Subicular Plateaus Signal Reward Locations during Goal-Directed Behavior.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Cellular Neuroscience

Background:

• The hippocampus is crucial for spatial learning and memory.
• The subiculum, the hippocampus's main output, plays a key role in navigation.
• Understanding subicular neuron firing patterns, especially bursting, is vital for deciphering navigational information encoding.

Purpose of the Study:

• To investigate the cellular mechanisms and behavioral relevance of bursting in subicular neurons during navigation.
• To determine how subicular bursting relates to goal-directed behavior and reward learning.

Main Methods:

• In vivo whole-cell recordings from dorsal subiculum neurons in head-fixed mice.
• Utilized a goal-directed navigation task to observe neuronal activity during behavior.
• Analyzed plateau potentials, a specific type of burst firing, and their relationship to membrane potential and behavior.

Main Results:

• Subicular bursting often occurs as plateau potentials, characterized by action potentials riding on a sustained depolarization.
• These plateaus are synaptic events requiring NMDA receptor activation.
• Plateaus initiated at hyperpolarized potentials were associated with reward locations, while those at depolarized potentials were more spatially distributed.
• Reward-related clustering dynamically changed during the learning of new reward locations.

Conclusions:

• Subicular plateaus represent a key cellular mechanism for hippocampal output bursting during navigation.
• The preceding membrane potential state of subicular neurons organizes the behavioral associations of these plateaus.
• This provides a cellular basis for how the hippocampus encodes spatial information and guides goal-directed behavior.