scholarly journals Prior expectations induce pre-stimulus sensory templates

2017 ◽  
Author(s):  
Peter Kok ◽  
Pim Mostert ◽  
Floris P. de Lange
Keyword(s):  
Sensory Neurons ◽  
Temporal Resolution ◽  
Representational Content ◽  
Sensory Cortex ◽  
Top Down ◽  
Neural Signals ◽  
Neural Signal ◽  
Bottom Up ◽  
Time Resolved ◽  
Sensory Inputs

AbstractPerception can be described as a process of inference, integrating bottom-up sensory inputs and top-down expectations. However, it is unclear how this process is neurally implemented. It has been proposed that expectations lead to pre-stimulus baseline increases in sensory neurons tuned to the expected stimulus, which in turn affects the processing of subsequent stimuli. Recent fMRI studies have revealed stimulus-specific patterns of activation in sensory cortex as a result of expectation, but this method lacks the temporal resolution necessary to distinguish pre- from post-stimulus processes. Here, we combined human MEG with multivariate decoding techniques to probe the representational content of neural signals in a time-resolved manner. We observed a representation of expected stimuli in the neural signal well before they were presented, demonstrating that expectations indeed induce a pre-activation of stimulus templates. These results suggest a mechanism for how predictive perception can be neurally implemented.

scholarly journals Prior expectations induce prestimulus sensory templates

2017 ◽  
Vol 114 (39) ◽  
pp. 10473-10478 ◽  
Author(s):  
Peter Kok ◽  
Pim Mostert ◽  
Floris P. de Lange
Keyword(s):  
Sensory Neurons ◽  
Temporal Resolution ◽  
Representational Content ◽  
Sensory Cortex ◽  
Top Down ◽  
Neural Signals ◽  
Neural Signal ◽  
Time Resolved ◽  
Sensory Inputs ◽  
Behavioral Improvement

Perception can be described as a process of inference, integrating bottom-up sensory inputs and top-down expectations. However, it is unclear how this process is neurally implemented. It has been proposed that expectations lead to prestimulus baseline increases in sensory neurons tuned to the expected stimulus, which in turn, affect the processing of subsequent stimuli. Recent fMRI studies have revealed stimulus-specific patterns of activation in sensory cortex as a result of expectation, but this method lacks the temporal resolution necessary to distinguish pre- from poststimulus processes. Here, we combined human magnetoencephalography (MEG) with multivariate decoding techniques to probe the representational content of neural signals in a time-resolved manner. We observed a representation of expected stimuli in the neural signal shortly before they were presented, showing that expectations indeed induce a preactivation of stimulus templates. The strength of these prestimulus expectation templates correlated with participants’ behavioral improvement when the expected feature was task-relevant. These results suggest a mechanism for how predictive perception can be neurally implemented.

Sensory regulation of quadrupedal locomotion: a top-down or bottom-up control system?

2012 ◽  
Vol 108 (3) ◽  
pp. 709-711 ◽  
Author(s):  
Yann Thibaudier ◽  
Marie-France Hurteau
Keyword(s):  
Control System ◽  
Central Pattern Generators ◽  
Top Down ◽  
Bottom Up ◽  
Sensory Inputs ◽  
Sensory Regulation ◽  
Before And After ◽  
Pattern Generators

Propriospinal pathways are thought to be critical for quadrupedal coordination by coupling cervical and lumbar central pattern generators (CPGs). However, the mechanisms involved in relaying information between girdles remain largely unexplored. Using an in vitro spinal cord preparation in neonatal rats, Juvin and colleagues ( Juvin et al. 2012 ) have recently shown sensory inputs from the hindlimbs have greater influence on forelimb CPGs than forelimb sensory inputs on hindlimb CPGs, in other words, a bottom-up control system. However, results from decerebrate cats suggest a top-down control system. It may be that both bottom-up and top-down control systems exist and that the dominance of one over the other is task or context dependent. As such, the role of sensory inputs in controlling quadrupedal coordination before and after injury requires further investigation.

scholarly journals Preferential effect of isoflurane on top-down vs. bottom-up pathways in sensory cortex

2014 ◽  
Vol 8 ◽  
Author(s):  
Aeyal Raz ◽  
Sean M. Grady ◽  
Bryan M. Krause ◽  
Daniel J. Uhlrich ◽  
Karen A. Manning ◽  
...  
Keyword(s):  
Sensory Cortex ◽  
Top Down ◽  
Bottom Up

Representation of affect in sensory cortex

2016 ◽  
Vol 39 ◽  
Author(s):  
Vladimir Miskovic ◽  
Karl Kuntzelman ◽  
Junichi Chikazoe ◽  
Adam K. Anderson
Keyword(s):  
Sensory Processing ◽  
Iterative Process ◽  
Empirical Support ◽  
External World ◽  
Sensory Cortex ◽  
Top Down ◽  
Bottom Up ◽  
Affective Influences ◽  
Affective Dimensions ◽  
Physical Dimensions

AbstractContemporary neuroscience suggests that perception is perhaps best understood as a dynamically iterative process that does not honor cleanly segregated “bottom-up” or “top-down” streams. We argue that there is substantial empirical support for the idea that affective influences infiltrate the earliest reaches of sensory processing and even that primitive internal affective dimensions (e.g., goodness-to-badness) are represented alongside physical dimensions of the external world.

