical improvements were apparent as early as the first week of treatment. After the second week, 5/6 of patients showed improvements in panic and anxiety, and 4/6 showed a decrease in depression, with sustained improvement at 6 months of follow-up. Right hemisphere resting motor threshold increased significantly after rTMS. LIMITATIONS: Limitations of this study are the open design and the small sample size. CONCLUSIONS: Slow rTMS to the right DLPFC resulted in significant clinical improvement and reduction of ipsilateral motor cortex excitability. Replications in larger sample will help to clarify the relevance of this preliminary data and to define the potential role of right DLPFC rTMS in panic with major depression.

Adult↗
PubMed2006

A real electro-magnetic placebo (REMP) device for sham transcranial magnetic stimulation (TMS).

OBJECTIVE: There is growing interest in neuropsychiatry for repetitive transcranial magnetic stimulation (rTMS) as a neuromodulatory treatment. However, there are limitations in interpreting rTMS effects as a real consequence of physiological brain changes or as placebo-mediated unspecific effects, which may be particularly strong in psychiatric patients. This is due to the fact that existing sham rTMS procedures are less than optimal. A new placebo tool is introduced here, called real electro-magnetic placebo (REMP) device, which can simulate the scalp sensation induced by the real TMS, while leaving both the visual impact and acoustic sensation of real TMS unaltered. METHODS: Physical, neurophysiological and behavioural variables of monophasic and biphasic single-pulse TMS and biphasic 1Hz and 20Hz rTMS procedures (at different intensities) were tested in subjects who were expert or naïve of TMS. Results of the real TMS were compared with those induced by the REMP device and with two other currently used sham procedures, namely the commercially available Magstim sham coil and tilting the real coil by 90 degrees . RESULTS: The REMP device, besides producing scalp sensations similar to the real TMS, attenuated the TMS-induced electric field (as measured by a dipole probe) to a biologically inactive level. Behaviourally, neither expert nor naïve TMS subjects identified the "coil at 90 degrees " or the "Magstim sham coil" as a real TMS intervention, whilst naïve subjects were significantly more likely to identify the REMP-attenuated TMS as real. CONCLUSIONS: The "goodness of sham" of the REMP device is demonstrated by physical, neurophysiological, and behavioural results. SIGNIFICANCE: Such placebo TMS is superior to the available sham procedures when applied on subjects naïve to TMS, as in case of patients undergoing a clinical rTMS trial.

Adult↗
PubMed2006

Number of lymph node metastases and its prognostic significance in early gastric cancer: a multicenter Italian study.

BACKGROUND AND OBJECTIVES: This study was aimed at evaluating the prognostic significance of the number of metastatic nodes in early gastric cancer (EGC). METHODS: In this multicenter retrospective study 652 cases of resected EGC were analyzed. We searched for lymph node metastases-associated risk factors and to identify subsets of patients with different prognosis according to the number of involved nodes. RESULTS: Nodal involvement was observed in 14.1%. A significant correlation was found between the presence of node metastases and tumor size (RR 1.34, P = 0.001), submucosal invasion (RR: 3.14, P = 0.007), Lauren diffuse/mixed type (RR: 4.88, P < 0.001) and Kodama Pen A type (RR: 4.59, P < 0.001). The 10-year survival rate was 92% for N0 cases, 82% and 73% for tumors with one to three and four to six positive nodes while it dropped to 27% with more than six metastatic nodes. Interestingly enough, the 10-year risk of recurrence diminished with the increasing number of retrieved nodes (>15) even in N0 patients. CONCLUSIONS: Nodal involvement confirmed to be a significant prognostic factor. In view of the trend to a lower risk of recurrence when more than 15 nodes were retrieved and the better staging achieved we consider D2 lymphadenectomy the treatment of choice.

Adult↗
PubMed2006

Giant hepatic adenoma with bone marrow metaplasia not associated with oral contraceptive intake.

