scholarly journals Cortical suppressive waves shape the representation of long-range apparent motion

2018 ◽  
Author(s):  
S Chemla ◽  
A Reynaud ◽  
M di Volo ◽  
Y Zerlaut ◽  
L Perrinet ◽  
...  
Keyword(s):  
Apparent Motion ◽  
Gain Control ◽  
Motion Path ◽  
Object Identity ◽  
Temporal Separation ◽  
Cortical Dynamics ◽  
Population Responses ◽  
Temporal Succession ◽  
Spatio Temporal ◽  
The Brain

SummaryHow does the brain link visual stimuli across space and time? Visual illusions provide an experimental paradigm to study these processes. When two stationary dots are flashed in close spatial and temporal succession, human observers experience a percept of motion. Large spatio-temporal separation challenges the visual system to keep track of object identity along the apparent motion path. Here, we utilize voltage-sensitive dye imaging in primary visual cortex (V1) of the awake monkey to investigate whether intra-cortical connections within V1 can shape cortical dynamics to represent the illusory motion. We find that the arrival of the second stimulus in V1 creates a suppressive wave traveling toward the retinotopic representation of the first. Computational approaches show that this suppressive wave can be explained by recurrent gain control fed by the intra-cortical network and contributes to precisely encode the expected motion velocity. We suggest that non-linear intra-cortical dynamics preformat population responses in V1 for optimal read-out by downstream areas.

Magnetoencephalography and the Cortical Dynamics of Language Processing

2019 ◽  
pp. 114-153
Author(s):  
Riitta Salmelin ◽  
Jan Kujala ◽  
Mia Liljeström
Keyword(s):  
Language Processing ◽  
Language Disorders ◽  
Scientific Data ◽  
Neural Processing ◽  
Powerful Method ◽  
Cortical Dynamics ◽  
Brain Correlates ◽  
Adults And Children ◽  
The Brain ◽  
Selection Of

When seeking to uncover the brain correlates of language processing, timing and location are of the essence. Magnetoencephalography (MEG) offers them both, with the highest sensitivity to cortical activity. MEG has shown its worth in revealing cortical dynamics of reading, speech perception, and speech production in adults and children, in unimpaired language processing as well as developmental and acquired language disorders. The MEG signals, once recorded, provide an extensive selection of measures for examination of neural processing. Like all other neuroimaging tools, MEG has its own strengths and limitations of which the user should be aware in order to make the best possible use of this powerful method and to generate meaningful and reliable scientific data. This chapter reviews MEG methodology and how MEG has been used to study the cortical dynamics of language.

scholarly journals Decision-related feedback in visual cortex lacks spatial selectivity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Katrina R. Quinn ◽  
Lenka Seillier ◽  
Daniel A. Butts ◽  
Hendrikje Nienborg
Keyword(s):  
Contextual Information ◽  
Relevant Information ◽  
Common Mechanism ◽  
Spatial Selectivity ◽  
Population Responses ◽  
Stimulus Choice ◽  
Visual Areas ◽  
Computational Work ◽  
Feature Based ◽  
The Brain

AbstractFeedback in the brain is thought to convey contextual information that underlies our flexibility to perform different tasks. Empirical and computational work on the visual system suggests this is achieved by targeting task-relevant neuronal subpopulations. We combine two tasks, each resulting in selective modulation by feedback, to test whether the feedback reflected the combination of both selectivities. We used visual feature-discrimination specified at one of two possible locations and uncoupled the decision formation from motor plans to report it, while recording in macaque mid-level visual areas. Here we show that although the behavior is spatially selective, using only task-relevant information, modulation by decision-related feedback is spatially unselective. Population responses reveal similar stimulus-choice alignments irrespective of stimulus relevance. The results suggest a common mechanism across tasks, independent of the spatial selectivity these tasks demand. This may reflect biological constraints and facilitate generalization across tasks. Our findings also support a previously hypothesized link between feature-based attention and decision-related activity.

Effect of background clutter on neural discrimination in the bat auditory midbrain

2021 ◽  
Author(s):  
Kathryne M Allen ◽  
Angeles Salles ◽  
Sanwook Park ◽  
Mounya Elhilali ◽  
Cynthia F. Moss
Keyword(s):  
Acoustic Scattering ◽  
Object Discrimination ◽  
Complex Environments ◽  
Acoustic Features ◽  
Temporal Separation ◽  
Complex Sounds ◽  
Electrophysiological Recordings ◽  
Background Clutter ◽  
Spatio Temporal ◽  
Neural Underpinnings

