Imaging excited neurons reveal brain insights
The excitement never stops at SPIE Photonics West and the Neurotechnologies Plenary in January didn’t disappoint. The first talk: “Exciting Insights into Neural Coding with Sculpted Wavefronts,” by New York University’s Shy Shoham, professor of ophthalmology, neuroscience, and physiology, and co-director of the NYU Tech4Health Institute.
He described his lab’s use of holographic optical neural interfaces to explore the brain’s readout of encoded external stimuli. It is the process by which stimulus is presented to the nervous system, converted to activity patterns in the brain, and then the activity pattens are read out to inform behavior. Shoham said it is a process that researchers know little about and that has been the subject of great controversy in neuroscience.
Shoham’s lab has had a longstanding interest in holographic optical neural interfaces, tools they have applied in the olfactory bulb of awake, behaving animals. “We would like to image odor responses and sequences and combine this with stimulation to probe perception and network structure,” he said.
To explore the brain’s readout function, studies that might also inform development of artificial neural networks and deep learning, “We would like to be able to reproduce the features of odor-evoked activity in [mitral] cells, monitor them, and measure how these patterns are interpreted by the mouse to guide its behavior, and do that in an all-optical fashion,” Shoham said.
For their study, mice were trained to detect synthetic 2-photon holographic stimulation patterns, which revealed sensitivity to about 20 neurons and a crucial role for synchrony in neural readout. Different odors, Shoham said, activate different sets of receptors. To stimulate and record, his lab used parallel opto-acoustic and transcranial ultrasound opened precision. It allowed bidirectional neural-interfacing by combining opto-acoustic functional imaging with precisely targeted ultrasonic neuromodulation.
Shy Shoham of New york University discusses his lab’s use of holographic optical neural interfaces at SPIE Photonics West 2022. Credit: Joey Cobbs
Holographic optogenetics confocally unraveled sculpting along with fluorescence guided focused ultrasound enabled real time in situ mapping of the researchers projected excitation patterns and the resulting tissue distortions. Optical shams distinguished between the detection of neural activity of the optically induced off-target artifacts.
“We have developed technologies that allow us to examine the detection of multiphoton stimulation patters in very small amounts of neurons and to use that to probe the read-out mechanisms [in the mouse brain],” Shoham said.
William G. Schulz is Managing Editor of Photonics Focus magazine. A version of this article appeared in the 2022 Photonics West Show Daily.
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