BACKGROUND: Hepatocellular adenomas are the most common benign liver tumors. They are usually related to oral contraceptive intake. CASE PRESENTATION: This case describes a 58-year-old woman admitted to our institution for a hepatic mass incidentally discovered during a routine examination. The patient, who was never on oral contraceptives, was asymptomatic upon admission. She underwent a thorough diagnostic evaluation and then a hepatic right trisegmentectomy. The histologic evaluation of the mass showed that it was a hepatocellular adenoma with areas of bone marrow metaplasia. CONCLUSION: Bone marrow metaplasia has rarely been found associated to liver tumors. The presence of marrow-derived hepatic progenitor cells might be the source of both adenoma hepatocytes and bone marrow differentiated cells. To our knowledge, this is only the second case in the English literature in which areas of bone marrow metaplasia were found in a hepatocellular adenoma.

Journal Article↗
PubMed2006

Human ventral parietal cortex plays a functional role on visuospatial attention and primary consciousness. A repetitive transcranial magnetic stimulation study.

In this paper, we used repetitive transcranial magnetic stimulation (rTMS) in 18 normal subjects to investigate whether the ventral posterior parietal cortex (PPC) plays a causal role on visuospatial attention and primary consciousness and whether these 2 functions are linearly correlated with each other. Two distinct experimental conditions involved a similar visual stimuli recognition paradigm. In "Consciousness" experiment, number of consciously perceived visual stimuli was lower by about 10% after rTMS (300 ms, 20 Hz, motor threshold intensity) on left or right PPC than after sham (pseudo) rTMS. In "Attentional" Posner's experiment, these stimuli were always consciously perceived. Compared with sham condition, parietal rTMS slowed of about 25 ms reaction time to go stimuli, thus disclosing effects on endogenous covert spatial attention. No linear correlation was observed between the rTMS-induced impairment on attention and conscious perception. Results suggest that PPC plays a slight but significant causal role in both visuospatial attention and primary consciousness. Furthermore, these high-level cognitive functions, as modulated by parietal rTMS, do not seem to share either linear or simple relationships.

Adult↗
PubMed2006

Perforated gastric carcinoma: a report of 10 cases and review of the literature.

BACKGROUND: Perforation is a rare complication of gastric carcinoma, accounting for less than 1% of all gastric cancer cases. The aim of the present study is to evaluate the prognostic value of perforation and to point out the surgical treatment options. METHODS: A total of 10 patients with perforated gastric carcinoma were retrospectively reviewed among 2564 consecutive cases of gastric cancer operated in three Centers belonging to the Italian Research Group for Gastric Cancer. The clinicopathological features including tumor stage and survival were analyzed and compared to literature data. RESULTS: Incidence rate was 0.39%. All patients underwent emergency surgery, being performed gastrectomy in 6 patients (mortality 17%) and repair surgery in 4 patients (mortality 75%). The survival of patients was related to the stage of the disease, with 2 long-survival cases. CONCLUSION: Perforation usually occurs in advanced stages of gastric cancer; nevertheless surgeons should not be always discouraged from a radical treatment of perforated gastric cancer, since perforation even occurs in early stages and seems not to be a negative prognostic factor itself. When possible, emergency gastrectomy should be performed, leaving repair surgery for unresectable tumors. A two-stage treatment is a good treatment option for frail patients with resectable tumors.

Journal Article↗
PubMed2006

Environmental security: a geographic information system analysis approach--the case of Kenya.

Studies into the relationships between environmental factors and violence or conflicts constitute a very debated research field called environmental security. Several authors think that environmental scarcity, which is scarcity of renewable resources, can contribute to generate violence or social unrest, particularly within states scarcely endowed with technical know-how and social structures, such as developing countries. In this work, we referred to the theoretical model developed by the Environmental Change and Acute Conflict Project. Our goal was to use easily available spatial databases to map the various sources of environmental scarcity through geographic information systems, in order to locate the areas apparently most at risk of suffering negative social effects and their consequences in terms of internal security. The analysis was carried out at a subnational level and applied to the case of Kenya. A first phase of the work included a careful selection of databases relative to renewable resources. Spatial operations among these data allowed us to obtain new information on the availability of renewable resources (cropland, forests, water), on the present and foreseen demographic pressure, as well as on the social and technical ingenuity. The results made it possible to identify areas suffering from scarcity of one or more renewable resources, indicating different levels of gravity. Accounts from Kenya seem to confirm our results, reporting clashes between tribal groups over the access to scarce resources in areas that our work showed to be at high risk.

