scholarly journals The Visual Callosal Connection: A Connection Like Any Other?

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Kerstin E. Schmidt
Keyword(s):  
Hierarchical Level ◽  
Similar Response ◽  
Callosal Connections ◽  
Visual Areas ◽  
Main Action ◽  
Functional Topography ◽  
Multiplicative Shift ◽  
Neuronal Groups ◽  
Feedback Connections

Recent work about the role of visual callosal connections in ferrets and cats is reviewed, and morphological and functional homologies between the lateral intrinsic and callosal network in early visual areas are discussed. Both networks selectively link distributed neuronal groups with similar response properties, and the actions exerted by callosal input reflect the functional topography of those networks. This supports the notion that callosal connections perpetuate the function of the lateral intrahemispheric circuit onto the other hemisphere. Reversible deactivation studies indicate that the main action of visual callosal input is a multiplicative shift of responses rather than a changing response selectivity. Both the gain of that action and its excitatory-inhibitory balance seem to be dynamically adapted to the feedforward drive by the visual stimulus onto primary visual cortex. Taken together anatomical and functional evidence from corticocortical and lateral circuits further leads to the conclusion that visual callosal connections share more features with lateral intrahemispheric connections on the same hierarchical level and less with feedback connections. I propose that experimental results about the callosal circuit in early visual areas can be interpreted with respect to lateral connectivity in general.

Hepatoprotective Role of Berberine on Doxorubicin Induced Hepatotoxicity - Involvement of Cyp

2020 ◽  
Vol 21 (7) ◽  
pp. 541-547
Author(s):  
Bao Sun ◽  
Yue Yang ◽  
Mengzi He ◽  
Yanan Jin ◽  
Xiaoyu Cao ◽  
...  
Keyword(s):  
Drug Metabolism ◽  
Cardiac Tissue ◽  
Liver Toxicity ◽  
Elevated Serum ◽  
Similar Response ◽  
Wide Range ◽  
Cytokine Levels ◽  
Major Organ ◽  
Anti Oxidant

Background: The liver is one of the major organ involved in drug metabolism. Cytochrome P450s are predominantly involved in drug metabolism. A wide range of CYPs have been reported in the liver which have been involved in its normal as well as in diseased conditions. Doxorubicin, one of the most potent chemotherapeutic drugs, although highly efficacious, also has adverse side effects, with its targets being liver and cardiac tissue. Objective: The study aims to evaluate the reversal potentials of berberine on Doxorubicin induced cyp conversion. Methodology: In the present study, the interplay between anti-oxidants, cytochrome and inflammatory markers in DOX induced liver toxicity and its possible reversal by berberine was ascertained. Results: DOX administration significantly elevated serum as well as tissue stress, which was reverted by berberine treatment. A similar response was observed in tissue inflammatory mediators as well as in serum cytokine levels. Most profound reduction in the cytochrome expression was found in Cyp 2B1, 2B2, and 2E1. However, 2C1, 2C6, and 3A1 although showed a decline, but it did not revert the expression back to control levels. Conclusion: It could be concluded that berberine may be an efficient anti-oxidant and immune modulator. It possesses low to moderate cytochrome modulatory potentials.

scholarly journals Adaptive Integration in the Visual Cortex by Depressing Recurrent Cortical Circuits

2008 ◽  
Vol 20 (7) ◽  
pp. 1847-1872 ◽  
Author(s):  
Mark C. W. van Rossum ◽  
Matthijs A. A. van der Meer ◽  
Dengke Xiao ◽  
Mike W. Oram
Keyword(s):  
Visual Cortex ◽  
Physiological Data ◽  
High Contrast ◽  
Cortical Circuits ◽  
Response Latencies ◽  
Low Contrast ◽  
Visual Areas ◽  
Higher Visual Areas ◽  
Recurrent Connections

Neurons in the visual cortex receive a large amount of input from recurrent connections, yet the functional role of these connections remains unclear. Here we explore networks with strong recurrence in a computational model and show that short-term depression of the synapses in the recurrent loops implements an adaptive filter. This allows the visual system to respond reliably to deteriorated stimuli yet quickly to high-quality stimuli. For low-contrast stimuli, the model predicts long response latencies, whereas latencies are short for high-contrast stimuli. This is consistent with physiological data showing that in higher visual areas, latencies can increase more than 100 ms at low contrast compared to high contrast. Moreover, when presented with briefly flashed stimuli, the model predicts stereotypical responses that outlast the stimulus, again consistent with physiological findings. The adaptive properties of the model suggest that the abundant recurrent connections found in visual cortex serve to adapt the network's time constant in accordance with the stimulus and normalizes neuronal signals such that processing is as fast as possible while maintaining reliability.