Top-down Atmospheric Inventories of CO2 and CH4 to Support the Global Stocktakes

2021 ◽  
Author(s):  
David Crisp ◽  
Mark Dowell ◽  
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Ghg Emissions ◽  
Atmospheric Measurements ◽  
Top Down ◽  
Bottom Up ◽  
Time Resolved ◽  
Rapid Changes ◽  
Task Team ◽  
Developed Nations

<p>Parties to the Paris Agreement agreed to report GHG emissions and removals to the United Nations Framework Convention on Climate Change (UNFCCC), which will evaluate progress toward the NDCs through Global Stocktakes (GSTs) conducted at five-year intervals, the first of which is scheduled in 2023. National emission reports are based on “bottom-up” inventories of emissions or removals, derived from statistics such as the number tons of coal or barrels of oil delivered to the commercial, residential, industrial or transportation sectors or the number of acres of forest converted to agriculture. These methods can provide accurate estimates for fossil fuel emissions, but are somewhat less reliable for tracking changes in emissions from agriculture, forestry and other land use (AFOLU) or rapid changes in emissions due to disturbance events, such as hurricanes, drought, wildfires, or climate change.</p><p>CO<sub>2</sub> and CH<sub>4</sub>  emissions and removals can also be estimated using high resolution, time-resolved measurements of their concentrations in the atmosphere. These data are analyzed with atmospheric inverse models to derive the flux distribution needed to match the observed atmospheric concentrations in the presence of the winds. These top-down atmospheric inventories complement bottom-up inventories by providing an integrated constraint on emissions from all sources and removals by all sinks. They are less source specific than bottom-up inventories, but are ideal for tracking rapid changes in large emitters or changes in emissions or uptake by forests, crops or the ocean associated with human activities, severe weather or climate change.</p><p>The GHG Task Team of the Joint CEOS/CGMS Working Group on Climate has embarked on an ambitious effort to use available ground-based and space based atmospheric measurements of CO<sub>2</sub> and CH<sub>4</sub> to develop a pilot, top-down atmospheric inventory to support the 2023 GST. CO<sub>2</sub> estimates derived from Orbiting Carbon Observatory-2 (OCO-2) data will be combined with surface CO<sub>2</sub> measurements from the World Meteorological Organization (WMO) Global Atmospheric Watch (GAW) and its partners to construct a CO<sub>2</sub> inventory. CH<sub>4</sub> estimates derived from Greenhouse gases Observing SATellite (GOSAT) and the Copernicus Sentinel 5 Precursor (S5P) data will be combined with ground based GHG data to construct a CH<sub>4</sub> inventory. These inventories will be compared with results from a parallel effort within CEOS to produce space-based bottom-up inventories for emissions and removals by AFOLU to provide more source specific constraints on emissions and removals.</p><p>With the current measurement and modeling capabilities, these pilot inventories may not improve the results delivered by developed nations, where high-quality bottom-up inventories have been produced for decades. They should have greater value in the developing world, where countries have much less experience and resources for developing inventories and/or a much larger fraction of their emissions come from AFOLU. They are also expected to yield much greater insight into the evolution of the natural carbon cycle as it responds to human activities, extreme weather and climate change. The pilot products prepared for the 2023 Global Stocktake will provide the basis for iterative improvements in the products and their delivery to users for future GSTs.</p>

scholarly journals Autistic traits are associated with atypical precision-weighted integration of top-down and bottom-up neural signals

Cognition ◽  
2020 ◽  
Vol 199 ◽  
pp. 104236 ◽  
Author(s):  
Michel-Pierre Coll ◽  
Emily Whelan ◽  
Caroline Catmur ◽  
Geoffrey Bird
Keyword(s):  
Autistic Traits ◽  
Top Down ◽  
Neural Signals ◽  
Bottom Up

scholarly journals Frontal and parietal alpha oscillations reflect attentional modulation of cross-modal matching

2018 ◽  
Author(s):  
Jonas Misselhorn ◽  
Uwe Friese ◽  
Andreas K. Engel
Keyword(s):  
Gamma Activity ◽  
Multisensory Perception ◽  
Top Down ◽  
Bottom Up ◽  
Alpha Oscillations ◽  
Sensory Inputs ◽  
Gamma Power ◽  
Sensory Cortices ◽  
Underlying Mechanisms ◽  
Selection Of

Multisensory perception is shaped by both attentional selection of relevant sensory inputs and exploitation of stimulus-driven factors that promote cross-modal binding. Underlying mechanisms of both top-down and bottom-up modulations have been linked to changes in alpha/gamma dynamics in primary sensory cortices and temporoparietal cortex. Accordingly, it has been proposed that alpha oscillations provide pulsed inhibition for gamma activity and thereby dynamically route cortical information flow. In this study, we employed a recently introduced multisensory paradigm incorporating both bottom-up and top-down aspects of cross-modal attention in an EEG study. The same trimodal stimuli were presented in two distinct attentional conditions, focused on visual-tactile or audio-visual components, for which cross-modal congruence of amplitude changes had to be evaluated. Neither top-down nor bottom-up cross-modal attention modulated alpha or gamma power in primary sensory cortices. Instead, we found alpha band effects in bilateral frontal and right parietal cortex. We propose that frontal alpha oscillations reflect the origin of top-down control regulating perceptual gains and that modulations of parietal alpha oscillations relates to intersensory re-orienting. Taken together, we suggest that the idea of selective cortical routing via alpha oscillations can be extended from sensory cortices to the frontoparietal attention network.

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