Intrinsic functional organization of retinotopic visual fields in human occipital cortex: A 3T fMRI study

NeuroImage ◽  
2009 ◽  
Vol 47 ◽  
pp. S63
Author(s):  
VG van de Ven ◽  
B Jans ◽  
M Been ◽  
R Goebel ◽  
P de Weerd
Keyword(s):  
Functional Organization ◽  
Visual Fields ◽  
Occipital Cortex ◽  
Fmri Study

Prefrontal Cortical Representation of Visuospatial Working Memory in Monkeys Examined by Local Inactivation With Muscimol

2001 ◽  
Vol 86 (4) ◽  
pp. 2041-2053 ◽  
Author(s):  
Toshiyuki Sawaguchi ◽  
Michiyo Iba
Keyword(s):  
Working Memory ◽  
Functional Organization ◽  
Visual Fields ◽  
Local Injection ◽  
Delayed Response ◽  
Visually Guided ◽  
Visuospatial Working Memory ◽  
Prefrontal Cortical ◽  
Response Task ◽  
Spatial Locations

In primates, dorsolateral areas of the prefrontal cortex (PFC) play a major role in visuospatial working memory. To examine the functional organization of the PFC for representing visuospatial working memory, we produced reversible local inactivation, with the local injection of muscimol (5 μg, 1 μl), at various sites ( n = 100) in the dorsolateral PFC of monkeys and observed the behavioral consequences in an oculomotor delayed-response task that required memory-guided saccades for locations throughout both visual fields. At 82 sites, the local injection of muscimol induced deficits in memory-guided saccades to a few specific, usually contralateral, target locations that varied with the location of the injection site. Such deficits depended on the delay length, and longer delays were associated with larger deficits in memory-guided saccades. The injection sites and affected spatial locations of the target showed a gross topographical relationship. No deficits appeared for a control task in which the subject was required to make a visually guided saccade to a visible target. These findings suggest that a specific site in the dorsolateral PFC is responsible for the working memory process for a specific visuospatial coordinate to guide goal-directed behavior. Further, memoranda for specific visuospatial coordinates appear to be represented in a topographical memory mapwithin the dorsolateral PFC to represent visuospatial working memory processes.

Connectivity and signal intensity in the parieto-occipital cortex predicts top-down attentional effect in visual masking: An fMRI study based on individual differences

NeuroImage ◽  
2009 ◽  
Vol 45 (2) ◽  
pp. 587-597 ◽  
Author(s):  
Hiroyuki Tsubomi ◽  
Takashi Ikeda ◽  
Takashi Hanakawa ◽  
Nobuyuki Hirose ◽  
Hidenao Fukuyama ◽  
...  
Keyword(s):  
Individual Differences ◽  
Signal Intensity ◽  
Visual Masking ◽  
Occipital Cortex ◽  
Top Down ◽  
Fmri Study ◽  
Attentional Effect

Attention and Sensory Interactions within the Occipital Cortex in the Early Blind: An fMRI Study

2007 ◽  
Vol 19 (2) ◽  
pp. 315-330 ◽  
Author(s):  
Kurt E. Weaver ◽  
Alexander A. Stevens
Keyword(s):  
Selective Attention ◽  
Occipital Cortex ◽  
Oddball Paradigm ◽  
Sensory Stimuli ◽  
Tactile Stimuli ◽  
Somatosensory Cortices ◽  
Fmri Study ◽  
Sensory Modalities ◽  
Sensory Interactions ◽  
Task Irrelevant

Visual deprivation early in life results in occipital cortical responsiveness across a broad range of perceptual and cognitive tasks. In the reorganized occipital cortex of early blind (EB) individuals, the relative lack of specificity for particular sensory stimuli and tasks suggests that attention effects may play a prominent role in these areas. We wished to establish whether occipital cortical areas in the EB were responsive to stimuli across sensory modalities (auditory, tactile) and whether these areas maintained or altered their activity as a function of selective attention. Using a three-stimulus oddball paradigm and event-related functional magnetic resonance imaging, auditory and tactile tasks presented separately demonstrated that several occipital regions of interest (ROIs) in the EB, but not sighted controls (SCs), responded to targets and task-irrelevant distracter stimuli of both modalities. When auditory and tactile stimuli were presented simultaneously with subjects alternating attention between sensory streams, only the calcarine sulcus continued to respond to stimuli in both modalities. In all other ROIs, responses to auditory targets were as large or larger than those observed in the auditory-alone condition, but responses to tactile targets were attenuated or abolished by the presence of unattended auditory stimuli. Both auditory and somatosensory cortices responded consistently to auditory and tactile targets, respectively. These results reveal mechanisms of orienting and selective attention within the visual cortex of EB individuals and suggest that mechanisms of enhancement and suppression interact asymmetrically on auditory and tactile streams during bimodal sensory presentation.

