scholarly journals Cortical excitability controls the strength of mental imagery

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Rebecca Keogh ◽  
Johanna Bergmann ◽  
Joel Pearson
Keyword(s):  
Visual Cortex ◽  
Mental Imagery ◽  
Visual Imagery ◽  
Cortical Excitability ◽  
Mental Health Research ◽  
Causative Role ◽  
Mental Images ◽  
Neurophysiological Mechanism ◽  
Early Visual Cortex ◽  
Sensory Imagery

Mental imagery provides an essential simulation tool for remembering the past and planning the future, with its strength affecting both cognition and mental health. Research suggests that neural activity spanning prefrontal, parietal, temporal, and visual areas supports the generation of mental images. Exactly how this network controls the strength of visual imagery remains unknown. Here, brain imaging and transcranial magnetic phosphene data show that lower resting activity and excitability levels in early visual cortex (V1-V3) predict stronger sensory imagery. Further, electrically decreasing visual cortex excitability using tDCS increases imagery strength, demonstrating a causative role of visual cortex excitability in controlling visual imagery. Together, these data suggest a neurophysiological mechanism of cortical excitability involved in controlling the strength of mental images.

scholarly journals Cortical excitability controls the strength of mental imagery

2016 ◽  
Author(s):  
Rebecca Keogh ◽  
Johanna Bergmann ◽  
Joel Pearson
Keyword(s):  
Visual Cortex ◽  
Mental Imagery ◽  
Visual Imagery ◽  
Cortical Excitability ◽  
Mental Health Research ◽  
Causative Role ◽  
Mental Images ◽  
Neurophysiological Mechanism ◽  
Early Visual Cortex ◽  
Sensory Imagery

AbstractMental imagery provides an essential simulation tool for remembering the past and planning the future, with its strength affecting both cognition and mental health. Research suggests that neural activity spanning prefrontal, parietal, temporal, and visual areas supports the generation of mental images. Exactly how this network controls the strength of visual imagery remains unknown. Here, brain imaging and transcranial magnetic phosphene data show that lower resting activity and excitability levels in early visual cortex (V1-V3) predict stronger sensory imagery. Electrically decreasing visual cortex excitability using tDCS increases imagery strength, demonstrating a causative role of visual cortex excitability in controlling visual imagery. These data suggest a neurophysiological mechanism of cortical excitability involved in controlling the strength of mental images.

scholarly journals Reconstructing imagined letters from early visual cortex reveals tight topographic correspondence between visual mental imagery and perception

2018 ◽  
Author(s):  
Mario Senden ◽  
Thomas Emmerling ◽  
Rick van Hoof ◽  
Martin Frost ◽  
Rainer Goebel
Keyword(s):  
Visual Cortex ◽  
Mental Imagery ◽  
Visual Imagery ◽  
Subjective Experience ◽  
Fine Tuning ◽  
Machine Learning Techniques ◽  
Visual Mental Imagery ◽  
Topographic Organization ◽  
Early Visual Cortex ◽  
Imagery Data

AbstractVisual mental imagery is the quasi-perceptual experience of “seeing in the mind’s eye”. While a tight correspondence between imagery and perception in terms of subjective experience is well established, their correspondence in terms of neural representations remains insufficiently understood. In the present study, we exploit the high spatial resolution of functional magnetic resonance imaging (fMRI) at 7T, the retinotopic organization of early visual cortex, and machine learning techniques to investigate whether visual imagery of letter shapes preserves the topographic organization of perceived shapes. Sub-millimeter resolution fMRI images were obtained from early visual cortex in six subjects performing visual imagery of four different letter shapes. Predictions of imagery voxel activation patterns based on a population receptive field encoding model and physical letter stimuli provided first evidence in favor of detailed topographic organization. Subsequent visual field reconstructions of imagery data based on the inversion of the encoding model further showed that visual imagery preserves the geometric profile of letter shapes. These results open new avenues for decoding as we show that a denoising autoencoder can be used to pretrain a classifier purely based on perceptual data before fine-tuning it on imagery data. Finally, we show that the autoencoder can project imagery-related voxel activations onto their perceptual counterpart allowing for visually recognizable reconstructions even at the single-trial level. The latter may eventually be utilized for the development of content-based BCI letter-speller systems.

scholarly journals Mental Imagery Follows Similar Cortical Reorganization as Perception: Intra-Modal and Cross-Modal Plasticity in Congenitally Blind

2018 ◽  
Vol 29 (7) ◽  
pp. 2859-2875 ◽  
Author(s):  
A W de Borst ◽  
B de Gelder
Keyword(s):  
Visual Cortex ◽  
Mental Imagery ◽  
Cortical Plasticity ◽  
Tactile Perception ◽  
Cortical Reorganization ◽  
Area V4 ◽  
Congenitally Blind ◽  
Early Visual Cortex ◽  
Blind Individuals ◽  
Discriminative Patterns

