scholarly journals Spatially segregated responses to visuo-tactile stimuli in mouse neocortex during active sensation

2017 ◽  
Author(s):  
J Couto ◽  
S Kandler ◽  
D Mao ◽  
BL McNaughton ◽  
L Arckens ◽  
...  
Keyword(s):  
Hierarchical Model ◽  
Alternative Hypothesis ◽  
Visual Responses ◽  
V1 Neurons ◽  
Tactile Stimuli ◽  
Sensory Cortices ◽  
Tactile Cues ◽  
Visual Cortices ◽  
Active Exploration ◽  
The Impact

ABSTRACTMultisensory integration is key for perception and animal survival yet how information from separate senses is integrated has been debated for decades. In the cortex, information from each sense is first processed in primary sensory areas and then combined in association areas. An alternative hypothesis to this hierarchical model is that primary sensory cortices partake in multisensory encoding. We probed tactile and visual responses in primary somatosensory and visual cortices in awake behaving animals using two-photon calcium imaging from layer 2/3 excitatory neurons. In support of an hierarchical model we found segregation of visual and tactile responses. Tactile stimuli evoked responses in S1 neurons. In striking contrast, V1 neurons failed to respond to tactile stimuli. This was true for passive whisker stimulation and for stimulation during active whisking. Furthermore, responses of V1 neurons to congruent visuo-tactile cues during active exploration, a condition where vision precedes touch, were completely abolished in darkness. The rostro-lateral area of the visual cortex responded to both visual and tactile aspects of the stimuli and may form a substrate for encoding multisensory signals during active exploration. Our results indicate that primary sensory areas mainly encode their primary sense and that the impact of other modalities may be restricted to modulatory effects.

scholarly journals Pure tones modulate the representation of orientation and direction in the primary visual cortex

2019 ◽  
Vol 121 (6) ◽  
pp. 2202-2214 ◽  
Author(s):  
John P. McClure ◽  
Pierre-Olivier Polack
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Stimulus ◽  
Visual Stimuli ◽  
Direction Selectivity ◽  
Multimodal Integration ◽  
Visual Responses ◽  
V1 Neurons ◽  
Pure Tones ◽  
The Impact

Multimodal sensory integration facilitates the generation of a unified and coherent perception of the environment. It is now well established that unimodal sensory perceptions, such as vision, are improved in multisensory contexts. Whereas multimodal integration is primarily performed by dedicated multisensory brain regions such as the association cortices or the superior colliculus, recent studies have shown that multisensory interactions also occur in primary sensory cortices. In particular, sounds were shown to modulate the responses of neurons located in layers 2/3 (L2/3) of the mouse primary visual cortex (V1). Yet, the net effect of sound modulation at the V1 population level remained unclear. In the present study, we performed two-photon calcium imaging in awake mice to compare the representation of the orientation and the direction of drifting gratings by V1 L2/3 neurons in unimodal (visual only) or multimodal (audiovisual) conditions. We found that sound modulation depended on the tuning properties (orientation and direction selectivity) and response amplitudes of V1 L2/3 neurons. Sounds potentiated the responses of neurons that were highly tuned to the cue’s orientation and direction but weakly active in the unimodal context, following the principle of inverse effectiveness of multimodal integration. Moreover, sound suppressed the responses of neurons untuned for the orientation and/or the direction of the visual cue. Altogether, sound modulation improved the representation of the orientation and direction of the visual stimulus in V1 L2/3. Namely, visual stimuli presented with auditory stimuli recruited a neuronal population better tuned to the visual stimulus orientation and direction than when presented alone. NEW & NOTEWORTHY The primary visual cortex (V1) receives direct inputs from the primary auditory cortex. Yet, the impact of sounds on visual processing in V1 remains controverted. We show that the modulation by pure tones of V1 visual responses depends on the orientation selectivity, direction selectivity, and response amplitudes of V1 neurons. Hence, audiovisual stimuli recruit a population of V1 neurons better tuned to the orientation and direction of the visual stimulus than unimodal visual stimuli.

scholarly journals A cortical circuit for audio-visual predictions

2021 ◽  
Author(s):  
Aleena R. Garner ◽  
Georg B. Keller
Keyword(s):  
Visual Stimulus ◽  
Neural Mechanism ◽  
Visual Responses ◽  
V1 Neurons ◽  
Optogenetic Stimulation ◽  
Sensory Modalities ◽  
Visual Cortices ◽  
Relevant Context ◽  
Cortical Circuit ◽  
Stimulation Of