The economic and financial viability of sheltered employment centres

2019 ◽  
Vol 57 (9) ◽  
pp. 2261-2283
Author(s):  
Vera Gelashvili ◽  
Eva María Aguilar Pastor ◽  
María-Jesús Segovia-Vargas ◽  
Maria-del-Mar Camacho-Miñano
Keyword(s):  
Training Programs ◽  
Similar Response ◽  
Economic Returns ◽  
Content Type ◽  
Strategic Plans ◽  
Low Levels ◽  
The Difference ◽  
Practical Implications ◽  
Very High

Purpose The purpose of this paper is to investigate whether sheltered employment centers (CEEs) which have a higher rate of professionalization of their managers have better economic returns than those that have a lower one. Design/methodology/approach A questionnaire has been drawn up for their managers. After collecting the answers, an index of professionalization classifies the CEEs with managers of high, medium and low levels of professionalism. This index is then correlated with the main financial ratios of companies. Findings The results show that companies with the highest level of managers’ professionalization, on average, have higher economic returns than companies with medium and low rates, although the difference is not very high. This study is an important contribution to academic literature, as it is the first to examine the professionalization of CEE managers. Research limitations/implications Finally, this paper is not short of limitations. The number of responses is small but there are similar studies with similar response rates. Additionally, the scarcity of responses may suggest that there is a lack of interest about the utility of professionalization by some CEEs managers because, perhaps, they do not have the necessary competences to understand its importance in management. Practical implications This study has some main implications for stakeholders: first, CEEs must pay more attention to the professionalization of their management team, because professionalization can lead to meeting its goals and guaranteeing the firm’s growth. Second, training programs in skills and attitudes should be designed to strengthen these competencies. Moreover, managers of social firms should know that the establishment of strategic plans will be useful to identify new opportunities in the market. Social implications Given the important role of these social firms for the employment of people with disabilities, training programs should be promoted by government in order to ensure the professionalization of these companies. Originality/value This research is an important contribution to the literature on this subject because there are no studies about the level of professionalization of CEEs, companies that represent an important value for the economy of a country.

Comparative Analysis of Words and Pictures through Associations

1976 ◽  
Vol 38 (1) ◽  
pp. 275-296
Author(s):  
Lorand B. Szalay ◽  
Jean A. Bryson
Keyword(s):  
Comparative Analysis ◽  
Information Value ◽  
Similar Response ◽  
Student Groups ◽  
University Of Maryland ◽  
Attitudinal Factors ◽  
The University ◽  
Perceptual Factors ◽  
Analytic Potential

The investigations focused on a picture-stimulated continued association approach, its information value and analytic potential. Student groups ( N = 50), each composed of both sexes, were from the University of Maryland. The study involved a comparative analysis of associations produced to words and pictures. The results show that the two approaches are closely comparable but produced responses which were differently focused. While the word-stimulated responses were somewhat more generic, the picture-stimulated associations were more narrow and specific. All the measures developed previously in the context of word-stimulated associations were found to be equally applicable and informative with picture-stimulated associations as well. From a theoretical viewpoint, the investigations were informative in demonstrating the importance of perceptual semantic and affective-attitudinal factors in the association process. Corresponding words and pictures elicited closely similar response distributions with correlations in the range of .7. As the role of perceptual factors is obvious in picture-stimulated associations, the results of the study have distinct implications for association theory, underlining the importance of centrally mediated mechanisms in the process of elicitation.

Effects of Feedback Projections From Area 18 Layers 2/3 to Area 17 Layers 2/3 in the Cat Visual Cortex

1999 ◽  
Vol 82 (5) ◽  
pp. 2667-2675 ◽  
Author(s):  
Susana Martinez-Conde ◽  
Javier Cudeiro ◽  
Kenneth L. Grieve ◽  
Rosa Rodriguez ◽  
Casto Rivadulla ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Small Region ◽  
Orientation Tuning ◽  
Area 17 ◽  
Visual Responses ◽  
Area 18 ◽  
Cat Visual Cortex ◽  
Effects Of Feedback ◽  
Feedback Connections

In the absence of a direct geniculate input, area 17 cells in the cat are nevertheless able to respond to visual stimuli because of feedback connections from area 18. Anatomic studies have shown that, in the cat visual cortex, layer 5 of area 18 projects to layer 5 of area 17, and layers 2/3 of area 18 project to layers 2/3 of area 17. What is the specific role of these connections? Previous studies have examined the effect of area 18 layer 5 blockade on cells in area 17 layer 5. Here we examine whether the feedback connections from layers 2/3 of area 18 influence the orientation tuning and velocity tuning of cells in layers 2/3 of area 17. Experiments were carried out in anesthetized and paralyzed cats. We blocked reversibly a small region (300 μm radius) in layers 2/3 of area 18 by iontophoretic application of GABA and recorded simultaneously from cells in layers 2/3 of area 17 while stimulating with oriented sweeping bars. Area 17 cells showed either enhanced or suppressed visual responses to sweeping bars of various orientations and velocities during area 18 blockade. For most area 17 cells, orientation bandwidths remained unaltered, and we never observed visual responses during blockade that were absent completely in the preblockade condition. This suggests that area 18 layers 2/3 modulate visual responses in area 17 layers 2/3 without fundamentally altering their specificity.