Abstract Cortical plasticity in congenitally blind individuals leads to cross-modal activation of the visual cortex and may lead to superior perceptual processing in the intact sensory domains. Although mental imagery is often defined as a quasi-perceptual experience, it is unknown whether it follows similar cortical reorganization as perception in blind individuals. In this study, we show that auditory versus tactile perception evokes similar intra-modal discriminative patterns in congenitally blind compared with sighted participants. These results indicate that cortical plasticity following visual deprivation does not influence broad intra-modal organization of auditory and tactile perception as measured by our task. Furthermore, not only the blind, but also the sighted participants showed cross-modal discriminative patterns for perception modality in the visual cortex. During mental imagery, both groups showed similar decoding accuracies for imagery modality in the intra-modal primary sensory cortices. However, no cross-modal discriminative information for imagery modality was found in early visual cortex of blind participants, in contrast to the sighted participants. We did find evidence of cross-modal activation of higher visual areas in blind participants, including the representation of specific-imagined auditory features in visual area V4.

scholarly journals Shared Representations for Working Memory and Mental Imagery in Early Visual Cortex

2013 ◽  
Vol 23 (15) ◽  
pp. 1427-1431 ◽  
Author(s):  
Anke Marit Albers ◽  
Peter Kok ◽  
Ivan Toni ◽  
H. Chris Dijkerman ◽  
Floris P. de Lange
Keyword(s):  
Working Memory ◽  
Visual Cortex ◽  
Mental Imagery ◽  
Shared Representations ◽  
Early Visual Cortex

The Depictive Nature of Visual Mental Imagery

1998 ◽  
pp. 221-227
Author(s):  
Norman Yujen Teng
Keyword(s):  
Content Analysis ◽  
Visual Cortex ◽  
Mental Imagery ◽  
Mental Representations ◽  
Image Representation ◽  
The Other ◽  
Mental Images ◽  
Visual Mental Imagery ◽  
Topographic Representation ◽  
The Brain

Tye argues that visual mental images have their contents encoded in topographically organized regions of the visual cortex, which support depictive representations; therefore, visual mental images rely at least in part on depictive representations. This argument, I contend, does not support its conclusion. I propose that we divide the problem about the depictive nature of mental imagery into two parts: one concerns the format of image representation and the other the conditions by virtue of which a representation becomes a depictive representation. Regarding the first part of the question, I argue that there exists a topographic format in the brain but that does not imply that there exists a depictive format of image representation. My answer to the second part of the question is that one needs a content analysis of a certain sort of topographic representations in order to make sense of depictive mental representations, and a topographic representation becomes a depictive representation by virtue of its content rather than its form.

scholarly journals Visual Mental Imagery Activates Topographically Organized Visual Cortex: PET Investigations

1993 ◽  
Vol 5 (3) ◽  
pp. 263-287 ◽  
Author(s):  
Stephen M. Kosslyn ◽  
Nathaniel M. Alpert ◽  
William L. Thompson ◽  
Vera Maljkovic ◽  
Steven B. Weise ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Mental Imagery ◽  
Anterior Part ◽  
Imagery Task ◽  
Area 17 ◽  
Mental Images ◽  
Imagery Condition ◽  
Posterior Portion ◽  
Large Size ◽  
Positron Emission

Cerebral blood flow was measured using positron emission tomography (PET) in three experiments while subjects performed mental imagery or analogous perceptual tasks. In Experiment 1, the subjects either visualized letters in grids and decided whether an X mark would have fallen on each letter if it were actually in the grid, or they saw letters in grids and decided whether an X mark fell on each letter. A region identified as part of area 17 by the Talairach and Tournoux (1988) atlas, in addition to other areas involved in vision, was activated more in the mental imagery task than in the perception task. In Experiment 2, the identical stimuli were presented in imagery and baseline conditions, but subjects were asked to form images only in the imagery condition; the portion of area 17 that was more active in the imagery condition of Experiment 1 was also more activated in imagery than in the baseline condition, as was part of area 18. Subjects also were tested with degraded perceptual stimuli, which caused visual cortex to be activated to the same degree in imagery and perception. In both Experiments 1 and 2, however, imagery selectively activated the extreme anterior part of what was identified as area 17, which is inconsistent with the relatively small size of the imaged stimuli. These results, then, suggest that imagery may have activated another region just anterior to area 17. In Experiment 3, subjects were instructed to close their eyes and evaluate visual mental images of upper case letters that were formed at a small size or large size. The small mental images engendered more activation in the posterior portion of visual cortex, and the large mental images engendered more activation in anterior portions of visual cortex. This finding is strong evidence that imagery activates topographically mapped cortex. The activated regions were also consistent with their being localized in area 17. Finally, additional results were consistent with the existence of two types of imagery, one that rests on allocating attention to form a pattern and one that rests on activating stored visual memories.