AbstractLearned associations between stimuli in different sensory modalities can shape the way we perceive these stimuli. However, it is not well understood how these interactions are mediated or at what level of the processing hierarchy they occur. Here we describe a neural mechanism by which an auditory input can shape visual representations of behaviorally relevant stimuli through direct interactions between auditory and visual cortices in mice. We show that the association of an auditory stimulus with a visual stimulus in a behaviorally relevant context leads to experience-dependent suppression of visual responses in primary visual cortex (V1). Auditory cortex axons carry a mixture of auditory and retinotopically matched visual input to V1, and optogenetic stimulation of these axons selectively suppresses V1 neurons that are responsive to the associated visual stimulus after, but not before, learning. Our results suggest that cross-modal associations can be communicated by long-range cortical connections and that, with learning, these cross-modal connections function to suppress responses to predictable input.

scholarly journals A cortical circuit for audio-visual predictions

2020 ◽  
Author(s):  
Aleena R. Garner ◽  
Georg B. Keller
Keyword(s):  
Visual Cortex ◽  
Auditory Cortex ◽  
Auditory Stimulus ◽  
Visual Stimulus ◽  
Neural Mechanism ◽  
Visual Responses ◽  
V1 Neurons ◽  
Sensory Modalities ◽  
Visual Cortices ◽  
Relevant Context

ABSTRACTLearned associations between stimuli in different sensory modalities can shape the way we perceive these stimuli (Mcgurk and Macdonald, 1976). During audio-visual associative learning, auditory cortex is thought to underlie multi-modal plasticity in visual cortex (McIntosh et al., 1998; Mishra et al., 2007; Zangenehpour and Zatorre, 2010). However, it is not well understood how processing in visual cortex is altered by an auditory stimulus that is predictive of a visual stimulus and what the mechanisms are that mediate such experience-dependent, audio-visual associations in sensory cortex. Here we describe a neural mechanism by which an auditory input can shape visual representations of behaviorally relevant stimuli through direct interactions between auditory and visual cortices. We show that the association of an auditory stimulus with a visual stimulus in a behaviorally relevant context leads to an experience-dependent suppression of visual responses in primary visual cortex (V1). Auditory cortex axons carry a mixture of auditory and retinotopically-matched visual input to V1, and optogenetic stimulation of these axons selectively suppresses V1 neurons responsive to the associated visual stimulus after, but not before, learning. Our results suggest that cross-modal associations can be stored in long-range cortical connections and that with learning these cross-modal connections function to suppress the responses to predictable input.

scholarly journals Measuring spatial allocative efficiency in basketball

2020 ◽  
Vol 16 (4) ◽  
pp. 271-289
Author(s):  
Nathan Sandholtz ◽  
Jacob Mortensen ◽  
Luke Bornn
Keyword(s):  
Spatial Distribution ◽  
Hierarchical Model ◽  
Opportunity Cost ◽  
Allocative Efficiency ◽  
Bayesian Hierarchical Model ◽  
National Basketball Association ◽  
Spatial Context ◽  
Bayesian Hierarchical ◽  
The Impact

AbstractEvery shot in basketball has an opportunity cost; one player’s shot eliminates all potential opportunities from their teammates for that play. For this reason, player-shot efficiency should ultimately be considered relative to the lineup. This aspect of efficiency—the optimal way to allocate shots within a lineup—is the focus of our paper. Allocative efficiency should be considered in a spatial context since the distribution of shot attempts within a lineup is highly dependent on court location. We propose a new metric for spatial allocative efficiency by comparing a player’s field goal percentage (FG%) to their field goal attempt (FGA) rate in context of both their four teammates on the court and the spatial distribution of their shots. Leveraging publicly available data provided by the National Basketball Association (NBA), we estimate player FG% at every location in the offensive half court using a Bayesian hierarchical model. Then, by ordering a lineup’s estimated FG%s and pairing these rankings with the lineup’s empirical FGA rate rankings, we detect areas where the lineup exhibits inefficient shot allocation. Lastly, we analyze the impact that sub-optimal shot allocation has on a team’s overall offensive potential, demonstrating that inefficient shot allocation correlates with reduced scoring.

scholarly journals Implementing Total Quality management practices and Employee Performance: Sanita - Lebanon

2021 ◽  
Vol 24 ◽  
pp. 538-548
Author(s):  
Rushdi Zaiter ◽  
Rabih El Kabbout ◽  
Mahnoud Koabaz ◽  
Ahmad Skaiky ◽  
Mohamad Zalghout ◽  
...  
Keyword(s):  
Quality Management ◽  
Total Quality Management ◽  
Management Practices ◽  
Alternative Hypothesis ◽  
Employee Performance ◽  
Industrial Sector ◽  
Middle Level ◽  
Total Quality ◽  
Quantitative Correlation ◽  
The Impact

The aim of the study is find out the impact of applying different total quality management (TQM) practices on the performance of employees in the Lebanese industrial sector. The implementation of total quality management in Lebanese companies is very narrow where few companies work to apply Total Quality Management elements and concepts in its operations. Sanita is a Lebanese company that has applied the principles of total quality management relatively in all of its operations, so it has a large share of its products in the Lebanese market. In this quantitative survey designed study, 160 self-administered questionnaires were distributed for employees working at different career level (Top level management / Middle level management / Supervisor / Operator /technician / other workers) in Sanita main branch (Halat -Lebanon) and Sanita factory (Zouk Mosbeh -Lebanon). The survey concluded various questions related to the dependent variable employee performance and the independent variable related to practices of total quality management (leadership, teamwork, training and education, empowerment, communication). Using the quantitative correlation Pearson test, a strong influence emerged for the implementation of TQM principles on the performance of employees at Sanita and its factories; thus accepting the main alternative hypothesis.

