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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

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...

Focal seizure with occipital onset

  Focal seizures with occipital onset originate in the occipital lobe, which is primarily responsible for visual processing. 1.       Ictal Patterns : o     The EEG findings during focal seizures with occipital onset typically show diphasic sharp waves that may evolve into rhythmic activity. This rhythmic activity can become more pronounced over time, often encompassing bilateral posterior head regions while remaining localized to the occipital area. 2.      Clinical Manifestations : o   Patients experiencing occipital seizures may present with visual symptoms, such as visual hallucinations, flashes of light, or other visual distortions. These seizures can also lead to eye movements, such as eyelid flutter or upward gaze, which are common manifestations of occipital lobe involvement. 3.      EEG Characteristics : o   The ictal pattern in occipital seizures is characterized by phase...

Focal seizure with mesial temporal onset

Focal seizures with mesial temporal onset are a specific type of focal seizure that originates in the mesial (medial) temporal lobe of the brain. 1.       Ictal Patterns : o    The ictal patterns associated with mesial temporal seizures often include rhythmic slowing that evolves into well-formed rhythmic activity. This can manifest as a phase-reversing rhythm on the EEG, typically observed in the temporal region. 2.      Clinical Manifestations : o    Patients experiencing focal seizures with mesial temporal onset may exhibit a range of clinical symptoms, including staring, manual and oral automatisms, and impaired awareness. These seizures can lead to alterations in consciousness, which may not always be recognized by observers. 3.      EEG Characteristics : o    The EEG findings during these seizures may show a progression from diffuse slowing to more organized rhythmic activity...

Ictal Epileptiform Patterns in different Neurological Conditions

Ictal epileptiform patterns can manifest differently across various neurological conditions, reflecting the underlying pathophysiology and the nature of the seizures. 1.       Focal-Onset Seizures : o     In focal-onset seizures, the ictal patterns can vary widely depending on the region of the brain involved. These seizures may present with specific EEG findings that correlate with the affected brain area, such as temporal lobe seizures showing distinct patterns that may not be visible unless a significant portion of the cortex is involved. 2.      Generalized-Onset Seizures : o     Generalized-onset seizures, such as generalized tonic-clonic seizures, typically exhibit more uniform ictal patterns across the EEG. These patterns can include generalized spike-and-wave discharges, which are characteristic of generalized epilepsy syndromes. 3.      Subclinical Seizures : o  ...

Clinical Significance of Ictal Epileptiform Patterns

The clinical significance of ictal epileptiform patterns is multifaceted and plays a crucial role in the diagnosis, management, and understanding of seizures. 1.       Identification of Seizures : o     Ictal patterns are essential for identifying the occurrence of seizures. They provide the electrographic evidence needed to confirm that a seizure has taken place, which is critical for diagnosis. 2.      Behavioral Correlation : o     Ictal patterns are almost always accompanied by behavioral changes when they last more than a few seconds. This behavioral change is a defining characteristic of seizures, as seizures are defined by abnormal behavior or experiences due to neuronal dysfunction. 3.      Differentiation of Seizure Types : o     The characteristics of ictal patterns, such as their frequency, location, and waveform, can help differentiate between various typ...

Cooccurring patterns of Ictal Epileptiform Patterns

Co-occurring patterns of ictal epileptiform patterns can provide important insights into the nature of seizures and their electrographic characteristics. 1.       Generalized-Onset Motor Seizures : o    Ictal patterns during generalized-onset motor seizures often include various artifacts, particularly muscle and movement artifacts. These artifacts can complicate the interpretation of the EEG. 2.      Interictal Epileptiform Discharges (IEDs) : o    Generalized interictal epileptiform discharges (IEDs) are commonly present at other times in the EEG. Their presence can help differentiate between ictal and non-ictal activity, as they may appear alongside ictal patterns. 3.      Postictal Changes : o     After an ictal event, postictal slowing or attenuation may occur. These features can sometimes help differentiate an ictal pattern from artifacts, although they are not entirely reliable as ...