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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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Glutamate. From its isolation to neurotransmitter function

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Dr. Rishabh Pathak

The journey of glutamate from its isolation to its recognition as a key neurotransmitter in the brain is a fascinating story that spans several decades of scientific discovery. Here is an overview of the milestones in the history of glutamate, highlighting its isolation and eventual identification as a major neurotransmitter:


1.      Isolation of Glutamate:

o    Glutamate, an amino acid, was first isolated in 1866 by the German chemist Karl Heinrich Ritthausen from wheat gluten.

o    In the early 20th century, researchers identified glutamate as a component of protein-rich foods and a building block of proteins in the body.

2.     Identification as a Neurotransmitter:

o    In the 1950s and 1960s, researchers began to investigate the role of glutamate in the central nervous system.

o    In 1957, Daniel McGeer and John McGeer discovered that glutamate is present in high concentrations in the brain and spinal cord.

o    In the 1960s, researchers such as John Curtis Watkins and Edward Roberts demonstrated that glutamate acts as an excitatory neurotransmitter in the brain.

o    In the 1970s, the concept of glutamate as a major neurotransmitter in the brain gained widespread acceptance, particularly in the field of neuroscience.

3.     Glutamate Receptors:

o    In the 1980s and 1990s, researchers identified and characterized several types of glutamate receptors in the brain, including NMDA (N-methyl-D-aspartate), AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid), and kainate receptors.

o    These receptors play crucial roles in synaptic transmission, plasticity, and neuronal communication.

4.    Excitatory Neurotransmission:

oGlutamate is now recognized as the primary excitatory neurotransmitter in the central nervous system, responsible for fast synaptic transmission and neuronal signaling.

o    It plays a key role in processes such as learning, memory, and motor function.

5.     Neurological Implications:

o    Dysregulation of glutamate signaling has been implicated in various neurological disorders, including epilepsy, stroke, Alzheimer's disease, and Parkinson's disease.

o    Research continues to explore the role of glutamate in brain function and its potential as a target for therapeutic interventions in neurological and psychiatric conditions.

Overall, the journey of glutamate from its isolation as an amino acid to its recognition as a major neurotransmitter in the brain represents a significant advancement in our understanding of brain function and neurological disorders.

 

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