Basic and Clinical Neuroscience
Volume:1 Issue: 4, Summer 2010

The applications of neurophysiological therapy techniques range far and few in the realm of modern day medicine. However, the concept of electromagnetic stimulation, the basis for many noninvasive brain stimulation (NIBS) techniques today, has been of interest to the scientific community since the late nineteenth century. Recently, transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), two noninvasive neurostimulation techniques, have begun to gain popularity and acceptance in the clinical neurophysiology, neurorehabilitaion, neurology, neuroscience, and psychiatry has spread widely, mostly in research applications, but increasingly with clinical aims in mind. These two neurophysiological techniques have proven to be valuable assets in not only the diagnosis, but also the treatment of many neurological disorders (post-stroke motor deficits, tinnitus, fibromyalgia, depression, epilepsy, autism, ageing and parkinson’s disease). Its effects can be modulated by combination with pharmacological treatment that has undergone resurgence in recent years. In this review we discuss how these integrated technology like NIBS for evaluation in the clinical evidence to date and what mechanism it work for stroke rehabilitation particularly. Then, we will review the current situation of stroke rehabilitation in Iran and new hopes that NIBS could bring for clinicians and patients in this nationally prioritized field.

We investigated differential role of cortical and subcortical regions in verbal and non-verbal sound processing in ten patients who were native speakers of Persian with unilateral cortical and/or unilateral and bilateral subcortical lesions and 40 normal speakers as control subjects. The verbal tasks included monosyllabic, disyllabic dichotic and diotic tasks, and nonverbal tasks were semantic, asemantic recognition and sound localization. Different profiles of ear extinction and hemispatial neglect was observed in our Left Hemisphere-Damaged (LHD) patients. Right Hemisphere-Damaged (RHD) patients with basal ganglia lesions showed mild hemi-spatial inattention of the ipsilesional and contralesional hemispace. LHD patients showed deficient performance in sound localization, but no evidence of significant impairment in sound localization was found in RHD patients except one. The patients with basal ganglia lesions irrespective of lesion side had impaired performance in semantic recognition. The results are suggestive of a network consisting of left and right basal ganglia and left cortical regions for non-verbal sound recognition. The results also indicate a different role for left basal ganglia in sound object segregation versus sound localization.

The nucleus cuneiformis (NCF) and ventrolateral periaqueductal gray (vlPAG), two adjacent areas, mediate the central pain modulation and project to the nucleus raphe magnus (NRM). This study examined whether the antinociceptive effect of morphine microinjected into the NCF is influenced by inactivation of vlPAG and NRM in rats. Animals were bilaterally microinjected with morphine (2.5 µg/0.3 µl saline) into the NCF. Electrolytic lesions were made in vlPAG (0.1 mA, 45 sec) and/or NRM (1 mA, 30 sec). Tail-flick latency (TFL) was measured at 30, 60, 90 and 120 min after microinjection. The results showed that TFLs are significantly decreased in vlPAG+NRM lesions group at 30 (P<0.001) and 60 (P<0.01) min after intra- NCF administration of morphine whereas TFLs did not affect in solely vlPAG lesion animals. Our findings show that concurrent lesions of NRM and vlPAG completely reversed the analgesic effect of morphine in NCF. However, vlPAG do not play a critical role directly in pain modulatory system elicited from NCF, at least at the level of morphine-induced analgesia. It can be concluded that its interactive effect in descending pain modulation from NCF to NRM should not be neglected.

Craving to methamphetamine is a significant health concern and exposure to methamphetamine cues in laboratory can induce craving. In this study, a task designing procedure for evaluating methamphetamine cue-induced craving in laboratory conditions is examined. First a series of visual cues which could induce craving was identified by 5 discussion sessions between expert clinicians and 10 methamphetamine smokers. Cues were categorized in 4 main clusters and photos were taken for each cue in studio, then 60 most evocative photos were selected and 10 neutral photos were added. In this phase, 50 subjects with methamphetamine dependence, had exposure to cues and rated craving intensity induced by the 72 cues (60 active evocative photos + 10 neutral photos) on self report Visual Analogue Scale (ranging from 0-100). In this way, 50 photos with high levels of evocative potency (CICT 50) and 10 photos with the most evocative potency (CICT 10) were obtained and subsequently, the task was designed. The task reliability (internal consistency) was measured by Cronbach’s alpha which was 91% for (CICT 50) and 71% for (CICT 10). The most craving induced was reported for category Drug use procedure (66.27±30.32) and least report for category Cues associated with drug use (31.38±32.96). Difference in cue-induced craving in (CICT 50) and (CICT 10) were not associated with age, education, income, marital status, employment and sexual activity in the past 30 days prior to study entry. Family living condition was marginally correlated with higher scores in (CICT 50). Age of onset for (opioids, cocaine and methamphetamine) was negatively correlated with (CICT 50) and (CICT 10) and age of first opiate use was negatively correlated with (CICT 50). Cue-induced craving for methamphetamine may be reliably measured by tasks designed in laboratory and designed assessment tasks can be used in cue reactivity paradigm, and imaging studies related to methamphetamine dependence.

