design-fabrication-ultralight-weight-adjustable-multi-electrode

Design and Fabrication of Ultralight Weight, Adjustable Multi-electrode Probes for Electrophysiological Recordings in Mice

The number of physiological investigations in the mouse, mus musculus, has experienced a recent surge, paralleling the growth in methods of genetic ...

Massachusetts Institute of Technology

Understanding how whisker-based tactile information is represented in the nervous system requires quantification of sensory input and observation of neural activity during whisking and whisker touch. Chronic electrophysiological methods have long been available to study neural responses in awake and behaving animals; however, methods to quantify the sensory input on whiskers have not yet been developed. Here we describe an unsupervised algorithm to track whisker movements in high-speed video recordings and to quantify the statistics of the tactile information on whiskers in freely behaving animals during haptic object exploration. The algorithm does not require human identification of whiskers, nor does it assume the shape, location, orientation, length of whiskers, or direction of the whisker movements. The algorithm performs well on temporary loss of whisker visibility and under low-light/low-contrast conditions even with inherent anisotropic noise and non-Gaussian variability in the signal. Using this algorithm, we define the speed [protraction (P), 1,081 +/- 322; retraction (R), 1,564 +/- 549 degrees /s], duration (P, 34 +/- 10; R, 24 +/- 8 ms), amplitude (P = R, 40 +/- 13 degrees ), and frequency (19 +/- 7 Hz) of active whisking in freely behaving mice. We furthermore quantify whisker deflection induced changes in whisking kinematics and calculate the statistics (i.e., speed, amplitude and duration) of whisker touch and finally show that whisker deprivation does not alter whisking kinematics during haptic exploration.

Unsupervised whisker tracking in unrestrained behaving animals.

Electrophysiological recordings from ensembles of neurons in behaving mice are a central tool in the study of neural circuits. Despite the widespread use of chronic electrophysiology, the precise positioning of recording electrodes required for high-quality recordings remains a challenge, especially in behaving mice. The complexity of available drive mechanisms, combined with restrictions on implant weight tolerated by mice, limits current methods to recordings from no more than 4-8 electrodes in a single target area. We developed a highly miniaturized yet simple drive design that can be used to independently position 16 electrodes with up to 64 channels in a package that weighs ~2 g. This advance over current designs is achieved by a novel spring-based drive mechanism that reduces implant weight and complexity. The device is easy to build and accommodates arbitrary spatial arrangements of electrodes. Multiple optical fibers can be integrated into the recording array and independently manipulated in depth. Thus, our novel design enables precise optogenetic control and highly parallel chronic recordings of identified single neurons throughout neural circuits in mice.

Article	Year
Unsupervised whisker tracking in unrestrained behaving animals. Journal of neurophysiology\| PubMed ID: 18463190	2008
The flexDrive: an ultra-light implant for optical control and highly parallel chronic recording of neuronal ensembles in freely moving mice. Frontiers in systems neuroscience\| PubMed ID: 23717267	2013

Jakob Voigts

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