scholarly journals Constructing and Forgetting Temporal Context in the Human Cerebral Cortex

2019 ◽  
Author(s):  
Hsiang-Yun Sherry Chien ◽  
Christopher J. Honey
Keyword(s):  
Higher Order ◽  
Hierarchical Organization ◽  
Temporal Context ◽  
Neural Responses ◽  
Prior Context ◽  
New Information ◽  
Cortical Hierarchy ◽  
Linear Integration ◽  
Sensory Cortices ◽  
Cortical Regions

SummaryHow does information from seconds earlier affect neocortical responses to new input? Here, we used empirical measurements and computational modeling to study the integration and forgetting of prior information. We found that when two groups of participants heard the same sentence in a narrative, preceded by different contexts, the neural responses of each group were initially different, but gradually fell into alignment. We observed a hierarchical gradient: sensory cortices aligned most quickly, followed by mid-level regions, while higher-order cortical regions aligned last. In some higher order regions, responses to the same sentence took more than 10 seconds to align. What kinds of computations can explain this hierarchical organization of contextual alignment? Passive linear integration models predict that regions which are slower to integrate new information should also be slower to forget old information. However, we found that higher order regions could rapidly forget prior context. The data were better captured by a model composed of hierarchical autoencoders in time (HAT). In HAT, cortical regions maintain a temporal context representation which is actively integrated with input at each moment, and this integration is gated by prediction error. These data and models suggest that sequences of information are combined throughout the cortical hierarchy using an active and gated integration process.

Novel Cognitive Functions Arise at the Convergence of Macroscale Gradients

2021 ◽  
pp. 1-16
Author(s):  
Heejung Jung ◽  
Tor D. Wager ◽  
R. McKell Carter
Keyword(s):  
Brain Regions ◽  
Higher Order ◽  
Hierarchical Organization ◽  
Functional Modules ◽  
Cortical Areas ◽  
Future Space ◽  
Close Proximity ◽  
Sensory Cortices ◽  
Developmental Characteristics ◽  
The Brain

Abstract Functions in higher-order brain regions are the source of extensive debate. Although past trends have been to describe the brain—especially posterior cortical areas—in terms of a set of functional modules, a new emerging paradigm focuses on the integration of proximal functions. In this review, we synthesize emerging evidence that a variety of novel functions in the higher-order brain regions are due to convergence: convergence of macroscale gradients brings feature-rich representations into close proximity, presenting an opportunity for novel functions to arise. Using the TPJ as an example, we demonstrate that convergence is enabled via three properties of the brain: (1) hierarchical organization, (2) abstraction, and (3) equidistance. As gradients travel from primary sensory cortices to higher-order brain regions, information becomes abstracted and hierarchical, and eventually, gradients meet at a point maximally and equally distant from their sensory origins. This convergence, which produces multifaceted combinations, such as mentalizing another person's thought or projecting into a future space, parallels evolutionary and developmental characteristics in such regions, resulting in new cognitive and affective faculties.

scholarly journals Hierarchical Organization of Corticothalamic Projections to the Pulvinar

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Reza Abbas Farishta ◽  
Denis Boire ◽  
Christian Casanova
Keyword(s):  
Higher Order ◽  
Hierarchical Organization ◽  
Hierarchical Level ◽  
Thalamic Nuclei ◽  
Cortical Areas ◽  
Visual Areas ◽  
Cortical Hierarchy ◽  
Area 21A ◽  
Extrastriate Areas ◽  
Corticothalamic Projections