Conflict, Psychological↗
PubMed2006

Prefrontal and parietal cortex in human episodic memory: an interference study by repetitive transcranial magnetic stimulation.

Neuroimaging findings, including repetitive transcranial magnetic stimulation (rTMS) interference, point to an engagement of prefrontal cortex (PFC) in learning and memory. Whether parietal cortex (PC) activity is causally linked to successful episodic encoding and retrieval is still uncertain. We compared the effects of event-related active or sham rTMS (a rapid-rate train coincident to the very first phases of memoranda presentation) to the left or right intraparietal sulcus, during a standardized episodic memory task of visual scenes, with those obtained in a fully matched sample of subjects who received rTMS on left or right dorsolateral PFC during the same task. In these subjects, specific hemispheric effects of rTMS included interference with encoding after left stimulation and disruption of retrieval after right stimulation. The interference of PC-rTMS on encoding/retrieval performance was negligible, lacking specificity even when higher intensities of stimulation were applied. However, right PC-rTMS of the same intensity lengthened reaction times in the context of a purely attentive visuospatial task. These results suggest that the activity of intraparietal sulci shown in several functional magnetic resonance studies on memory, unlike that of the dorsolateral PFC, is not causally engaged to a useful degree in memory encoding and retrieval of visual scenes. The parietal activations accompanying the memorization processes could reflect the engagement of a widespread brain attentional network, in which interference on a single 'node' is insufficient for an overt disruption of memory performance.

Adult↗
PubMed2006

rTMS for PTSD: induced merciful oblivion or elimination of abnormal hypermnesia?

Neuroimaging studies and experimental data suggest that symptoms of posttraumatic stress disorder (PTSD) are associated with dysfunctions of neural circuits linking prefrontal cortex and the limbic system that have a role in autobiographic episodic memory. High-frequency repetitive transcranial magnetic stimulation (rTMS) of the right dorsolateral prefrontal cortex (DLPFC) has been suggested to be beneficial to patients with PTSD, transiently alleviating re-experiencing as well as avoidance reactions and associated anxiety symptoms. In healthy humans, converging evidence suggests that rTMS of the right DLPFC interferes with episodic memory retrieval. Hence, we hypothesize that daily applications of rTMS in PTSD patients may reduce access to the set of autobiographical stored events, that, if re-experienced, may cause the overt PTSD symptoms.

Autobiographies as Topic↗
PubMed2005

Functional frontoparietal connectivity during encoding and retrieval processes follows HERA model. A high-resolution study.

Recent neuroimaging studies of long-term episodic memory have suggested that left prefrontal cortex predominates in encoding condition, whereas right prefrontal cortex predominates in retrieval condition (hemispheric encoding and retrieval asymmetry, HERA model). The present electroencephalographic (EEG) study investigated the functional coupling of fronto-parietal regions during long-term memorization of visuo-spatial contents (i.e. landscapes, interiors of apartments), to test the predictions of the HERA model. Global fronto-parietal coupling was estimated by spectral coherence, whereas the "direction" of the fronto-parietal information flow was estimated by directed transfer function (DTF). The EEG rhythms of interest were theta (4-7 Hz), alpha (8-13 Hz), beta (14-30 Hz), and gamma (30-45 Hz). Statistically significant coherence in line with the HERA model was obtained at the gamma band. Namely, the fronto-parietal gamma coherence prevailed in the left hemisphere during the encoding condition and in the right hemisphere during the retrieval condition. The DTF estimates of the gamma band showed a dominant parietal-to-frontal directional flow in the right hemisphere during the encoding condition and in the left hemisphere during the retrieval condition (i.e. hemisphere-condition combination not involved by the HERA model). In contrast, a balanced bidirectional flow of the fronto-parietal coupling was observed in the left hemisphere during the encoding condition and in the right hemisphere during the retrieval condition (i.e. hemisphere-condition combination involved by the HERA model). In conclusion, the present encoding-retrieval conditions induced maximal fronto-parietal gamma coupling with bidirectional information flow in the hemisphere-condition combination predicted by the HERA model.

