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Unveiling Hidden Neural Codes: SIMPL – A Scalable and Fast Approach for Optimizing Latent Variables and Tuning Curves in Neural Population Data

Dr. Rishabh Pathak
This research paper presents SIMPL (Scalable Iterative Maximization of Population-coded Latents), a novel, computationally efficient algorithm designed to refine the estimation of latent variables and tuning curves from neural population activity. Latent variables in neural data represent essential low-dimensional quantities encoding behavioral or cognitive states, which neuroscientists seek to identify to understand brain computations better. Background and Motivation Traditional approaches commonly assume the observed behavioral variable as the latent neural code. However, this assumption can lead to inaccuracies because neural activity sometimes encodes internal cognitive states differing subtly from observable behavior (e.g., anticipation, mental simulation). Existing latent variable models face challenges such as high computational cost, poor scalability to large datasets, limited expressiveness of tuning models, or difficulties interpreting complex neural network-based functio...
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Transcranial Current Stimulation (TCS)

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Dr. Rishabh Pathak

Transcranial Current Stimulation (TCS) is a non-invasive neuromodulation technique that involves applying low-intensity electrical currents to the scalp to modulate brain activity. There are two main types of Transcranial Current Stimulation: Transcranial Direct Current Stimulation (tDCS) and Transcranial Alternating Current Stimulation (tACS). Here is an overview of Transcranial Current Stimulation (TCS):


1.      Transcranial Direct Current Stimulation (tDCS):

otDCS involves delivering a constant, low-intensity electrical current (typically between 1-2 mA) through electrodes placed on the scalp. The current flows from anode to cathode and can modulate neuronal excitability in the underlying brain regions.

otDCS is known for its ability to induce polarity-dependent effects on cortical excitability. Anodal stimulation is generally associated with increased excitability, while cathodal stimulation is linked to decreased excitability.

otDCS has been studied for its potential therapeutic applications in various neurological and psychiatric conditions, including depression, chronic pain, stroke rehabilitation, and cognitive enhancement.

2.     Transcranial Alternating Current Stimulation (tACS):

otACS involves delivering alternating current at specific frequencies to the brain through scalp electrodes. By entraining neural oscillations, tACS can influence brain rhythms and synchronization in targeted regions.

otACS is used to modulate endogenous brain oscillations and has been investigated for its effects on cognitive functions, sensory processing, motor control, and sleep regulation.

oDifferent frequencies of tACS (e.g., theta, alpha, beta, gamma) can be applied to match the natural oscillatory patterns of the brain and potentially enhance neural network activity.

3.     Mechanisms of Action:

oThe mechanisms underlying the effects of TCS are complex and involve changes in neuronal membrane potentials, synaptic plasticity, neurotransmitter release, and network connectivity.

oTCS is thought to influence neuronal firing rates, cortical excitability, and functional connectivity within distributed brain networks, leading to alterations in behavior and cognition.

4.    Safety and Considerations:

o TCS is generally considered safe when administered within established guidelines and safety protocols. Adverse effects are typically mild and transient, including tingling sensations, itching, or mild discomfort at the electrode sites.

oIndividual variability in response to TCS, optimal stimulation parameters, and long-term effects are areas of ongoing research and consideration.

In summary, Transcranial Current Stimulation (TCS), including tDCS and tACS, is a non-invasive neuromodulation technique that can modulate brain activity by applying electrical currents to the scalp. These methods have shown promise in research and clinical applications for studying brain function, enhancing cognitive abilities, and potentially treating various neurological and psychiatric disorders.

 

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