scholarly journals Near-optimal decoding of transient stimuli from coupled neuronal subpopulations

2014 ◽  
Author(s):  
James Trousdale ◽  
Samuel R. Carroll ◽  
Fabrizio Gabbiani ◽  
Krešimir Josić
Keyword(s):  
Visual Processing ◽  
Information Transfer ◽  
Partial Information ◽  
Rotation Axis ◽  
Biophysical Model ◽  
General Mechanism ◽  
Small Subset ◽  
Vertical System ◽  
Optimal Decoding

Coupling between sensory neurons impacts their tuning properties and correlations in their responses. How such coupling affects sensory representations and ultimately behavior remains unclear. We investigated the role of neuronal coupling during visual processing using a realistic biophysical model of the vertical system (VS) cell network in the blow fly. These neurons are thought to encode the horizontal rotation axis during rapid free flight manoeuvres. Experimental findings suggest neurons of the vertical system are strongly electrically coupled, and that several downstream neurons driving motor responses to ego-rotation receive inputs primarily from a small subset of VS cells. These downstream neurons must decode information about the axis of rotation from a partial readout of the VS population response. To investigate the role of coupling, we simulated the VS response to a variety of rotating visual scenes and computed optimal Bayesian estimates from the relevant subset of VS cells. Our analysis shows that coupling leads to near-optimal estimates from a subpopulation readout. In contrast, coupling between VS cells has no impact on the quality of encoding in the response of the full population. We conclude that coupling at one level of the fly visual system allows for near-optimal decoding from partial information at the subsequent, pre-motor level. Thus, electrical coupling may provide a general mechanism to achieve near-optimal information transfer from neuronal subpopulations across organisms and modalities.

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

NATURAL SCIENTISTS AND RUSSIAN SCIENTIFIC FILMMAKING IN THE PRE-REVOLUTIONARY PERIOD (SCIENCE DIVISION OF THE A.A. KHANZHONKOV COMPANY)

2020 ◽  
Vol 42 (3) ◽  
pp. 355-368
Author(s):  
YEVGENIY ALEKSANDROV
Keyword(s):  
Information Transfer ◽  
Delayed Reaction ◽  
Russian Scientific ◽  
Physical Problems ◽  
Education Community ◽  
Future System ◽  
The Future ◽  
The Spectator ◽  
Revolutionary Period

The aim of the article is to recall the fi steps of comprehension by the scientific community of possibilities of a newly born means of the reality reflection. The means was initially oriented for obtaining reliable information and supposing a delayed reaction of the spectator in the process of communication. Recollection and understanding become more important under the distance education condition. Pre-revolutionary Russia lived anticipating changes, and the filmmaking was considered by the society as one of those progressive phenomena evidencing the coming of a new age. The scientists’ activity during the development of scientific fi in pre-revolutionary Russia was long hushed up and wasn’t considered as forming a basis for the future system of educational audio-visual communication. In this process there participated striking, creative personalities, mostly belonged to the community of Imperial Moscow University, which activity was during the age of changes. The significant contribution of pleiad of eminent scientists’ activity to the new direction formation was a reason to unify in one paper both their whole professional life data and information about their time-limited period of scientific fi In the future a more profound study of their achievements are considered to be promising. In the introduction the anterior period of the Russian fi appearance, where the scientific and education community of Russia was exploring the possibilities of a new means of information transfer for education purposes, is considered. Two main units are dedicated to the role of scientists in the development of scientific filmmaking for research and popularization of biomedical and physical problems.

scholarly journals Biofilm Lithography enables high-resolution cell patterning via optogenetic adhesin expression

2018 ◽  
Vol 115 (14) ◽  
pp. 3698-3703 ◽  
Author(s):  
Xiaofan Jin ◽  
Ingmar H. Riedel-Kruse
Keyword(s):  
Escherichia Coli ◽  
Cell Patterning ◽  
Biophysical Model ◽  
Microbial Consortia ◽  
Bacterial Biofilms ◽  
Surface Pretreatment ◽  
Resolution Cell ◽  
Stimulation Of

