Optical imaging of neuronal populations during decision-making

Area of Science:

• Neuroscience
• Animal Behavior

Background:

• The leech nervous system provides a model for understanding neural circuits underlying decision-making.
• Investigating how identical sensory inputs can lead to different motor outputs (crawling vs. swimming) is crucial for understanding behavioral flexibility.

Purpose of the Study:

• To identify neural correlates of decision-making in the leech nervous system.
• To determine the earliest neuronal signals that predict behavioral choices between crawling and swimming.
• To investigate the role of specific neurons, like cell 208, in biasing behavioral output.

Main Methods:

• Stimulating leeches with identical sensory inputs to elicit either crawling or swimming.
• Monitoring neuronal activity using voltage-sensitive dyes.
• Quantifying neuronal discrimination times.
• Applying principal component analysis (PCA) and linear discriminant analysis (LDA) to neuronal population data.
• Manipulating the activity of specific neurons (cell 208) via hyperpolarization and depolarization.

Main Results:

• Identified single neurons that discriminate between future behaviors before the behaviors are externally observable.
• Discovered neuronal populations, identified via PCA and LDA, that discriminate earlier than any single neuron.
• Highlighted cell 208 as a key neuron in the decision-making process.
• Demonstrated that altering cell 208's membrane potential biases the leech's behavior towards swimming (hyperpolarization) or crawling/delayed swimming (depolarization).

Conclusions:

• Decision-making in the leech can be predicted by the activity of specific neurons and neuronal populations.
• Cell 208 plays a critical role in biasing the choice between swimming and crawling behaviors.
• This study provides insights into the neural mechanisms of choice and behavioral control in a simple nervous system.