scholarly journals Neural Correlates of Cognition in Primary Visual versus Neighboring Posterior Cortices during Visual Evidence-Accumulation-based Navigation

2019 ◽  
Author(s):  
Sue Ann Koay ◽  
Stephan Y. Thiberge ◽  
Carlos D. Brody ◽  
David W. Tank
Keyword(s):  
Neural Activity ◽  
Visual Cues ◽  
Feedback Loop ◽  
Main Role ◽  
List Type ◽  
Perceptual Decision Making ◽  
Visual Evidence ◽  
Visual Cortices ◽  
Sensory Responses

SummaryStudies of perceptual decision-making have often assumed that the main role of sensory cortices is to provide sensory input to downstream processes that accumulate and drive behavioral decisions. We performed a systematic comparison of neural activity in primary visual (V1) to secondary visual and retrosplenial cortices, as mice performed a task where they should accumulate pulsatile visual cues through time to inform a navigational decision. Even in V1, only a small fraction of neurons had sensory-like responses to cues. Instead, in all areas neurons were sequentially active, and contained information ranging from sensory to cognitive, including cue timings, evidence, place/time, decision and reward outcome. Per-cue sensory responses were amplitude-modulated by various cognitive quantities, notably accumulated evidence. This inspired a multiplicative feedback-loop circuit hypothesis that proposes a more intricate role of sensory areas in the accumulation process, and furthermore explains a surprising observation that perceptual discrimination deviates from Weber-Fechner Law.Highlights / eTOC BlurbMice made navigational decisions based on accumulating pulsatile visual cuesThe bulk of neural activity in visual cortices was sequential and beyond-sensoryAccumulated pulse-counts modulated sensory (cue) responses, suggesting feedbackA feedback-loop neural circuit explains behavioral deviations from Weber’s LawIn a task where navigation was informed by accumulated pulsatile visual evidence, neural activity in visual cortices predominantly coded for cognitive variables across multiple timescales, including outside of a visual processing context. Even sensory responses to visual pulses were amplitude-modulated by accumulated pulse counts and other variables, inspiring a multiplicative feedback-loop circuit hypothesis that in turn explained behavioral deviations from Weber-Fechner Law.

scholarly journals Responses of primate frontal cortex neurons during natural vocal communication

2015 ◽  
Vol 114 (2) ◽  
pp. 1158-1171 ◽  
Author(s):  
Cory T. Miller ◽  
A. Wren Thomas ◽  
Samuel U. Nummela ◽  
Lisa A. de la Mothe
Keyword(s):  
Frontal Cortex ◽  
Neural Activity ◽  
Vocal Communication ◽  
Language Evolution ◽  
Premotor Cortex ◽  
Neuron Activity ◽  
Call Production ◽  
Multiple Regions ◽  
Sensory Responses

The role of primate frontal cortex in vocal communication and its significance in language evolution have a controversial history. While evidence indicates that vocalization processing occurs in ventrolateral prefrontal cortex neurons, vocal-motor activity has been conjectured to be primarily subcortical and suggestive of a distinctly different neural architecture from humans. Direct evidence of neural activity during natural vocal communication is limited, as previous studies were performed in chair-restrained animals. Here we recorded the activity of single neurons across multiple regions of prefrontal and premotor cortex while freely moving marmosets engaged in a natural vocal behavior known as antiphonal calling. Our aim was to test whether neurons in marmoset frontal cortex exhibited responses during vocal-signal processing and/or vocal-motor production in the context of active, natural communication. We observed motor-related changes in single neuron activity during vocal production, but relatively weak sensory responses for vocalization processing during this natural behavior. Vocal-motor responses occurred both prior to and during call production and were typically coupled to the timing of each vocalization pulse. Despite the relatively weak sensory responses a population classifier was able to distinguish between neural activity that occurred during presentations of vocalization stimuli that elicited an antiphonal response and those that did not. These findings are suggestive of the role that nonhuman primate frontal cortex neurons play in natural communication and provide an important foundation for more explicit tests of the functional contributions of these neocortical areas during vocal behaviors.

scholarly journals Rhythmic modulation of visual perception by continuous rhythmic auditory stimulation

2020 ◽  
Author(s):  
Anna-Katharina R. Bauer ◽  
Freek van Ede ◽  
Andrew J. Quinn ◽  
Anna C. Nobre
Keyword(s):  
Visual Perception ◽  
Neural Activity ◽  
Sensory Modality ◽  
Auditory Stimulation ◽  
Visual Performance ◽  
List Type ◽  
Sensory Modalities ◽  
Visual Areas ◽  
Visual Cortical