Abstract Signals from lower cortical visual areas travel to higher-order areas for further processing through cortico-cortical projections, organized in a hierarchical manner. These signals can also be transferred between cortical areas via alternative cortical transthalamic routes involving higher-order thalamic nuclei like the pulvinar. It is unknown whether the organization of transthalamic pathways may reflect the cortical hierarchy. Two axon terminal types have been identified in corticothalamic (CT) pathways: the types I (modulators) and II (drivers) characterized by thin axons with small terminals and by thick axons and large terminals, respectively. In cats, projections from V1 to the pulvinar complex comprise mainly type II terminals, whereas those from extrastriate areas include a combination of both terminals suggesting that the nature of CT terminals varies with the hierarchical order of visual areas. To test this hypothesis, distribution of CT terminals from area 21a was charted and compared with 3 other visual areas located at different hierarchical levels. Results demonstrate that the proportion of modulatory CT inputs increases along the hierarchical level of cortical areas. This organization of transthalamic pathways reflecting cortical hierarchy provides new and fundamental insights for the establishment of more accurate models of cortical signal processing along transthalamic cortical pathways.

scholarly journals Sequence learning attenuates cortical responses in both frontal and perceptual cortices in early infancy

2021 ◽  
Author(s):  
Sagi Jaffe-Dax ◽  
Anna Herbolzheimer ◽  
Vikranth Rao Bejjanki ◽  
Lauren L Emberson
Keyword(s):  
Frontal Lobe ◽  
Higher Order ◽  
Neural Responses ◽  
Neural Connections ◽  
Young Infants ◽  
Learning Tasks ◽  
Cortical Responses ◽  
Sensory Cortices ◽  
Infant Brain ◽  
Sequential Information

Prior work using a variety of imaging modalities has found that the frontal lobe is involved in higher-order sequential and statistical learning in young infants. Separate lines of work have found evidence of modulation of posterior sensory cortices during and after learning tasks. How do these processes relate together? Here, we build from a well-regarded EEG task that found evidence that the frontal lobe of young infants tracked higher-order sequential information (Basirat et al., 2014) and ask whether posterior perceptual cortices respond differentially to predictable vs. unpredictable sequences as well. First, replicating and extending past work, we found evidence of frontal lobe involvement in this task. Second, consistent with our hypotheses, we found that there is a corresponding attenuation of neural responses in the posterior perceptual cortices (temporal and occipital) to predictable compared to unpredictable audiovisual sequences. This study provides convergent evidence that the frontal lobe is crucial for higher-level learning in young infants but that it likely works as part of a large, distributed network of regions to modulate infant neural responses as a result of learning. Overall, this work challenges the view that the infant brain is not dynamic and disconnected, lacking in long-range neural connections. Instead, this paper reveals patterns of a highly dynamic and interconnected infant brain that change rapidly as a result of new, learnable experiences.

Compressed sensorimotor-to-transmodal hierarchical organization in schizophrenia

2021 ◽  
pp. 1-14
Author(s):  
Debo Dong ◽  
Dezhong Yao ◽  
Yulin Wang ◽  
Seok-Jun Hong ◽  
Sarah Genon ◽  
...  
Keyword(s):  
Sensory Information ◽  
Resting State Fmri ◽  
Brain Regions ◽  
High Order ◽  
Hierarchical Organization ◽  
System Level ◽  
Integrative System ◽  
Sensorimotor Region ◽  
Cortical Hierarchy ◽  
High Level

Abstract Background Schizophrenia has been primarily conceptualized as a disorder of high-order cognitive functions with deficits in executive brain regions. Yet due to the increasing reports of early sensory processing deficit, recent models focus more on the developmental effects of impaired sensory process on high-order functions. The present study examined whether this pathological interaction relates to an overarching system-level imbalance, specifically a disruption in macroscale hierarchy affecting integration and segregation of unimodal and transmodal networks. Methods We applied a novel combination of connectome gradient and stepwise connectivity analysis to resting-state fMRI to characterize the sensorimotor-to-transmodal cortical hierarchy organization (96 patients v. 122 controls). Results We demonstrated compression of the cortical hierarchy organization in schizophrenia, with a prominent compression from the sensorimotor region and a less prominent compression from the frontal−parietal region, resulting in a diminished separation between sensory and fronto-parietal cognitive systems. Further analyses suggested reduced differentiation related to atypical functional connectome transition from unimodal to transmodal brain areas. Specifically, we found hypo-connectivity within unimodal regions and hyper-connectivity between unimodal regions and fronto-parietal and ventral attention regions along the classical sensation-to-cognition continuum (voxel-level corrected, p < 0.05). Conclusions The compression of cortical hierarchy organization represents a novel and integrative system-level substrate underlying the pathological interaction of early sensory and cognitive function in schizophrenia. This abnormal cortical hierarchy organization suggests cascading impairments from the disruption of the somatosensory−motor system and inefficient integration of bottom-up sensory information with attentional demands and executive control processes partially account for high-level cognitive deficits characteristic of schizophrenia.

