Head-mountable high speed camera for optical neural recording

Abstract

We report a head-mountable CMOS camera for recording rapid neuronal activity in freely-moving rodents using fluorescent activity reporters. This small, lightweight camera is capable of detecting small changes in light intensity (0.2% ΔI/I) at 500 fps. The camera has a resolution of 32 × 32, sensitivity of 0.62 V/lux·s, conversion gain of 0.52 μV/e- and well capacity of 2.1 Me-. The camera, containing intensity offset subtraction circuitry within the imaging chip, is part of a miniaturized epi-fluorescent microscope and represents a first generation, mobile scientific-grade, physiology imaging camera.

Design Constraints for Mobile, High-Speed Fluorescence Brain Imaging in Awake Animals

“…All clock and control signals are generated by this FPGA board. The full specifications and performance of this sensor is presented in a separate communication [18]. …”

A second-generation imaging system for freely moving animals

“…This work build upon our previous works in designing a small, head-mountable imaging system for awake and behaving animals [6], [7]. Previously, we designed a 32 x 32 pixel image sensor with an analog output.…”

“…One improvement over the old design [6], [7] is a better implementation of the on-chip dF calculation circuit. Having such a circuit can cut down the data resolution by half, thus reducing the data throughput rate.…”

Implantable CMOS Imaging Devices

“…To overcome this difficulty, three types of imaging devices have been developed: a fiber endoscope [25][26][27][28][29], a head-mountable device [28][29][30], and a brain-implantable device [31][32][33][34][35][36], as shown in Figure 10.20. In the following sections, these devices are introduced, and the brain-implantable device is described in detail.…”

“…Recently, a miniaturized microscope system used with a CMOS image sensor, which is also mounted on a mouse head [28][29][30][31], has been developed and was demonstrated to be effective for a freely moving mouse. The head-mountable device is composed of lenses, a CMOS image sensor, and an LED for the excitation light source, as shown in Figure 10.22b.…”