Skip to main content

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 ...
Post a Comment

How does the deletion of ENT1 impact glutamate levels in the nucleus accumbens?

Image
Dr. Rishabh Pathak

The deletion of type 1 equilibrative nucleoside transporter (ENT1) can impact glutamate levels in the nucleus accumbens (NAc) through various mechanisms. In the context of the study discussed in the PDF file, the researchers found that ENT1 null mice exhibited increased ethanol-preferring behavior, which was correlated with elevated glutamate levels in the NAc. Here's how the deletion of ENT1 may influence glutamate levels in the NAc:


1.      Regulation of Adenosine Levels: ENT1 is a transporter responsible for the reuptake of adenosine, a neuromodulator that can inhibit glutamate release. In ENT1 null mice, the absence of functional ENT1 may lead to altered adenosine signaling, potentially resulting in increased glutamate release in the NAc. This dysregulation of adenosine-glutamate interactions could contribute to elevated glutamate levels in the NAc.


2.     Enhanced Glutamate Signaling: The absence of ENT1 may disrupt the normal clearance of extracellular adenosine, leading to increased glutamate signaling in the NAc. Glutamate is a major excitatory neurotransmitter in the brain, and elevated glutamate levels can impact synaptic transmission and neuronal activity in the NAc, potentially influencing reward-related behaviors such as ethanol preference.


3.  Neuronal Excitability: Changes in glutamate levels can affect neuronal excitability and synaptic transmission in the NAc. Increased glutamate signaling resulting from the deletion of ENT1 may alter the balance of excitatory and inhibitory neurotransmission in this brain region, potentially influencing the neural circuits involved in reward processing and addiction.


4. Behavioral Consequences: Elevated glutamate levels in the NAc, as observed in ENT1 null mice, may contribute to the development or maintenance of ethanol-preferring behavior. Glutamate plays a crucial role in mediating the rewarding effects of drugs of abuse, and alterations in glutamatergic signaling in the NAc can impact behavioral responses to ethanol and other substances.


Overall, the deletion of ENT1 can disrupt adenosine-glutamate interactions, leading to increased glutamate levels in the NAc. This dysregulation of glutamatergic signaling may contribute to the behavioral phenotype observed in ENT1 null mice, including their preference for ethanol consumption .

 

Categories:

Comments

Post a Comment

Popular posts from this blog

Relation of Model Complexity to Dataset Size

Dr. Rishabh Pathak
Core Concept The relationship between model complexity and dataset size is fundamental in supervised learning, affecting how well a model can learn and generalize. Model complexity refers to the capacity or flexibility of the model to fit a wide variety of functions. Dataset size refers to the number and diversity of training samples available for learning. Key Points 1. Larger Datasets Allow for More Complex Models When your dataset contains more varied data points , you can afford to use more complex models without overfitting. More data points mean more information and variety, enabling the model to learn detailed patterns without fitting noise. Quote from the book: "Relation of Model Complexity to Dataset Size. It’s important to note that model complexity is intimately tied to the variation of inputs contained in your training dataset: the larger variety of data points your dataset contains, the more complex a model you can use without overfitting....
Post a Comment
Read more

Linear Models

Dr. Rishabh Pathak
1. What are Linear Models? Linear models are a class of models that make predictions using a linear function of the input features. The prediction is computed as a weighted sum of the input features plus a bias term. They have been extensively studied over more than a century and remain widely used due to their simplicity, interpretability, and effectiveness in many scenarios. 2. Mathematical Formulation For regression , the general form of a linear model's prediction is: y^ ​ = w0 ​ x0 ​ + w1 ​ x1 ​ + … + wp ​ xp ​ + b where; y^ ​ is the predicted output, xi ​ is the i-th input feature, wi ​ is the learned weight coefficient for feature xi ​ , b is the intercept (bias term), p is the number of features. In vector form: y^ ​ = wTx + b where w = ( w0 ​ , w1 ​ , ... , wp ​ ) and x = ( x0 ​ , x1 ​ , ... , xp ​ ) . 3. Interpretation and Intuition The prediction is a linear combination of features — each feature contributes prop...
Post a Comment
Read more

Predicting Probabilities

Dr. Rishabh Pathak
1. What is Predicting Probabilities? The predict_proba method estimates the probability that a given input belongs to each class. It returns values in the range [0, 1] , representing the model's confidence as probabilities. The sum of predicted probabilities across all classes for a sample is always 1 (i.e., they form a valid probability distribution). 2. Output Shape of predict_proba For binary classification , the shape of the output is (n_samples, 2) : Column 0: Probability of the sample belonging to the negative class. Column 1: Probability of the sample belonging to the positive class. For multiclass classification , the shape is (n_samples, n_classes) , with each column corresponding to the probability of the sample belonging to that class. 3. Interpretation of predict_proba Output The probability reflects how confidently the model believes a data point belongs to each class. For example, in ...
Post a Comment
Read more

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 ...
Post a Comment
Read more

Supervised Learning

Dr. Rishabh Pathak
What is Supervised Learning? ·     Definition: Supervised learning involves training a model on a labeled dataset, where the input data (features) are paired with the correct output (labels). The model learns to map inputs to outputs and can predict labels for unseen input data. ·     Goal: To learn a function that generalizes well from training data to accurately predict labels for new data. ·          Types: ·          Classification: Predicting categorical labels (e.g., classifying iris flowers into species). ·          Regression: Predicting continuous values (e.g., predicting house prices). Key Concepts: ·     Generalization: The ability of a model to perform well on previously unseen data, not just the training data. ·         Overfitting and Underfitting: ·    ...
Post a Comment
Read more