scholarly journals Hypnotic visual hallucination induces greater lateralised brain activity than visual imagery

2021 ◽  
Author(s):  
Renzo C. Lanfranco ◽  
Álvaro Rivera-Rei ◽  
David Huepe ◽  
Agustín Ibáñez ◽  
Andrés Canales-Johnson
Keyword(s):  
Mental Imagery ◽  
Sensory Processing ◽  
Visual Imagery ◽  
Visual Hallucination ◽  
Right Hemisphere ◽  
Brain Activity ◽  
Top Down ◽  
Neural Processes ◽  
Sense Of Reality ◽  
The Right

AbstractHypnotic suggestions can produce a broad range of perceptual experiences, including hallucinations. Visual hypnotic hallucinations differ in many ways from regular mental images. For example, they are usually experienced as automatic, vivid, and real images, typically compromising the sense of reality. While both hypnotic hallucination and mental imagery are believed to mainly rely on the activation of the visual cortex via top-down mechanisms, it is unknown how they differ in the neural processes they engage. Here we used an adaptation paradigm to test and compare top-down processing between hypnotic hallucination, mental imagery, and visual perception in very highly hypnotisable individuals whose ability to hallucinate was assessed. By measuring the N170/VPP event-related complex and using multivariate decoding analysis, we found that hypnotic hallucination of faces involves greater top-down activation of sensory processing through lateralised mechanisms in the right hemisphere compared to mental imagery. Our findings suggest that the neural signatures that distinguish hypnotically hallucinated faces from imagined faces lie in the right brain hemisphere.

scholarly journals Visual Hypo and Hypergnosia as Exemplars of Poles of Psychic Tonus in the Occipital Lobes: Multiple Case Analyses

2008 ◽  
Vol 19 (4) ◽  
pp. 153-168
Author(s):  
Claude M. J. Braun ◽  
Anik Guimond
Keyword(s):  
Visual Imagery ◽  
Visual Hallucination ◽  
Right Hemisphere ◽  
Hemispheric Specialization ◽  
Unilateral Lesion ◽  
Temporal Lobes ◽  
Parietal Lobes ◽  
Multiple Case ◽  
The Right ◽  
Occipital Lobes

The “psychic tonus” model or PTM [1] of hemispheric specialization states that the left hemisphere is a psychic and behavioral activator and that the right hemisphere is an inhibitor. The PTM predicts that the tonus of visual representation ought to manifest hemispheric specialization in the occipital lobes. Specifically PTM predicts that pathological positive visual tonus (visual hallucination) ought to be associated more frequently with right occipital lesions. PTM also predicts that pathological negative visual tonus (loss of visual imagery) ought to result more often from left occipital lesions. We reviewed 78 cases of post lesion hallucination and 12 cases of post lesion loss of evocation of images, all following a unilateral lesion. Analyses of these relevant previously published cases support the predictions. In accordance with previously published demonstrations of hemispheric specialization for auditory tonus in the temporal lobes and for somesthetic tonus in the parietal lobes, the present findings extend the psychic tonus model of hemispheric specialization to vision in the occipital lobes.

scholarly journals Prefrontal High Gamma in ECoG tags periodicity of musical rhythms in perception and imagination

2019 ◽  
Author(s):  
S. A. Herff ◽  
C. Herff ◽  
A. J. Milne ◽  
G. D. Johnson ◽  
J. J. Shih ◽  
...  
Keyword(s):  
Auditory Processing ◽  
Right Hemisphere ◽  
Brain Activity ◽  
Activity Patterns ◽  
Superior Temporal Gyrus ◽  
Gamma Activity ◽  
Rhythm Perception ◽  
High Gamma ◽  
The Right ◽  
Musical Rhythms

