scholarly journals Bottom-up and top-down computations in high-level visual cortex

2016 ◽  
Author(s):  
Kendrick N. Kay ◽  
Jason D. Yeatman
Keyword(s):  
Cognitive Task ◽  
Temporal Cortex ◽  
Intraparietal Sulcus ◽  
Neural Processing ◽  
Top Down ◽  
Cognitive Demands ◽  
Bottom Up ◽  
Stimulus Match ◽  
Ventral Temporal Cortex ◽  
High Level

SummaryThe ability to read a page of text or recognize a person’s face depends on category-selective visual regions in ventral temporal cortex (VTC). To understand how these regions mediate word and face recognition, it is necessary to characterize how stimuli are represented and how this representation is used in the execution of a cognitive task. Here, we show that the response of a category-selective region in VTC can be computed as the degree to which the low-level properties of the stimulus match a category template. Moreover, we show that during execution of a task, the bottom-up representation is scaled by the intraparietal sulcus (IPS), and that the level of IPS engagement reflects the cognitive demands of the task. These results provide a unifying account of neural processing in VTC in the form of a model that addresses both bottom-up and top-down effects and quantitatively predicts VTC responses.

scholarly journals Bottom-up and top-down computations in word- and face-selective cortex

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Kendrick N Kay ◽  
Jason D Yeatman
Keyword(s):  
Face Recognition ◽  
Cognitive Task ◽  
Temporal Cortex ◽  
Intraparietal Sulcus ◽  
Neural Processing ◽  
Top Down ◽  
Cognitive Demands ◽  
Bottom Up ◽  
Stimulus Match ◽  
Ventral Temporal Cortex

The ability to read a page of text or recognize a person's face depends on category-selective visual regions in ventral temporal cortex (VTC). To understand how these regions mediate word and face recognition, it is necessary to characterize how stimuli are represented and how this representation is used in the execution of a cognitive task. Here, we show that the response of a category-selective region in VTC can be computed as the degree to which the low-level properties of the stimulus match a category template. Moreover, we show that during execution of a task, the bottom-up representation is scaled by the intraparietal sulcus (IPS), and that the level of IPS engagement reflects the cognitive demands of the task. These results provide an account of neural processing in VTC in the form of a model that addresses both bottom-up and top-down effects and quantitatively predicts VTC responses.

scholarly journals The Human Intraparietal Sulcus Modulates Task-Evoked Functional Connectivity

2019 ◽  
Vol 30 (3) ◽  
pp. 875-887
Author(s):  
Kai Hwang ◽  
James M Shine ◽  
Dillan Cellier ◽  
Mark D’Esposito
Keyword(s):  
Functional Connectivity ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Intraparietal Sulcus ◽  
Top Down ◽  
Adaptive Communication ◽  
Wide Range ◽  
Functional Connectivity Strength ◽  
Ventral Temporal Cortex ◽  
Cortical Regions

Abstract Past studies have demonstrated that flexible interactions between brain regions support a wide range of goal-directed behaviors. However, the neural mechanisms that underlie adaptive communication between brain regions are not well understood. In this study, we combined theta-burst transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging to investigate the sources of top-down biasing signals that influence task-evoked functional connectivity. Subjects viewed sequences of images of faces and buildings and were required to detect repetitions (2-back vs. 1-back) of the attended stimuli category (faces or buildings). We found that functional connectivity between ventral temporal cortex and the primary visual cortex (VC) increased during processing of task-relevant stimuli, especially during higher memory loads. Furthermore, the strength of functional connectivity was greater for correct trials. Increases in task-evoked functional connectivity strength were correlated with increases in activity in multiple frontal, parietal, and subcortical (caudate and thalamus) regions. Finally, we found that TMS to superior intraparietal sulcus (IPS), but not to primary somatosensory cortex, decreased task-specific modulation in connectivity patterns between the primary VC and the parahippocampal place area. These findings demonstrate that the human IPS is a source of top-down biasing signals that modulate task-evoked functional connectivity among task-relevant cortical regions.

scholarly journals Flexible top-down modulation in human ventral temporal cortex

2018 ◽  
Author(s):  
Ruyuan Zhang ◽  
Kendrick Kay
Keyword(s):  
Cognitive Processes ◽  
Cognitive Task ◽  
Temporal Cortex ◽  
Independent Experiment ◽  
Perceptual Task ◽  
Top Down ◽  
Quantitative Understanding ◽  
Conventional Models ◽  
Ventral Temporal Cortex ◽  
Contrast Response

