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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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Types of Phantom Spike and Wave

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Dr. Rishabh Pathak

Phantom Spike and Wave (PhSW) can be categorized into different types based on specific features such as amplitude, location, gender of the patient, and the state of wakefulness. The two primary forms of PhSW are often referred to by the acronyms WHAM and FOLD. 

1. WHAM (Waking, High amplitude, Anterior, usually Male)

    • Characteristics:
      • Waking State: This form typically occurs during wakefulness.
      • High Amplitude: The spikes in this pattern are defined as having a high amplitude, generally greater than 45 μV.
      • Anterior Location: The discharges are predominantly recorded from the frontal regions of the scalp.
      • Demographics: More commonly observed in male patients.
    • Clinical Context:
      • WHAM patterns may be associated with various neurological conditions and can indicate significant underlying pathology, particularly in males during awake states.

2. FOLD (Female, Occipital, Low amplitude, Drowsy)

    • Characteristics:
      • Drowsy State: This form is typically observed during drowsiness or light sleep.
      • Low Amplitude: The spikes are of lower amplitude compared to WHAM, often less than 40 μV, making them sometimes difficult to discern.
      • Occipital Location: The discharges are predominantly recorded from the occipital regions of the scalp.
      • Demographics: More commonly seen in female patients.
    • Clinical Context:
      • FOLD patterns are often associated with benign conditions and may be seen in patients with a history of migraines or other non-epileptic phenomena. They are generally considered to have a better prognosis compared to WHAM patterns.

Summary of Differences

Feature

WHAM

FOLD

State

Waking

Drowsy

Amplitude

High amplitude (≥ 45 μV)

Low amplitude (< 40 μV)

Location

Anterior (frontal regions)

Occipital (occipital regions)

Demographics

Usually Male

Usually Female

 

Additional Notes

    • Prevalence: PhSW is relatively uncommon, occurring in about 0.5% to 1% of EEGs, but its occurrence is slightly more likely in females overall.
    • Age Range: The pattern is most likely to occur during adolescence and young adulthood, with a higher occurrence rate in this demographic.

Understanding these types of Phantom Spike and Wave patterns is crucial for clinicians in diagnosing and managing patients with neurological symptoms, as they can provide insights into the underlying conditions and their potential implications.

 

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