Alpha Rhythm↗
PubMed2005

Repetitive transcranial magnetic stimulation (rTMS) in the treatment of obsessive-compulsive disorder (OCD) and Tourette's syndrome (TS).

There is evidence that motor and premotor cortex are hyperexcitable in obsessive-compulsive disorder (OCD) and Tourette's syndrome (TS). We tested whether low-frequency repetitive transcranial magnetic stimulation (rTMS) could normalize overactive motor cortical regions and thereby improve symptoms. Subjects with OCD or TS were treated with active rTMS to the supplementary motor area (SMA) for 10 daily sessions at 1 Hz, 100% of motor threshold, 1200 stimuli/day. Suggestions of clinical improvement were apparent as early as the first week of rTMS. At the second week of treatment, statistically significant reductions were seen in the YBOCS, YGTSS, CGI, HARS, HDRS, SAD, BDI, SCL-90, and SASS. Symptoms improvement was correlated with a significant increase of the right resting motor threshold and was stable at 3 months follow-up. Slow rTMS to SMA resulted in a significant clinical improvement and a normalization of the right hemisphere hyperexcitability, thereby restoring hemispheric symmetry in motor threshold.

Adult↗
PubMed2005

Hypofunctioning of sensory gating mechanisms in patients with obsessive-compulsive disorder.

BACKGROUND: In obsessive-compulsive disorder (OCD) patients, functional abnormalities in basal ganglia/precentral circuitries cause cortical hyperexcitability and lack of inhibitory control. These loops can be partly explored by median-nerve somatosensory evoked potentials (SEPs), which functionally reflect the brain responsiveness to somatosensory stimuli. In healthy humans, SEPs' amplitude during voluntary finger movements is lower than during muscular relaxation (i.e., sensory gating). Cortical hyperexcitability in OCD could be eventually responsible for a reduction of sensory gating. This might have pathophysiologic implications for motor compulsions. METHODS: Median-nerve SEPs were recorded in 11 OCD patients and 9 healthy volunteers during muscle relaxation ("Relax") or finger movements of the stimulated hand ("Move"). Latencies and amplitudes of pre- and postcentral SEP components were compared between groups during "Relax" and "Move" conditions. RESULTS: In OCD patients, the responsiveness to sensory stimuli was enhanced for precentral SEPs. Sensory gating ("Relax" vs. "Move") in control subjects involved both pre- and postcentral SEPs, the former being reduced in amplitude by approximately 60%. In OCD patients, sensory gating was spatially restricted to precentral SEP components and was significantly reduced compared with control subjects (approximately 30%). CONCLUSIONS: Enhanced precentral SEPs and hypofunctioning of centrifugal sensory gating in OCD might reflect the inability to modulate sensory information due to a "tonic" high level of cortical excitability of motor and related areas, likely resulting from basal ganglia dysfunction. This might offer new insights into the pathophysiology of OCD.

Adult↗
PubMed2004

Age-related functional changes of prefrontal cortex in long-term memory: a repetitive transcranial magnetic stimulation study.

Neuroimaging findings suggest that the lateralization of prefrontal cortex activation associated with episodic memory performance is reduced by aging. It is still a matter of debate whether this loss of asymmetry during encoding and retrieval reflects compensatory mechanisms or de-differentiation processes. We addressed this issue by the transient interference produced by repetitive transcranial magnetic stimulation (rTMS), which directly assesses causal relationships between performance and stimulated regions. We compared the effects of rTMS (a rapid-rate train occurring simultaneously to the presentation of memoranda) applied to the left or right dorsolateral prefrontal cortex (DLPFC) on visuospatial recognition memory in 66 healthy subjects divided in two classes of age (<45 and >50 years). In young subjects, rTMS of the right DLPFC interfered with retrieval more than left DLPFC stimulation. The asymmetry of the effect progressively vanished with aging, as indicated by bilateral interference effects on recognition performance. Conversely, the predominance of left DLPFC effect during encoding was not abolished in elders, thus probing its causal role for encoding along the life span. Findings confirm that the neural correlates of retrieval modify along aging, suggesting that the bilateral engagement of the DLPFC has a compensatory role on the elders' episodic memory performance.

