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Energy Manifold Natural Gradient Descent: From Riemannian Optimization to Modern Neuroscience, NeuroAI and Quantum Physics

Dr. Rishabh Pathak
When Geometry, Energy, Artificial Intelligence and Neuroscience Converge Modern Artificial Intelligence is rapidly moving beyond the idea that learning simply means minimizing an error function. Increasingly, researchers are asking a deeper question: what is the structure of the space in which learning takes place? This question becomes particularly important when the system being modelled is constrained, nonlinear, dynamic, or governed by physical principles. A recent work titled “Energy Manifold Natural Gradient Descent: Riemannian Optimization for Neural PDE Solvers” , by Zhangyong Liang and Huanhuan Gao, introduces Energy Manifold Natural Gradient Descent (EMNGD) , a mathematical framework that extends energy-based natural-gradient optimization from unconstrained Euclidean parameter spaces to constrained Riemannian parameter manifolds . At its core, the framework proposes a simple but powerful principle: An optimization algorithm should not only determine how to reduce error; it sh...
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Photomyogenic Artifacts

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Dr. Rishabh Pathak

Photomyogenic artifacts in EEG recordings are a type of artifact caused by light-induced muscle contractions, often observed in response to flashing lights during photic stimulation. Here is a detailed overview of photomyogenic artifacts based on the provided document:

1.     Description:

o Photomyogenic artifacts result from muscle contractions triggered by specific visual stimuli, such as flashing lights during photic stimulation.

2.   Characteristics:

oTriggered Response: Photomyogenic artifacts occur in response to visual stimuli, with muscle contractions induced by the light.

o  Frequency: These artifacts can exhibit rhythmicity based on the frequency of the light stimulation.

3.   Location:

oPhotomyogenic artifacts are typically observed over the frontal and periorbital regions bilaterally, reflecting the muscle groups involved in the response.

4.   Latency:

o The photomyogenic response has a specific latency from the strobe's flash, typically around 50 milliseconds, allowing for synchronization with the visual stimulation.

5.    Behavior:

o Photomyogenic artifacts may extend to include larger regions if the myoclonus involves the neck or body, potentially leading to simultaneous electrode and movement artifacts.

6.   Occurrence:

o  These artifacts may be present with eyes opened or closed but tend to occur more frequently with eyes closed, disappearing immediately when the photic stimulation ceases.

7.    Clinical Impact:

o Recognizing and understanding photomyogenic artifacts is crucial for differentiating them from genuine EEG activity during interpretation.

o    Failure to identify and account for photomyogenic artifacts can lead to misinterpretation of EEG recordings and inaccurate clinical assessments.

8.   Artifact Mitigation:

o  Minimizing exposure to triggering visual stimuli or adjusting the stimulation parameters can help reduce the occurrence of photomyogenic artifacts during EEG recordings.

o Signal processing techniques, such as artifact rejection algorithms, can aid in mitigating the impact of these artifacts on EEG data quality.

Understanding the characteristics and impact of photomyogenic artifacts is essential for EEG practitioners to ensure accurate interpretation of EEG recordings and reliable clinical assessments. Proper identification and management of these artifacts contribute to obtaining high-quality EEG data for effective diagnosis and treatment planning.

 

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