The Neural Correlates of Object Familiarity and Domain Specificity in the Human Visual Cortex: An fMRI Study

2011 ◽  
Vol 23 (10) ◽  
pp. 2878-2891 ◽  
Author(s):  
Gian Daniele Zannino ◽  
Francesco Barban ◽  
Emiliano Macaluso ◽  
Carlo Caltagirone ◽  
Giovanni A. Carlesimo
Keyword(s):  
Functional Organization ◽  
Temporal Cortex ◽  
Visual Noise ◽  
Visual Object ◽  
Structural Description ◽  
Visual Object Recognition ◽  
Living Things ◽  
Fmri Study ◽  
Functional Locus ◽  
Object Familiarity

Ventral occipito-temporal cortex is known to play a major role in visual object recognition. Still unknown is whether object familiarity and semantic domain are critical factors in its functional organization. Most models assume a functional locus where exemplars of familiar categories are represented: the structural description system. On the assumption that familiarity should modulate the effect of visual noise on form recognition, we attempted to individualize the structural description system by scanning healthy subjects while they looked at familiar (living and nonliving things) and novel 3-D objects, either with increasing or decreasing visual noise. Familiarity modulated the visual noise effect (particularly when familiar items were living things), revealing a substrate for the structural description system in right occipito-temporal cortex. These regions also responded preferentially to living as compared to nonliving items. Overall, these results suggest that living items are particularly reliant on the structural description system.

The Role of Temporal Synchrony as a Binding Cue for Visual Persistence in Early Visual Areas: An fMRI Study

2009 ◽  
Vol 102 (6) ◽  
pp. 3461-3468 ◽  
Author(s):  
Yvonne J. Wong ◽  
Adrian J. Aldcroft ◽  
Mary-Ellen Large ◽  
Jody C. Culham ◽  
Tutis Vilis
Keyword(s):  
Visual Memory ◽  
Iconic Memory ◽  
Occipital Cortex ◽  
Independent Manner ◽  
Object Persistence ◽  
Motion Cues ◽  
Temporal Synchrony ◽  
Fmri Study ◽  
Visual Areas

We examined the role of temporal synchrony—the simultaneous appearance of visual features—in the perceptual and neural processes underlying object persistence. When a binding cue (such as color or motion) momentarily exposes an object from a background of similar elements, viewers remain aware of the object for several seconds before it perceptually fades into the background, a phenomenon known as object persistence. We showed that persistence from temporal stimulus synchrony, like that arising from motion and color, is associated with activation in the lateral occipital (LO) area, as measured by functional magnetic resonance imaging. We also compared the distribution of occipital cortex activity related to persistence to that of iconic visual memory. Although activation related to iconic memory was largely confined to LO, activation related to object persistence was present across V1 to LO, peaking in V3 and V4, regardless of the binding cue (temporal synchrony, motion, or color). Although persistence from motion cues was not associated with higher activation in the MT+ motion complex, persistence from color cues was associated with increased activation in V4. Taken together, these results demonstrate that although persistence is a form of visual memory, it relies on neural mechanisms different from those of iconic memory. That is, persistence not only activates LO in a cue-independent manner, it also recruits visual areas that may be necessary to maintain binding between object elements.

