scholarly journals Temporal Processing Across Multiple Topographic Maps in the Electrosensory System

2008 ◽  
Vol 100 (2) ◽  
pp. 852-867 ◽  
Author(s):  
Rüdiger Krahe ◽  
Joseph Bastian ◽  
Maurice J. Chacron
Keyword(s):  
Frequency Tuning ◽  
Phase Locking ◽  
The Body ◽  
The Other ◽  
Stimulus Class ◽  
Cellular Mechanisms ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Sensory Stimuli ◽  
Low Pass

Multiple topographic representations of sensory space are common in the nervous system and presumably allow organisms to separately process particular features of incoming sensory stimuli that vary widely in their attributes. We compared the response properties of sensory neurons within three maps of the body surface that are arranged strictly in parallel to two classes of stimuli that mimic prey and conspecifics, respectively. We used information-theoretic approaches and measures of phase locking to quantify neuronal responses. Our results show that frequency tuning in one of the three maps does not depend on stimulus class. This map acts as a low-pass filter under both conditions. A previously described stimulus-class-dependent switch in frequency tuning is shown to occur in the other two maps. Only a fraction of the information encoded by all neurons could be recovered through a linear decoder. Particularly striking were low-pass neurons the information of which in the high-frequency range could not be decoded linearly. We then explored whether intrinsic cellular mechanisms could partially account for the differences in frequency tuning across maps. Injection of a Ca2+ chelator had no effect in the map with low-pass characteristics. However, injection of the same Ca2+ chelator in the other two maps switched the tuning of neurons from band-pass/high-pass to low-pass. These results show that Ca2+-dependent processes play an important part in determining the functional roles of different sensory maps and thus shed light on the evolution of this important feature of the vertebrate brain.

scholarly journals A Novel Image Restoration Method based on Iterative Algorithm

2021 ◽  
Vol 15 ◽  
pp. 519-524
Author(s):  
Saiyan Wu ◽  
Hui Yang
Keyword(s):  
Iterative Algorithm ◽  
Blind Deconvolution ◽  
Convergence Result ◽  
The Other ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Blind Image Deblurring ◽  
Low Pass ◽  
Blind Restoration ◽  
Restoration Method

In the paper, we proposed a new iterative algorithm and use a entirely new iterative factor. Firstly, we adopt the Exp function in the iterative factor, because we want each iterative result preserves the nonnegative constraint; Secondly, we make the iterative factor in a reciprocal form ,this way can produce two advantages, one is we can get a more stable and continuous results after each iteration; the other is we can achieve this algorithm in hardware more convenient. Thirdly, we add a low-pass filter and the edge of the scale in the iterative factor, this way we can get a better result, the image SNR is higher and the MSE is lower. Meanwhile for the image sequence, we adopt the two-step iterative algorithm. The result shows the algorithm own the faster convergence speed and the better convergence result. Different from the other algorithm for blind restoration, although we should select the parameter in the starting of the algorithm, the algorithm doesn’t sensitive for the parameter. So the algorithm possesses very strong adaptability for the blind image deblurring. So a novel algorithm based on an iterative and nonnegative algorithm was proposed to perform blind deconvolution.

scholarly journals Accelerometer-Based Automated Counting of Ten Exercises without Exercise-Specific Training or Tuning

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Samuel Zelman ◽  
Michael Dow ◽  
Thasina Tabashum ◽  
Ting Xiao ◽  
Mark V. Albert
Keyword(s):  
Physical Therapy ◽  
Wearable Sensors ◽  
Training And Development ◽  
The Body ◽  
Activity Tracking ◽  
Counting System ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Threshold Crossing ◽  
Low Pass

Measuring physical activity using wearable sensors is essential for quantifying adherence to exercise regiments in clinical research and motivating individuals to continue exercising. An important aspect of wearable activity tracking is counting particular movements. One limitation of many previous models is the need to design the counting for a specific exercise. However, during physical therapy, some movements are unique to the patient and also valuable to track. To address this, we create an automatic repetition counting system that is flexible enough to measure multiple distinct and repeating movements during physical therapy without being trained on the specific motion. Accelerometers, using smartphones, were attached to the body or held by participants to track repetitive motions during different exercises. 18 participants completed a series of 10 exercises for 30 seconds, including arm circles, bicep curls, bridges, sit-ups, elbow extensions, leg lifts, lunges, push-ups, squats, and upper trunk rotations. To count the repetitions of each exercise, we apply three analysis techniques: (a) threshold crossing, (b) threshold crossing with a low-pass filter, and (c) Fourier transform. The results demonstrate that arm circles and push-ups can be tracked well, while less periodic and irregular motions such as upper trunk rotations are more difficult. Overall, threshold crossing with low-pass filtering achieves the best performance among these methods. We conclude that the proposed automatic counting system is capable of tracking exercise repetition without prior training and development for that activity.