Bacterial biofilms represent a promising opportunity for engineering of microbial communities. However, our ability to control spatial structure in biofilms remains limited. Here we engineerEscherichia coliwith a light-activated transcriptional promoter (pDawn) to optically regulate expression of an adhesin gene (Ag43). When illuminated with patterned blue light, long-term viable biofilms with spatial resolution down to 25 μm can be formed on a variety of substrates and inside enclosed culture chambers without the need for surface pretreatment. A biophysical model suggests that the patterning mechanism involves stimulation of transiently surface-adsorbed cells, lending evidence to a previously proposed role of adhesin expression during natural biofilm maturation. Overall, this tool—termed “Biofilm Lithography”—has distinct advantages over existing cell-depositing/patterning methods and provides the ability to grow structured biofilms, with applications toward an improved understanding of natural biofilm communities, as well as the engineering of living biomaterials and bottom–up approaches to microbial consortia design.

Repetition Suppression of Induced Gamma Activity Predicts Enhanced Orienting toward a Novel Stimulus in 6-month-old Infants

2008 ◽  
Vol 20 (12) ◽  
pp. 2137-2152 ◽  
Author(s):  
Kelly A. Snyder ◽  
Andreas Keil
Keyword(s):  
Visual Processing ◽  
Novelty Detection ◽  
Neural Mechanisms ◽  
Human Infant ◽  
Gamma Activity ◽  
Repeated Stimulus ◽  
Repetition Suppression ◽  
The Face ◽  
Over 40 Years

Habituation refers to a decline in orienting or responding to a repeated stimulus, and can be inferred to reflect learning about the properties of the repeated stimulus when followed by increased orienting to a novel stimulus (i.e., novelty detection). Habituation and novelty detection paradigms have been used for over 40 years to study perceptual and mnemonic processes in the human infant, yet important questions remain about the nature of these processes in infants. The aim of the present study was to examine the neural mechanisms underlying habituation and novelty detection in infants. Specifically, we investigated changes in induced alpha, beta, and gamma activity in 6-month-old infants during repeated presentations of either a face or an object, and examined whether these changes predicted behavioral responses to novelty at test. We found that induced gamma activity over occipital scalp regions decreased with stimulus repetition in the face condition but not in the toy condition, and that greater decreases in the gamma band were associated with enhanced orienting to a novel face at test. The pattern and topography of these findings are consistent with observations of repetition suppression in the occipital–temporal visual processing pathway, and suggest that encoding in infant habituation paradigms may reflect a form of perceptual learning. Implications for the role of repetition suppression in infant habituation and novelty detection are discussed with respect to a biased competition model of visual attention.

scholarly journals Type 2 Diabetes (T2D) Associated Polymorphisms Regulate Expression of Adjacent Transcripts in Transformed Lymphocytes, Adipose, and Muscle from Caucasian and African-American Subjects

2011 ◽  
Vol 96 (2) ◽  
pp. E394-E403 ◽  
Author(s):  
Neeraj K. Sharma ◽  
Kurt A. Langberg ◽  
Ashis K. Mondal ◽  
Steven C. Elbein ◽  
Swapan K. Das
Keyword(s):  
Genome Wide Association ◽  
Small Subset ◽  
Nucleotide Polymorphisms ◽  
Healthy Individuals ◽  
Allelic Expression Imbalance ◽  
Single Nucleotide ◽  
Metabolic Traits ◽  
Genome Wide

