Modulation of cortical circuits by top-down processing and arousal state in health and disease

2018 ◽  
Vol 52 ◽  
pp. 172-181 ◽  
Author(s):  
Renata Batista-Brito ◽  
Edward Zagha ◽  
Jacob M Ratliff ◽  
Martin Vinck
eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Luis Carlos Garcia del Molino ◽  
Guangyu Robert Yang ◽  
Jorge F Mejias ◽  
Xiao-Jing Wang

Pyramidal cells and interneurons expressing parvalbumin (PV), somatostatin (SST), and vasoactive intestinal peptide (VIP) show cell-type-specific connectivity patterns leading to a canonical microcircuit across cortex. Experiments recording from this circuit often report counterintuitive and seemingly contradictory findings. For example, the response of SST cells in mouse V1 to top-down behavioral modulation can change its sign when the visual input changes, a phenomenon that we call response reversal. We developed a theoretical framework to explain these seemingly contradictory effects as emerging phenomena in circuits with two key features: interactions between multiple neural populations and a nonlinear neuronal input-output relationship. Furthermore, we built a cortical circuit model which reproduces counterintuitive dynamics observed in mouse V1. Our analytical calculations pinpoint connection properties critical to response reversal, and predict additional novel types of complex dynamics that could be tested in future experiments.


2021 ◽  
Author(s):  
Maria Kon ◽  
Gregory Francis

A fundamental characteristic of human visual perception is the ability to group together disparate elements in a scene and treat them as a single unit. The mechanisms by which humans create such groupings remain unknown, but grouping seems to play an important role in a wide variety of visual phenomena, and a good understanding of these mechanisms might provide guidance for how to improve machine vision algorithms. Here, we build on a proposal that some groupings are the result of connections in cortical area V2 that join disparate elements, thereby allowing them to be selected and segmented together. In previous instantiations of this proposal, connection formation was based on the anatomy (e.g., extent) of receptive fields, which made connection formation obligatory when the stimulus conditions stimulate the corresponding receptive fields. We now propose dynamic circuits that provide greater flexibility in the formation of connections and that allow for top-down control of perceptual grouping. With computer simulations we explain how the circuits work and show how they can account for a wide variety of Gestalt principles of perceptual grouping and two texture segmentation tasks. We propose that human observers use such top-down control to implement task-dependent connection strategies that encourage particular groupings of stimulus elements in order to promote performance on various kinds of visual tasks.


2017 ◽  
Author(s):  
Luis Carlos Garcia del Molino ◽  
Guangyu Robert Yang ◽  
Jorge F Mejias ◽  
Xiao-Jing Wang

2016 ◽  
Author(s):  
Ilya E. Monosov

SummaryExpectations of rewards and punishments can promote similar behavioral states, such as vigilance, as well as distinct behavioral states, such as approach or avoidance. However, the cortical circuits that underlie this behavioral diversity are poorly understood. In a Pavlovian procedure in which monkeys displayed a diverse repertoire of reward, punishment, and uncertainty related behaviors not mandated by the task, I show that many anterior-cingulate (ACC) neurons represent expected value and uncertainty in a valence-specific manner, for example about either rewards or punishments. This flexibility may facilitate the top-down control of many reward- and punishment-related actions and behavioral states.


PROTEOMICS ◽  
2014 ◽  
Vol 14 (10) ◽  
pp. 1195-1210 ◽  
Author(s):  
Zachery R. Gregorich ◽  
Ying Ge

2017 ◽  
Author(s):  
Luis Carlos Garcia del Molino ◽  
Guangyu Robert Yang ◽  
Jorge F Mejias ◽  
Xiao-Jing Wang

2017 ◽  
Author(s):  
Luis Carlos Garcia del Molino ◽  
Guangyu Robert Yang ◽  
Jorge F. Mejias ◽  
Xiao-Jing Wang

AbstractPyramidal cells and interneurons expressing parvalbumin, somatostatin, or vasoactive intestinal peptide show cell type-specific connectivity patterns leading to a canonical microcircuit across cortex. Dissecting the dynamics of this microcircuit is essential to our understanding of the mammalian cortex. However, experiments recording from this circuit often report counterintuitive and seemingly contradictory findings. For example, the response of a V1 neural population to top-down behavioral modulation can reverse from positive to negative when the bottom-up thalamic input changes. We developed a theoretical framework to explain such response reversal, and we showed how this complex dynamics can emerge in circuits that possess two key features: the presence of multiple interneuron populations and a non-linear dependence between the input and output of the populations. Furthermore, we built a cortical circuit model and the comparison of our simulations with real data shows that our model reproduces the complex dynamics observed experimentally in mouse V1. Our explicit calculations allowed us to pinpoint the connections critical to response reversal, and to predict the existence of more types of complex dynamics that could be experimentally tested and the conditions to observe them.


2020 ◽  
Author(s):  
Kevin Jooß ◽  
Luis F. Schachner ◽  
Rachel Watson ◽  
Zachary B. Gillespie ◽  
Sarah A. Howard ◽  
...  

AbstractWe report a novel platform (native capillary zone electrophoresis – top-down mass spectrometry; nCZE-TDMS) for the separation and characterization of whole nucleosomes, their histone subunits, and PTMs. As the repeating unit of chromatin, mononucleosomes (Nucs) are a ~200 kDa complex of DNA and histone proteins involved in the regulation of key cellular processes central to human health and disease. Unraveling the covalent modification landscape of histones and their defined stoichiometries within Nucs helps to explain epigenetic regulatory mechanisms. In nCZE-TDMS, online Nuc separation is followed by a three-tier tandem MS approach that measures the intact mass of Nucs, ejects and detects the constituent histones, and fragments to sequence the histone. The new platform was optimized with synthetic Nucs to reduce both sample requirements and cost significantly compared to direct infusion. Limits of detection were in the low attomole range, with linearity over ~three orders of magnitude. The nCZE-TDMS platform was applied to endogenous Nucs from two cell lines distinguished by overexpression or knockout of histone methyltransferase NSD2/MMSET, where analysis of constituent histones revealed changes in histone abundances over the course of the CZE separation. We are confident the nCZE-TDMS platform will help advance nucleosome-level research in the fields of chromatin and epigenetics.


Author(s):  
Rebecca Jordan ◽  
Georg B. Keller

ABSTRACTProcessing in cortical circuits is driven by combinations of cortical and subcortical inputs. These signals are often conceptually categorized as bottom-up input, conveying sensory information, and top-down input, conveying contextual information. Using intracellular recordings in mouse visual cortex, we measured neuronal responses to visual input, locomotion, and visuomotor mismatches. We show that layer 2/3 (L2/3) neurons compute a difference between top-down motor-related input and bottom-up visual flow input. Most L2/3 neurons responded to visuomotor mismatch with either hyperpolarization or depolarization, and these two response types were associated with distinct physiological properties. Consistent with a subtraction of bottom-up and top-down input, visual and motor-related inputs had opposing influence in L2/3 neurons. In infragranular neurons, we found no evidence of a difference-computation and responses were consistent with a positive integration of visuomotor inputs. Our results provide evidence that L2/3 functions as a bidirectional comparator of top-down and bottom-up input.


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