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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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Open Packed Positions Vs Closed Packed Positions

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Dr. Rishabh Pathak

Open packed positions and closed packed positions are two important concepts in understanding joint biomechanics and functional movement. Here is a comparison between open packed positions and closed packed positions:

Open Packed Positions:

1.    Definition:

o    Open packed positions, also known as loose packed positions or resting positions, refer to joint positions where the articular surfaces are not maximally congruent, allowing for some degree of joint play and mobility.

2.    Characteristics:

o    Less congruency of joint surfaces.

o    Ligaments and joint capsule are relatively relaxed.

o    More joint mobility and range of motion.

3.    Functions:

o    Joint mobility and flexibility.

o    Absorption and distribution of forces during movement.

4.    Examples:

o    Knee: Slightly flexed position.

o    Shoulder: Arm at the side of the body.

o    Hip: Position of slight flexion and abduction.

Closed Packed Positions:

1.    Definition:

o    Closed packed positions, also known as close-packed positions, refer to joint positions where the articular surfaces are maximally congruent, providing the greatest stability and resistance to external forces.

2.    Characteristics:

o    Maximal congruency of joint surfaces.

o    Ligaments and joint capsule are taut and under tension.

o    Least mobility but most stability.

3.    Functions:

o    Joint stability and resistance to dislocation.

o    Weight-bearing support and load distribution.

4.    Examples:

o    Knee: Full extension.

o    Shoulder: Maximum abduction and external rotation.

o    Hip: Full extension and internal rotation.

Comparison:

  • Stability vs. Mobility:
    • Closed packed positions offer maximum stability but limited mobility, while open packed positions provide more mobility but less stability.
  • Joint Play:
    • Open packed positions allow for joint play and flexibility, whereas closed packed positions minimize joint play for stability.
  • Clinical Significance:
    • Open packed positions are often used for joint mobilization techniques and assessments of joint mobility, while closed packed positions are utilized to assess joint stability and integrity.

Understanding the differences between open packed and closed packed positions is crucial in clinical assessments, rehabilitation protocols, and sports training programs to optimize joint function, prevent injuries, and enhance overall movement efficiency.

 

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