scholarly journals Transient Activity in the Human Calcarine Cortex During Visual-Mental Imagery: An Event-Related fMRI Study

2000 ◽  
Vol 12 (supplement 2) ◽  
pp. 15-23 ◽  
Author(s):  
Isabelle Klein ◽  
Anne-Lise Paradis ◽  
Jean-Baptiste Poline ◽  
Stephen M. Kosslyn ◽  
Denis Le Bihan
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Mental Imagery ◽  
Visual Imagery ◽  
Mental Image ◽  
Functional Magnetic Resonance ◽  
Visual Mental Imagery ◽  
Fmri Study ◽  
Transient Activity ◽  
Imagery Processing

Although it is largely accepted that visual-mental imagery and perception draw on many of the same neural structures, the existence and nature of neural processing in the primary visual cortex (or area V1) during visual imagery remains controversial. We tested two general hypotheses: The first was that V1 is activated only when images with many details are formed and used, and the second was that V1 is activated whenever images are formed, even if they are not necessarily used to perform a task. We used event-related functional magnetic resonance imaging (ER-fMRI) to detect and characterize the activity in the calcarine sulcus (which contains the primary visual cortex) during single instances of mental imagery. The results revealed reproducible transient activity in this area whenever participants generated or evaluated a mental image. This transient activity was strongly enhanced when participants evaluated characteristics of objects, whether or not details actually needed to be extracted from the image to perform the task. These results show that visual imagery processing commonly involves the earliest stages of the visual system.

scholarly journals Differential effect of visual motion adaption upon visual cortical excitability

2017 ◽  
Vol 117 (3) ◽  
pp. 903-909 ◽  
Author(s):  
Astrid J. A. Lubeck ◽  
Angelique Van Ombergen ◽  
Hena Ahmad ◽  
Jelte E. Bos ◽  
Floris L. Wuyts ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Motion ◽  
Cortical Excitability ◽  
Roll Motion ◽  
Subjective Visual Vertical ◽  
Motion Adaptation ◽  
Visual Vertical ◽  
Early Visual Cortex ◽  
Phosphene Threshold ◽  
Visual Cortical

The objectives of this study were 1) to probe the effects of visual motion adaptation on early visual and V5/MT cortical excitability and 2) to investigate whether changes in cortical excitability following visual motion adaptation are related to the degree of visual dependency, i.e., an overreliance on visual cues compared with vestibular or proprioceptive cues. Participants were exposed to a roll motion visual stimulus before, during, and after visual motion adaptation. At these stages, 20 transcranial magnetic stimulation (TMS) pulses at phosphene threshold values were applied over early visual and V5/MT cortical areas from which the probability of eliciting a phosphene was calculated. Before and after adaptation, participants aligned the subjective visual vertical in front of the roll motion stimulus as a marker of visual dependency. During adaptation, early visual cortex excitability decreased whereas V5/MT excitability increased. After adaptation, both early visual and V5/MT excitability were increased. The roll motion-induced tilt of the subjective visual vertical (visual dependence) was not influenced by visual motion adaptation and did not correlate with phosphene threshold or visual cortex excitability. We conclude that early visual and V5/MT cortical excitability is differentially affected by visual motion adaptation. Furthermore, excitability in the early or late visual cortex is not associated with an increase in visual reliance during spatial orientation. Our findings complement earlier studies that have probed visual cortical excitability following motion adaptation and highlight the differential role of the early visual cortex and V5/MT in visual motion processing. NEW & NOTEWORTHY We examined the influence of visual motion adaptation on visual cortex excitability and found a differential effect in V1/V2 compared with V5/MT. Changes in visual excitability following motion adaptation were not related to the degree of an individual's visual dependency.

How do we define “sameness” of the processing of mental images and general reasoning processes?

2002 ◽  
Vol 25 (2) ◽  
pp. 196-197
Author(s):  
Margaret Jean Intons-Peterson
Keyword(s):  
Mental Imagery ◽  
Null Hypothesis ◽  
Mental Images ◽  
Target Article ◽  
Sensory Imagery

This commentary raises questions about the central concepts in the null hypothesis presented by the author of the target article and urges expansion of the treatment of mental imagery to forms of sensory imagery beyond the visual.

When is early visual cortex activated during visual mental imagery?

2003 ◽  
Vol 129 (5) ◽  
pp. 723-746 ◽  
Author(s):  
Stephen M. Kosslyn ◽  
William L. Thompson
Keyword(s):  
Visual Cortex ◽  
Mental Imagery ◽  
Visual Mental Imagery ◽  
Early Visual Cortex
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