A Novel Confocal Laser Scanning Microscope for Functional Recording of Fast Neuronal Activity

Baylor College of Medicine
posted on 07/23/2008

Due to cellular complexity, studying fast signaling in neurons is often limited by: 1). the number of sites that can be simultaneously probed with conventional tools, such as patch pipettes, and 2). the recording speed of imaging tools, such as confocal or multiphoton microscopy. To overcome these spatiotemporal limitations, the developers created an addressable confocal microscope that permits concurrent optical recordings from multiple user-selected sites of interest at high frame rates.

Their system utilizes acousto-optic deflectors (AODs) for rapid positioning of a focused laser beam and a digital micromirror device (DMD) for addressable spatial filtering to achieve confocality. A registration algorithm synchronizes the AODs and DMD such that point illumination and point detection are always colocalized in conjugate image planes. The current system has an adjustable spatial resolution of approximately 0.5 to 1 um. Furthermore, they show that recordings can be made at an aggregate sampling rate of approximately 40 kHz.

Advantages

The system is capable of optical sectioning; this property is used to create 3-D reconstructions of fluorescently labeled test specimens and visualize neurons in brain tissue. Additionally, the system can be used to simultaneously record parameters of neuronal activity at several sites in living neurons such as intracellular calcium transients.

Innovation Details

File Number: BLG 03-056

Web site: http://www.bcm.edu/blg/showned.cfm?03-056

Other Information:

The developers have been focusing their efforts on the DMD aspect of the apparatus. Currently, they can make fast confocal recordings at a rate that is suitable for recording neuronal activity at several SOIs. The effective frame rate for an arbitrary number of user-selected SOIs is given by:
Frame rate = 25,000 Hz x 1/SOIs (for SOIs>1).

For the limiting case of one SOI, the illumination does not have to be scanned so the fluorescence collection is only dependent of the speed of analog-to-digital conversion of the system.

The system is capable of true random-access scanning so the distance between any two consecutive SOIs is of no consequence. This allows the system to adapt between recording from a few SOIs at a fast frame rate, or at many SOIs at slower frame rates.

IP Protection

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This innovation currently is not available for online licensing. Please contact Stewart Davis at Baylor College of Medicine for more information.

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