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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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Needle Spikes in Different Neurological Conditions

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Dr. Rishabh Pathak

Needle spikes, also known as occipital spikes of blindness, are primarily associated with visual impairment, but they can also be observed in various neurological conditions. 

1. Congenital Blindness

    • Primary Association: Needle spikes are most commonly seen in individuals with congenital blindness or severe visual impairment from early infancy. They are often benign and do not necessarily indicate the presence of epilepsy.
    • Retinopathy: The presence of needle spikes is particularly associated with retinopathy, such as retrolental fibroplasia, which is linked to cerebral pathology.

2. Epilepsy

    • Co-occurrence with Epileptic Disorders: While needle spikes are generally benign, they can occur in patients with epilepsy. In these cases, the presence of needle spikes may be associated with other interictal epileptiform discharges, indicating a potential risk for seizures.
    • Differentiation from Other Patterns: It is crucial to differentiate needle spikes from other types of interictal epileptiform discharges (IEDs), as the latter may suggest a higher likelihood of seizure activity.

3. Cerebral Pathologies

    • Cortical Dysplasia: Needle spikes may be observed in patients with cortical dysplasia, a condition that can lead to focal epilepsies. The presence of needle spikes in these patients may indicate underlying structural brain abnormalities.
    • Other Neurological Disorders: Needle spikes can also be seen in various neurological conditions that involve cerebral pathology, such as traumatic brain injury or developmental disorders, where visual impairment is present.

4. Developmental Disorders

    • Intellectual Disabilities: In children with intellectual disabilities or developmental delays, needle spikes may be present alongside other EEG abnormalities. The clinical significance in these cases can vary, and the presence of needle spikes may not always correlate with seizure activity.
    • Visual Afferent Abnormalities: Needle spikes may occur in the context of visual afferent abnormalities, where the visual system is affected but not necessarily leading to seizures.

5. Age-Related Considerations

    • Changes Over Time: The characteristics of needle spikes can change with age. They are typically more prominent in early childhood and may decrease in frequency and amplitude during adolescence. This age-related change can be significant in understanding their clinical relevance in different neurological conditions.

Summary

In summary, needle spikes are primarily associated with congenital blindness but can also be observed in various neurological conditions, including epilepsy, cortical dysplasia, and developmental disorders. Their presence may indicate underlying cerebral pathology, and while they are often benign, careful interpretation in the context of the patient's clinical history is essential for accurate diagnosis and management.

 

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