The discrimination of complex sounds is a fundamental function of the auditory system. This operation must be robust in the presence of noise and acoustic clutter. Echolocating bats are auditory specialists that discriminate sonar objects in acoustically complex environments. Bats produce brief signals, interrupted by periods of silence, rendering echo snapshots of sonar objects. Sonar object discrimination requires that bats process spatially and temporally overlapping echoes to make split-second decisions. The mechanisms that enable this discrimination are not well understood, particularly in complex environments. We explored the neural underpinnings of sonar object discrimination in the presence of acoustic scattering caused by physical clutter. We performed electrophysiological recordings in the inferior colliculus of awake big brown bats, to broadcasts of pre-recorded echoes from physical objects. We acquired single unit responses to echoes and discovered a sub-population of IC neurons that encode acoustic features that can be used to discriminate between sonar objects. We further investigated the effects of environmental clutter on this population's encoding of acoustic features. We discovered that the effect of background clutter on sonar object discrimination is highly variable and depends on object properties and target-clutter spatio-temporal separation. In many conditions, clutter impaired discrimination of sonar objects. However, in some instances clutter enhanced acoustic features of echo returns, enabling higher levels of discrimination. This finding suggests that environmental clutter may augment acoustic cues used for sonar target discrimination and provides further evidence in a growing body of literature that noise is not universally detrimental to sensory encoding.

scholarly journals Cloning, Characterization, and Expression Features of Chicken CDS2 Splicing Variants

2020 ◽  
Author(s):  
Yuanyuan Xu ◽  
Shuping Zhang ◽  
Yujun Guo ◽  
Wen Chen ◽  
Yanqun Huang
Keyword(s):  
Adipose Tissue ◽  
Real Time ◽  
Real Time Pcr ◽  
Expression Patterns ◽  
Mrna Levels ◽  
Exogenous Insulin ◽  
Quantitative Real Time Pcr ◽  
Temporal Expression ◽  
Spatio Temporal ◽  
The Brain

Abstract Background: The CDS gene encodes the CDP-diacylglycerol synthase enzyme that catalyzes the formation of CDP-diacylglycerol (CDP-DAG) from phosphatidic acid. At present, there are no reports of CDS2 in birds. Here, we identified chicken CDS2 transcripts by combining conventional RT- PCR amplification, 5' RACE (Fig. 1A), and 3' RACE, explored the spatio-temporal expression profiles of total CDS2 and the longest transcript variant CDS2-4, and investigated the effect of exogenous insulin on total the mRNA level of CDS2 by quantitative real-time PCR. Results: Four transcripts of chicken CDS2 (CDS2-1, -2, -3, and -4) were identified, which were alternatively spliced at the 3′-untranslated region (UTR). CDS2 was widely expressed in all tissues examined and the longest variant CDS2-4 was the major transcript. Both total CDS2 and CDS2-4 were prominently expressed in adipose tissue and the heart, and exhibited low expression in the liver and pectoralis of 49 day-old chickens. Quantitative real-time PCR revealed that total CDS2 and CDS2-4 had different spatio-temporal expression patterns in chicken. Total CDS2 exhibited a similar temporal expression tendency with a high level in the later period of incubation (embryonic day 19 [E19] or 1-day-old) in the brain, liver, and pectoralis. While CDS2-4 presented a distinct temporal expression pattern in these tissues, CDS2-4 levels peaked at 21 days in the brain and pectoralis, while liver CDS2-4 mRNA levels were highest at the early stage of hatching (E10). Total CDS2 (P < 0.001) and CDS2-4 (P = 0.0090) mRNA levels in the liver were differentially regulated throughout development of the chicken. Exogenous insulin significantly downregulated the level of total CDS2 at 240 min in the pectoralis of Silky chickens (P < 0.01). Total CDS2 levels in the liver of Silky chickens were higher than that of the broiler in the basal state and after insulin stimulation. Conclusion: Chicken CDS2 has multiple transcripts with variation at the 3′-UTR, which was prominently expressed in adipose tissue. Total CDS2 and CDS2-4 presented distinct spatio-temporal expression patterns, and they were differentially regulated with age in liver. Insulin could regulate chicken CDS2 levels in a breed- and tissue-specific manner.

scholarly journals The relative coding strength of object identity and nonidentity features in human occipito-temporal cortex and convolutional neural networks

2020 ◽  
Author(s):  
Yaoda Xu ◽  
Maryam Vaziri-Pashkam
Keyword(s):  
Visual Processing ◽  
Visual Pathway ◽  
Feature Representation ◽  
Object Categorization ◽  
Object Identity ◽  
Visual Areas ◽  
Ventral Visual Pathway ◽  
Identity Representation ◽  
The Brain ◽  
Early Human