ABSTRACTVisual neuroscientists have long characterized attention as inducing a scaling or additive effect on fixed parametric functions describing neural responses (e.g., contrast response functions). Here, we instead propose that top-down effects are more complex and manifest in ways that depend not only on attention but also other cognitive processes involved in executing a task. To substantiate this theory, we analyze fMRI responses in human ventral temporal cortex (VTC) in a study where stimulus eccentricity and cognitive task are varied. We find that as stimuli are presented farther into the periphery, bottom-up stimulus-driven responses decline but top-down attentional enhancement increases substantially. This disproportionate enhancement of weak responses cannot be easily explained by conventional models of attention. Furthermore, we find that attentional effects depend on the specific cognitive task performed by the subject, indicating the influence of additional cognitive processes other than attention (e.g., decision-making). The effects we observe replicate in an independent experiment from the same study, and also generalize to a separate study involving different stimulus manipulations (contrast and phase coherence). Our results suggest that a quantitative understanding of top-down modulation requires more nuanced and more precise characterization of multiple cognitive factors involved in completing a perceptual task.

scholarly journals Causal Evidence for the Role of Neuronal Oscillations in Top–Down and Bottom–Up Attention

2019 ◽  
Vol 31 (5) ◽  
pp. 768-779 ◽  
Author(s):  
Justin Riddle ◽  
Kai Hwang ◽  
Dillan Cellier ◽  
Sofia Dhanani ◽  
Mark D'Esposito
Keyword(s):  
Visual Field ◽  
Conjunction Search ◽  
Intraparietal Sulcus ◽  
Top Down ◽  
Neuronal Oscillations ◽  
Bottom Up ◽  
Search Condition ◽  
Gamma Frequency ◽  
Task Conditions ◽  
Beta Frequency

Beta and gamma frequency neuronal oscillations have been implicated in top–down and bottom–up attention. In this study, we used rhythmic TMS to modulate ongoing beta and gamma frequency neuronal oscillations in frontal and parietal cortex while human participants performed a visual search task that manipulates bottom–up and top–down attention (single feature and conjunction search). Both task conditions will engage bottom–up attention processes, although the conjunction search condition will require more top–down attention. Gamma frequency TMS to superior precentral sulcus (sPCS) slowed saccadic RTs during both task conditions and induced a response bias to the contralateral visual field. In contrary, beta frequency TMS to sPCS and intraparietal sulcus decreased search accuracy only during the conjunction search condition that engaged more top–down attention. Furthermore, beta frequency TMS increased trial errors specifically when the target was in the ipsilateral visual field for the conjunction search condition. These results indicate that beta frequency TMS to sPCS and intraparietal sulcus disrupted top–down attention, whereas gamma frequency TMS to sPCS disrupted bottom–up, stimulus-driven attention processes. These findings provide causal evidence suggesting that beta and gamma oscillations have distinct functional roles for cognition.

Orphan Implementations of Public Policy for Conflict-Oriented Issues

2021 ◽  
Vol 21 (2) ◽  
pp. 43-63
Author(s):  
Shulamith Gertel Groome
Keyword(s):  
Public Policy ◽  
Decision Making ◽  
Public Interest ◽  
Policy Process ◽  
Frame Of Reference ◽  
Limited Resources ◽  
Top Down ◽  
Bottom Up ◽  
Field Level ◽  
High Level

This paper aims to broaden our understanding of public policy characterized by issues of non-consensus. The idea of flexible, independent administrative decision-making for a conflict-oriented policy-type is addressed in terms of chronological constructions of policy process. Distributions of limited resources are a source of public contention likely to draw ambiguous high-level policy decisions that lack practical administrative directives. Conflicting institutional, professional and stakeholder influences, at various levels of policy processes, illuminate circumstances fostering implementations incongruent with politically motivated macro-declarations. Yet, this does not necessarily represent failed policy. A reevaluation of administrative systems, by critical deconstruction of the dominant top-down discourse, provides a frame of reference for valid divergent implementations. A conceptual progression from field-level interpretation and adaptation of macro policy, initiatory orphan implementations emerge as policy itself. This revised bottom-up modality of the policy process implies a working balance of combined outputs, providing equitable outcome to serve largescale public interest.

scholarly journals Bottom-up Retinotopic Organization Supports Top-down Mental Imagery

2013 ◽  
Vol 7 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Ruey-Song Huang ◽  
Martin I. Sereno
Keyword(s):  
Premotor Cortex ◽  
Brain Regions ◽  
Retrosplenial Cortex ◽  
Wide Field ◽  
Top Down ◽  
Bottom Up ◽  
Retinotopic Maps ◽  
Upper Visual Field ◽  
Retinotopic Organization ◽  
High Level

Finding a path between locations is a routine task in daily life. Mental navigation is often used to plan a route to a destination that is not visible from the current location. We first used functional magnetic resonance imaging (fMRI) and surface-based averaging methods to find high-level brain regions involved in imagined navigation between locations in a building very familiar to each participant. This revealed a mental navigation network that includes the precuneus, retrosplenial cortex (RSC), parahippocampal place area (PPA), occipital place area (OPA), supplementary motor area (SMA), premotor cortex, and areas along the medial and anterior intraparietal sulcus. We then visualized retinotopic maps in the entire cortex using wide-field, natural scene stimuli in a separate set of fMRI experiments. This revealed five distinct visual streams or ‘fingers’ that extend anteriorly into middle temporal, superior parietal, medial parietal, retrosplenial and ventral occipitotemporal cortex. By using spherical morphing to overlap these two data sets, we showed that the mental navigation network primarily occupies areas that also contain retinotopic maps. Specifically, scene-selective regions RSC, PPA and OPA have a common emphasis on the far periphery of the upper visual field. These results suggest that bottom-up retinotopic organization may help to efficiently encode scene and location information in an eye-centered reference frame for top-down, internally generated mental navigation. This study pushes the border of visual cortex further anterior than was initially expected.

