scholarly journals Behavioural test battery for the Back of the Brain project

2021 ◽  
Author(s):  
Ro Julia Robotham ◽  
Sheila Kerry ◽  
Grace E Rice ◽  
Alex Leff ◽  
Matt Lambon Ralph ◽  
...  
Keyword(s):  
Visual Perception ◽  
Cerebral Artery ◽  
Visual Recognition ◽  
Posterior Cerebral Artery ◽  
Test Battery ◽  
Low Level ◽  
Symptom Profile ◽  
Behavioural Test ◽  
High Level ◽  
The Brain

Much of the patient literature on the visual recognition of faces, words and objects is based on single case studies of patients selected according to their symptom profile. The Back of the Brain project aims to provide novel insights into the cerebral and cortical architecture underlying visual recognition of complex stimuli by adopting a different approach. A large group of patients was recruited according to their lesion location (in the areas supplied by the posterior cerebral artery) rather than their symptomatology. All patients were assessed with the same battery of sensitive tests of visual perception enabling the identification of dissociations as well as associations between deficits in face, word and object recognition. This paper provides a detailed description of the extensive behavioural test battery that was developed for the Back of the Brain project and that enables assessment of low-level, intermediate and high-level visual perceptual abilities. •Extensive behavioural test battery for assessing low-level, intermediate and high-level visual perception in patients with posterior cerebral artery stroke •Method enabling direct comparison of visual face, word and object processing abilities in patients with posterior cerebral artery stroke

scholarly journals Visual perception as retrospective Bayesian decoding from high- to low-level features

2017 ◽  
Vol 114 (43) ◽  
pp. E9115-E9124 ◽  
Author(s):  
Stephanie Ding ◽  
Christopher J. Cueva ◽  
Misha Tsodyks ◽  
Ning Qian
Keyword(s):  
Working Memory ◽  
Visual Perception ◽  
Human Perception ◽  
Quantitative Comparison ◽  
Global Precedence ◽  
Low Level ◽  
Memory Representations ◽  
High Level ◽  
The Brain ◽  
Different Parts

When a stimulus is presented, its encoding is known to progress from low- to high-level features. How these features are decoded to produce perception is less clear, and most models assume that decoding follows the same low- to high-level hierarchy of encoding. There are also theories arguing for global precedence, reversed hierarchy, or bidirectional processing, but they are descriptive without quantitative comparison with human perception. Moreover, observers often inspect different parts of a scene sequentially to form overall perception, suggesting that perceptual decoding requires working memory, yet few models consider how working-memory properties may affect decoding hierarchy. We probed decoding hierarchy by comparing absolute judgments of single orientations and relative/ordinal judgments between two sequentially presented orientations. We found that lower-level, absolute judgments failed to account for higher-level, relative/ordinal judgments. However, when ordinal judgment was used to retrospectively decode memory representations of absolute orientations, striking aspects of absolute judgments, including the correlation and forward/backward aftereffects between two reported orientations in a trial, were explained. We propose that the brain prioritizes decoding of higher-level features because they are more behaviorally relevant, and more invariant and categorical, and thus easier to specify and maintain in noisy working memory, and that more reliable higher-level decoding constrains less reliable lower-level decoding.

scholarly journals A neurocognitive model of ideological thinking

2021 ◽  
pp. 1-15
Author(s):  
Leor Zmigrod
Keyword(s):  
Empirical Evidence ◽  
Motivational Factors ◽  
Cognitive Systems ◽  
Social Forces ◽  
Low Level ◽  
Cognitive Principles ◽  
High Level ◽  
Ideological Attitudes ◽  
The Brain

Abstract Ideological behavior has traditionally been viewed as a product of social forces. Nonetheless, an emerging science suggests that ideological worldviews can also be understood in terms of neural and cognitive principles. The article proposes a neurocognitive model of ideological thinking, arguing that ideological worldviews may be manifestations of individuals’ perceptual and cognitive systems. This model makes two claims. First, there are neurocognitive antecedents to ideological thinking: the brain’s low-level neurocognitive dispositions influence its receptivity to ideological doctrines. Second, there are neurocognitive consequences to ideological engagement: strong exposure and adherence to ideological doctrines can shape perceptual and cognitive systems. This article details the neurocognitive model of ideological thinking and synthesizes the empirical evidence in support of its claims. The model postulates that there are bidirectional processes between the brain and the ideological environment, and so it can address the roles of situational and motivational factors in ideologically motivated action. This endeavor highlights that an interdisciplinary neurocognitive approach to ideologies can facilitate biologically informed accounts of the ideological brain and thus reveal who is most susceptible to extreme and authoritarian ideologies. By investigating the relationships between low-level perceptual processes and high-level ideological attitudes, we can develop a better grasp of our collective history as well as the mechanisms that may structure our political futures.