ABSTRACTAny given visual object input is characterized by multiple visual features, such as identity, position and size. Despite the usefulness of identity and nonidentity features in vision and their joint coding throughout the primate ventral visual processing pathway, they have so far been studied relatively independently. Here we document the relative coding strength of object identity and nonidentity features in a brain region and how this may change across the human ventral visual pathway. We examined a total of four nonidentity features, including two Euclidean features (position and size) and two non-Euclidean features (image statistics and spatial frequency content of an image). Overall, identity representation increased and nonidentity feature representation decreased along the ventral visual pathway, with identity outweighed the non-Euclidean features, but not the Euclidean ones, in higher levels of visual processing. A similar analysis was performed in 14 convolutional neural networks (CNNs) pretrained to perform object categorization with varying architecture, depth, and with/without recurrent processing. While the relative coding strength of object identity and nonidentity features in lower CNN layers matched well with that in early human visual areas, the match between higher CNN layers and higher human visual regions were limited. Similar results were obtained regardless of whether a CNN was trained with real-world or stylized object images that emphasized shape representation. Together, by measuring the relative coding strength of object identity and nonidentity features, our approach provided a new tool to characterize feature coding in the human brain and the correspondence between the brain and CNNs.SIGNIFICANCE STATEMENTThis study documented the relative coding strength of object identity compared to four types of nonidentity features along the human ventral visual processing pathway and compared brain responses with those of 14 CNNs pretrained to perform object categorization. Overall, identity representation increased and nonidentity feature representation decreased along the ventral visual pathway, with the coding strength of the different nonidentity features differed at higher levels of visual processing. While feature coding in lower CNN layers matched well with that of early human visual areas, the match between higher CNN layers and higher human visual regions were limited. Our approach provided a new tool to characterize feature coding in the human brain and the correspondence between the brain and CNNs.

Neuroethics

2021 ◽  
pp. 405-420
Author(s):  
Georg Northoff
Keyword(s):  
Deep Brain Stimulation ◽  
Psychiatric Disorders ◽  
Brain Stimulation ◽  
Empirical Data ◽  
Moral Agency ◽  
Ethical Issues ◽  
Spatio Temporal ◽  
The Brain ◽  
Deep Brain

Neuroethics, located at the interface of conceptual and empirical dimensions, carries major implications for psychiatry, such as the neuroscientific basis of ethical concepts as moral agency. Drawing on data in neuroscience, this chapter highlights issues central to psychiatric ethics. First, it addresses a reductionistic model of the brain, often conceived as purely neuronal, and then it discusses empirical data suggesting that the brain’s activity is strongly aligned to its respective social (e.g., relation to others) and ecological (e.g., relation to the environment and nature) contexts; this implies a relational rather than reductionist model. Second, it suggests that self (e.g., the experience or sense of a self) and personhood (e.g., the person as existent independent of experience) must also be understood in such a social and ecological and, therefore, relational and spatio-temporal sense. Ethical concepts like agency, therefore, cannot be limited solely to the person and brain, but must rather be understood in a relational and neuro-ecological/social way. Third, it discusses deep brain stimulation as a treatment that promotes enhancement. In sum, this chapter presents findings in neuroscience that carry major implications for our view of brain, mental features, psychiatric disorders, and ethical issues like agency, responsibility, and enhancement.

4. Motion perception

2017 ◽  
pp. 50-58
Author(s):  
Brian Rogers
Keyword(s):  
Motion Perception ◽  
Apparent Motion ◽  
Time To Contact ◽  
Motion System ◽  
Visual Systems ◽  
Temporal Process ◽  
The World ◽  
Induced Motion ◽  
After Effect ◽  
Spatio Temporal

The ability to detect motion is one of the most important properties of our visual system and the visual systems of nearly every other species. Motion perception is not just important for detecting the movement of objects—both for catching prey and for avoiding predators—but it is also important for providing information about the 3-D structure of the world, for maintaining balance, determining our direction of heading, segregating the scene and breaking camouflage, and judging time-to-contact with other objects in the world. ‘Motion perception’ describes the spatio-temporal process of motion perception and the perceptual effects that tell us something about the characteristics of the motion system: apparent motion, the motion after-effect, and induced motion.

scholarly journals Capillary-associated microglia regulate vascular structure and function through PANX1-P2RY12 coupling in mice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kanchan Bisht ◽  
Kenneth A. Okojie ◽  
Kaushik Sharma ◽  
Dennis H. Lentferink ◽  
Yu-Yo Sun ◽  
...  
Keyword(s):  
Myeloid Cell ◽  
Structure And Function ◽  
Pannexin 1 ◽  
Vascular Physiology ◽  
Blood Flow Increase ◽  
Bona Fide ◽  
Spatio Temporal ◽  
And Function ◽  
The Brain

AbstractMicroglia are brain-resident immune cells with a repertoire of functions in the brain. However, the extent of their interactions with the vasculature and potential regulation of vascular physiology has been insufficiently explored. Here, we document interactions between ramified CX3CR1 + myeloid cell somata and brain capillaries. We confirm that these cells are bona fide microglia by molecular, morphological and ultrastructural approaches. Then, we give a detailed spatio-temporal characterization of these capillary-associated microglia (CAMs) comparing them with parenchymal microglia (PCMs) in their morphological activities including during microglial depletion and repopulation. Molecularly, we identify P2RY12 receptors as a regulator of CAM interactions under the control of released purines from pannexin 1 (PANX1) channels. Furthermore, microglial elimination triggered capillary dilation, blood flow increase, and impaired vasodilation that were recapitulated in P2RY12−/− and PANX1−/− mice suggesting purines released through PANX1 channels play important roles in activating microglial P2RY12 receptors to regulate neurovascular structure and function.

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