She elaborated on important electrical properties of neuronal membrane that helps in neuronal signal transmission.There was good discussion on the capacitance, time constant and length constant property of the neuronal membrane.There was good discussion on the capacitance, time constant and length constant property of the neuronal membrane.
Kala P Nair (2nd year MPhil scholar) presented a seminar titled "Ionic basis of neuronal signalling".
She elaborated on important electrical properties of neuronal membrane that helps in neuronal signal transmission.There was good discussion on the capacitance, time constant and length constant property of the neuronal membrane.There was good discussion on the capacitance, time constant and length constant property of the neuronal membrane. Ajay Kumar Nair (PhD Scholar) presented the first seminar of the academic year on the topic "Living and Celebrating Life: From the Neuroscience Research Perspective".
He shared the larger context of life and its origins and the astounding speed of activity in both the astronomical, microscopic and atomic scales. He reminded that we have far more microbes in our bodies than we have human cells... and that we are perhaps living colonies. He then reviewed the questions raised and contribution provided by Neuroscience in general and the research done in the department of Neurophysiology, NIMHANS over the past few decades. Next, he focused on the challenges and benefits of research, how easy it is to get things wrong, but to take solace that errors will be uncovered and knowledge being cumulative, will grow even though uncertainty might well remain. He ended the seminar with the video of Carl Sagan's timeless wisdom on the pale blue dot and followed it with the takeaways from the seminar. A good discussion ensued and we felt good that the seminar series had thus begun. Abhilash PL (PhD Scholar) presented his seminar on "Microglia - Structural remodeling".
Abhilash gave an overview of the morphology and functions of microglia - these cells are of mesodermal origin - from hematopoietic cells - and are found in higher concentrations where circulation is higher, synaptic density is higher and neuronal activity is higher. Amoeboid microglia are a highly mobile phagocytic form that are active especially during development. Resting microglia have ramified branches and facilitate synapses. Activated microglia retract their branching processes and have a higher secretory functions (pro-inflammatory cytokines such as IL-1, TNF alpha, ROS, NO etc). In the phagocytic phase, they have no processes at all and engulf debris. Multinucleated microglia are found in aging and HIV patients and these cannot differentiate between live and dead neurons. Gitter cells are post phagocytic microglia. Actin remodeling takes place via the Rac signaling pathway. Damaged cells secrete more ATP (beyond the threshold, as ATP is also released as co-transmitter during normal synaptic activity) and this is picked up by the purinergic receptors (P2X4R, ionotropic - cause migration) and (P2Y2R, G-protein coupled - causes rapid process extension). Kumaresan (MPhil Scholar) reviewed the basics of Potassium channels in his seminar, covering the various approaches to classification, mode of action and also shared the deveresearch in this area.
Sunil J Tripathi (PhD scholar) presented his seminar entitled "Effect of Stress on Prefrontal Cortex".
Stress induced plasticity in the hippocampal formation and the amygdaloid nuclear complex have been extensively studied. The Pre-frontal cortex is sensitive to both acute and chronic stress. Sunil reviewed recent studies on stress induced neuroplasticity in the PFC. During a non-stressed condition, the PFC is involved in 'top-down' (lead by PFC) attention regulation. During a stress situation, there is a switch to amygdala lead 'bottom-up' attention regulation. An optimal amount of Noradrenaline and Dopamine levels in the PFC is necessary for optimal function - there is an inverted U-shaped relationship between noradrenaline levels and working memory - too low a level of Noradrenaline may not be sufficient for arousal and too much causes impaired functioning. This is due to the lower affinity of Noradrenaline to alpha-1 receptor(which suppress neuronal firing) in comparison to alpha-2 receptors(that cause enhanced firing) so that at moderate levels of noradrenaline, optimal working memory function is achieved. Dr Jyothi (PhD Scholar) presented her seminar on "Intersection of Buddhist Meditation and Neurosciences".
