ORCID Profile
0000-0002-7310-8034
Current Organisations
University of Queensland
,
University of Cambridge
,
Tehran University of Medical Sciences
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Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.EPLEPSYRES.2009.05.003
Abstract: Temporal lobe epilepsy (TLE) is the most resistant type of epilepsy. Currently available drugs for epilepsy are not antiepileptogenic. A novel treatment for epilepsy would be to block or reverse the process of epileptogenesis. We used intermittent feeding (IF) regimen of the dietary restriction (DR) to study its effect on epileptogenesis and neuroprotection in the pilocarpine model of TLE in rats. The effect of IF regimen on the induction of status epilepticus (SE), the duration of latent period, and the frequency, duration, severity and the time of occurrence of Spontaneous Recurrent Seizures (SRS) were investigated. We also studied the effect of IF regimen on hippoc al neurons against the excitotoxic damage of prolonged SE (about 4h) induced by pilocarpine. The animals (Wistar, male, 200-250g) were ided into four main groups: AL-AL (ad libitum diet throughout), AL-IF (PfS) [IF post-first seizure], AL-IF (PSE) [IF post-SE] and IF-IF (IF diet throughout), and two AL and IF control groups. SE was induced by pilocarpine (350mg/kg, i.p.) and with diazepam (6mg/kg, i.p.) injected after 3h, the behavioral signs of SE terminated at about 4h (AL animals, n=29, 260.43+/-8.74min IF animals, n=19, 224.32+/-20.73min). Behavioral monitoring was carried out by 24h video recording for 3 weeks after the first SRS. Rat brains were then prepared for histological study with Nissl stain and cell counting was done in CA1, CA2 and CA3 regions of the hippoc us. The results show that the animals on IF diet had significantly less SE induction and significantly longer duration of latent period (the period of epileptogenesis) was seen in IF-IF group compared to the AL-AL group. The severity of SRS was significantly more in AL-IF (PfS) compared to the AL-IF (PSE) group. These results indicate that IF diet can make rats resistant to the induction of SE and can prolong the process of epileptogenesis. The results of the histological study show that the number of pyramidal neurons was statistically less in CA1, CA2 and CA3 of the hippoc us in the experimental groups compared to the control groups. However, IF regimen could not protect the hippoc al neurons against the excitotoxic injury caused by a prolonged SE. We conclude that IF regimen can significantly influence various behavioral characteristics of pilocarpine model of TLE. Further studies can elaborate the exact mechanisms as well as its possible role in the treatment of human TLE.
Publisher: Cold Spring Harbor Laboratory
Date: 27-05-2020
DOI: 10.1101/2020.05.26.117598
Abstract: When faced with predatorial threats, escape towards shelter is an adaptive action that offers long-term protection against the attacker. From crustaceans to mammals, animals rely on knowledge of safe locations in the environment to instinctively execute rapid shelter-directed escape actions 1,2 . While previous work has identified neural mechanisms of escape initiation 3–5 , it is not known how the escape circuit incorporates spatial information to execute rapid flights along the most efficient route to shelter. Here we show that mouse retrosplenial cortex (RSP) and superior colliculus (SC) form a circuit that encodes shelter direction vector and is specifically required for accurately orienting to shelter during escape. Shelter direction is encoded in RSP and SC neurons in egocentric coordinates and SC shelter-direction tuning depends on RSP activity. Inactivation of the RSP-SC pathway disrupts orientation to shelter and causes escapes away from the optimal shelter-directed route, but does not lead to generic deficits in orientation or spatial navigation. We find that the RSP and SC are monosynaptically connected and form a feedforward lateral inhibition microcircuit that strongly drives the inhibitory collicular network due to higher RSP input convergence and synaptic integration efficiency in inhibitory SC neurons. This results in broad shelter direction tuning in inhibitory SC neurons and sharply tuned excitatory SC neurons. These findings are recapitulated by a biologically-constrained spiking network model where RSP input to the local SC recurrent ring architecture generates a circular shelter-direction map. We propose that this RSP-SC circuit might be specialized for generating collicular representations of memorized spatial goals that are readily accessible to the motor system during escape, or more broadly, during navigation when the goal must be reached as fast as possible.
