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Bhattacharya S.M.,Vivekananda Institute of Medical science | Jha A.,All India Institute of Hygiene and Public Health
Fertility and Sterility | Year: 2010

This comparative cross-sectional study found that women with polycystic ovary syndrome are at a significantly higher risk of depression compared with non-PCOS women. The study fails to find enough evidence to explain the high prevalence of depression among PCOS patients by the selected sociodemographic, clinical, and biochemical parameters. © 2010 American Society for Reproductive Medicine.


Chakravarty A.,Vivekananda Institute of Medical Science
Medical Hypotheses | Year: 2010

A trigger is an integral part of any acute migraine attack. In this article, the author argues that triggers, identifiable or not, must be present in all attacks of migraine headache. It is hypothesized that triggers, internal or external, induce the onset of cortical spreading depression (CSD) in a pre-existing hyper-excitable cortex of a migraine brain, initiating the process of pain generation. The author hypothesizes on a second site of action of triggers at the level of trigeminal nuclear complex (TNC) in brain stem, the cell station of second order neuron pathway for migraine pain transmission to the sensory cortex. The author suggests existence of a hypothetical 'gate' at TNC level where incoming trigeminal migraine pain impulses would 'compete' with descending inhibitory signals from brain stem pain modulatory neurons, to get entry into the central nervous system. The author draws analogy with the 'gate control' mechanism operative at the dorsal horn level for spinally transmitted somatic and visceral pain. It is suggested that the hypothetical 'gate' at TNC level is controlled by activity of 5HT receptors, thus supporting the concept of an additional site of action of triptans in aborting acute migraine pain. The suggested hypothesis on mechanism of action of triggers, offers theoretical basis for efficacy of currently available pharmacologic and non-pharmacologic therapies for abortive and prophylactic treatment of migraine. © 2009 Elsevier Ltd. All rights reserved.


Mukherjee A.,Vivekananda Institute of Medical science | Chakravarty A.,Vivekananda Institute of Medical science
Frontiers in Neurology | Year: 2010

Spasticity, a classical clinical manifestation of an upper motor neuron lesion, has been traditionally and physiologically defined as a velocity dependent increase in muscle tone caused by the increased excitability of the muscle stretch reflex. Clinically spasticity manifests as an increased resistance offered by muscles to passive stretching (lengthening) and is often associated with other commonly observed phenomenon like clasp-knife phenomenon, increased tendon reflexes, clonus, and flexor and extensor spasms. The key to the increased excitability of the muscle stretch reflex (muscle tone) is the abnormal activity of muscle spindles which have an intricate relation with the innervations of the extrafusal muscle fibers at the spinal level (feed-back and feed-forward circuits) which are under influence of the supraspinal pathways (inhibitory and facilitatory). The reflex hyperexcitability develops over variable period of time following the primary lesion (brain or spinal cord) and involves adaptation in spinal neuronal circuitries caudal to the lesion. It is highly likely that in humans, reduction of spinal inhibitory mechanisms (in particular that of disynaptic reciprocal inhibition) is involved. While simply speaking the increased muscle stretch reflex may be assumed to be due to an altered balance between the innervations of intra and extrafusal fibers in a muscle caused by loss of inhibitory supraspinal control, the delayed onset after lesion and the frequent reduction in reflex excitability over time, suggest plastic changes in the central nervous system following brain or spinal lesion. It seems highly likely that multiple mechanisms are operative in causation of human spasticity, many of which still remain to be fully elucidated. This will be apparent from the variable mechanisms of actions of anti-spasticity agents used in clinical practice. © 2010 Mukherjee and Chakravarty.


Chakravarty A.,Vivekananda Institute of Medical Science
Annals of Indian Academy of Neurology | Year: 2012

The nondominant inferior parietal lobule is probably a major "store house" of artistic creativity. The ventromedial prefrontal lobe (VMPFL) is supposed to be involved in creative cognition and the dorsolateral prefrontal lobe (DLPFL) in creative output. The conceptual ventral and dorsal visual system pathways likely represent the inferior and superior longitudinal fasciculi. During artistic production, conceptualization is conceived in the VMPFL and the executive part is operated through the DLFPL. The latter transfers the concept to the visual brain through the superior longitudinal fasciculus (SLF), relaying on its path to the parietal cortex. The conceptualization at VMPFL is influenced by activity from the anterior temporal lobe through the uncinate fasciculus and limbic system pathways. The final visual image formed in the visual brain is subsequently transferred back to the DLPFL through the SLF and then handed over to the motor cortex for execution. During art appreciation, the image at the visual brain is transferred to the frontal lobe through the SLF and there it is matched with emotional and memory inputs from the anterior temporal lobe transmitted through the uncinate fasiculus. Beauty is perceived at the VMPFL and transferred through the uncinate fasciculus to the hippocampo-amygdaloid complex in the anterior temporal lobe. The limbic system (Papez circuit) is activated and emotion of appreciation is evoked. It is postulated that in practice the entire circuitry is activated simultaneously.


Chakravarty A.,Vivekananda Institute of Medical Science
Journal of Stroke and Cerebrovascular Diseases | Year: 2012

The case of a 77-year-old hypertensive man presenting with hemifacial spasm and glossodynia is reported. Imaging studies revealed gross dolichoectasia of the vertebrobasilar arterial system with pontine compression. It is suggested that the neurologic symptoms most likely resulted from pontine compression, rather than from any compression of the cranial nerves. © 2012 by National Stroke Association.