She presented an overview of meditation and a variety of meditative practices and highlighted that the term meditation is very loosely used to cover very different practices (ranging from focus on breathing to exercises to dhikr chanting of Sufis) that have correspondingly different effects on the body and mind. Jyothi then introduced the basic concepts of Buddhism and considered the connections between Sila (moral excellence), Samadhi or Bhavana (meditation) and Prajna (wisdom) as connected to mental evolution. She discussed about Buddhist meditative practices of Samatha, Vipasyana and Maithri that are being studied in our department. The principle underlying Buddhist contemplative practices is the notion that 'mind is malleable'. Emotions and mental qualities can be modified and trained just like any other skill. In this respect the Buddhist principles resonate with current cognitive models of Neurosciences and hence with the theme of neuroplasticity. She gave an overview of some of the scientific studies on meditation (there are more than 2500 entries on pubmed and almost 300 studies published in 2012). Generally these studies can be classified based on their effect on neuroplasticity, autonomic function and immune function. She concluded her seminar with a discussion on what meditation is not (it is not just relaxation or an escapism etc). Jyothi Prasad (Research Fellow) presented her seminar on "Animal Models of Parkinson's Disease".
Abhilash PL (1st year PhD scholar) presented his seminar on "Astrocytes in neurodegenerative diseases".
After a brief introduction of the morphology and classification of astrocytes (broadly protoplasmic - with short 30 micron processes and fibrous with 300 micron long processes), Abhilash went over the GFAP (expressed more during reactive astrogliosis) and S100Beta (Ca binding protein that gets expressed more during injury) expression and then came to the various functional roles of astrocytes. Astrocytes have a significant role in the lifespan of synapse formation (from birth to death of synapes) and interestingly, under healthy conditions they maintain own territorial domains with less than 5% of overlap between astrocyte processes. Through the astrocytic gap junctions, K+ buffering and Ca+ wave propogation take place. In the tripartite synapse, only 20% of the glutamate released is taken up by the postsynaptic terminal with 80% of it being cleared up by astrocytes. Astrocytes are also involved in Glutathione synthesis and produce precursers that allow neurons to also manufacture Glutathione (as they can't take in Glutathione from extracellular space). Astrocytes are implicated in neurodegenerative diseases such as ALS (can serve as an early marker for some SOD mutant mice models as reactive astrogliosis is observed at 5 weeks while motor neuron loss is seen only at 15 weeks),Alzheimers and Parkinsons Disease(astrocytes can secrete MPTP like toxins. Microglia could be causative for astrogliosis). Suwarna Chakraborty (1st year PhD Scholar) presented her seminar on "Role of Cerebellum in Cognition".
After providing an anatomical overview, she reviewed the well known motor functions of the different deep nuclei. The dentate nucleus (cerebro-cerebellum), which is the largest and connected to the cerebrum, works as a comparator that generates an error signal and provides planning and timing information.The other nuclei - Fastigious, emboliform and globase (spino-cerebellum) - have output to the spinal tracts and is involved in fine movements. The vestibulo cerebellum is involved in posture maintenance and eye movements. The Mossy fibers (from the vestibular nuclei) and the climbing fibres (from the inferior olive) both provide input the Purkinje fibres. The former provide input on the context and the latter forms the error signal. Interestingly, Long Term Depression (LTD) which forms the memory element of the cerebellar motor learning, happens when both these fibre tracts are simultaneously active. If only one these fibre pathways are active, LTP (Long Term Potentiation) ensues. Therefore the cerebral cortex and the cerebellum have different mechanisms for LTP and LTD. Suwarna then reviewed a number of studies evaluating cognitive functions and cerebellum. These included attention, working memory and spatial memory in various animal models (eg: pcd - purkinje cell degeneration model). Merlin (2nd year MPhil Scholar) presented her seminar on "Role of Basal Ganglia in Cognition".
While the role of basal ganglia in motor activity is very well established, its role in cognition is increasingly being noted. Merlin introduced the anatomical features of the basal ganglia and after looking at studies that showed cognitive impairments in patients in movement disorders such as Huntington's disease and Parkinson's disease, she highlighted a number of cognitive functions where the basal ganglia are implicated. These cognitive functions include:
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August 2019
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