Because of more exposure to mercury compounds, the prenatal and postnatal neurotoxic effects of mercury compounds have gained more attention in last decade. The aim of this study was to investigate the effects of mercuric chloride intoxication on spinal cord development during prenatal period. 36 adult Sprague-dawley rats after observing vaginal mating plaque (zero day of gestation) were divided into six groups: three control groups that received normal saline solution and three experimental groups that injected with mercuric chloride, 2mg/kg/IP, in 8th, 9th and 10th days of gestation. Then, embryos were removed from uterus in 15th day and spinal cord of embryos was studied by histological techniques. Microscopic study of spinal cord showed that cell death, mitosis division, and extracellular spaces were increased and cells accumulation were decreased in experimental groups. Diameter of ventricular zone was increased and diameter of mantle and marginal zones were decreased. The present study showed that mercuric chloride intoxication in prenatal period can induce cell death and results in neural tube deficits in prenatal rats.

Diabetes mellitus is accompanied with disturbances in learning, memory, and cognitive skills in the human society and experimental animals. Due to anti-diabetic and antioxidant activity of Rumex patientia (RP), this research study was conducted to evaluate the efficacy of chronic Rumex patientia feeding on alleviation of learning and memory disturbance in streptozotocindiabetic rats. Male Wistar rats were divided into control, diabetic, RP-treatedcontrol and -diabetic groups. For induction of diabetes, streptozotcin (STZ) was administered at a dose of 60 mg/Kg. Meanwhile, RP-treated groups received RP seed powder mixed with standard pelleted food at a weight ratio of 6% for 4 weeks. For evaluation of learning and memory, initial latency (IL) and step-through latency (STL) were determined at the end of study using passive avoidance test. It was found out that regarding initial latency, there was no significant difference among the groups. In addition, diabetic rats developed a significant impairment in retention and recall in passive avoidance test (p<0.01), as it is evident by a lower STL. Furthermore, RP treatment of diabetic rats did produce a significant improvement in retention and recall (p<0.05). Taken together, chronic RP feeding could improve retention and recall capability in passive avoidance test in STZ-diabetic rats.

Mercury is the second most metal pollutant in the world and has the potential to induce many pathologic conditions, especially in nervous system, such as depression. Here we tried to find out if nitric oxide has any possible role in the pathophysiology of depression induced by this metal. Although the role of nitric oxide has been shown in mood control, here we use specific doses of nitric oxide inducer and/or inhibitors which had no effect on normal rats. 120 male wistar rats weighting 200-250 gram were divided into two main groups: control and methyl mercury(MM) treated. Each main group was divided into four different sub-goups: Saline, L-Arginine, L-Name or 7-nitroindazole (7-NI) respectively. The duration of taking MM or saline was daily for 15 days for both. After the 15th injection a forced swimming test was done. This test shows behavioral immobility (BI) or latency of attempt to escape (LAE), as a depression indicator. Our study showed that low dose L-arginine is protective against MM induced depression as it could turn behavioral immobility (BI) to normal levels in groups taking MM plus L-Arginine, while in group taking just MM, BI was much longer showing the intensity of depression. L-Name and 7-NI did aggravated depression in MM groups but not control ones, on the other hand just in the case of 7-NI the result was significant. Our results showed 1) MM could induce depression in rat 2) L-Arginine could improve depression to normal situation in MM group, while in control group has no effec 3) 7-NI, a selective nNOS inhibitor can aggravate mental depression in intoxicated rats. These results showed the important role of nNOS in protection against MM induced depression.

There are three types of nerve fibers that are involved in the transmission of pain stimuli: C fibers (slower fibers) for thermal, mechanical and chemical stimuli, A-delta fibers for thermal or mechanical stimuli and A-beta fibers for touch stimuli. Clinically, this is crucial in making an accurate assessment of the pain level experienced by a suffering patient, in indicating the appropriate therapy and studying the response to treatment. The threshold is actually the experience of the patient, whereas the intensity measured is an external event. But often pain investigators tend to define the threshold in terms of the stimuli. Pressure, Thermal, Electrical and LASER are some of the pain induction methods that we have discussed in this article.