AbstractRhythmic auditory stimuli are known to elicit matching activity patterns in neural populations. Furthermore, recent research has established the particular importance of high-gamma brain activity in auditory processing by showing its involvement in auditory phrase segmentation and envelope-tracking. Here, we use electrocorticographic (ECoG) recordings from eight human listeners, to see whether periodicities in high-gamma activity track the periodicities in the envelope of musical rhythms during rhythm perception and imagination. Rhythm imagination was elicited by instructing participants to imagine the rhythm to continue during pauses of several repetitions. To identify electrodes whose periodicities in high-gamma activity track the periodicities in the musical rhythms, we compute the correlation between the autocorrelations (ACC) of both the musical rhythms and the neural signals. A condition in which participants listened to white noise was used to establish a baseline. High-gamma autocorrelations in auditory areas in the superior temporal gyrus and in frontal areas on both hemispheres significantly matched the autocorrelation of the musical rhythms. Overall, numerous significant electrodes are observed on the right hemisphere. Of particular interest is a large cluster of electrodes in the right prefrontal cortex that is active during both rhythm perception and imagination. This indicates conscious processing of the rhythms’ structure as opposed to mere auditory phenomena. The ACC approach clearly highlights that high-gamma activity measured from cortical electrodes tracks both attended and imagined rhythms.

scholarly journals Decreases in Frontal and Parietal Lobe Regional Cerebral Blood Flow Related to Habituation

1992 ◽  
Vol 12 (4) ◽  
pp. 546-553 ◽  
Author(s):  
Steven Warach ◽  
Ruben C. Gur ◽  
Raquel E. Gur ◽  
Brett E. Skolnick ◽  
Walter D. Obrist ◽  
...  
Keyword(s):  
Right Hemisphere ◽  
Parietal Lobe ◽  
Brain Activity ◽  
Inhalation Technique ◽  
Attentional Processes ◽  
Left Handed ◽  
Verbal Tasks ◽  
Spatial Tasks ◽  
Regional Specificity ◽  
The Right

We previously reported decreased mean CBF between consecutive resting conditions, ascribed to habituation. Here we address the regional specificity of habituation over three consecutive flow studies. Regional CBF (rCBF) was measured in 55 adults (12 right-handed men, 12 right-handed women, 14 left-handed men, 17 left-handed women), with the 133Xe inhalation technique, during three conditions: Resting, verbal tasks (analogies), and spatial tasks (line orientation). Changes in rCBF attributable to the cognitive tasks were eliminated by correcting these values to a resting equivalent. There was a progressive decrease in mean rCBF over time, reflecting habituation. This effect differed by region, with specificity at frontal (prefrontal, inferior frontal, midfrontal, superior frontal) and inferior parietal regions. In the inferior parietal region, habituation was more marked in the left than the right hemisphere. Right-handers showed greater habituation than did left-handers. There was no sex difference in global habituation, but males showed greater left whereas females showed greater right hemispheric habituation. The results suggest that habituation to the experimental setting has measurable effects on rCBF, which are differently lateralized for men and women. These effects are superimposed on task activation and are most pronounced in regions that have been implicated in attentional processes. Thus, regional decrement in brain activity related to habituation seems to complement attentional effects, suggesting a neural network for habituation reciprocating that for attention.

Modulation of Spatial Orientation Processing by Mental Imagery Instructions: A MEG Study of Representational Momentum

2000 ◽  
Vol 12 (4) ◽  
pp. 569-582 ◽  
Author(s):  
Michel-Ange Amorim ◽  
Wilfried Lang ◽  
Gerald Lindinger ◽  
Dagmar Mayer ◽  
Lüder Deecke ◽  
...  
Keyword(s):  
Mental Imagery ◽  
Spatial Orientation ◽  
Visual Motion ◽  
Brain Activity ◽  
Representational Momentum ◽  
The Body ◽  
Body Motion ◽  
Body Tilt ◽  
Rotational Equilibrium ◽  
The Right