abstract Context: Genome-wide association scans (GWAS) have identified novel single nucleotide polymorphisms (SNPs) that increase T2D susceptibility and indicated the role of nearby genes in T2D pathogenesis. Objective: We hypothesized that T2D-associated SNPs act as cis-regulators of nearby genes in human tissues and that expression of these transcripts may correlate with metabolic traits, including insulin sensitivity (SI). Design, Settings, and Patients: Association of SNPs with the expression of their nearest transcripts was tested in adipose and muscle from 168 healthy individuals who spanned a broad range of SI and body mass index (BMI) and in transformed lymphocytes (TLs). We tested correlations between the expression of these transcripts in adipose and muscle with metabolic traits. Utilizing allelic expression imbalance (AEI) analysis we examined the presence of other cis-regulators for those transcripts in TLs. Results: SNP rs9472138 was significantly (P = 0.037) associated with the expression of VEGFA in TLs while rs6698181 was detected as a cis-regulator for the PKN2 in muscle (P = 0.00027) and adipose (P = 0.018). Significant association was also observed for rs17036101 (P = 0.001) with expression of SYN2 in adipose of Caucasians. Among 19 GWAS-implicated transcripts, expression of VEGFA in adipose was correlated with BMI (r = −0.305) and SI (r = 0.230). Although only a minority of the T2D-associated SNPs were validated as cis-eQTLs for nearby transcripts, AEI analysis indicated presence of other cis-regulatory polymorphisms in 54% of these transcripts. Conclusions: Our study suggests that a small subset of GWAS-identified SNPs may increase T2D susceptibility by modulating expression of nearby transcripts in adipose or muscle.

scholarly journals Gestation, equality and freedom: ectogenesis as a political perspective

2019 ◽  
Vol 46 (2) ◽  
pp. 76-82 ◽  
Author(s):  
Giulia Cavaliere
Keyword(s):  
Status Quo ◽  
Positive Case ◽  
The Political ◽  
Small Subset ◽  
Human Fetuses ◽  
Political Perspective ◽  
Women's Equality ◽  
The Status ◽  
Limited Scope

The benefits of full ectogenesis, that is, the gestation of human fetuses outside the maternal womb, for women ground many contemporary authors’ arguments on the ethical desirability of this practice. In this paper, I present and assess two sets of arguments advanced in favour of ectogenesis: arguments stressing ectogenesis’ equality-promoting potential and arguments stressing its freedom-promoting potential. I argue that although successfully grounding a positive case for ectogenesis, these arguments have limitations in terms of their reach and scope. Concerning their limited reach, I contend that ectogenesis will likely benefit a small subset of women and, arguably, not the group who most need to achieve equality and freedom. Concerning their limited scope, I contend that these defences do not pay sufficient attention to the context in which ectogenesis would be developed and that, as a result, they risk leaving the status quo unchanged. After providing examples of these limitations, I move to my proposal concerning the role of ectogenesis in promoting women’s equality and freedom. This proposal builds on Silvia Federici’s, Mariarosa Dalla Costa’s and Selma James’ readings of the international feminist campaign ‘Wages for Housework’. It maintains that the political perspective and provocation that ectogenesis can advance should be considered and defended.

scholarly journals Emerging Role of Immune Therapy in HCC

2021 ◽  
Author(s):  
Stacey M. Stein
Keyword(s):  
Kinase Inhibitors ◽  
Immune Therapy ◽  
Treatment Options ◽  
Single Agent ◽  
Small Subset ◽  
Vascular Endothelial ◽  
Number Of Patients ◽  
Endothelial Growth Factor ◽  
Expected Increase

AbstractHepatocellular carcinoma (HCC) remains a prevalent cancer diagnosis with an expected increase in incidence in the next decade. Treatment options for advanced disease have expanded significantly in the last decade since sorafenib was first approved in 2007. There have been approvals for multiple tyrosine kinase inhibitors (TKIs) with modest improvements in survival. Single-agent PD-1 inhibition has shown responses in ∼15% of patients, with a tail of the curve that is very beneficial to a small subset of patients. Most recently, studies of combination therapy with immune therapy drugs are showing more durable responses in a larger number of patients with unprecedented response rates over 30%. Different strategies have been pursued, including PD-1 and PD-L1 combinations with vascular endothelial growth factor inhibition, TKIs, and anti-CTLA-4 antibodies. This article provides a review of studies both completed and ongoing with immune therapy in advanced HCC.

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