Differences in “bottom-up” and “top-down” neural activity in current and former cigarette smokers: Evidence for neural substrates which may promote nicotine abstinence through increased cognitive control

NeuroImage ◽  
2011 ◽  
Vol 56 (4) ◽  
pp. 2258-2275 ◽  
Author(s):  
Liam Nestor ◽  
Ella McCabe ◽  
Jennifer Jones ◽  
Luke Clancy ◽  
Hugh Garavan
2002 ◽  
Vol 25 (2) ◽  
pp. 194-195
Author(s):  
Stephen Grossberg

Recent neural models clarify many properties of mental imagery as part of the process whereby bottom-up visual information is influenced by top-down expectations, and how these expectations control visual attention. Volitional signals can transform modulatory top-down signals into supra-threshold imagery. Visual hallucinations can occur when the normal control of these volitional signals is lost.


Author(s):  
Sonia Bansal ◽  
John M Gaspar ◽  
Benjamin M Robinson ◽  
Carly J Leonard ◽  
Britta Hahn ◽  
...  

Abstract The antisaccade task is considered a test of cognitive control because it creates a conflict between the strong bottom-up signal produced by the cue and the top-down goal of shifting gaze to the opposite side of the display. Antisaccade deficits in schizophrenia are thought to reflect impaired top-down inhibition of the prepotent bottom-up response to the cue. However, the cue is also a highly task-relevant stimulus that must be covertly attended to determine where to shift gaze. We tested the hypothesis that difficulty in overcoming the attentional relevance of the cue, rather than its bottom-up salience, is key in producing impaired performance in people with schizophrenia (PSZ). We implemented 3 versions of the antisaccade task in which we varied the bottom-up salience of the cue while holding its attentional relevance constant. We found that difficulty in performing a given antisaccade task—relative to a prosaccade version using the same stimuli—was largely independent of the cue’s bottom-up salience. The magnitude of impairment in PSZ relative to control subjects was also independent of bottom-up salience. The greatest impairment was observed in a version where the cue lacked bottom-up salience advantage over other locations. These results indicate that the antisaccade deficit in PSZ does not reflect an impairment in overcoming bottom-up salience of the cue, but PSZ are instead impaired at overcoming its attentional relevance. This deficit may still indicate an underlying inhibitory control impairment but could also reflect a hyperfocusing of attentional resources on the cue.


2013 ◽  
Vol 368 (1628) ◽  
pp. 20130069 ◽  
Author(s):  
Koorosh Mirpour ◽  
James W. Bisley

When searching for an object, we usually avoid items that are visually different from the target and objects or places that have been searched already. Previous studies have shown that neural activity in the lateral intraparietal area (LIP) can be used to guide this behaviour; responses to task irrelevant stimuli or to stimuli that have been fixated previously in the trial are reduced compared with responses to potential targets. Here, we test the hypothesis that these reduced responses have a different genesis. Two animals were trained on a visual foraging task, in which they had to find a target among a number of physically identical potential targets (T) and task irrelevant distractors. We recorded neural activity and local field potentials (LFPs) in LIP while the animals performed the task. We found that LFP power was similar for potential targets and distractors but was greater in the alpha and low beta bands when a previously fixated T was in the response field. We interpret these data to suggest that the reduced single-unit response to distractors is a bottom-up feed-forward result of processing in earlier areas and the reduced response to previously fixated Ts is a result of active top-down suppression.


2003 ◽  
Vol 26 (1) ◽  
pp. 96-96
Author(s):  
Angus W. MacDonald

AbstractThis commentary challenges the authors to use their computational modeling techniques to support one of their central claims: that schizophrenic deficits in bottom-up (Gestalt-type tasks) and top-down (cognitive control tasks) context processing tasks arise from the same dysfunction. Further clarification about the limits of cognitive coordination would also strengthen the hypothesis.


2017 ◽  
Author(s):  
Gina M. Grimshaw ◽  
Laura Kranz ◽  
David Carmel ◽  
Rosie Moody ◽  
Christel Devue

Attending to emotional stimuli is often beneficial, because they provide important social and environmental cues. Sometimes, however, current goals require that we ignore them. To what extent can we control emotional distraction? Here we show that the ability to ignore emotional distractions depends on the type of cognitive control that is engaged. Participants completed a simple perceptual task at fixation while irrelevant images appeared peripherally. In two experiments, we manipulated the proportion of trials in which images appeared, in order to encourage use of either reactive control (rare distractors) or proactive control (frequent distractors). Under reactive control, both negative and positive images were more distracting than neutral images, even though they were irrelevant and appeared in unattended locations. However, under proactive control, distraction by both emotional and neutral images was eliminated. Proactive control was triggered by the meaning, and not the location, of distracting images. Our findings argue against simple bottom-up or top-down explanations of emotional distraction, and instead show how the flexible use of cognitive control supports adaptive processing of emotional distractors.


PsycCRITIQUES ◽  
2005 ◽  
Vol 50 (19) ◽  
Author(s):  
Michael Cole
Keyword(s):  
Top Down ◽  

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