Modulation of cell membrane potential in cultured vascular endothelium

1996 ◽  
Vol 270 (3) ◽  
pp. C819-C824 ◽  
Author(s):  
L. Vaca ◽  
A. Licea ◽  
L. D. Possani
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Cell Membrane Potential ◽  
Resting Potential ◽  
Similar Response ◽  
Aortic Endothelial Cells ◽  
Ionic Conductances ◽  
Selective Channel ◽  
Inwardly Rectifying

The present study explores the role of different ionic conductances in the regulation of membrane potential under resting conditions and after bradykinin (BK) or thapsigargin (TG) stimulation of cultured bovine aortic endothelial cells. Under resting conditions, the cell membrane potential observed was -62+/- 5 mV. The main conductance under these conditions is an inwardly rectifying potassium (IRK) channel. Application of 50 nM BK induced a transient hyperpolarization to -87 +/- 4 mV followed by sustained depolarization to -35 +/- 5 mV. The transient hyperpolarization was eliminated by 1 microM noxiustoxin, a blocker of calcium-activated postassium channels (K(Ca)). the sustained depolarization induced by BK was prevented by incubating the cells with the calcium channel blocker lanthanum. TG evoked a similar response in membrane potential, with the exception that the onset of the hyperpolarization was slower compared with BK. The results presented here indicate that the cell resting potential is maintained at -62 +/- 2 mV by the IRK channel. BK or TG stimulation induces a transient hyperpolarization of approximately -20 mV produced by activation of a KCa. This hyperpolarization is followed by a sustained depolarization produced by activation of a calcium-selective channel sensitive to lanthanum.

The Relationship Between Narcissism and Taking Charge: The Role of Energy at Work and Hierarchical Level

2018 ◽  
Vol 123 (2) ◽  
pp. 472-487 ◽  
Author(s):  
Kong Zhou ◽  
Wenxing Liu ◽  
Mingze Li ◽  
Zhihui Cheng ◽  
Xiaofei Hu
Keyword(s):  
Indirect Effect ◽  
Hierarchical Level ◽  
Mediation Model ◽  
Managerial Practices ◽  
Moderated Mediation Model ◽  
Narcissistic Personality ◽  
Human Energy ◽  
Taking Charge ◽  
The Relationship

Drawing on the framework of human energy in organizations, this study proposed a moderated mediation model between narcissism and taking charge, as well as the role of energy at work and the employee’s hierarchy within organizations. A sample of 312 employees at one Chinese manufacturing company suggested that employees with narcissistic personality are more apt to exhibit taking charge at work via their energy at work. In addition, the results also indicated that employees’ hierarchical level within organization reinforced the indirect effect of energy at work between narcissism and taking charge. These findings have important implications for narcissism research and managerial practices.

Role of Feedback Connections in Central Visual Processing

2020 ◽  
Vol 6 (1) ◽  
pp. 313-334
Author(s):  
Farran Briggs
Keyword(s):  
Visual Processing ◽  
Physiological Response ◽  
Functional Role ◽  
Functional Roles ◽  
Vision Science ◽  
The Core ◽  
Feedback Circuits ◽  
Corticothalamic Feedback ◽  
Feedback Connections

The physiological response properties of neurons in the visual system are inherited mainly from feedforward inputs. Interestingly, feedback inputs often outnumber feedforward inputs. Although they are numerous, feedback connections are weaker, slower, and considered to be modulatory, in contrast to fast, high-efficacy feedforward connections. Accordingly, the functional role of feedback in visual processing has remained a fundamental mystery in vision science. At the core of this mystery are questions about whether feedback circuits regulate spatial receptive field properties versus temporal responses among target neurons, or whether feedback serves a more global role in arousal or attention. These proposed functions are not mutually exclusive, and there is compelling evidence to support multiple functional roles for feedback. In this review, the role of feedback in vision will be explored mainly from the perspective of corticothalamic feedback. Further generalized principles of feedback applicable to corticocortical connections will also be considered.

Sign in / Sign up

Export Citation Format

Share Document