Cortical hierarchy

Hierarchical cortical organization is found in cortical hierarchy sensory systems, cortical hierarchy, in the reward system, and in the memory systems, cortical hierarchy. Adjacent cortical areas in the hierarchy are connected by strong forward connections, and weaker backprojections which have synapses in cortical layer 1. There is convergence from cortical area to cortical area, in that neurons in a cortical area receive inputs from a limited region topologically of the preceding cortical area. This enables neurons to operate with the number of synapses from the preceding cortical area received by a neuron limited to in the order of 10, synapses.

Cortical information processing is structurally and functionally organized into hierarchical pathways, with primary sensory cortical regions providing modality specific information and associative cortical regions playing a more integrative role. Historically, there has been debate as to whether primary cortical regions mature earlier than associative cortical regions, or whether both primary and associative cortical regions mature simultaneously. Identifying whether primary and associative cortical regions mature hierarchically or simultaneously will not only deepen our understanding of the mechanisms that regulate brain maturation, but it will also provide fundamental insight into aspects of adolescent behavior, learning, neurodevelopmental disorders and computational models of neural processing. This mini-review article summarizes the current evidence supporting the sequential and hierarchical nature of cortical maturation, and then proposes a new cellular model underlying this process. Finally, unresolved issues associated with hierarchical cortical maturation are also addressed. The concept of cortical hierarchy has been widely recognized for years Guillery, It is based on established structure-function relationships in the thalamo-cortical system that consist of primary sensory areas and several distinct higher-order association areas that are important for cognitive functions Komura et al.

Cortical hierarchy

A fundamental aspect of human experience is that it is segmented into discrete events. This may be underpinned by transitions between distinct neural states. Using an innovative data-driven state segmentation method, we investigate how neural states are organized across the cortical hierarchy and where in the cortex neural state boundaries and perceived event boundaries overlap. Our results show that neural state boundaries are organized in a temporal cortical hierarchy, with short states in primary sensory regions, and long states in lateral and medial prefrontal cortex. State boundaries are shared within and between groups of brain regions that resemble well-known functional networks. Perceived event boundaries overlap with neural state boundaries across large parts of the cortical hierarchy, particularly when those state boundaries demarcate a strong transition or are shared between brain regions. Taken together, these findings suggest that a partially nested cortical hierarchy of neural states forms the basis of event segmentation. This article addresses the question of how the brain segments naturalistic events and the relationship between perceived event boundaries and neural pattern shifts. By applying an innovative analysis to a large, publicly available dataset, they observe evidence of different timescales of neural state shifts that correspond with perceived event bounds. These results will be of interest to cognitive neuroscientists investigating the relationship between neural states and event segmentation. Segmentation of information into meaningful units is a fundamental feature of our conscious experience in real-life contexts. Spatial information processing is characterized by segmenting spatial regions into objects e. In a similar way, temporal information processing is characterized by segmenting our ongoing experience into separate events Kurby and Zacks, ; Newtson et al.

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Many studies have identified the role of localized and distributed cognitive functionality by mapping either local task-related activity or distributed functional connectivity FC. However, few studies have directly explored the relationship between a brain region's localized task activity and its distributed task FC. Here we systematically evaluated the differential contributions of task-related activity and FC changes to identify a relationship between localized and distributed processes across the cortical hierarchy. We found that across multiple tasks, the magnitude of regional task-evoked activity was high in unimodal areas, but low in transmodal areas. In contrast, we found that task-state FC was significantly reduced in unimodal areas relative to transmodal areas. This revealed a strong negative relationship between localized task activity and distributed FC across cortical regions that was associated with the previously reported principal gradient of macroscale organization. Moreover, this dissociation corresponded to hierarchical cortical differences in the intrinsic timescale estimated from resting-state fMRI and region myelin content estimated from structural MRI.

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Cortical hierarchy

Federal government websites often end in. The site is secure. Preview improvements coming to the PMC website in October Learn More or Try it out now. Concepts shape the interpretation of facts. However, this concept has been interpreted in many different ways, which are not well aligned. This observation suggests that the concept is ill defined.

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Brain Sci. Event boundaries have previously been shown to align with changes in features of the narrative, such as characters, causes, goals, and spatial locations Zacks et al. Intellectual Property Law. Salzman, C. Society Members Society member access to a journal is achieved in one of the following ways: Sign in through society site Many societies offer single sign-on between the society website and Oxford Academic. Isn't this analysis just another way of saying that the PSDs have different shapes during rest and during movie viewing? Literary Studies 19th Century. Other metrics of pre-stimulus neural variability, such as single-cell temporal variance 10 , synchrony 54 and neural oscillation power 15 , 55 , have all previously been linked to task performance. Do Oi, Oj refer to the number of neural state boundaries in searchlights I,j? Corporate Governance.

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Together, these findings show that the timescale of information processing in particular brain regions is not only driven by stable differences in the rate of temporal integration of information, which may be associated with interregional interactions in the neural circuitry Honey et al. Bajo, V. Does this method produce results that are at least qualitatively similar? If the brain segments ongoing input in a nested hierarchical fashion, we would expect to find especially long-lasting neural states in the frontal cortex, which is often considered the top of the cortical hierarchy Fuster, Boundaries shown in red coincide with an event boundary. P values tested for a difference in session-wise population metrics between hit and miss trials two-sided Wilcoxon signed-rank test without correction multiple comparison. Music Theory and Analysis. A model for stimulus generalization in Pavlovian conditioning. Literary Studies Romanticism. Photostimulation was designed such that it causally drove behavior as the task required the mouse to lick after photostimulation to receive a reward. C Increase in absolute overlap between neural state boundaries and event boundaries when neural state boundaries are weighted by their strengths, in comparison to using binary boundaries as in A. The first two panels show the two metrics of Fig. Complementary and Alternative Medicine. The results in Figure 6A seem rather noisy to me, and I imagine that this is because the regression procedure on the PSD is influenced by many interacting and confounding variables.