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Uncertainty in Multiclass Classification

Dr. Rishabh Pathak
1. What is Uncertainty in Classification? Uncertainty refers to the model’s confidence or doubt in its predictions. Quantifying uncertainty is important to understand how reliable each prediction is. In multiclass classification , uncertainty estimates provide probabilities over multiple classes, reflecting how sure the model is about each possible class. 2. Methods to Estimate Uncertainty in Multiclass Classification Most multiclass classifiers provide methods such as: predict_proba: Returns a probability distribution across all classes. decision_function: Returns scores or margins for each class (sometimes called raw or uncalibrated confidence scores). The probability distribution from predict_proba captures the uncertainty by assigning a probability to each class. 3. Shape and Interpretation of predict_proba in Multiclass Output shape: (n_samples, n_classes) Each row corresponds to the probabilities of ...
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Periodic Epileptiform Discharges Compared to Environmental Device Artifacts

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Dr. Rishabh Pathak

Periodic Epileptiform Discharges (PEDs) can sometimes be mistaken for environmental device artifacts due to their periodic nature. However, there are several key differences that help distinguish between these two types of EEG patterns. 

Comparison of Periodic Epileptiform Discharges (PEDs) and Environmental Device Artifacts:

1.      Waveform Characteristics:

§  PEDs: Typically exhibit a triphasic waveform, characterized by a sharply contoured initial spike followed by a slow wave. This specific morphology is consistent and indicative of epileptiform activity.

§  Environmental Device Artifacts: These artifacts may have a regular interval and can appear similar to PEDs, but they usually lack the distinct triphasic waveform. The waveforms may be more irregular and do not conform to the typical patterns seen in PEDs.

2.     Distribution:

§  PEDs: Often localized to specific regions of the scalp, particularly in cases of focal brain lesions or encephalopathy. They can be bilateral but typically show a more defined distribution.

§  Environmental Device Artifacts: These artifacts may not have a consistent distribution and can appear across multiple electrodes without a clear pattern. They often do not correspond to the anatomical distribution of brain activity.

3.     Inter-discharge Interval:

§  PEDs: Characterized by regular inter-discharge intervals, often occurring at consistent time intervals (e.g., every 1 to 2 seconds).

§  Environmental Device Artifacts: While they may appear periodic, the intervals can be irregular and do not follow a predictable pattern. The timing may vary based on the device's operation or external factors.

4.    Response to Movement:

§  PEDs: Generally remain stable and do not change significantly with patient movement or external stimuli. They are intrinsic to the brain's electrical activity.

§  Environmental Device Artifacts: Often change in amplitude or morphology with patient movement or changes in the environment. They may be influenced by the proximity of the device to the electrodes.

5.     Clinical Context:

§  PEDs: Associated with specific neurological conditions, such as encephalopathy, seizures, or brain lesions. Their presence is clinically significant and warrants further investigation.

§  Environmental Device Artifacts: Typically arise from external sources, such as electrical devices or equipment, and are not indicative of neurological dysfunction. They are often considered noise in the EEG recording.

6.    Background Activity:

§  PEDs: Usually accompanied by low-amplitude background activity, which may be disorganized or show slowing.

§  Environmental Device Artifacts: The background activity may remain unchanged, but the artifacts can obscure the underlying EEG signals without a corresponding change in the brain's electrical activity.

Summary:

While both Periodic Epileptiform Discharges (PEDs) and environmental device artifacts can present as rhythmic patterns on an EEG, they can be distinguished by their waveform characteristics, distribution, inter-discharge intervals, response to movement, clinical context, and accompanying background activity. Recognizing these differences is essential for accurate interpretation of EEG recordings and appropriate clinical management.

 

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