AbstractAt any given moment our sensory systems receive multiple, often rhythmic, inputs from the environment. Processing of temporally structured events in one sensory modality can guide both behavioural and neural processing of events in other sensory modalities, but how this occurs remains unclear. Here, we used human electroencephalography (EEG) to test the cross-modal influences of a continuous auditory frequency-modulated (FM) sound on visual perception and visual cortical activity. We report systematic fluctuations in perceptual discrimination of brief visual stimuli in line with the phase of the FM sound. We further show that this rhythmic modulation in visual perception is related to an accompanying rhythmic modulation of neural activity recorded over visual areas. Importantly, in our task, perceptual and neural visual modulations occurred without any abrupt and salient onsets in the energy of the auditory stimulation and without any rhythmic structure in the visual stimulus. As such, the results provide a critical validation for the existence and functional role of cross-modal entrainment and demonstrates its utility for organising the perception of multisensory stimulation in the natural environment.Highlightscross-modal influences are mediated by the synchronisation of neural oscillationsvisual performance fluctuates in line with the phase of a frequency-modulated soundcross-modal entrainment of neural activity predicts fluctuation in visual performancecross-modal entrainment organises perception of multisensory stimuli

scholarly journals Clustering-based positive feedback between a kinase and its substrate enables effective T-cell receptor signaling

2020 ◽  
Author(s):  
Elliot Dine ◽  
Ellen H. Reed ◽  
Jared E. Toettcher
Keyword(s):  
T Cell ◽  
Positive Feedback ◽  
Feedback Loop ◽  
Src Family Kinases ◽  
Molecular Organization ◽  
List Type ◽  
Positive Feedback Loop ◽  
Downstream Signaling ◽  
Protein Clusters

AbstractProtein clusters and condensates are pervasive in mammalian signaling. Yet how the signaling capacity of higher-order assemblies differs from simpler forms of molecular organization is still poorly understood. Here, we present an optogenetic approach to switch between light-induced clusters and simple protein heterodimers with a single point mutation. We apply this system to study how clustering affects signaling from the kinase Zap70 and its substrate LAT, proteins that normally form membrane-localized clusters during T cell activation. We find that light-induced clusters of LAT and Zap70 trigger potent activation of downstream signaling pathways even in non-T cells, whereas one-to-one dimers do not. We provide evidence that clusters harbor a local positive feedback loop between three components: Zap70, LAT, and Src-family kinases that bind to phosphorylated LAT and further activate Zap70. Overall, our study provides evidence for a specific role of protein condensates in cell signaling, and identifies a simple biochemical circuit that can robustly sense protein oligomerization state.Highlights-A general system for studying the role of protein clusters versus dimers.-Membrane clusters of the kinase Zap70 and its substrate LAT trigger potent downstream signaling.-Clustering Zap70 with LAT is required for full activation of Zap70 kinase activity.-A positive feedback loop connects phosphorylated LAT to Zap70 activation via Src-family kinases.

scholarly journals Amplitude modulations of sensory responses, and deviations from Weber’s Law in pulsatile evidence accumulation

2020 ◽  
Author(s):  
Sue Ann Koay ◽  
Stephan Y. Thiberge ◽  
Carlos D. Brody ◽  
David W. Tank
Keyword(s):  
Feedback Loop ◽  
Gain Control ◽  
Ongoing Activity ◽  
Posterior Cortex ◽  
Neural Data ◽  
Evidence Accumulation ◽  
Neuronal Populations ◽  
Visual Evidence ◽  
Sensory Responses ◽  
The Brain

AbstractHow do animals make behavioral decisions based on noisy sensory signals, which are moreover a tiny fraction of ongoing activity in the brain? Some theories suggest that sensory responses should be accumulated through time to reduce noise. Others suggest that feedback-based gain control of sensory responses allow small signals to be selectively amplified to drive behavior. We recorded from neuronal populations across posterior cortex as mice performed a decision-making task based on accumulating randomly timed pulses of visual evidence. Here we focus on a subset of neurons, with putative sensory responses that were time-locked to each pulse. These neurons exhibited a variety of amplitude (gain-like) modulations, notably by choice and accumulated evidence. These neural data inspired a hypothetical accumulation circuit with a multiplicative feedback-loop architecture, which parsimoniously explains deviations in perceptual discrimination from Weber-Fechner Law. Our neural observations thus led to a model that synthesizes both accumulation and feedback hypotheses.

scholarly journals Prestimulus Subsequent Memory Effects for Auditory and Visual Events

2010 ◽  
Vol 22 (6) ◽  
pp. 1212-1223 ◽  
Author(s):  
Leun J. Otten ◽  
Angela H. Quayle ◽  
Bhamini Puvaneswaran
Keyword(s):  
Neural Activity ◽  
Visual Cues ◽  
Brain Activity ◽  
Memory Formation ◽  
Functional Interpretation ◽  
General Role ◽  
Electrical Brain Activity ◽  
Visual Events ◽  
Set Up

