scholarly journals Author response: Front-end Weber-Fechner gain control enhances the fidelity of combinatorial odor coding

2019 ◽  
Author(s):  
Nirag Kadakia ◽  
Thierry Emonet
Keyword(s):  
Gain Control ◽  
Author Response ◽  
Odor Coding ◽  
Front End

scholarly journals Front-end Weber-Fechner gain control enhances the fidelity of combinatorial odor coding

2018 ◽  
Author(s):  
Nirag Kadakia ◽  
Thierry Emonet
Keyword(s):  
Scaling Law ◽  
Gain Control ◽  
Vital Role ◽  
Biophysical Model ◽  
Natural Environments ◽  
Odor Coding ◽  
Tuning Curves ◽  
Front End ◽  
Receptor Neurons ◽  
Odor Signals

Odor identity is encoded by spatiotemporal patterns of activity in olfactory receptor neurons (ORNs). In natural environments, the intensity and timescales of odor signals can span several orders of magnitude, and odors can mix with one another, potentially scrambling the combinatorial code mapping neural activity to odor identity. Recent studies have shown that inDrosophila melanogasterthe ORNs that express the olfactory co-receptor Orco scale their gain inversely with mean odor concentration according to the Weber-Fechner Law of psychophysics. Here we use a minimal biophysical model of signal transduction, ORN firing, and signal decoding to investigate the implications of this front-end scaling law for the neural representations of odor identity. We find that Weber-Fechner scaling enhances coding capacity and promotes the reconstruction of odor identity from dynamic odor signals, even in the presence of confounding background odors and rapid intensity fluctuations. We show that these enhancements are further aided by downstream transformations in the antennal lobe and mushroom body. Thus, despite the broad overlap between individual ORN tuning curves, a mechanism of front-end adaptation, when endowed with Weber-Fechner scaling, may play a vital role in preserving representations of odor identity in naturalistic odor landscapes.

scholarly journals Front-end Weber-Fechner gain control enhances the fidelity of combinatorial odor coding

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Nirag Kadakia ◽  
Thierry Emonet
Keyword(s):  
Gain Control ◽  
Feedback Mechanism ◽  
Olfactory Receptor Neurons ◽  
Receptor Sensitivity ◽  
Adaptation Mechanism ◽  
Odor Coding ◽  
Front End ◽  
Receptor Neurons ◽  
Odor Classification ◽  
Odor Signals

We showed previously (Gorur-Shandilya et al., 2017) that Drosophila olfactory receptor neurons (ORNs) expressing the co-receptor Orco scale their gain inversely with mean odor intensity according to Weber-Fechner’s law. Here, we show that this front-end adaptation promotes the reconstruction of odor identity from dynamic odor signals, even in the presence of confounding background odors and rapid intensity fluctuations. These enhancements are further aided by known downstream transformations in the antennal lobe and mushroom body. Our results, which are applicable to various odor classification and reconstruction schemes, stem from the fact that this adaptation mechanism is not intrinsic to the identity of the receptor involved. Instead, a feedback mechanism adjusts receptor sensitivity based on the activity of the receptor-Orco complex, according to Weber-Fechner’s law. Thus, a common scaling of the gain across Orco-expressing ORNs may be a key feature of ORN adaptation that helps preserve combinatorial odor codes in naturalistic landscapes.

scholarly journals 14.85 µW Analog Front-End for Photoplethysmography Acquisition with 142-dBΩ Gain and 64.2-pArms Noise

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 512
Author(s):  
Binghui Lin ◽  
Mohamed Atef ◽  
Guoxing Wang
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Low Noise ◽  
Total Power ◽  
Cmos Process ◽  
Control Block ◽  
Silicon Area ◽  
Front End ◽  
Analog Front End

A low-power, high-gain, and low-noise analog front-end (AFE) for wearable photoplethysmography (PPG) acquisition systems is designed and fabricated in a 0.35 μm CMOS process. A high transimpedance gain of 142 dBΩ and a low input-referred noise of only 64.2 pArms was achieved. A Sub-Hz filter was integrated using a pseudo resistor, resulting in a small silicon area. To mitigate the saturation problem caused by background light (BGL), a BGL cancellation loop and a new simple automatic gain control block are used to enhance the dynamic range and improve the linearity of the AFE. The measurement results show that a DC photocurrent component up-to-10 μA can be rejected and the PPG output swing can reach 1.42 Vpp at THD < 1%. The chip consumes a total power of 14.85 μW using a single 3.3-V power supply. In this work, the small area and efficiently integrated blocks were used to implement the PPG AFE and the silicon area is minimized to 0.8 mm × 0.8 mm.

Design of Local Oscillator Based on DDS of High Performance Short-Wave Receiver

2013 ◽  
Vol 834-836 ◽  
pp. 1140-1144 ◽  
Author(s):  
Yong Tai Chen ◽  
Chang Jing Sun ◽  
Bin Zang ◽  
Long Cheng ◽  
Jing Tang ◽  
...  
Keyword(s):  
High Performance ◽  
Gain Control ◽  
Local Oscillator ◽  
Short Wave ◽  
Frequency Multiplier ◽  
Test Results ◽  
Frequency Range ◽  
Front End ◽  
Tracking Filter ◽  
Spurious Signals

Phase noise and spurious signals of local oscillator will affect the performance of short-wave receiver. The structure of receiver's front-end part based on DDS is introduced to realize a high-performance local oscillator of short-wave receiver. Then measures were taken to improve the LO's performance, including using external directly frequency multiplier as DDS' clock to improve the purity of frequency spectrum, tracking filter to degrade harmonics and gain control circuit to remain constant amplitude in the desired frequency range. At last, test results show that the above-mentioned measures improve the receiver's performance.

Design and Implementation of RF Front-End for GPS Receiver Utilizing Discrete Components

2010 ◽  
Vol 44-47 ◽  
pp. 1330-1334
Author(s):  
Ji Cheng Ding ◽  
Lin Zhao ◽  
Shuai He Gao ◽  
Li Xiong Xia ◽  
Jun Ling Zhang
Keyword(s):  
Automatic Gain Control ◽  
Gain Control ◽  
Intermediate Frequency ◽  
Hardware Platform ◽  
Filter Bandwidth ◽  
Front End ◽  
Rf Front End ◽  
If Digitalization ◽  
Band Module ◽  
Base Band

A GPS radio frequency (RF) front-end based on discrete components is designed and implemented in this paper. Research on the structures of RF front-ends for GPS receivers, and an intermediate frequency (IF) digitalization front-end is expounded in details. Analyze the design considerations of filter bandwidth, sampling frequency, quantization bits, and automatic gain control, which would effect on the whole performance of RF front-end. Then, appropriate discrete components are selected, and a low IF RF front-end hardware platform with orthogonal structure is implemented. Test results indicate that the hardware platform combined with base-band module could effectively complete signals acquisition.

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