1,721,003 research outputs found
High-density electrophysiological recordings in macaque using a chronically implanted 128-channel passive silicon probe
Full text linkObjective - The analysis of interactions among local populations of neurons in the cerebral cortex (e.g. within cortical microcolumns) requires high resolution and high channel count recordings from chronically implanted laminar microelectrode arrays. The request for high-density recordings of a large number of recording sites can presently only be accomplished by probes realized using complementary metal-oxide-semiconductor (CMOS) technology. In preparation for their use in non-human primates, we aimed for neural probe validation in a head-fixed approach analyzing the long-term recording capability. Approach - We examined chronically implanted silicon-based laminar probes, realized using a CMOS technology in combination with micromachining, to record from the primary visual cortex (V1) of a monkey. We used a passive CMOS probe that had 128 electrodes arranged at a pitch of 22.5 microm in four columns and 32 rows on a slender shank. In order to validate the performance of a dedicated microdrive, the overall dimensions of probe and interface boards were chosen to be compatible with the final active CMOS probe with integrated circuitry. Main results - Using the passive probe, we recorded simultaneously local field potentials (LFP) and spiking multiunit activity (MUA) in V1 of an awake behaving macaque monkey. We found that an insertion through the dura and subsequent readjustments of the chronically implanted neural probe was possible and allowed us to record stable LFPs for more than five months. The quality of MUA degraded within the first month but remained sufficiently high to permit mapping of receptive fields during the full recording period. Significance - We conclude that the passive silicon probe enables semi-chronic recordings of high quality of LFP and MUA for a time span exceeding five months. The new microdrive compatible with a commercial recording chamber successfully demonstrated the readjustment of the probe position while the implemented plug structure effectively reduced brain tissue movement relative to the probe
High-density CMOS neural probes
No full textSilicon neural probes for high-density neural recording have become the preferred tool for a number of electrophysiologists around the world. Even though it has a great promise, the technology is still in its infancy. It has now become possible to integrate high-performance CMOS circuits right on the silicon probes, thus increasing the signal quality and going beyond the geometrical limits posed by the shape of the probe. Here we do a systematic review of various trade-offs associated with designing a monolithic CMOS neural probe and providing examples of some of the state-of-the-art solutions
A 128-channel neural stimulation and recording ASIC for scalable cortical visual prosthesis
No full textThis work was partially funded by the European Union's Horizon 2020 research and innovation program (Grant Agreement number 899287, NeuraViPeR)
Fine-scale mapping of cortical laminar activity during sleep slow oscillations using high-density linear silicon probes
No full textA silicon-based neural probe with densely-packed low-impedance titanium nitride microelectrodes for ultrahigh-resolution in vivo recordings
No full textAn Artificial Iris ASIC with High Voltage Liquid Crystal Driver, 10 nA Light Range Detector and 40 nA Blink Detector for LCD flicker removal
No full textFace recognition for long-term interaction
Full text linkFace recognition is one of the few biometric methods that possess both accuracy and intrusiveness. For this reason it has drawn attention of many researchers and numerous algorithms have been proposed. Various fields such as network security, surveillance benefits from the face recognition because it provides more efficient coding scheme. Since the face recognition is a real world problem and there are cases when not all the input data is not known beforehand. In this project the focus is on the online learning strategy. We implemented online nonparametric discriminant analysis methodology for long-term face recognition problem. The advantage of using NDA over LDA is explained briefly. Besides reviewing the online version of NDA, we propose an optimized version based on 'affective forgetting'. In order to guarantee real-time response, the online learning strategy has been extended with a pruning mechanism which gets rid of the oldest samples. Experimental results on the FRIENDS dataset demonstrated that the performance of classification is not affected by replacing the former samples with new ones
Descripción Verbal de Escenas a partir de Imágenes y su Aplicación para Discapacitados Visuales
No full textTesis (Maestría en Tecnología Avanzada), Instituto Politécnico Nacional, CICATA, Unidad Querétaro, 2017, 1 archivo PDF, (92 páginas). tesis. ipn.m
An artificial iris ASIC with high voltage liquid crystal driver and 10nA light range detector and 40nA blink detector for LCD flicker removal
Full text linkIn a functional eye, the iris controls the pupil diameter to regulate the exposure of the retina. While iris deficiencies such as aniridia or leiomyoma can be mitigated with fixed or adaptive artificial irises [1] and adaptive transparency glasses exist to alleviate this situation, they do not mimic the normal functionality of the natural iris. To address this, a fully encapsulated, self-contained artificial iris embedded in a smart contact lens is proposed. A control ASIC is developed in 0.18 μm 16 V BCD TSMC with typ. 1.9 μw current consumption from 3 V supply voltage at office light condition
- …