scholarly journals Perceptual decisions are biased toward relevant prior choices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helen Feigin ◽  
Shira Baror ◽  
Moshe Bar ◽  
Adam Zaidel
Keyword(s):  
Sensory Information ◽  
Irrelevant Stimulus ◽  
Stimulus Feature ◽  
Serial Dependence ◽  
Low Level ◽  
Subsequent Test ◽  
Key Factor ◽  
High Level ◽  
Motor Actions ◽  
The Brain

AbstractPerceptual decisions are biased by recent perceptual history—a phenomenon termed 'serial dependence.' Here, we investigated what aspects of perceptual decisions lead to serial dependence, and disambiguated the influences of low-level sensory information, prior choices and motor actions. Participants discriminated whether a brief visual stimulus lay to left/right of the screen center. Following a series of biased ‘prior’ location discriminations, subsequent ‘test’ location discriminations were biased toward the prior choices, even when these were reported via different motor actions (using different keys), and when the prior and test stimuli differed in color. By contrast, prior discriminations about an irrelevant stimulus feature (color) did not substantially influence subsequent location discriminations, even though these were reported via the same motor actions. Additionally, when color (not location) was discriminated, a bias in prior stimulus locations no longer influenced subsequent location discriminations. Although low-level stimuli and motor actions did not trigger serial-dependence on their own, similarity of these features across discriminations boosted the effect. These findings suggest that relevance across perceptual decisions is a key factor for serial dependence. Accordingly, serial dependence likely reflects a high-level mechanism by which the brain predicts and interprets new incoming sensory information in accordance with relevant prior choices.

scholarly journals Reconstructing feedback representations in ventral visual pathway with a generative adversarial autoencoder

2020 ◽  
Author(s):  
Haider Al-Tahan ◽  
Yalda Mohsenzadeh
Keyword(s):  
Neural Network ◽  
Visual Information ◽  
Visual Pathway ◽  
Functional Magnetic Resonance ◽  
Low Level ◽  
Ventral Visual Pathway ◽  
High Level ◽  
Feedback Connections ◽  
The Brain ◽  
Insight Into

AbstractWhile vision evokes a dense network of feedforward and feedback neural processes in the brain, visual processes are primarily modeled with feedforward hierarchical neural networks, leaving the computational role of feedback processes poorly understood. Here, we developed a generative autoencoder neural network model and adversarially trained it on a categorically diverse data set of images. We hypothesized that the feedback processes in the ventral visual pathway can be represented by reconstruction of the visual information performed by the generative model. We compared representational similarity of the activity patterns in the proposed model with temporal (magnetoencephalography) and spatial (functional magnetic resonance imaging) visual brain responses. The proposed generative model identified two segregated neural dynamics in the visual brain. A temporal hierarchy of processes transforming low level visual information into high level semantics in the feedforward sweep, and a temporally later dynamics of inverse processes reconstructing low level visual information from a high level latent representation in the feedback sweep. Our results append to previous studies on neural feedback processes by presenting a new insight into the algorithmic function and the information carried by the feedback processes in the ventral visual pathway.Author summaryIt has been shown that the ventral visual cortex consists of a dense network of regions with feedforward and feedback connections. The feedforward path processes visual inputs along a hierarchy of cortical areas that starts in early visual cortex (an area tuned to low level features e.g. edges/corners) and ends in inferior temporal cortex (an area that responds to higher level categorical contents e.g. faces/objects). Alternatively, the feedback connections modulate neuronal responses in this hierarchy by broadcasting information from higher to lower areas. In recent years, deep neural network models which are trained on object recognition tasks achieved human-level performance and showed similar activation patterns to the visual brain. In this work, we developed a generative neural network model that consists of encoding and decoding sub-networks. By comparing this computational model with the human brain temporal (magnetoencephalography) and spatial (functional magnetic resonance imaging) response patterns, we found that the encoder processes resemble the brain feedforward processing dynamics and the decoder shares similarity with the brain feedback processing dynamics. These results provide an algorithmic insight into the spatiotemporal dynamics of feedforward and feedback processes in biological vision.

