scholarly journals Neural correlates underlying the attentional spotlight in human parietal cortex independent of task difficulty

2017 ◽  
Vol 38 (10) ◽  
pp. 4996-5018 ◽  
Author(s):  
Hang Zeng ◽  
Ralph Weidner ◽  
Gereon R. Fink ◽  
Qi Chen
Keyword(s):  
Parietal Cortex ◽  
Task Difficulty ◽  
Neural Correlates ◽  
Attentional Spotlight

scholarly journals The convergence and divergence of episodic and semantic functions across lateral parietal cortex

2020 ◽  
Author(s):  
Gina F. Humphreys ◽  
JeYoung Jung ◽  
Matthew A. Lambon Ralph
Keyword(s):  
White Matter ◽  
Semantic Memory ◽  
Parietal Cortex ◽  
Memory Retrieval ◽  
Task Difficulty ◽  
Structural Connectivity ◽  
Angular Gyrus ◽  
Episodic Retrieval ◽  
Semantic Retrieval ◽  
White Matter Connectivity

AbstractSeveral decades of neuropsychological and neuroimaging research have highlighted the importance of lateral parietal cortex (LPC) across a myriad of cognitive domains. Yet, despite the prominence of this region the underlying function of LPC remains unclear. Two domains that have placed particular emphasis on LPC involvement are semantic memory and episodic memory retrieval. From each domain, sophisticated models have been proposed as to the underlying function, as well as the more domain-general that LPC is engaged by any form of internally-directed cognition (episodic and semantic retrieval both being examples if this process). Here we directly address these alternatives using a combination of fMRI and DTI white-matter connectivity data. The results show that ventral LPC (angular gyrus) was positively engaged during episodic retrieval but disengaged during semantic memory retrieval. In addition, the level of activity negatively varied with task difficulty in the semantic task whereas episodic activation was independent of difficulty. In contrast, dorsal LPC (intraparietal sulcus) showed domain general activation that was positively correlated with task difficulty. In terms of structural connectivity, a dorsal-ventral and anterior-posterior gradient of connectivity was found to different processing networks (e.g., mid-angular gyrus (AG) connected with episodic retrieval). We propose a unifying model in which LPC as a whole might share a common underlying function (e.g., multimodal buffering) and variations across subregions arise due to differences in the underlying white matter connectivity.

scholarly journals Distinct Neural Correlates of Linguistic and Non-Linguistic Demand

2021 ◽  
pp. 1-24
Author(s):  
Ian A. Quillen ◽  
Melodie Yen ◽  
Stephen M. Wilson
Keyword(s):  
Task Difficulty ◽  
Right Hemisphere ◽  
Semantic Network ◽  
Inferior Frontal Gyrus ◽  
Neural Correlates ◽  
Normal Individuals ◽  
Linguistic Demand ◽  
Neurologically Normal ◽  
The Right ◽  
Temporal Language

In this study, we investigated how the brain responds to task difficulty in linguistic and non-linguistic contexts. This is important for the interpretation of functional imaging studies of neuroplasticity in post-stroke aphasia, because of the inherent difficulty of matching or controlling task difficulty in studies with neurological populations. Twenty neurologically normal individuals were scanned with fMRI as they performed a linguistic task and a non-linguistic task, each of which had two levels of difficulty. Critically, the tasks were matched across domains (linguistic, non-linguistic) for accuracy and reaction time, such that the differences between the easy and difficult conditions were equivalent across domains. We found that non-linguistic demand modulated the same set of multiple demand (MD) regions that have been identified in many prior studies. In contrast, linguistic demand modulated MD regions to a much lesser extent, especially nodes belonging to the dorsal attention network. Linguistic demand modulated a subset of language regions, with the left inferior frontal gyrus most strongly modulated. The right hemisphere region homotopic to Broca’s area was also modulated by linguistic but not non-linguistic demand. When linguistic demand was mapped relative to non-linguistic demand, we also observed domain by difficulty interactions in temporal language regions as well as a widespread bilateral semantic network. In sum, linguistic and non-linguistic demand have strikingly different neural correlates. These findings can be used to better interpret studies of patients recovering from aphasia. Some reported activations in these studies may reflect task performance differences, while others can be more confidently attributed to neuroplasticity.

scholarly journals Effects of Task Demands on Neural Correlates of Acoustic and Semantic Processing in Challenging Listening Conditions

2021 ◽  
Vol 64 (9) ◽  
pp. 3697-3706
Author(s):  
Dhatri S. Devaraju ◽  
Amy Kemp ◽  
David A. Eddins ◽  
Rahul Shrivastav ◽  
Bharath Chandrasekaran ◽  
...  
Keyword(s):  
Task Difficulty ◽  
Semantic Processing ◽  
Neural Correlates ◽  
Task Demands ◽  
Acoustic Properties ◽  
Lower Probability ◽  
Temporal Envelope ◽  
Lexical Semantic ◽  
Listening Strategies ◽  
Semantic Processes