Adult↗
PubMed2004

Involvement of the human dorsal premotor cortex in unimanual motor control: an interference approach using transcranial magnetic stimulation.

Unilateral movements are enabled through a distributed network of motor cortical areas but the relative contribution from the parts of this network is largely unknown. Failure of this network potentially results in mirror activation of the primary motor cortex (M1) ipsilateral to the intended movement. Here we tested the role of the right dorsal premotor cortex (dPMC) in 11 healthy subjects by disrupting its activity with 20 Hz repetitive transcranial magnetic stimulation (rTMS) whilst the subjects exerted a unilateral contraction of the left first dorsal interosseous (FDI). We found that disruption of right dPMC enhanced mirror activation of the ipsilateral left M1, as probed by motor evoked potential (MEP) amplitude to the right FDI. This was not the case with sham rTMS, when rTMS was directed to the right M1, or with rTMS of the right dPMC but without contraction of the left FDI. Findings suggest that activity in the dPMC contributes to the suppression of mirror movements during intended unilateral movements.

Adult↗
PubMed2004

Human cortical rhythms during visual delayed choice reaction time tasks. A high-resolution EEG study on normal aging.

Neuroimaging cognitive study of aging requires simple tasks ensuring a high rate of correct performances even in stressful neurophysiological settings. Here two simple delayed choice reaction time tasks were used to unveil event-related desynchronization (ERD) of theta (4-6 Hz) and alpha (6-12 Hz) electroencephalographic rhythms across normal aging. In the first condition, a cue stimulus (one bit) was memorized along a brief delay period (3.5-5.5 s). The explicit demand was visuo-spatial, but the retention could be also based on phonological and somatomotor coding. In the second condition, the cue stimulus remained available along the delay period. Correct performances were higher than 95% in both groups and tasks, although they were significantly better in young than elderly subjects (P < 0.03). During the delay period, theta and alpha ERD accompanying correct responses were recognized in the two groups, the alpha ERD being stronger and prolonged during the memory than non-memory task. On the other hand, the fronto-parietal theta and parietal alpha ERD were stronger in young than elderly subjects during both tasks. Notably, the frontal alpha ERD was negligible in elderly subjects. In conclusion, the present simple tasks unveiled in elderly compared to young subjects (i) a weaker involvement of (para)hippocampal-cortical circuits as revealed by theta ERD and (ii) a weaker involvement of "executive" thalamo-cortical circuits as revealed by frontal alpha ERD. These effects might worsen behavioral performances to the simple cognitive tasks with age. The present protocol is promising for the neuroimaging study of pathological aging.

Adult↗
PubMed2004

Reduction of cortical myoclonus-related epileptic activity following slow-frequency rTMS.

In a drug-resistant epilepsy patient with continuous forearm/hand positive myoclonia due to a focal cortical dysplasia of the right motor cortex, cortical jerk-related and electromyographic activity were recorded for 15 min before and after 1 Hz rTMS (15 min, 10% below the resting excitability threshold) of the right motor cortex. A stable negative cortical spike, time-locked with contralateral muscle jerks (60 > 100 microV), was detected only at perirolandic electrodes (maximal amplitudes: block 1 = 21.3 microV, block 2 = 22 microV, block 3 = 25.9 microV). After rTMS, only 20 muscle jerks accomplished the criterion of > 100 microV; blind back-averaging of these disclosed a topographically similar cortical spike, but with amplitude reduced by at least 50% (11.2 microV). This represents in vivo evidence of the possibility to selectively modulate the activity of an epileptic focus by intervening with local low-frequency rTMS.

Action Potentials↗