scholarly journals Slow Firing Single Units Are Essential for Optimal Decoding of Silent Speech

2022 ◽  
Author(s):  
Philip Kennedy ◽  
A. Ganesh ◽  
A.J. Cervantes
Keyword(s):  
Single Unit ◽  
Essential Feature ◽  
Single Units ◽  
Loss Of Function ◽  
Neural Signals ◽  
Motor Speech ◽  
Long Duration ◽  
Decoding Accuracy ◽  
Optimal Decoding ◽  
Silent Speech

Abstract Summary The motivation of someone who is locked-in, that is, paralyzed and mute, is to find relief for their loss of function. The data presented in this report is part of an attempt to restore one of those lost functions, namely, speech. An essential feature of the development of a speech prosthetic is optimal decoding of patterns of recorded neural signals during silent or covert speech, that is, speaking ‘inside the head’ with no audible output due to the paralysis of the articulators. The aim of this paper is to illustrate the importance of both fast and slow single unit firings recorded from an individual with locked-in syndrome and from an intact participant speaking silently. Long duration electrodes were implanted in the motor speech cortex for up to 13 years in the locked-in participant. The data herein provide evidence that slow firing single units are essential for optimal decoding accuracy. Additional evidence indicates that slow firing single units can be conditioned in the locked-in participant five years after implantation, further supporting their role in decoding.

Construction of Power Stations Designed and Built as Single Units

1983 ◽  
Vol 197 (1) ◽  
pp. 1-26 ◽  
Author(s):  
H Masding
Keyword(s):  
Power Plant ◽  
Single Unit ◽  
Capital Cost ◽  
Single Units ◽  
Construction Time ◽  
Power Stations ◽  
Engineering Costs ◽  
Running Cost ◽  
The Uk

This paper sets out an assessment of the value and practicality of the construction of fossil fired generating plant designed and built as single units and includes a proposal for the design and layout of a single unit designed to maximize the benefits derived from this concept. The conclusion is that an acceptable design of power plant, based on the construction of single 600 MW units, can be developed for the UK system which could prove to be advantageous in construction time, in capital cost and in running cost. The layout applies equally effectively to large ‘green field’ sites or for replanting existing stations; in addition, the plant can be replicated in detail and thereby reduce design and engineering costs. Finally the layout can also be applied in principle to smaller units for overseas utilities as required by their system developments.

scholarly journals Arterial baroreflex regulation of muscle sympathetic single-unit activity in men: influence of resting blood pressure

2020 ◽  
Vol 318 (4) ◽  
pp. H937-H946 ◽  
Author(s):  
Anthony V. Incognito ◽  
Milena Samora ◽  
Andrew D. Shepherd ◽  
Roberta A. Cartafina ◽  
Gabriel M. N. Guimarães ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Single Unit ◽  
Cardiac Cycle ◽  
Single Units ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Pharmacological Manipulation ◽  
Operating Range ◽  
Resting Blood Pressure ◽  
Spike Firing

The arterial baroreflex has dominant control over multiunit muscle sympathetic nerve activity (MSNA) burst occurrence, but whether this extends to all single units or is influenced by resting blood pressure status is unclear. In 22 men (32 ± 8 yr), we assessed 68 MSNA single units during sequential bolus injections of nitroprusside and phenylephrine (modified Oxford). Sympathetic baroreflex sensitivity (sBRS) was quantified as the weighted negative linear regression slope between diastolic blood pressure (DBP) and single-unit spike firing probability and multiple spike firing. Strong negative linear relationships ( r ≥ −0.50) between DBP and spike firing probability were observed in 63/68 (93%) single units (−2.27 ± 1.27%·cardiac cycle−1·mmHg−1 [operating range, 18 ± 8 mmHg]). In contrast, only 45/68 (66%) single units had strong DBP-multiple spike firing relationships (−0.13 ± 0.18 spikes·cardiac cycle−1·mmHg−1 [operating range, 14 ± 7 mmHg]). Participants with higher resting DBP (65 ± 3 vs. 77 ± 3 mmHg, P < 0.001) had similar spike firing probability sBRS (low vs. high, −2.08 ± 1.08 vs. −2.46 ± 1.42%·cardiac cycle−1·mmHg−1, P = 0.33), but a smaller sBRS operating range (20 ± 6 vs. 16 ± 9 mmHg, P = 0.01; 86 ± 24 vs. 52 ± 25% of total range, P < 0.001) and a higher proportion of single units without arterial baroreflex control outside this range [6/31 (19%) vs. 21/32 (66%), P < 0.001]. Participants with higher resting DBP also had fewer single units with arterial baroreflex control of multiple spike firing (79 vs. 53%, P = 0.04). The majority of MSNA single units demonstrate strong arterial baroreflex control over spike firing probability during pharmacological manipulation of blood pressure. Changes in single-unit sBRS operating range and control of multiple spike firing may represent altered sympathetic recruitment patterns associated with the early development of hypertension. NEW & NOTEWORTHY Muscle sympathetic single units can be differentially controlled during stress. In contrast, we demonstrate that 93% of single units maintain strong arterial baroreflex control during pharmacological manipulation of blood pressure. Interestingly, the operating range and proportion of single units that lose arterial baroreflex control outside of this range are influenced by resting blood pressure levels. Altered single unit, but not multiunit, arterial baroreflex control may represent changes in sympathetic recruitment patterns in early stage development of hypertension.