On-Line Attentional Selection From Competing Stimuli in Opposite Visual Fields: Effects on Human Visual Cortex and Control Processes

2006 ◽  
Vol 96 (5) ◽  
pp. 2601-2612 ◽  
Author(s):  
Joy J. Geng ◽  
Evelyn Eger ◽  
Christian C. Ruff ◽  
Árni Kristjánsson ◽  
Pia Rotshtein ◽  
...  
Keyword(s):  
Visual Fields ◽  
Occipital Cortex ◽  
Attentional Selection ◽  
Functional Coupling ◽  
Repetition Suppression ◽  
On Line ◽  
Orthogonal Orientation ◽  
And Control ◽  
Visual Hemifields ◽  
Anticipatory Attention

We used fMRI to investigate competition and on-line attentional selection between targets and distractors in opposite visual hemifields. Displays comprised a high-contrast square-wave grating, defined as target by its orientation, presented alone (unilateral) or with a similar distractor of orthogonal orientation in the opposite hemifield (bilateral displays). The target appeared unpredictably on the left or right, precluding anticipatory attention to one side. We found greater activation in target-contralateral superior occipital gyrus for unilateral than for bilateral displays, indicating suppression of the target’s visual representation by distractor presence despite the competing distractor projecting to a different occipital hemisphere. Several frontal and parietal regions showed greater activation for bilateral than unilateral trials, suggesting involvement in on-line attentional selection. This was particularly pronounced for regions in bilateral intraparietal sulcus (IPS), which also showed greater functional coupling with occipital cortex specifically on bilateral trials that required selection plus some repetition-suppression effects when target side was repeated, but again only on bilateral trials requiring selection. Our results indicate that competition between visual stimuli in opposite hemifields can influence occipital cortex, and implicate IPS in resolution of this competition by selection.

scholarly journals Sports in Natural Environment, Sports in Urban Environment: An fMRI Study about Stress and Attention/Awareness

2021 ◽  
pp. 789-798
Author(s):  
Antonio Baena-Extremera ◽  
Julio F. García ◽  
Andrés C. Martínez ◽  
Cristina Martín-Pérez
Keyword(s):  
Perceived Stress ◽  
Natural Environment ◽  
Premotor Cortex ◽  
Motor Planning ◽  
Occipital Cortex ◽  
The Other ◽  
Group Differences ◽  
Hair Cortisol ◽  
Urban Images ◽  
Fmri Study

This study aimed to explore, on one side, the differences between a group of athletes exercising outdoor (OG) and another group exercising indoor (IG) in stress and awareness, and, on the other side, between-group differences in the fMRI activations during the visualization of natural environment images versus urban images. In addition, we aimed to analyze the associations between the resulting task-related brain activations and stress and attention-awareness in each group separately. All the participants (N = 49; OG = 21, 11 females, mean age = 40, SD = 6.49; and IG = 25, 11 females, mean age = 40; 6.19) underwent an fMRI scan and completed the Perceived Stress Scale and the Mindful Attention Awareness Scale. Besides, we collected a sample of hair cortisol. Participants viewed three types of images: water nature, green nature and urban images. Two-sample t-test with corrected p=0.001 values were carried out. Further correlational analyses were performed to estimate the associations between task-related brain activations and our pyscho-emotional measures in each group. Fisher tests were used to explore for potential between-group differences in the correlational indexes. In OG, compared to IG, we found a higher activation of the middle occipital cortex and a cluster comprising the supplementary motor area (SMA), the premotor cortex and the pre-SMA while viewing green nature images versus urban images. In OG, more than in IG, the higher activation of the left SMA cluster negatively correlated with perceived stress, while in the IG, more than in OG, the higher premotor cortex activation was positively related to the total score on MAAS. No significant association was found with the hair cortisol levels. Exercising outdoor would relate to better psycho-emotional outcomes, also for athletes. On the other side, the exposition to green nature led to higher activation of brain areas related to motor planning, but also to emotion regulation and emotional response.

scholarly journals Functional organization of face processing in the human superior temporal sulcus: a 7T high-resolution fMRI study

2017 ◽  
Vol 13 (1) ◽  
pp. 102-113 ◽  
Author(s):  
Anne-Kathrin Schobert ◽  
Corrado Corradi-Dell’Acqua ◽  
Sascha Frühholz ◽  
Wietske van der Zwaag ◽  
Patrik Vuilleumier
Keyword(s):  
High Resolution ◽  
Face Processing ◽  
Functional Organization ◽  
Superior Temporal Sulcus ◽  
Fmri Study
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