Supporting Community Engagement Through Real-World Instructional Learning

2021 ◽  
pp. 415-431
Author(s):  
Caroline M. Crawford ◽  
Janice Moore Newsum ◽  
Sharon Andrews White ◽  
Jennifer Young Wallace
Keyword(s):  
Conceptual Framework ◽  
Community Engagement ◽  
Lifelong Learning ◽  
Real World ◽  
Higher Order ◽  
Instructional Process ◽  
Community Environment ◽  
New Information ◽  
Instructional Environments ◽  
Competency Based

The ability to attain knowledge for implementation within real-world environments is a shift in understanding within many instructional environments. Shifting from competency-based understandings wherein a knowledge base is attained as well as implemented towards a capability-based understanding that emphasizes the conceptual framework of information shift towards higher order knowledge creation within novel situations and environments is essential. Lifelong learning within nuanced understandings of new situations and new experiences is essential. Normally, these novel situations and experiences occur within a real-world community environment wherein the learner is critically analyzing new information and opinions from innumerable engaged people within the community. This style of learning is vital to understand within a competency-based learning environment, as well. Therefore, real-world instructional learning embeds the supporting community engagement at distinctly appropriate and impactful points throughout the instructional process, resulting in outstanding conceptual frameworks with the continuous understanding around cognitive engagement.

scholarly journals Signal propagation via cortical hierarchies

2020 ◽  
Vol 4 (4) ◽  
pp. 1072-1090 ◽  
Author(s):  
Bertha Vézquez-Rodríguez ◽  
Zhen-Qi Liu ◽  
Patric Hagmann ◽  
Bratislav Misic
Keyword(s):  
Shortest Paths ◽  
Signal Propagation ◽  
Brain Regions ◽  
Hierarchical Organization ◽  
Attention Networks ◽  
Diffusion Spectrum Imaging ◽  
Cortical Hierarchy ◽  
Spectrum Imaging ◽  
Structural Networks ◽  
The Brain

The wiring of the brain is organized around a putative unimodal-transmodal hierarchy. Here we investigate how this intrinsic hierarchical organization of the brain shapes the transmission of information among regions. The hierarchical positioning of individual regions was quantified by applying diffusion map embedding to resting-state functional MRI networks. Structural networks were reconstructed from diffusion spectrum imaging and topological shortest paths among all brain regions were computed. Sequences of nodes encountered along a path were then labeled by their hierarchical position, tracing out path motifs. We find that the cortical hierarchy guides communication in the network. Specifically, nodes are more likely to forward signals to nodes closer in the hierarchy and cover a range of unimodal and transmodal regions, potentially enriching or diversifying signals en route. We also find evidence of systematic detours, particularly in attention networks, where communication is rerouted. Altogether, the present work highlights how the cortical hierarchy shapes signal exchange and imparts behaviorally relevant communication patterns in brain networks.