scholarly journals Multispectral molecular imaging of capillary endothelium to facilitate preoperative endovascular brain mapping

2009 ◽  
Vol 110 (5) ◽  
pp. 975-980 ◽  
Author(s):  
H. Charles Manning ◽  
Sheila D. Shay ◽  
Robert A. Mericle
Keyword(s):  
Molecular Imaging ◽  
Cerebral Artery ◽  
Brain Mapping ◽  
Right Hemisphere ◽  
Posterior Cerebral Artery ◽  
Vascular Occlusion ◽  
Brain Parenchyma ◽  
Capillary Endothelium ◽  
Imaging Probe ◽  
The Brain

Object Brain mapping aims to localize neurological function to specific regions of the human brain. Preoperative endovascular brain mapping (PEBM) is a novel approach that allows clear visualization of nonfunctional (silent) brain parenchyma in real time during a resection. It has potential to improve neurosurgical guidance because brain shift does not alter the maps, and the map is visualized directly on the brain in situ rather than on a nearby image. Therefore, the risk of a new neurological deficit should be reduced. The authors report the first PEBM approach that combines selective molecular targeting of brain endothelium with multispectral (optical) imaging in preclinical animal models. Methods Sprague-Dawley rats and New Zealand white rabbits were selectively catheterized, and a fluorescein isothiocyanate–derivatized tomato lectin–based imaging probe was administered into the carotid artery or posterior cerebral artery, measuring < 500 μm in diameter. After binding/uptake of the imaging probe, and removal of unbound probe, a craniotomy was performed to directly visualize the “brain map.” Results Selective localization of the imaging probe to the right hemisphere in rats or right posterior cerebral artery in rabbits was clearly visualized after craniotomy. Cross-sections of stained capillaries demonstrated that the imaging probe did not cause vascular occlusion. Gross regional selectivity of the imaging probe was documented by multispectral molecular imaging of intact brains, with discrete localization and endothelium-directed targeting validated by histological examination. Conclusions The authors have demonstrated the first molecular endothelium-targeted approach to PEBM that does not require manipulation of the intact blood-brain barrier or result in vascular occlusion. Furthermore, the presented multispectral molecular imaging technique appears to be a suitable methodology for the generation of region-selective brain maps of vascularized brain parenchyma. Further refinement of the PEBM approach, as well as the development of improved imaging probes, may result in clinical advancement of PEBM where direct visual discrimination of nonfunctional silent brain parenchyma at the time of resection could significantly improve neurosurgical outcomes.

scholarly journals Electrophysiological signatures of hierarchical learning

2021 ◽  
Author(s):  
Meng Liu ◽  
Wenshan Dong ◽  
Shaozheng Qin ◽  
Tom Verguts ◽  
Qi Chen
Keyword(s):  
Cognitive Process ◽  
Human Perception ◽  
Learning Task ◽  
Prediction Errors ◽  
Neural Basis ◽  
Hierarchical Learning ◽  
Low Level ◽  
High Level ◽  
The Brain ◽  
Better Than

AbstractHuman perception and learning is thought to rely on a hierarchical generative model that is continuously updated via precision-weighted prediction errors (pwPEs). However, the neural basis of such cognitive process and how it unfolds during decision making, remain poorly understood. To investigate this question, we combined a hierarchical Bayesian model (i.e., Hierarchical Gaussian Filter, HGF) with electrophysiological (EEG) recording, while participants performed a probabilistic reversal learning task in alternatingly stable and volatile environments. Behaviorally, the HGF fitted significantly better than two control, non-hierarchical, models. Neurally, low-level and high-level pwPEs were independently encoded by the P300 component. Low-level pwPEs were reflected in the theta (4-8 Hz) frequency band, but high-level pwPEs were not. Furthermore, the expressions of high-level pwPEs were stronger for participants with better HGF fit. These results indicate that the brain employs hierarchical learning, and encodes both low- and high-level learning signals separately and adaptively.

scholarly journals A Way to Improve Functional Face Localiser: The Influence of Low-Level Visual Features

2018 ◽  
Author(s):  
Olga Korolkova
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Functional Mri ◽  
Intensity Distribution ◽  
Visual Features ◽  
Common Procedure ◽  
Low Level ◽  
Quality And Reliability ◽  
Areas Of Interest ◽  
The Brain

