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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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What are the typical frequency ranges for low and high stimulation frequencies that may produce photomyogenic artifacts?

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Dr. Rishabh Pathak


Photomyogenic artifacts in EEG recordings can be influenced by the frequency of photic stimulation. The typical frequency ranges for low and high stimulation frequencies that may produce these artifacts are as follows:


1.      Low Stimulation Frequencies:

o Low stimulation frequencies are generally considered to be below 6 Hz. At these frequencies, photomyogenic artifacts tend to resemble other EMG potentials more closely. The artifacts produced may not exhibit a well-formed photic driving response, and the waveforms can appear more irregular and less synchronized with the stimulus. The muscle contractions may be less pronounced, leading to lower amplitude artifacts.

2.     High Stimulation Frequencies:

o High stimulation frequencies are typically above 6 Hz, with common ranges extending up to 30 Hz or higher. At these higher frequencies, photomyogenic artifacts can appear less like typical EMG and more similar to the photic driving response. The waveforms at high frequencies tend to have sharper contours and can show a more rhythmic pattern that aligns more closely with the frequency of the photic stimulus. However, they still differ from the photic driving response in terms of their waveform characteristics and may not always be time-locked to the strobe stimulation.

In summary, low stimulation frequencies (below 6 Hz) are associated with more irregular and less synchronized photomyogenic artifacts, while high stimulation frequencies (above 6 Hz) can produce artifacts that are sharper and more rhythmic, but still distinct from true photic driving responses.

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