Under appropriate conditions, an observer's memory for the final position of an abruptly halted moving object is distorted in the direction of the represented motion. This phenomenon is called “representational momentum” (RM). We examined the effect of mental imagery instructions on the modulation of spatial orientation processing by testing for RM under conditions of picture versus body rotation perception and imagination. Behavioral data were gathered via classical reaction time and error measurements, whereas brain activity was recorded with the help of magnetoence-phalography (MEG). Due to the so-called inverse problem and to signal complexity, results were described at the signal level rather than with the source location modeling. Brain magnetic field strength and spatial distribution, as well as latency of P200m evoked fields were used as neurocognitive markers. A task was devised where a subject examined a rotating sea horizon as seen from a virtual boat in order to extrapolate either the picture motion or the body motion relative to the picture while the latter disappeared temporarily until a test-view was displayed as a final orientation candidate. Results suggest that perceptual interpretation and extrapolation of visual motion in the roll plane capitalize on the fronto-parietal cortical networks involving working memory processes. Extrapolation of the rotational dynamics of sea horizon revealed a RM effect simulating the role of gravity in rotational equilibrium. Modulation of the P200m component reflected spatial orientation processing and a non-voluntary detection of an incongruity between displayed and expected final orientations given the implied motion. Neuromagnetic properties of anticipatory (Contingent Magnetic Variation) and evoked (P200m) brain magnetic fields suggest, respectively, differential allocation of attentional resources by mental imagery instructions (picture vs. body tilt), and a communality of neural structures (in the right centro-parietal region) for the control of both RM and mental rotation processes. Finally, the RM of the body motion is less prone to forward shifts than that of picture motion evidencing an internalization of the implied mass of the virtual body of the observer.

scholarly journals Optical Mapping of Brain Activity Underlying Directionality and Its Modulation by Expertise in Mandarin/English Interpreting

2021 ◽  
Vol 15 ◽  
Author(s):  
Yan He ◽  
Yinying Hu ◽  
Yaxi Yang ◽  
Defeng Li ◽  
Yi Hu
Keyword(s):  
Prefrontal Cortex ◽  
Cognitive Skills ◽  
Near Infrared ◽  
Right Hemisphere ◽  
Brain Activity ◽  
Brain Regions ◽  
Broca’S Area ◽  
Broca's Area ◽  
Functional Near Infrared Spectroscopy ◽  
The Right

Recent neuroimaging research has suggested that unequal cognitive efforts exist between interpreting from language 1 (L1) to language 2 (L2) compared with interpreting from L2 to L1. However, the neural substrates that underlie this directionality effect are not yet well understood. Whether directionality is modulated by interpreting expertise also remains unknown. In this study, we recruited two groups of Mandarin (L1)/English (L2) bilingual speakers with varying levels of interpreting expertise and asked them to perform interpreting and reading tasks. Functional near-infrared spectroscopy (fNIRS) was used to collect cortical brain data for participants during each task, using 68 channels that covered the prefrontal cortex and the bilateral perisylvian regions. The interpreting-related neuroimaging data was normalized by using both L1 and L2 reading tasks, to control the function of reading and vocalization respectively. Our findings revealed the directionality effect in both groups, with forward interpreting (from L1 to L2) produced more pronounced brain activity, when normalized for reading. We also found that directionality was modulated by interpreting expertise in both normalizations. For the group with relatively high expertise, the activated brain regions included the right Broca’s area and the left premotor and supplementary motor cortex; whereas for the group with relatively low expertise, the activated brain areas covered the superior temporal gyrus, the dorsolateral prefrontal cortex (DLPFC), the Broca’s area, and visual area 3 in the right hemisphere. These findings indicated that interpreting expertise modulated brain activation, possibly because of more developed cognitive skills associated with executive functions in experienced interpreters.

scholarly journals Virtual reality-based sensorimotor adaptation shapes subsequent spontaneous and naturalistic stimulus-driven brain activity

2021 ◽  
Author(s):  
Meytal Wilf ◽  
Celine Dupuis ◽  
Davide Nardo ◽  
Diana Huber ◽  
Sibilla Sander ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Large Scale ◽  
Right Hemisphere ◽  
Functional Neuroimaging ◽  
Brain Activity ◽  
Visual Response ◽  
Spatial Shift ◽  
Before And After ◽  
Behavioural Tests ◽  
The Right

