Origin of Consciousness -- Neurophysics

We make "conscious" decisions based on the sensory inputs at given time. These inputs like vision and hearing are transferred to and integrated at somewhere in the cortex unconsciously first. Then after high-level of parallel processing, it comes to consciousness to make a decision, one at a time. The reliability and speed of decision making process are the most critical for survival of the fittest. Arisaka's group is active on several collaborations on UCLA campus to address a few key issues on consciousness.

Motion of Inner Hair Cells

Our ability of hearing is absolutely remarkable; the sound sensor, inner heir cells are sensitive to motions less than 1 nm which is smaller than Brownian motion. How can our listening achieve such an incredible sensitivity? This is the question that Prof. Dolores Bozovic at Department of Physics and Astronomy, UCLA, is trying to solve by modeling physical principles. Arisaka has been collaborating with her group since 2006. We have set up a ultra high-speed CMOS camera (SA-1) by Photron in her lab.

This movie shows the motion of inner heir cell of a bull frog under spontaneous oscillation (without a membrane on top). The top-left shows raw images and the bottom-left shows the processed image, where the bright red indicates increasing signals in time and the bright green indicate decreasing signals. On the right, the central locations of five hair cells (A, B, C, D, E) are traced every 1 msec with an accuracy of a few nm. This is the very first high-speed image of this kind. Below is a list of recent publications with Prof. Dolores Bozovic.

Correlated movement of hair bundles coupled to the otolithic membrane in the bullfrog sacculus

Strimbu CE, Ramunno-Johnson D, Fredrickson L, Arisaka K, Bozovic D. Hear Res. 2009 Oct;256(1-2):58-63

Distribution of frequencies of spontaneous oscillations in hair cells of the bullfrog sacculus

Ramunno-Johnson D, Strimbu CE, Fredrickson L, Arisaka K, Bozovic D., Biophys J. 2009 Feb;96(3):1159-68

Early Development of Cortex

Prof. Carlos Portera-Gailliau at Department of Neurology, UCLA, is investigating how cortical circuits are assembled during early development. A new technique of two photon excitation (2PE) microscope allows to observe deep inside of mouse's cortex. Unfortunately the conventional 2PE is rater slow (~one frame per second). To observe the action potentials of multiple neurons in real time, Adrian Cheng (Arisaka's PhD student) and members form Portera's group have developed the world fastest 2PE microscope, using multiple beam arrangement with HAPD readout.

The movie above illustrates the principle of the Spatiotemporal Multiplexing two photon microscope (STEM). The result was published at Nature Method below:

Simultaneous two-photon calcium imaging at different depths with spatiotemporal multiplexing

Cheng A, Gonçalves JT, Golshani P, Arisaka K, Portera-Cailliau C., Nat Methods. 2011 Feb;8(2):139-42

Perception of Space - Virtual Reality Experiment

Prof. Mayank Mehta's Group at Department of Physics and Astronomy, UCLA, has been focusing on recognition of space in a Hippocampus. Together with Mehta's team, Arisaka's group (PhD students, Daniel Aharoni and Bernard Willers) has developed Virtual Reality (VR) systems for rats. With this system, a rat navigates in a virtual environment by means of vision and/or sound, looking for the locations of awards (sugar water). The VR system is essential to create a controlled environment for behavior study.

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