Response to Visual, Chemical, and Tactile Stimuli

2020 ◽  
pp. 333-360
Author(s):  
Jonathan H. Cohen ◽  
Charles E. Epifanio
Keyword(s):  
Chemical Cues ◽  
Vertical Plane ◽  
Early Life History ◽  
Water Soluble ◽  
Future Research ◽  
Free Swimming ◽  
Egg Hatching ◽  
Tactile Stimuli ◽  
Settlement And Metamorphosis ◽  
Tactile Cues

Early life history in marine benthic crustaceans often includes externally brooded eggs that hatch into free-swimming planktonic larvae. These larvae are relatively strong swimmers, and movement in the vertical plane provides a number of advantages, including modulation of horizontal transport and assurance of favorable predator–prey interactions. Swimming behavior in larval crustaceans is regulated by predictable external cues in the water column, primarily light, gravity, and hydrostatic pressure. Light-regulated behavior depends upon the optical physics of seawater and the physiology of light-detecting sensory structures in the larvae, which overall vary little with ontogeny. Swimming in response to light contributes to ecologically significant behaviors in planktonic crustacean larvae, including shadow responses, depth regulation, and diel vertical migration. Moreover, the photoresponses themselves, and in turn the evoked behaviors, change with the needs of larvae as development progresses. Regarding other sensory modalities, crustacean embryos and larvae respond to chemical cues using bimodal sensilla (chemosensory and mechanosensory) as contact receptors, and aesthetascs for detection of water-soluble cues. Processes and behaviors are stimulated by larval detection of chemical cues throughout ontogeny, including egg-hatching, avoidance of predators during free-swimming stages, and, ultimately, settlement and metamorphosis in juvenile habitats. The latter process can also involve tactile cues. The sensory-mediated behaviors described here for crustacean larvae have parallels in numerous arthropod and nonarthropod taxa. Emerging directions for future research on sensory aspects of behavior in crustacean larvae include multimodal sensory integration and behavioral responses to changing environmental stressors.

Purges and Production: Soviet Economic Growth, 1928–1940

1975 ◽  
Vol 35 (3) ◽  
pp. 567-590 ◽  
Author(s):  
Barbaba G. Katz
Keyword(s):  
Growth Rate ◽  
Industrial Production ◽  
Alternative Hypothesis ◽  
Second World War ◽  
Constant Elasticity ◽  
Constant Elasticity Of Substitution ◽  
Sequence Of Events ◽  
Massive Scale ◽  
The Impact ◽  
Second World

Did preparations for the Second World War account for the precipitous drop in the growth rate of Soviet industrial production from 10–12 percent per annum in the period 1928–1937 to only 2–3 percent per annum in the period 1937–1940? According to some who study the Soviet economy the answer is “yes.” This view has been succinctly expressed by Stanley Cohn: “After 1937, the rising spectre of Hitler forced the Soviet leadership to shift resources into armaments on a massive scale. As a result, the growth rate fell drastically to 3.6 percent per year between 1937 and 1940.” Such a sequence of events, however, has never been empirically demonstrated. The purpose of this paper is to investigate formally the validity of this explanation, via aggregate production functions, particularly of the CES (constant elasticity of substitution) variety, as well as to explore an alternative hypothesis, espoused, among others, by Naum Jasny, Alec Nove and Warren Nutter. This hypothesis stresses a domestic factor as the major contributor to the disruption in industrial production: namely, the impact of Stalin's terror in the form of chaos-producing political purges.

scholarly journals Disentangling Europe

2019 ◽  
Vol 9 (1) ◽  
pp. 7-35
Author(s):  
Sanja Badanjak
Keyword(s):  
Causal Power ◽  
Alternative Hypothesis ◽  
The Political ◽  
Economic Policies ◽  
Niche Parties ◽  
Political Outcomes ◽  
Political Landscapes ◽  
The Impact ◽  
Matching Techniques ◽  
The Eu