scholarly journals Uncoupling Sensation and Perception in Human Time Processing

2020 ◽  
Vol 32 (7) ◽  
pp. 1369-1380 ◽  
Author(s):  
Nicola Binetti ◽  
Alessandro Tomassini ◽  
Karl Friston ◽  
Sven Bestmann
Keyword(s):  
Constant Velocity ◽  
Subjective Experience ◽  
Brain Activity ◽  
Posterior Cingulate Cortex ◽  
Higher Order ◽  
Neural Basis ◽  
Subjective Duration ◽  
Msec Duration ◽  
Sensory Cortices ◽  
Higher Visual Areas

Timing emerges from a hierarchy of computations ranging from early encoding of physical duration (time sensation) to abstract time representations (time perception) suitable for storage and decisional processes. However, the neural basis of the perceptual experience of time remains elusive. To address this, we dissociate brain activity uniquely related to lower-level sensory and higher-order perceptual timing operations, using event-related fMRI. Participants compared subsecond (500 msec) sinusoidal gratings drifting with constant velocity (standard) against two probe stimuli: (1) control gratings drifting at constant velocity or (2) accelerating gratings, which induced illusory shortening of time. We tested two probe intervals: a 500-msec duration (Short) and a longer duration required for an accelerating probe to be perceived as long as the standard (Long—individually determined). On each trial, participants classified the probe as shorter or longer than the standard. This allowed for comparison of trials with an “Objective” (physical) or “Subjective” (perceived) difference in duration, based on participant classifications. Objective duration revealed responses in bilateral early extrastriate areas, extending to higher visual areas in the fusiform gyrus (at more lenient thresholds). By contrast, Subjective duration was reflected by distributed responses in a cortical/subcortical areas. This comprised the left superior frontal gyrus and the left cerebellum, and a wider set of common timing areas including the BG, parietal cortex, and posterior cingulate cortex. These results suggest two functionally independent timing stages: early extraction of duration information in sensory cortices and Subjective experience of duration in a higher-order cortical–subcortical timing areas.

scholarly journals Hierarchical Organization of Auditory Temporal Context Sensitivity

1996 ◽  
Vol 16 (21) ◽  
pp. 6987-6998 ◽  
Author(s):  
Michael S. Lewicki ◽  
Benjamin J. Arthur
Keyword(s):  
Context Sensitivity ◽  
Hierarchical Organization ◽  
Temporal Context

scholarly journals The Path to Memory Is Guided by Strategy: Distinct Networks Are Engaged in Associative Encoding under Visual and Verbal Strategy and Influence Memory Performance in Healthy and Impaired Individuals

2012 ◽  
Vol 24 (6) ◽  
pp. 1398-1410 ◽  
Author(s):  
Jena B. Hales ◽  
James B. Brewer
Keyword(s):  
Stimulus Type ◽  
Memory Performance ◽  
Stimulus Modality ◽  
Verbal Stimuli ◽  
New Information ◽  
Associative Strategy ◽  
Cortical Regions ◽  
Cortical Involvement ◽  
Encoding Strategies ◽  
Study Participants

Given the diversity of stimuli encountered in daily life, a variety of strategies must be used for learning new information. Relating and encoding visual and verbal stimuli into memory has been probed using various tasks and stimulus types. Engagement of specific subsequent memory and cortical processing regions depends on the stimulus modality of studied material; however, it remains unclear whether different encoding strategies similarly influence regional activity when stimulus type is held constant. In this study, participants encoded object pairs using a visual or verbal associative strategy during fMRI, and subsequent memory was assessed for pairs encoded under each strategy. Each strategy elicited distinct regional processing and subsequent memory effects: middle/superior frontal, lateral parietal, and lateral occipital for visually associated pairs and inferior frontal, medial frontal, and medial occipital for verbally associated pairs. This regional selectivity mimics the effects of stimulus modality, suggesting that cortical involvement in associative encoding is driven by strategy and not simply by stimulus type. The clinical relevance of these findings, probed in a patient with a recent aphasic stroke, suggest that training with strategies utilizing unaffected cortical regions might improve memory ability in patients with brain damage.

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