Publisher: Elsevier BV
Date: 02-2022
Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
Date: 04-2007
DOI: 10.3171/PED.2007.106.4.316
Abstract: The simultaneous presence of multiple spinal neural tube defects is unusual. There have been only a few of these cases reported in the literature. The authors report on three cases of double spina bifida cystica. One patient had two myelomeningoceles (MMCs) at the cervical and lumbosacral regions, one was noted to have both thoracolumbar and sacral defects, and the third presented with double MMCs at lumbar and lumbosacral levels. All three neonates in these cases underwent surgical treatment and ventriculoperitoneal (VP) shunt insertion for associated hydrocephalus. One child died at the age of 2 months despite a well-functioning VP shunt. The other two patients had no complications. Current models of neural tube closure do not thoroughly explain the mechanisms of multiple spinal dysraphism, but the multisite closure model provides a better understanding of caudal neural tube closure than other closure-site models.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2007
Publisher: Public Library of Science (PLoS)
Date: 28-05-2021
DOI: 10.1371/JOURNAL.PCBI.1009074
Abstract: Understanding the function of the nervous system necessitates mapping the spatial distributions of its constituent cells defined by function, anatomy or gene expression. Recently, developments in tissue preparation and microscopy allow cellular populations to be imaged throughout the entire rodent brain. However, mapping these neurons manually is prone to bias and is often impractically time consuming. Here we present an open-source algorithm for fully automated 3D detection of neuronal somata in mouse whole-brain microscopy images using standard desktop computer hardware. We demonstrate the applicability and power of our approach by mapping the brain-wide locations of large populations of cells labeled with cytoplasmic fluorescent proteins expressed via retrograde trans-synaptic viral infection.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Society for Neuroscience
Date: 25-06-2014
Publisher: Springer Science and Business Media LLC
Date: 21-12-2022
Publisher: BMJ
Date: 09-2008
Abstract: The administration of analgesics to patients with acute abdominal pain due to acute appendicitis is controversial. A study was undertaken to assess the analgesic effect of morphine in patients with acute appendicitis. A randomised double-blind clinical trial was conducted in Sina hospital, a general teaching hospital, from January 2004 to March 2005. Patients scheduled for appendectomy were randomised to receive 0.1 mg/kg morphine sulfate or saline (0.9%) to a maximum dose of 10 mg over a 5 min period. Patients were examined by surgeons not involved in their care before and after drug administration and their pain intensity and signs were recorded at each visit. The physicians were also asked to indicate their own treatment plan. The main outcome measures were pain intensity using a visual analogue scale (VAS) and signs of acute appendicitis. A favourable reduction in VAS score was defined as a change of >13 mm. Of the 71 patients enrolled in the study, 35 were allocated to receive morphine and 36 to receive placebo. One patient left the hospital before receiving morphine. No significant differences were seen between the two groups with regard to age, sex and initial VAS score. A more favourable change in VAS score was reported in the morphine group with a significantly greater reduction in the median VAS score than in the placebo group. Morphine administration did not cause significant changes in patients' signs or in the physicians' plans or diagnoses. No adverse events were seen in either group. Morphine can reduce pain in patients with acute appendicitis without affecting diagnostic accuracy. NCT00477061.
Publisher: Cold Spring Harbor Laboratory
Date: 21-10-2020
DOI: 10.1101/2020.10.21.348771
Abstract: Understanding the function of the nervous system necessitates mapping the spatial distributions of its constituent cells defined by function, anatomy or gene expression. Recently, developments in tissue preparation and microscopy allow cellular populations to be imaged throughout the entire rodent brain. How-ever, mapping these neurons manually is prone to bias and is often impractically time consuming. Here we present an opensource algorithm for fully automated 3D detection of neuronal somata in mouse whole-brain microscopy images using standard desktop computer hardware. We demonstrate the applicability and power of our approach by mapping the brain-wide locations of large populations of cells labeled with cytoplasmic fluorescent proteins expressed via retrograde trans-synaptic viral infection.
Publisher: Society for Neuroscience
Date: 23-09-2015
DOI: 10.1523/JNEUROSCI.0627-15.2015
Abstract: The medial amygdala (MeA) is a central hub in the olfactory neural network. It receives vomeronasal information directly from the accessory olfactory bulb (AOB) and main olfactory information largely via odor-processing regions such as the olfactory cortical amygdala (CoA). How these inputs are processed by MeA neurons is poorly understood. Using the GAD67-GFP mouse, we show that MeA principal neurons receive convergent AOB and CoA inputs. Somatically recorded AOB synaptic inputs had slower kinetics than CoA inputs, suggesting that they are electrotonically more distant. Field potential recording, pharmacological manipulation, and Ca 2+ imaging revealed that AOB synapses are confined to distal dendrites and segregated from the proximally located CoA synapses. Moreover, unsynchronized AOB inputs had significantly broader temporal summation that was dependent on the activation of NMDA receptors. These findings show that MeA principal neurons process main and accessory olfactory inputs differentially in distinct dendritic compartments. SIGNIFICANCE STATEMENT In most vertebrates, olfactory cues are processed by two largely segregated neural pathways, the main and accessory olfactory systems, which are specialized to detect odors and nonvolatile chemosignals, respectively. Information from these two pathways ultimately converges at higher brain regions, one of the major hubs being the medial amygdala. Little is known about how olfactory inputs are processed by medial amygdala neurons. This study shows that in idual principal neurons in this region receive input from both pathways and that these synapses are spatially segregated on their dendritic tree. We provide evidence suggesting that this dendritic segregation leads to distinct input integration and impact on neuronal output hence, dendritic mechanisms control olfactory processing in the amygdala.
Publisher: Cold Spring Harbor Laboratory
Date: 24-01-2021
DOI: 10.1101/2021.01.22.427789
Abstract: The extent to which we successfully navigate the environment depends on our ability to continuously track our heading direction and speed. Angular head velocity (AHV) cells, which encode the speed and direction of head turns during navigation, are fundamental to this process, yet the mechanisms that determine their function remain unknown. By performing chronic single-unit recordings in the retrosplenial cortex (RSP) of the mouse and tracking the activity of in idual AHV neurons between freely moving and head-restrained conditions, we find that vestibular inputs dominate AHV signalling. In addition, we discover that self-generated optic flow input onto these neurons increases the gain and signal-to-noise ratio of angular velocity coding during free exploration. Psychophysical experiments and neural decoding further reveal that vestibular-visual integration increases the perceptual accuracy of egocentric angular velocity and the fidelity of its representation by RSP ensembles. We propose that while AHV coding is dependent on vestibular input, it also uses vision to maximise navigation accuracy in nocturnal and diurnal environments.
Location: United Kingdom of Great Britain and Northern Ireland
Location: Iran (Islamic Republic of)
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Sepiedeh Keshavarzi.