Chakravarty A.,Vivekananda Institute of Medical Science
Annals of Indian Academy of Neurology | Year: 2011

The case of an 82-year-old female with probable Alzheimer's disease (AD), who developed unusual artistic creativity after development of her disease, is described. The possible pathogenetic mechanism is discussed. The patient showed no inclination toward visual arts during her premorbid years. However, 4 years after development of AD suggestive symptoms she started painting beautiful pictures rather impulsively. Some such paintings have been appreciated even by a qualified art expert. Such de novo development of artistic creativity had been described earlier in subjects with the semantic form of fronto-temporal dementia (FTD), but not in AD. The prevailing concept of lateralized compromise and paradoxical functional facilitation, proposed in connection with FTD subjects, may not be applicable in AD subjects where the affection is more diffuse and more posterior in the brain. Hence, the likely pathogenetic mechanism involved in the case described may remain uncertain. Possibilities are discussed.


Chatterjee S.,Vivekananda Institute of Medical science
Journal of Pediatric Neurosciences | Year: 2011

Central nervous system tuberculosis in children presents commonly as tubercular meningitis, post-tubercular meningitis hydrocephalus, and much more rarely as space-occupying lesions known as tuberculomas. The occurrence of this condition, though previously reported only in the developing world, is now frequently reported in human immunodeficiency virus positive migrants in the western world. The exact pathogenesis of this condition is still incompletely understood, and the mainstay of treatment is chemotherapeutic regimes. Neurosurgical intervention is rarely necessary, and is confined to cases of hydrocephalus after tubercular meningitis and to large tubeculomas with space-occupying effects.


Bhattacharya S.M.,Vivekananda Institute of Medical science
Journal of Obstetrics and Gynaecology Research | Year: 2010

Aim: To study the relationship of various sperm characteristics and hypo-osmotic swelling test (HOS test) with repeat unexplained early pregnancy loss. Methods: Semen samples from husbands of 74 couples with a history of repeat early pregnancy loss (group A) were analyzed according to World Health Organization criteria, and a HOS test was performed in each case. Semen samples from 65 husbands with proven fertility (group B) were also studied for comparison. Results: No statistically significant differences were noted in the age of the husbands, sperm concentration, sperm morphology and percent motile sperm between groups A and B. The mean HOS test scores of the two groups were significantly different (group A: 60.4%; group B: 76.9%; P = 0.01 [normal value: >60%]). In group A, 33.8% of cases (25/74) and in group B, 12.3% of cases (8/65) showed low HOS test scores. Conclusion: The sperm HOS test may be helpful to screen for any paternal factor associated with repeat embryonic or early fetal loss and in a resource-poor setting, and may be utilized in any clinical laboratory. © 2010 Japan Society of Obstetrics and Gynecology.


Chakravarty A.,Vivekananda Institute of Medical Science
Medical Hypotheses | Year: 2010

The smile on Mona Lisa's face remains enigmatous and a topic of much discussion in art circle over the centuries. In this essay the author proposes a new principle of art neuroscience or the science of aesthetics namely 'dynamism' which artists often employ to impart an illusion of movement in their art works which are essentially static. This illusion is possibly generated through imaginative thinking which involves frontal cortical activation in the viewer's brain coupled with activation of the motion area (area V5/MT) of the viewer's visual cortex. It is suggested that this principle of dynamism is somewhat different from the previously described concept of kinetic art. The author hypothesizes that the great painter Leonardo da Vinci very intelligently painted the angles of the mouth of Mona Lisa's face to evoke this illusion of movement (smile) to increase the aesthetic value of this great work of art. © 2010 Elsevier Ltd.


Chakravarty A.,Vivekananda Institute of Medical Science
Medical Hypotheses | Year: 2010

Creativity is a complex neuro-psycho-philosophical phenomenon which is difficult to define literally. Fundamentally it involves the ability to understand and express novel orderly relationships. The creative process involves four stages - preparation, incubation, illumination and verification. A high level of general intelligence, domain specific knowledge and special skills are necessary pre-requisites. It is possible that in addition, some creative people might have architectural alternations of specific portions of the posterior neocortex. Associated with such pre-requisites, the process of creative innovation (incubation and illumination stages) necessitates the need for an ability of divergent thinking, a novelty seeking behavior, some degree of suppression of latent inhibition and a subtle degree of frontal dysfunction. The author hypothesizes that these features are often inter-linked and subtle frontally disinhibited behavior is conducive towards creativity by allowing uninterrupted flow of creative thought possessing and opening up new avenues towards problem solving. Perhaps the most essential feature of the creative brain is its degree of connectivity - both inter-hemispheric and intra-hemispheric. Connectivity correlates or binds together functions of apparently structurally isolated domains on brain modules sub-serving different functions. It is felt that creative cognition is a self rewarding process where divergent thinking would promote connectivity through development of new synapses. In addition, the phenomenon of synaesthesia has often been observed in creative visual artists. Creative innovation often occurs during low arousal states and creative people often manifests features of affective disorders. This suggests a role of neurotransmitters in creative innovation. Dopaminergic pathways are involved in the novelty seeking attitude of creative people while norepinephrine levels are depressed during discovery of novel orderly relationships. The relationship between mood and catecholamines and that of creative cognition is often in an inverted U-shaped form. It is hypothesized that that subtle frontal dysfunction is a pre-requisite for creative cognition but here again the relationship is also in an inverted U-form. © 2009 Elsevier Ltd.

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