A Very Linear Low-Pass Filter with Automatic Frequency Tuning

2013 ◽  
Vol 21 (1) ◽  
pp. 182-187 ◽  
Author(s):  
J. Galan ◽  
M. Pedro ◽  
T. Sanchez-Rodriguez ◽  
F. Munoz ◽  
R. G. Carvajal ◽  
...  
Keyword(s):  
Frequency Tuning ◽  
Automatic Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Automatic Frequency Tuning

scholarly journals Temporal Modulation Transfer Functions in Cat Primary Auditory Cortex: Separating Stimulus Effects From Neural Mechanisms

2002 ◽  
Vol 87 (1) ◽  
pp. 305-321 ◽  
Author(s):  
Jos J. Eggermont
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Transfer Functions ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Modulation Transfer ◽  
Temporal Modulation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass

We present here a comparison between the local field potentials (LFP) and multiunit (MU) responses, comprising 401 single units, in primary auditory cortex (AI) of 31 cats to periodic click trains, gamma-tone and time-reversed gamma-tone trains, AM noise, AM tones, and frequency-modulated (FM) tones. In a large number of cases, the response to all six stimuli was obtained for the same neurons. We investigate whether cortical neurons are likely to respond to all types of repetitive transients and modulated stimuli and whether a dependence on modulating waveform, or tone or noise carrier, exists. In 97% of the recordings, a temporal modulation transfer function (tMTF) for MU activity was obtained for gamma-tone trains, in 92% for periodic click trains, in 83% for time-reversed gamma-tone trains, in 82% for AM noise, in 71% for FM tones, and only in 53% for AM tones. In 31% of the cases, the units responded to all six stimuli in an envelope-following way. These particular units had significantly larger onset responses to each stimulus compared with all other units. The overall response distribution shows the preference of AI units for stimuli with short rise times such as clicks and gamma tones. It also shows a clear asymmetry in the ability to respond to AM noise and AM tones and points to a strong effect of the frequency content of the carrier on the subcortical processing of AM stimuli. Yet all temporal response properties were independent of characteristic frequency and frequency-tuning curve bandwidth. We show that the observed differences in the tMTFs for different stimuli are to a large extent produced by the different degree of phase locking of the neuronal firings to the envelope of the first stimulus in the train or first modulation period. A normalization procedure, based on these synchronization differences, unified the tMTFs for all stimuli except clicks and allowed the identification of a largely stimulus-invariant, low-pass temporal filter function that most likely reflects the properties of synaptic depression and facilitation. For nonclick stimuli, the low-pass filter has a cutoff frequency of ∼10 Hz and a slope of ∼6 dB/octave. For nonclick stimuli, there was a systematic difference between the vector strength for LFPs and MU activity that can likely be attributed to postactivation suppression mechanisms.

LOW-POWER, LOW-VOLTAGE, DUAL-OUTPUT, SECOND GENERATION CURRENT CONVEYOR AND ITS APPLICATION IN LOW-PASS FILTER DESIGN

2013 ◽  
Vol 22 (06) ◽  
pp. 1350044 ◽  
Author(s):  
MOHAMMAD HOSSEIN MAGHAMI ◽  
AMIR M. SODAGAR
Keyword(s):  
Second Generation ◽  
Current Conveyor ◽  
The Body ◽  
Total Power ◽  
Cmos Process ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Silicon Area ◽  
Total Power Consumption ◽  
Low Pass

A new simple dual-output second generation current conveyor (DO-CCII) circuit is proposed. Designed in a standard 0.5-μm CMOS process, the circuit operates at ±1.5 V supply voltages with a total power consumption of 106 nW. Main characteristics of the proposed DO-CCII are its simplicity, small silicon area consumption, and not suffering from the body effect of MOS transistors. The proposed circuit is employed to implement a first-order low-pass filter with upper -3 dB cut-off frequency of as low as 3.2 Hz.

Consonant Confusions Associated with Hearing Loss above 2000 Hz

1974 ◽  
Vol 17 (4) ◽  
pp. 669-681 ◽  
Author(s):  
Annabelle E. Sher ◽  
Elmer Owens
Keyword(s):  
Normal Hearing ◽  
Initial Position ◽  
The Other ◽  
Final Position ◽  
High Tone ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Speech Stimuli ◽  
Low Pass ◽  
Manner Of Articulation

A 100-item test for the identification of phonemes was presented to two groups of listeners. One group consisted of 35 patients with normal hearing up to 2000 Hz accompanied by a high-tone loss. The other group consisted of persons with normal hearing who heard the speech stimuli presented through a low-pass filter with a cutoff at 2040 Hz. There were no significant differences between the two groups in overall scores, in probabilities of error for individual phonemes, or in the kinds of error substitutions made. Findings were as follows: (1) the overall scores indicated difficulty in phonemic identification; (2) the phonemes contributing to this difficulty were primarily /b, p, t, k, s, θ/ in both the initial and final positions, /t∫, ∫, f, dƷ, z, v/ in the final position only, and /d/ in the initial position only; and (3) the phonemes substituted for the stimulus phonemes in the initial position were the same in manner of articulation as the stimulus phoneme, and typically only one confusion occurred per stimulus phoneme. The phonemes substituted for the stimulus phonemes in the final position were not necessarily the same in manner of articulation as the stimulus phoneme, and more than one confusion generally occurred for each stimulus phoneme.

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