SYNCHRONOUS CHAOS IN HIGH-DIMENSIONAL MODULAR NEURAL NETWORKS

1996 ◽  
Vol 06 (11) ◽  
pp. 2055-2067 ◽  
Author(s):  
THOMAS WENNEKERS ◽  
FRANK PASEMANN
Keyword(s):  
Neural Networks ◽  
Single Unit ◽  
System Size ◽  
Single Units ◽  
High Dimensional ◽  
Coexisting Attractors ◽  
Modular Neural Networks ◽  
Coupled Maps ◽  
Low Dimensional ◽  
The Relationship

The relationship between certain types of high-dimensional neural networks and low-dimensional prototypical equations (neuromodules) is investigated. The high-dimensional systems consist of finitely many pools containing identical, dissipative and nonlinear single-units operating in discrete time. Under the assumption of random connections inside and between pools, the system can be reduced to a set of only a few equations, which — asymptotically in time and system size — describe the behavior of every single unit arbitrarily well. This result can be viewed as synchronization of the single units in each pool. It is stated as a theorem on systems of nonlinear coupled maps, which gives explicit conditions on the single unit dynamics and the nature of the random connections. As an application we compare a 2-pool network with the corresponding two-dimensional dynamics. The bifurcation diagrams of both systems become very similar even for moderate system size (N=50) and large disorder in the connection strengths (50% of mean), despite the fact, that the systems exhibit fairly complex behavior (quasiperiodicity, chaos, coexisting attractors).

Spatiotemporal firing patterns in the frontal cortex of behaving monkeys

1993 ◽  
Vol 70 (4) ◽  
pp. 1629-1638 ◽  
Author(s):  
M. Abeles ◽  
H. Bergman ◽  
E. Margalit ◽  
E. Vaadia
Keyword(s):  
Firing Rate ◽  
Single Unit ◽  
Timing Jitter ◽  
Spatiotemporal Patterns ◽  
Single Units ◽  
Firing Patterns ◽  
Independent Test ◽  
Chance Events ◽  
Behaving Monkeys ◽  
Repeating Patterns

1. Activity of up to 10 single units was recorded in parallel from frontal areas of behaving monkeys. 2. Spatiotemporal firing patterns were revealed by a method that detects all excessively repeating patterns regardless of their complexity or single-unit composition. 3. Excess of repeating patterns was found in 30-60% of the cases examined when timing jitter of 1-3 ms was allowed. 4. An independent test refuted the hypothesis that these patterns represented chance events. 5. In a given behavioral condition there were usually many different patterns, each repeating several times, and not one (or a few) pattern repeating many times. 6. In 13 out of 20 cases, when a single unit elevated its firing rate in association with an external event beyond 40/s, most of the spikes within that period were associated with excessively repeating spatiotemporal patterns. 7. Of 157 types of patterns whose excess was most marked, 107 were composed of spikes from one single unit, 45 of the patterns contained spikes from two single units, and only one was composed of spikes from three different single units. 8. These properties suggest that the patterns were generated by reverberations in a synfire mode within self-exciting cell assemblies.