In many ways, the process of Europeanization has been running parallel to other processes, most prominently, that of globalization. While it appears that many of the changes, we see in the political landscapes of the member states can be attributed to the impact of the EU , it may also be the case that these are brought about by increased economic interdependence. The rise in popularity of niche parties and a hollowing out of alternatives with regard to economic policies are two of the most prominent effects that are found to be correlated with an increased participation in European integration. In this paper, I am assessing these claims against the alternative hypothesis, which places the causal power with globalization in general, rather than the integration specific to Europe. By employing matching techniques, I am providing a cleared picture of the dependence of the above mentioned domestic political outcomes on the parallel and often confounding processes of Europeanization and globalization.

scholarly journals Comparison of futility monitoring guidelines using completed phase III oncology trials

2016 ◽  
Vol 14 (1) ◽  
pp. 48-58 ◽  
Author(s):  
Qiang Zhang ◽  
Boris Freidlin ◽  
Edward L Korn ◽  
Susan Halabi ◽  
Sumithra Mandrekar ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Sample Size ◽  
Alternative Hypothesis ◽  
Phase Iii ◽  
Interim Result ◽  
Type I ◽  
Conditional Power ◽  
Phase Iii Clinical Trials ◽  
The Impact ◽  
Analytical Approaches

Background: Futility (inefficacy) interim monitoring is an important component in the conduct of phase III clinical trials, especially in life-threatening diseases. Desirable futility monitoring guidelines allow timely stopping if the new therapy is harmful or if it is unlikely to demonstrate to be sufficiently effective if the trial were to continue to its final analysis. There are a number of analytical approaches that are used to construct futility monitoring boundaries. The most common approaches are based on conditional power, sequential testing of the alternative hypothesis, or sequential confidence intervals. The resulting futility boundaries vary considerably with respect to the level of evidence required for recommending stopping the study. Purpose: We evaluate the performance of commonly used methods using event histories from completed phase III clinical trials of the Radiation Therapy Oncology Group, Cancer and Leukemia Group B, and North Central Cancer Treatment Group. Methods: We considered published superiority phase III trials with survival endpoints initiated after 1990. There are 52 studies available for this analysis from different disease sites. Total sample size and maximum number of events (statistical information) for each study were calculated using protocol-specified effect size, type I and type II error rates. In addition to the common futility approaches, we considered a recently proposed linear inefficacy boundary approach with an early harm look followed by several lack-of-efficacy analyses. For each futility approach, interim test statistics were generated for three schedules with different analysis frequency, and early stopping was recommended if the interim result crossed a futility stopping boundary. For trials not demonstrating superiority, the impact of each rule is summarized as savings on sample size, study duration, and information time scales. Results: For negative studies, our results show that the futility approaches based on testing the alternative hypothesis and repeated confidence interval rules yielded less savings (compared to the other two rules). These boundaries are too conservative, especially during the first half of the study (<50% of information). The conditional power rules are too aggressive during the second half of the study (>50% of information) and may stop a trial even when there is a clinically meaningful treatment effect. The linear inefficacy boundary with three or more interim analyses provided the best results. For positive studies, we demonstrated that none of the futility rules would have stopped the trials. Conclusion: The linear inefficacy boundary futility approach is attractive from statistical, clinical, and logistical standpoints in clinical trials evaluating new anti-cancer agents.

scholarly journals Physiological Correlates of Sensory Consciousness: Evidence for a Generalized Awareness Negativity

2021 ◽  
Author(s):  
Cole Dembski ◽  
Christof Koch ◽  
Michael Pitts
Keyword(s):  
Experimental Studies ◽  
Neural Correlates ◽  
Stimulus Onset ◽  
Convincing Evidence ◽  
Future Research ◽  
Neural Signals ◽  
Tactile Stimuli ◽  
Neurological Patients ◽  
Sensory Cortices ◽  
Sensory Consciousness

We critically review the recent literature on six EEG and MEG markers of the neural correlates of consciousness (NCC) for visual, auditory and tactile stimuli in neurotypical volunteers and neurological patients. After ruling out four of these as candidate NCC, we focus on two prominent evoked signals: an early, modality-specific negativity, termed the visual or auditory awareness negativity (VAN and AAN, respectively) and a late, modality-independent positivity termed the P3b. More than twelve diverse experimental studies found that the P3b is absent despite consciously seeing, hearing, or feeling stimuli, ruling out the P3b as a true NCC. In contrast, no convincing evidence for a dissociation between the awareness negativities and consciousness has been reported thus far. Furthermore, there is evidence for an equivalent signal in the tactile domain, which we term the somatosensory awareness negativity (SAN). These three neural signals are usually maximal on the side of the scalp contralateral to the evoking stimulus, above the associated sensory cortices. We conclude that the data from these three modalities is consistent with a generalized awareness negativity (GAN) correlated with perceptual consciousness that arises 120-200 ms following stimulus onset and originates from the underlying sensory cortices. The identification of this GAN points towards new, promising avenues for future research and raises an array of concrete questions that can be empirically investigated.

Sign in / Sign up

Export Citation Format

Share Document