scholarly journals Shared neural mechanisms of visual perception and imagery

2019 ◽  
Author(s):  
Nadine Dijkstra ◽  
Sander Erik Bosch ◽  
Marcel van Gerven
Keyword(s):  
Visual Perception ◽  
Frontal Cortex ◽  
Visual Imagery ◽  
Visual Experience ◽  
Neural Mechanisms ◽  
Neural Processing ◽  
Top Down ◽  
Bottom Up ◽  
Neural Representations

For decades, the extent to which visual imagery relies on similar neural mechanisms as visual perception has been a topic of debate. Here, we review recent neuroimaging studies comparing these two forms of visual experience. Their results suggest that there is large overlap in neural processing during perception and imagery: neural representations of imagined and perceived stimuli are similar in visual, parietal and frontal cortex. Furthermore, perception and imagery seem to rely on similar top-down connectivity. The most prominent difference is the absence of bottom-up processing during imagery. These findings fit well with the idea that imagery and perception rely on similar emulation or prediction processes.

scholarly journals Neural tracking of speech mental imagery during rhythmic inner counting

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Lingxi Lu ◽  
Qian Wang ◽  
Jingwei Sheng ◽  
Zhaowei Liu ◽  
Lang Qin ◽  
...  
Keyword(s):  
Mental Imagery ◽  
Auditory Perception ◽  
Processing Time ◽  
Human Subjects ◽  
Inferior Frontal Gyrus ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Neural Processing ◽  
Top Down ◽  
Rate Frequency

The subjective inner experience of mental imagery is among the most ubiquitous human experiences in daily life. Elucidating the neural implementation underpinning the dynamic construction of mental imagery is critical to understanding high-order cognitive function in the human brain. Here, we applied a frequency-tagging method to isolate the top-down process of speech mental imagery from bottom-up sensory-driven activities and concurrently tracked the neural processing time scales corresponding to the two processes in human subjects. Notably, by estimating the source of the magnetoencephalography (MEG) signals, we identified isolated brain networks activated at the imagery-rate frequency. In contrast, more extensive brain regions in the auditory temporal cortex were activated at the stimulus-rate frequency. Furthermore, intracranial stereotactic electroencephalogram (sEEG) evidence confirmed the participation of the inferior frontal gyrus in generating speech mental imagery. Our results indicate that a disassociated neural network underlies the dynamic construction of speech mental imagery independent of auditory perception.

scholarly journals Developmental Increase in Top–Down and Bottom–Up Processing in a Phonological Task: An Effective Connectivity, fMRI Study

2009 ◽  
Vol 21 (6) ◽  
pp. 1135-1145 ◽  
Author(s):  
Tali Bitan ◽  
Jimmy Cheon ◽  
Dong Lu ◽  
Douglas D. Burman ◽  
James R. Booth
Keyword(s):  
Language Processing ◽  
Effective Connectivity ◽  
Inferior Frontal Gyrus ◽  
Temporal Cortex ◽  
Control Process ◽  
Brain Regions ◽  
Top Down ◽  
Bottom Up ◽  
Age Related ◽  
Task Irrelevant

We examined age-related changes in the interactions among brain regions in children performing rhyming judgments on visually presented words. The difficulty of the task was manipulated by including a conflict between task-relevant (phonological) information and task-irrelevant (orthographic) information. The conflicting conditions included pairs of words that rhyme despite having different spelling patterns (jazz–has), or words that do not rhyme despite having similar spelling patterns (pint–mint). These were contrasted with nonconflicting pairs that have similar orthography and phonology (dime–lime) or different orthography and phonology (press–list). Using fMRI, we examined effective connectivity among five left hemisphere regions of interest: fusiform gyrus (FG), inferior frontal gyrus (IFG), intraparietal sulcus (IPS), lateral temporal cortex (LTC), and medial frontal gyrus (MeFG). Age-related increases were observed in the influence of the IFG and FG on the LTC, but only in conflicting conditions. These results reflect a developmental increase in the convergence of bottom–up and top–down information on the LTC. In older children, top–down control process may selectively enhance the sensitivity of the LTC to bottom–up information from the FG. This may be evident especially in situations that require selective enhancement of task-relevant versus task-irrelevant information. Altogether these results provide a direct evidence for a developmental increase in top–down control processes in language processing. The developmental increase in bottom–up processing may be secondary to the enhancement of top–down processes.

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