Thalamus and claustrum control parallel layer 1 circuits in retrosplenial cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• The granular retrosplenial cortex (RSG) plays a crucial role in spatial and non-spatial behaviors.
• The specific neural mechanisms and codes governing RSG function are not well understood.

Purpose of the Study:

• To investigate the neural circuits and cell types within the RSG responsible for processing distinct behavioral information.
• To elucidate the role of the RSG in spatial orientation and related computations.

Main Methods:

• Optogenetic circuit mapping in mice.
• Analysis of neuronal subtypes, including low-rheobase (LR) and regular-spiking (RS) pyramidal cells.
• Investigation of axonal and dendritic arborization patterns in RSG layer 1.
• Computational modeling of neuronal dynamics.

Main Results:

• A double dissociation was identified, showing parallel processing of spatial and non-spatial inputs in superficial RSG.
• Spatial inputs (anterior thalamus, dorsal subiculum) selectively activate LR pyramidal cells.
• Non-spatial inputs (claustrum, anterior cingulate) preferentially target RS cells.
• LR neurons, through specific synaptic dynamics, can compute head rotation speed from head direction inputs.

Conclusions:

• The RSG utilizes parallel circuits with distinct neuronal subtypes (LR and RS cells) to process disparate information streams.
• Specific sublaminar organization within RSG layer 1 facilitates this parallel processing.
• LR neurons are uniquely positioned to perform spatial orientation computations, such as head rotation speed estimation.