Pathway-like Activation of 3D Neuronal Constructs with an Optical Interface.

Area of Science:

• Neuroscience
• Bioengineering
• Computational Biology

Background:

• Three-dimensional neuronal constructs (organoids, spheroids, tissue mimics) are vital tools for modeling brain function and disease in vitro.
• Existing models often lack interfaces that replicate the feedforward sensory pathway activation characteristic of the intact brain.
• Accurate modeling requires methods to deliver patterned, pathway-like inputs to these 3D neuronal networks.

Purpose of the Study:

• To develop an optical interface for optogenetically stimulating three-dimensional neuronal constructs.
• To mimic sensory pathway-like inputs to cortical neurons within 3D constructs.
• To investigate network responses and computational features evoked by patterned optical stimulation.

Main Methods:

• Cortical neurons were cultured in 3D constructs, with dendrites and axons guided into microchannel-confined bundles.
• Optogenetic stimulation was applied to these neurite bundles using patterned light, simulating distinct sensory inputs.
• Evoked neuronal network responses were assessed using calcium imaging.

Main Results:

• The optical interface successfully delivered distinct input patterns, mimicking sensory pathway activation.
• Neuronal network responses exhibited characteristics of neuronal population coding, including input pattern separability.
• Individual neurons displayed mixed selectivity, a key feature of cortical information processing.

Conclusions:

• This study demonstrates the first pathway-like activation of neuronal networks within 3D constructs using an all-optical interface.
• The developed interface bypasses the need for expensive microelectrode arrays, offering a cost-effective alternative.
• This technology holds potential for advancing research into cortical information processing and the computational effects of neurological disorders.