Microneurographic evidence in healthy middle-aged humans for a sympathoexcitatory reflex activated by atrial pressure

2013 ◽  
Vol 305 (6) ◽  
pp. H931-H938 ◽  
Author(s):  
Philip J. Millar ◽  
Hisayoshi Murai ◽  
Beverley L. Morris ◽  
John S. Floras
Keyword(s):  
Single Unit ◽  
Sympathetic Neurons ◽  
Muscle Sympathetic Nerve Activity ◽  
Venous Pressure ◽  
Atrial Pressure ◽  
Single Units ◽  
Positive Pressure ◽  
Lower Body ◽  
Middle Aged ◽  
Healthy Humans

Atrial mechanoreceptors, stimulated by increased pressure or volume, elicit in healthy humans a net sympathoinhibitory response. The co-existence of an atrial reflex eliciting muscle sympathoexcitation has been postulated but undetected by conventional multi-unit muscle sympathetic nerve activity (MSNA). We hypothesized that in response to a selective increase in atrial pressure, single-unit MSNA would reveal a subpopulation of efferent sympathetic neurons with firing patterns opposite to the integrated multi-unit MSNA envelope. Multi- and single-unit MSNA recordings were acquired in eight healthy middle-aged subjects (age, 57 ± 8 years; body mass index, 25 ± 2 kg/m2) submitted to selective decreases or increases in atrial pressure by nonhypotensive lower body negative pressure (LBNP; −10 mmHg) or nonhypertensive lower body positive pressure (LBPP; +10 mmHg), respectively. Single-unit MSNA firing responses were classified as anticipated if spike frequency and incidence increased with LBNP or decreased with LBPP and paradoxical if they decreased with LBNP or increased with LBPP. LBNP decreased (3.2 ± 2.8 to 1.4 ± 3.1 mmHg, P < 0.01) and LBPP increased (3.3 ± 2.7 to 4.9 ± 2.8 mmHg, P < 0.01) estimated central venous pressure without affecting stroke volume, systemic pressure, or resistance. Multi-unit MSNA increased with LBNP (31 ± 17 to 38 ± 19 bursts/min, P < 0.01) and diminished with LBPP (33 ± 15 to 28 ± 15 bursts/min, P < 0.01). Of 21 single-units identified, 76% exhibited firing responses to both LBNP and LBPP concordant with multi-unit MSNA, whereas 24% demonstrated discordant or paradoxical responses. The detection of two subpopulations of single-units within the multi-unit MSNA recording, exhibiting opposite firing characteristics, establishes the first evidence in humans for the existence of an excitatory cardiac-muscle sympathetic reflex activated by increasing atrial pressure.

scholarly journals De novo FZR1 loss-of-function variants cause developmental and epileptic encephalopathies including Myoclonic Atonic Epilepsy

2021 ◽  
Author(s):  
Sathiya N. Manivannan ◽  
Jolien Roovers ◽  
Noor Smal ◽  
Candace T. Myers ◽  
Dilsad Turkdogan ◽  
...  
Keyword(s):  
De Novo ◽  
Statistical Tests ◽  
Essential Feature ◽  
Missense Variant ◽  
Anaphase Promoting Complex ◽  
Loss Of Function ◽  
Childhood Onset ◽  
Epileptic Encephalopathies ◽  
Missense Variants ◽  
Generalized Epilepsy

FZR1, which encodes the Cdh1 subunit of the Anaphase Promoting Complex, plays an important role in neurodevelopment, both through the control of the cell cycle and through its multiple functions in post-mitotic neurons. In this study, the evaluation of 250 unrelated patients with developmental epileptic encephalopathies (DEE) and a connection on GeneMatcher led to the identification of three de novo missense variants in FZR1. Two variants led to the same amino acid change. All individuals had a DEE with childhood-onset generalized epilepsy, intellectual disability, mild ataxia, and normal head circumference. Two individuals were diagnosed with the DEE subtype Myoclonic Atonic Epilepsy (MAE). We provide gene burden testing using two independent statistical tests to support FZR1 association with DEE. Further, we provide functional evidence that the missense variants are loss-of-function (LOF) alleles using Drosophila neurodevelopment assays. Using three fly mutant alleles of the Drosophila homolog fzr and overexpression studies, we show that patient variants do not support proper neurodevelopment. Along with a recent report of a patient with neonatal-onset DEE with microcephaly who also carries a de novo FZR1 missense variant, our study consolidates the relationship between FZR1 and DEE, and expands the associated phenotype. We conclude that heterozygous LOF of FZR1 leads to DEE associated with a spectrum of neonatal to childhood-onset seizure types, developmental delay, and mild ataxia. Microcephaly can be present but is not an essential feature of FZR1-encephalopathy. In summary, our approach of targeted sequencing using novel gene candidates and functional testing in Drosophila will help solve undiagnosed MAE/DEE cases.