Our everyday life summons numerous novel sensorimotor experiences, to which our brain needs to adapt in order to function properly. However, tracking plasticity of naturalistic behaviour and associated brain modulations is challenging. Here we tackled this question implementing a prism adaptation training in virtual reality (VRPA) in combination with functional neuroimaging. Three groups of healthy participants (N=45) underwent VRPA (with a spatial shift either to the left/right side, or with no shift), and performed fMRI sessions before and after training. To capture modulations in free-flowing, task-free brain activity, the fMRI sessions included resting state and free viewing of naturalistic videos. We found significant decreases in spontaneous functional connectivity between large-scale cortical networks, namely attentional and default mode/fronto-parietal networks, only for adaptation groups. Additionally, VRPA was found to bias visual representations of naturalistic videos, as following rightward adaptation, we found upregulation of visual response in an area in the parieto-occipital sulcus (POS) in the right hemisphere. Notably, the extent of POS upregulation correlated with the size of the VRPA induced after-effect measured in behavioural tests. This study demonstrates that a brief VRPA exposure is able to change large-scale cortical connectivity and correspondingly bias the representation of naturalistic sensory inputs.

Attentional Modulation of the Emotional Expression Processing Studied with ERPs and sLORETA

2014 ◽  
Vol 28 (1) ◽  
pp. 32-46 ◽  
Author(s):  
Eligiusz Wronka ◽  
Wioleta Walentowska
Keyword(s):  
Emotional Expression ◽  
Right Hemisphere ◽  
Brain Activity ◽  
Extrastriate Cortex ◽  
Attentional Modulation ◽  
Early Stages ◽  
Facial Stimuli ◽  
The Right ◽  
Expression Processing ◽  
The Brain

Recent ERP studies demonstrate that the processing of facial emotional expression can be modulated by attention. The aim of the present study was to investigate the neural correlates of attentional influence on the emotional expression processing at early stages. We recorded ERP responses to facial stimuli containing neutral versus emotional expression in two different conditions. The first task was to discriminate facial expressions, while the second task was to categorize face gender. Enhanced positivity at occipital and occipito-temporal locations between 110 and 170 ms poststimulus was elicited by facial stimuli presented in the expression task when compared to the gender task. This effect temporally overlapped with the P1 and N170 components, which reflect the early stages of face processing. To localize the sources of the brain activity underlying observed attentional modulation, we used Standardized Low Resolution Electromagnetic Tomography. Enhanced activity within the extrastriate cortex for the expression task was obtained as the reflection of early ERP effect. Additionally, we found stronger activation within the superior temporal and the fusiform gyrus of the right hemisphere in the expression task when compared to the gender task. Our findings undoubtedly confirm that early stages of the emotional expression processing can be modified by top-down attention.

Seating Preference, Hypnotizability, and Imagery Ability

1980 ◽  
Vol 50 (3_suppl) ◽  
pp. 1175-1178 ◽  
Author(s):  
Jacquelyn Cranney ◽  
Kevin M. Mc Conkey
Keyword(s):  
Mental Imagery ◽  
Right Hemisphere ◽  
Imagery Ability ◽  
Hypnotic Susceptibility ◽  
Creative Imagination ◽  
Male And Female ◽  
The Right ◽  
Female Subjects

The effects of a specific hemispheric mode of functioning as indexed by lateralized seating preference was tested separately for male and female subjects in terms of their performance on the Harvard Group Scale of Hypnotic Susceptibility, Form A, the Creative Imagination Scale, and Betts' Questionnaire Upon Mental Imagery. Males, but not females, who preferred right-side seating scored higher on the Harvard scale but not on the Creative Imagination Scale or Betts' imagery questionnaire. Findings provide some support for the notion that hypnotizability is associated with the right hemisphere for right-handed persons.

