Biology subjects

Kumbhare, D.

Publications and source records attributed to Kumbhare, D..

4 recordsLinked to original sources

bioRxiv2024

Deep Brain Stimulation of Nucleus Basalis of Meynert improves learning in rat model of dementia.

BackgroundDeep brain stimulation (DBS) of the nucleus basalis of Meynert (NBM) has been preliminarily investigated as a potential treatment for dementia. The degeneration of NBM cholinergic neurons is a pathological feature of many forms of dementia. Although stimulation of the NBM has been demonstrated to improve learning, the ideal parameters for NBM stimulation have not been elucidated. This study assesses the differential effects of varying stimulation patterns and duration on learning in a dementia rat model. Methods192-IgG-saporin (or vehicle) was injected into the NBM to produce dementia in rats. Next, all rats underwent unilateral implantation of a DBS electrode in the NBM. The experimental groups consisted of i-normal, ii-untreated demented, and iii-demented rats receiving NBM DBS. The stimulation paradigms included testing different modes (tonic and burst) and durations (1-hr, 5-hrs, and 24-hrs/day) over 10 daily sessions. Memory was assessed pre- and post-stimulation using two established learning paradigms: novel object recognition (NOR) and auditory operant chamber learning. ResultsBoth normal and stimulated rats demonstrated improved performance in NOR and auditory learning as compared to the unstimulated demented group. The burst stimulation groups performed better than the tonic stimulated group. Increasing the daily stimulation duration to 24-hr did not further improve cognitive performance in an auditory recognition task and degraded the results on a NOR task as compared with 5-hr. ConclusionThe present findings suggest that naturalistic NBM burst DBS may offer a potential effective therapy for treating dementia and suggests potential strategies for the reevaluation of current human NBM stimulation paradigms.

animal behavior and cognition↗

bioRxiv2022

Investigation of Soft Magnetic Material Cores in Transcranial Magnetic Stimulation Coils and the Effect of Changing Core Shapes on the Induced Electric Field in Small Animals

Transcranial magnetic stimulation (TMS) is a safe, effective and non-invasive treatment for several psychiatric and neurological disorders. Lately, there has been a surge in research utilizing this novel technology in treating other neurological and psychiatric ailments. The application of TMS on several neurological disorders requires the induced electric and magnetic fields to be focused and targeted to a small region in the brain. TMS of a focal cortical territory will ensure modulation of specific brain circuitry without affecting unwanted surrounding regions. This can be achieved by altering the properties of the magnetic core material used for the TMS system. In this study, soft ferromagnetic materials having high permeability, high saturation magnetization and low coercivity have been investigated as TMS coil cores in finite element simulations. Also, magnetic field measurements have been carried out using different cores in the TMS coil. Finite element analysis of the rat head model is carried out using Sim4life software while investigating variations associated with changing the ferromagnetic core material and shape in the coil. Materials proposed for the analysis in this study include Iron Cobalt Vanadium alloy (Fe-Co-V) also known as Permendur, Carbon Steel (AISI 1010) and Manganese Zinc ferrites (MnZn ferrites). Simulation results indicated significant magnetic field distribution variation when introducing a ferromagnetic core in TMS coil, concentrating the magnetic field to the targeted region in the rat head model without stimulating adjacent regions. It was observed that the v-tip sharpened core attained the highest magnetic field and best focality among other cores in simulations and experimentally.

bioengineering↗

bioRxiv2021

Mechanistic target of rapamycin complex 1 (mTORC1) activity occurs predominantly in the periphery of human skeletal muscle fibers, in close proximity to focal adhesion complexes, following anabolic stimuli

Following anabolic stimuli (e.g. mechanical loading and/or amino acid provision) the mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of protein synthesis, translocates toward the cell periphery. However, it is unknown if mTORC1 activity occurs prior to or following this translocation. We therefore aimed to determine the cellular location of mTORC1 activity in human skeletal muscle following anabolic stimuli. Fourteen young, healthy males either ingested a protein-carbohydrate beverage (0.25g/kg protein, 0.75g/kg carbohydrate) alone (n=7, 23{+/-}5yrs, 76.8{+/-}3.6kg, 13.6{+/-}3.8%BF, FED) or following a whole-body resistance exercise bout (n=7, 22{+/-}2yrs, 78.1{+/-}3.6kg, 12.2{+/-}4.9%BF, EXFED). Vastus lateralis muscle biopsies were obtained at rest (PRE) and 120 and 300min following anabolic stimuli. The spatial regulation of mTORC1 activity was assessed through immunofluorescent staining of p-RPS6Ser240/244, an mTORC1-specific phosphorylation event. p-RPS6Ser240/244 measured by immunofluorescent staining or immunoblot was positively correlated (r=0.76, p<0.001). Peripheral staining intensity of p-RPS6Ser240/244 increased above PRE in both FED and EXFED at 120min (~54% and ~138% respectively, p<0.05) but was greater in EXFED at both post-stimuli time points (p<0.05). The peripheral-central ratio of p-RPS6240/244 staining was displayed a similar pattern, suggesting mTORC1 activity occurs predominantly in the periphery of fibers. Moreover, p-RPS6Ser240/244 intensity within paxillin-positive regions, a marker of focal adhesion complexes, was elevated at 120min irrespective of stimulus (p=0.006) before returning to PRE at 300min. These data confirm that mTORC1 activity occurs in the region of human muscle fibers to which mTORC1 translocates following anabolic stimuli and identifies focal adhesion complexes as a potential site of mTORC1 activation in vivo.

cell biology↗

bioRxiv2019

A Computational Model of Thalamic Tonic-burst Motor Projection Neurons and Their Regulation by Pallidal GABAergic Neurons

A modified computational model of pallidal receiving ventral oral posterior (Vop) thalamocortical motor relay neurons was adapted based on in vivo observations in our rodent model. The model accounts for different input neuronal firing patterns in the primary motor output nucleus of basal ganglia, the globus pallidus interna (GPi) and subsequently generate Vop outputs as observed in vivo under different conditions. Hyperpolarizing input de-inactivates its T-type calcium channel and sets the thalamic neurons in the preferable burst firing mode over a tonic mode and induces low threshold spikes (LTS). In the hyperpolarized state, both spontaneously and in response to excitatory (e.g. corticothalamic) inputs, burst spiking occurs on the crest of the LTS. By selecting and determining the timing and extent of opening of thalamic T-type calcium channels via GABAergic hyperpolarizing input, the GPi precisely regulates Vop-cortical burst motor signaling. Different combinations of tonic, burst, irregular tonic and irregular burst inputs from GPi were used to verify our model. In vivo data obtained from recordings in the entopedunucular nucleus (EP; rodent equivalent of GPi) from resting head restrained healthy and dystonic rats were used to simulate the influences of different inputs from GPi. In all cases, GPi neuronal firing patterns are demonstrated to act as a firing mode selector for thalamic Vop neurons.

neuroscience↗