Single Units and Sensation: 25 Years on

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 230-230
Author(s):  
B Lee
Keyword(s):  
Visual System ◽  
Single Unit ◽  
Single Units ◽  
Single Unit Recording ◽  
Unit Recording ◽  
Visual Neuroscience ◽  
Neurophysiological Data ◽  
20Th Anniversary ◽  
Single Unit Recordings ◽  
Perceptual Psychology

In 1972 Horace Barlow (“Single units and sensation: a neuron doctrine for perceptual psychology?” Perception1 371 – 394) proposed a set of dogmas to guide vision scientists in interpreting neurophysiological data. The 20th anniversary of ECVP is an appropriate occasion to ask if single-unit recordings have really helped us understand the visual system. The answer may be affirmative, but interpreting single-unit data has proved to be much more of a challenge than was anticipated in that early and optimistic era of single-unit recording. I review data from retinal and cortical experiments to illustrate this thesis, and ask if Barlow's dogmas are still relevant to current visual neuroscience.

scholarly journals Population Responses Represent Vocalization Identity, Intensity, and Signal-to-Noise Ratio in Primary Auditory Cortex

2019 ◽  
Author(s):  
Ruiye Ni ◽  
David A. Bender ◽  
Dennis L. Barbour
Keyword(s):  
Auditory Cortex ◽  
Single Unit ◽  
Temporal Dynamics ◽  
Population Analysis ◽  
Primary Auditory Cortex ◽  
Population Coding ◽  
Single Units ◽  
Neural Population ◽  
Population Responses ◽  
Noise Ratio

AbstractThe ability to process speech signals under challenging listening environments is critical for speech perception. Great efforts have been made to reveal the underlying single unit encoding mechanism. However, big variability is usually discovered in single-unit responses, and the population coding mechanism is yet to be revealed. In this study, we are aimed to study how a population of neurons encodes behaviorally relevant signals subjective to change in intensity and signal-noise-ratio (SNR). We recorded single-unit activity from the primary auditory cortex of awake common marmoset monkeys (Callithrix jacchus) while delivering conspecific vocalizations degraded by two different background noises: broadband white noise (WGN) and vocalization babble (Babble). By pooling all single units together, the pseudo-population analysis showed the population neural responses track intra- and inter-trajectory angle evolutions track vocalization identity and intensity/SNR, respectively. The ability of the trajectory to track the vocalizations attribute was degraded to a different degree by different noises. Discrimination of neural populations evaluated by neural response classifiers revealed that a finer optimal temporal resolution and longer time scale of temporal dynamics were needed for vocalizations in noise than vocalizations at multiple different intensities. The ability of population responses to discriminate between different vocalizations were mostly retained above the detection threshold.Significance StatementHow our brain excels in the challenge of precise acoustic signal encoding against noisy environment is of great interest for scientists. Relatively few studies have strived to tackle this mystery from the perspective of neural population responses. Population analysis reveals the underlying neural encoding mechanism of complex acoustic stimuli based upon a pool of single units via vector coding. We suggest the spatial population response vectors as one important way for neurons to integrate multiple attributes of natural acoustic signals, specifically, marmots’ vocalizations.

scholarly journals Ventral pallidum neurons signal relative threat

2020 ◽  
Author(s):  
Mahsa Moaddab ◽  
Madelyn H. Ray ◽  
Michael A. McDannald
Keyword(s):  
Single Unit ◽  
Critical Role ◽  
Single Units ◽  
Male Rats ◽  
Ventral Pallidum ◽  
Anatomical Connectivity ◽  
Specific Signal ◽  
Relative Value ◽  
Reward Value ◽  
Integral Role

AbstractVentral pallidum (VP) neurons scale firing increases to reward value and decrease firing to aversive cues. Anatomical connectivity suggests a critical role for the VP in threat-related behavior. Here we tested whether firing decreases in VP neurons conform to relative threat by recording single units while male rats discriminated cues predicting unique foot shock probabilities. Rats behavior and VP single unit firing discriminated danger, uncertainty and safety cues. We found that two VP populations (Low firing and Intermediate firing) signaled relative threat, proportionally decreased firing according shock probability: danger < uncertainty < safety. Low firing neurons showed reward firing increases, consistent with a general signal for relative value. Intermediate firing neurons were unresponsive to reward, revealing a specific signal for relative threat. The results suggest an integral role for the VP in threat-related behavior.