It has been assumed that the effective encoding of information into memory primarily depends on neural activity elicited when an event is initially encountered. Recently, it has been shown that memory formation also relies on neural activity just before an event. The precise role of such activity in memory is currently unknown. Here, we address whether prestimulus activity affects the encoding of auditory and visual events, is set up on a trial-by-trial basis, and varies as a function of the type of recognition judgment an item later receives. Electrical brain activity was recorded from the scalps of 24 healthy young adults while they made semantic judgments on randomly intermixed series of visual and auditory words. Each word was preceded by a cue signaling the modality of the upcoming word. Auditory words were preceded by auditory cues and visual words by visual cues. A recognition memory test with remember/know judgments followed after a delay of about 45 min. As observed previously, a negative-going, frontally distributed modulation just before visual word onset predicted later recollection of the word. Crucially, the same effect was found for auditory words and observed on stay as well as switch trials. These findings emphasize the flexibility and general role of prestimulus activity in memory formation, and support a functional interpretation of the activity in terms of semantic preparation. At least with an unpredictable trial sequence, the activity is set up anew on each trial.

scholarly journals Rat Prefrontal Cortex Inactivations during Decision Making Are Explained by Bistable Attractor Dynamics

2017 ◽  
Vol 29 (11) ◽  
pp. 2861-2886 ◽  
Author(s):  
Alex T. Piet ◽  
Jeffrey C. Erlich ◽  
Charles D. Kopec ◽  
Carlos D. Brody
Keyword(s):  
Decision Making ◽  
Neural Activity ◽  
Memory Model ◽  
Network Configuration ◽  
Perceptual Decision Making ◽  
Attractor Networks ◽  
Attractor Dynamics ◽  
Flexible Models ◽  
Evidence Integration

Two-node attractor networks are flexible models for neural activity during decision making. Depending on the network configuration, these networks can model distinct aspects of decisions including evidence integration, evidence categorization, and decision memory. Here, we use attractor networks to model recent causal perturbations of the frontal orienting fields (FOF) in rat cortex during a perceptual decision-making task (Erlich, Brunton, Duan, Hanks, & Brody, 2015 ). We focus on a striking feature of the perturbation results. Pharmacological silencing of the FOF resulted in a stimulus-independent bias. We fit several models to test whether integration, categorization, or decision memory could account for this bias and found that only the memory configuration successfully accounts for it. This memory model naturally accounts for optogenetic perturbations of FOF in the same task and correctly predicts a memory-duration-dependent deficit caused by silencing FOF in a different task. Our results provide mechanistic support for a “postcategorization” memory role of the FOF in upcoming choices.

Role of spectrin in membrane fusion and in shape change of human erythrocyte ghost

1978 ◽  
Vol 36 (2) ◽  
pp. 328-329
Author(s):  
Hideo Hayashi ◽  
Yoshikazu Hirai ◽  
John T. Penniston
Keyword(s):  
Conformational Changes ◽  
Human Erythrocyte ◽  
Shape Change ◽  
Membrane Surface ◽  
Slight Modification ◽  
Active Role ◽  
Main Role ◽  
Bank Blood ◽  
Human Erythrocyte Ghost

Spectrin is a membrane associated protein most of which properties have been tentatively elucidated. A main role of the protein has been assumed to give a supporting structure to inside of the membrane. As reported previously, however, the isolated spectrin molecule underwent self assemble to form such as fibrous, meshwork, dispersed or aggregated arrangements depending upon the buffer suspended and was suggested to play an active role in the membrane conformational changes. In this study, the role of spectrin and actin was examined in terms of the molecular arrangements on the erythrocyte membrane surface with correlation to the functional states of the ghosts.Human erythrocyte ghosts were prepared from either freshly drawn or stocked bank blood by the method of Dodge et al with a slight modification as described before. Anti-spectrin antibody was raised against rabbit by injection of purified spectrin and partially purified.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

Sports Photography and Historical Development

2018 ◽  
Vol 5 (1) ◽  
pp. 93-115
Author(s):  
Miloš Stamenković
Keyword(s):  
Historical Development ◽  
Emotional Reaction ◽  
Main Role ◽  
Primary Role

SummarySports photography undoubtedly has a significant place in sports press and publicism. It’s main and primary role is to present sports to the readers as art, which it is. Sport is characterized by dynamic and varied movements, and the main role of sports photography is reflected in the fact that it is in this way that sport shows its essence. Having in mind that photography tells more than a thousand words it sends a clear message to the reader as well to people who are informed about events via sports portals. Sports photography is a multidimensional art for many reasons. When we say “multi”, it primarily refers to a wider range that sports photography has to offer, which means sports photography is not only directed at presenting athletes on the move and the main actors who contribute to achieving the results by their engagement – it also has the role of sports “psychophotography” which is an analysis and capture of the emotional reaction of an athlete after winning or losing from the opposing team.

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