Purpose Listeners shift their listening strategies between lower level acoustic information and higher level semantic information to prioritize maximum speech intelligibility in challenging listening conditions. Although increasing task demands via acoustic degradation modulates lexical-semantic processing, the neural mechanisms underlying different listening strategies are unclear. The current study examined the extent to which encoding of lower level acoustic cues is modulated by task demand and associations with lexical-semantic processes. Method Electroencephalography was acquired while participants listened to sentences in the presence of four-talker babble that contained either higher or lower probability final words. Task difficulty was modulated by time available to process responses. Cortical tracking of speech—neural correlates of acoustic temporal envelope processing—were estimated using temporal response functions. Results Task difficulty did not affect cortical tracking of temporal envelope of speech under challenging listening conditions. Neural indices of lexical-semantic processing (N400 amplitudes) were larger with increased task difficulty. No correlations were observed between the cortical tracking of temporal envelope of speech and lexical-semantic processes, even after controlling for the effect of individualized signal-to-noise ratios. Conclusions Cortical tracking of the temporal envelope of speech and semantic processing are differentially influenced by task difficulty. While increased task demands modulated higher level semantic processing, cortical tracking of the temporal envelope of speech may be influenced by task difficulty primarily when the demand is manipulated in terms of acoustic properties of the stimulus, consistent with an emerging perspective in speech perception.

The Anterior Hippocampus Supports a Coarse, Global Environmental Representation and the Posterior Hippocampus Supports Fine-grained, Local Environmental Representations

2013 ◽  
Vol 25 (11) ◽  
pp. 1908-1925 ◽  
Author(s):  
Hallvard Røe Evensmoen ◽  
Hanne Lehn ◽  
Jian Xu ◽  
Menno P. Witter ◽  
Lynn Nadel ◽  
...  
Keyword(s):  
Parietal Cortex ◽  
Shape Analysis ◽  
Neural Correlates ◽  
Structural Shape ◽  
Fine Grained ◽  
Global Environmental ◽  
Inferior Parietal Cortex ◽  
The World ◽  
Route Information ◽  
Environmental Representation

Representing an environment globally, in a coarse way, and locally, in a fine-grained way, are two fundamental aspects of how our brain interprets the world that surrounds us. The neural correlates of these representations have not been explicated in humans. In this study we used fMRI to investigate these correlates and to explore a possible functional segregation in the hippocampus and parietal cortex. We hypothesized that processing a coarse, global environmental representation engages anterior parts of these regions, whereas processing fine-grained, local environmental information engages posterior parts. Participants learned a virtual environment and then had to find their way during fMRI. After scanning, we assessed strategies used and representations stored. Activation in the hippocampal head (anterior) was related to the multiple distance and global direction judgments and to the use of a coarse, global environmental representation during navigation. Activation in the hippocampal tail (posterior) was related to both local and global direction judgments and to using strategies like number of turns. A structural shape analysis showed that the use of a coarse, global environmental representation was related to larger right hippocampal head volume and smaller right hippocampal tail volume. In the inferior parietal cortex, a similar functional segregation was observed, with global routes represented anteriorly and fine-grained route information such as number of turns represented posteriorly. In conclusion, moving from the anterior to the posterior hippocampus and inferior parietal cortex reflects a shift from processing coarse global environmental representations to processing fine-grained, local environmental representations.

Neural correlates of successful memory retrieval in aging: Do executive functioning and task difficulty matter?

2016 ◽  
Vol 1631 ◽  
pp. 53-71 ◽  
Author(s):  
Lucie Angel ◽  
Christine Bastin ◽  
Sarah Genon ◽  
Eric Salmon ◽  
Séverine Fay ◽  
...  
Keyword(s):  
Executive Functioning ◽  
Memory Retrieval ◽  
Task Difficulty ◽  
Neural Correlates ◽  
And Task

scholarly journals Distinct effects of prefrontal and parietal cortex inactivations on an accumulation of evidence task in the rat

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Jeffrey C Erlich ◽  
Bingni W Brunton ◽  
Chunyu A Duan ◽  
Timothy D Hanks ◽  
Carlos D Brody
Keyword(s):  
Decision Making ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Neural Correlates ◽  
Brain Regions ◽  
Integration Time ◽  
Detailed Model ◽  
Evidence Accumulation ◽  
Posterior Parietal ◽  
Cortical Regions

Numerous brain regions have been shown to have neural correlates of gradually accumulating evidence for decision-making, but the causal roles of these regions in decisions driven by accumulation of evidence have yet to be determined. Here, in rats performing an auditory evidence accumulation task, we inactivated the frontal orienting fields (FOF) and posterior parietal cortex (PPC), two rat cortical regions that have neural correlates of accumulating evidence and that have been proposed as central to decision-making. We used a detailed model of the decision process to analyze the effect of inactivations. Inactivation of the FOF induced substantial performance impairments that were quantitatively best described as an impairment in the output pathway of an evidence accumulator with a long integration time constant (>240 ms). In contrast, we found a minimal role for PPC in decisions guided by accumulating auditory evidence, even while finding a strong role for PPC in internally-guided decisions.

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