The Dose-Match Interaction in Umbilical Cord Blood (UCB) Transplantation: An Analysis of the Impact of Cell Dose and HLA-Match on the Disease-Free Survival (DFS) of 989 Patients Transplanted with Single Units for Hematologic Malignancy.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 333-333 ◽  
Author(s):  
Juliet N. Barker ◽  
Andromachi Scaradavou ◽  
Cladd Stevens ◽  
Pablo Rubinstein
Keyword(s):  
Single Unit ◽  
Disease Risk ◽  
Hematologic Malignancy ◽  
Dose Range ◽  
Disease Free Survival ◽  
Outcome Data ◽  
Single Units ◽  
Unit Selection ◽  
Cell Dose ◽  
The Impact

Abstract Total nucleated cell (TNC) dose and HLA-match are both recognized determinants of engraftment, transplant-related mortality (TRM), and DFS after UCB transplantation (UCBT). However, how to “trade off” dose and match in unit selection is not well defined. Therefore, we analyzed the impact of pre-freeze TNC dose and HLA-match upon 3 year transplant outcomes after 3-6/6 HLA-A, B antigen, DRB1 allele matched UCBT provided by the NCBP. Patients were transplanted with myeloablative conditioning using single units for the treatment of acute (n = 768) or chronic (n = 156) leukemia or myelodysplasia (n = 65) between 1993–2005. The 989 patients with outcome data to date (91% of single unit grafts provided in this interval) had a median age of 9 years (range 0–62). Individually, decreasing TNC dose adversely affected engraftment, TRM, and DFS as previously shown, whereas increasing HLA-mismatch adversely impacted these outcomes as well as the incidence of severe acute graft-vs-host disease (aGVHD). For example, using recipients of 5/6 units as a reference, the relative risk (RR) for grades III-IV aGVHD for recipients of 6/6 units was 0.3 (p = 0.03); for 4/6 unit recipients was 1.6 (p = 0.003); and for 3/6 unit recipients was 2.1 (p = 0.002). An analysis of the 3 year DFS combining both pre-freeze TNC dose and HLA-match, using recipients of 5/6 matched 2.5–4.9 x 107/kg units as the reference, is shown. Match/ Dose N RR: Death or Relapse (95%CI) p 6/6: any dose 50 0.4 (0.2–0.7) 0.002 5/6: TNC 0.7–2.4 66 1.7 (1.2–2.4) 0.003 5/6: TNC 2.5–4.9 116 1.0 (Reference) - 5/6: TNC ≥ 5.0 141 0.9 (0.6–1.2) 0.5 4/6: TNC 0.7–2.4 132 1.8 (1.4–2.5) < 0.001 4/6: TNC 2.5–4.9 222 1.3 (0.95–1.7) 0.12 4/6: TNC ≥ 5.0 198 0.9 (0.7–1.3) 0.9 3/6: any dose 64 1.5 (1.0–2.1) 0.045 Notably, within the dose range transplanted to date, recipients of 6/6 units had a significantly superior DFS which was not explained by other variables such as age, disease risk, or transplant center. In contrast, recipients of 3/6 units had inferior DFS, also regardless of dose. Further, recipients of 5/6 units with a TNC 2.5–4.9 x 107/kg (mean 3.5) had a DFS that was similar to those receiving larger 4/6 units ≥ 5.0 x 107/kg (mean 5.9) but with a lower risk of severe aGVHD. Recipients of small (< 2.5 x 107/kg) units that were either 5/6 or 4/6 matched had significantly inferior outcome. This data has significant implications for the practice of unit selection for patients with hematologic malignancy. Most importantly, it suggests that the best transplant survival can be obtained by selecting a 6/6 HLA-matched unit, although the cell dose threshold for these units has not been established. If no 6/6 units are available, 5/6 units above a dose of 2.5 x 107/kg are superior to 4/6 units of any dose. In addition, small (< 2.5 x 107/kg) 5/6 or 4/6 units are inadequate as a single unit graft. Units that are 3/6 HLA-matched should also be avoided. Finally, this analysis suggests improved UCBT outcome will be dependent upon the ability to obtain units that are both of sufficient TNC dose and HLA-match requiring an increase in the global inventory of ethnically and racially diverse UCB units of high cell dose.

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