PRAXIS AND LANGUAGE ORGANIZATION IN LEFT-HANDERS

2020 ◽  
Vol 18 (1) ◽  
pp. 15-28
Author(s):  
Grzegorz Króliczak ◽  
Brian J. Piper ◽  
Weronika Potok ◽  
Mikołaj Buchwald ◽  
Paweł Kleka ◽  
...  
Keyword(s):  
Bimanual Coordination ◽  
Right Hemisphere ◽  
Functional Neuroimaging ◽  
Spatial Processing ◽  
Language Functions ◽  
Attentional Resources ◽  
Neural Processes ◽  
The Mean ◽  
The Right

The performance of learned manual gestures (praxis) and the production of speech are thought to depend on related neural processes. If this relationship is not invoked by an unknown, third variable then shifts in their laterality, including dissociations of these two functions, would be unlikely unless the sharing of some neural resources with other functions is advantageous. This could be the case in lefthanders, in whom actions requiring manual precision are controlled by their right hemispheres, and whose representations could attract the control of skilled gesture. Functional neuroimaging (fMRI) was used to study praxis and language functions. Their lateralization indices were measured in 56 consecutively tested lefthanders (28 females), with the mean age of 23.3±4.9 years (range 18.4 – 47 years), and an Edinburgh Handedness Inventory quotient between –100 and –55.6 (with the mean of –83.8±14.2). We show that atypical, bilateral organization or right-lateralization of praxis is more common than atypical organization/lateralization of language, observed, respectively, in 23 (41%) vs. 15 (26.8%) of cases. Specifically, we found: (a) seven cases (12.5%) of clear, and an additional three cases (5.4%) of less pronounced dissociations of atypically represented praxis from typically represented language; (b) 13 cases (23.2%) with atypically organized praxis also associated with atypically organized language, and (c) only two cases (3.6%) of rather strongly atypical lateralization of language, yet with quite typical lateralization of praxis. These outcomes are consistent with an idea that, in some lefthanders, the guidance of skilled manual actions can profit from tighter links with the right hemisphere, whose motor specialization is linked in this particular population to manual precision, but in general to attentional resources, visuo-spatial processing and even bimanual coordination. Because of the presumed links of praxis with productive language, such transfers are often, and unsurprisingly accompanied by the reorganization of the latter. Yet, the very rare cases of reversed language functions, without any pronounced shifts in representations of praxis, indicate that such a pattern of segregation – or inverse dissociation – of these two functions could be maladaptive.

scholarly journals Anhedonia to Gentle Touch in Fibromyalgia: Normal Sensory Processing but Abnormal Evaluation

2020 ◽  
Vol 10 (5) ◽  
pp. 306 ◽  
Author(s):  
Rebecca Boehme ◽  
Helene van Ettinger-Veenstra ◽  
Håkan Olausson ◽  
Björn Gerdle ◽  
Saad S. Nagi
Keyword(s):  
Sensory Processing ◽  
Early Stage ◽  
Pain Catastrophizing ◽  
Brain Activity ◽  
Functional Brain Imaging ◽  
Opposite Pattern ◽  
Tactile Stimuli ◽  
Morphometry Analysis ◽  
The Right ◽  
Healthy Participants

Social touch is important for interpersonal interaction. Gentle touch and slow brushing are typically perceived as pleasant, the degree of pleasantness is linked to the activity of the C-tactile (CT) fibers, a class of unmyelinated nerves in the skin. The inability to experience pleasure in general is called anhedonia, a common phenomenon in the chronic pain condition fibromyalgia. Here, we studied the perception and cortical processing of gentle touch in a well-characterized cohort of fibromyalgia. Patients and controls participated in functional brain imaging while receiving tactile stimuli (brushing) on the forearm. They were asked to provide ratings of pleasantness of the tactile stimulus and ongoing pain. We found high distress, pain catastrophizing, and insomnia, and a low perceived state of health in fibromyalgia. Further, patients rated both slow (CT-optimal) and fast (CT-suboptimal) brushing as less pleasant than healthy participants. While there was no difference in brain activity during touch, patients showed deactivation in the right posterior insula (contralateral to the stimulated arm) during pleasantness rating and activation during pain rating. The opposite pattern was observed in healthy participants. Voxel-based morphometry analysis revealed reduced grey matter density in patients, in the bilateral hippocampus and anterior insula. Our results suggest anhedonia to gentle touch in fibromyalgia with intact early-stage sensory processing but dysfunctional evaluative processing. These findings contribute to our understanding of the mechanisms underlying anhedonia in fibromyalgia.

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