In functional MRI studies a very common procedure is to use one or more functional localisers, to delineate the regions in the brain that consistently show more activation to a particular type of events or stimuli. One example is faces versus places localiser, which helps to distinguish between areas that are active during visual perception of faces and other complex images like buildings. However, it is important to make sure that the low-level properties of the images do not differ significantly between the categories of stimuli, as it can lead to incorrect identification of the areas of interest. Here we discuss one possible way to improve the specificity of face localiser, achieved by eliminating the differences in colour and intensity distribution between images of faces and of buildings using the SHINE toolbox. A group of participants (N=8) was tested on both localisers with corrected and uncorrected images, and differences in visual cortex activation were found. Therefore we recommend to use this or similar procedure to enhance the quality and reliability of functional localisers.

Cerebrovascular Disease 1: Vascular Territories (DRAFT)

2018 ◽  
Author(s):  
Tamara Kaplan ◽  
Tracey Milligan
Keyword(s):  
Cerebrovascular Disease ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Anterior Cerebral Artery ◽  
Posterior Cerebral Artery ◽  
Sensory Loss ◽  
Homonymous Hemianopia ◽  
Leg Weakness ◽  
Sensory Changes ◽  
The Brain

The video in this chapter explores cerebrovascular disease, and focuses on vascular territories. It discusses the middle cerebral artery (MCA), posterior cerebral artery (PCA), and anterior cerebral artery (ACA), along with the portions of the brain they supply, as well as the different presentations of stroke in the three territories - contralateral weakness, sensory loss, and aphasia in MCA stroke, contralateral homonymous hemianopia in PCA stroke, and contralateral leg weakness and sensory changes in ACA stroke.

scholarly journals Olfactory Stimulation Modulates Visual Perception Without Training

2021 ◽  
Vol 15 ◽  
Author(s):  
Yoshiaki Tsushima ◽  
Yurie Nishino ◽  
Hiroshi Ando
Keyword(s):  
Visual Perception ◽  
Direct Evidence ◽  
Olfactory Stimulation ◽  
Perceptual Training ◽  
Temporal Area ◽  
Low Level ◽  
Considerable Research ◽  
Sensory Modalities ◽  
Visual Cortices ◽  
High Level

Considerable research shows that olfactory stimulations affect other modalities in high-level cognitive functions such as emotion. However, little known fact is that olfaction modulates low-level perception of other sensory modalities. Although some studies showed that olfaction had influenced on the other low-level perception, all of them required specific experiences like perceptual training. To test the possibility that olfaction modulates low-level perception without training, we conducted a series of psychophysical and neuroimaging experiments. From the results of a visual task in which participants reported the speed of moving dots, we found that participants perceived the slower motions with a lemon smell and the faster motions with a vanilla smell, without any specific training. In functional magnetic resonance imaging (fMRI) studies, brain activities in the visual cortices [V1 and human middle temporal area (hMT)] changed based on the type of olfactory stimulation. Our findings provide us with the first direct evidence that olfaction modulates low-level visual perception without training, thereby indicating that olfactory-visual effect is not an acquired behavior but an innate behavior. The present results show us with a new crossmodal effect between olfaction and vision, and bring a unique opportunity to reconsider some fundamental roles of olfactory function.

scholarly journals Transient coma as Percheron’s artery stroke

2019 ◽  
Author(s):  
Maria sofia Cotelli ◽  
Patrizia Civelli ◽  
Elisa Tosana ◽  
Marinella Turla
Keyword(s):  
Cerebral Artery ◽  
Posterior Cerebral Artery ◽  
Anatomic Variation ◽  
Brain Structures ◽  
Characteristic Pattern ◽  
Caucasian Woman ◽  
Arterial Trunk ◽  
Artery Of Percheron ◽  
The Brain ◽  
Thalamic Infarcts

The artery of Percheron is a rare anatomic variation in the brain vascularization, in which a single arterial trunk arises from the posterior cerebral artery to supply both sides of brain structures, i.e., the thalamus and midbrain. Occlusion of this uncommon vessel results in a characteristic pattern of bilateral paramedian thalamic infarcts with or without mesencephalic infarctions. We report the case of a Caucasian woman who completely recovers after transient coma due to Percheron artery infarction.

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