Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 993
Filter
1.
Sci Rep ; 14(1): 11465, 2024 05 20.
Article in English | MEDLINE | ID: mdl-38769421

ABSTRACT

Childhood maltreatment is reportedly associated with atypical gray matter structures in the primary visual cortex (V1). This study explores the hypothesis that retinal structures, the sensory organs of vision, are associated with brain atypicality and child maltreatment and examines their interrelation. General ophthalmologic examinations, visual cognitive tasks, retinal imaging, and structural magnetic resonance imaging (MRI) were conducted in children and adolescents aged 9-18 years with maltreatment experiences (CM) and typically developing (TD) children. The retinal nerve fiber layer (RNFL), the most superficial of the ten distinct retinal layers, was found to be significantly thinner in both eyes in CM. While whole-brain analysis using Voxel-based morphometry revealed a significantly larger gray matter volume (GMV) in the thalamus in CM, no significant correlation with RNFL thickness was observed. However, based on region-of-interest analysis, a thinner RNFL was associated with a larger GMV in the right V1. Although it cannot be ruled out that this outcome resulted from maltreatment alone, CM demonstrated subclinical structural atypicality in the retina, which may also correlate with the immaturity of V1 development. Examination of retinal thickness offers a novel clinical approach to capturing characteristics associated with childhood maltreatment.


Subject(s)
Child Abuse , Gray Matter , Magnetic Resonance Imaging , Retina , Visual Cortex , Humans , Child , Gray Matter/diagnostic imaging , Gray Matter/pathology , Male , Adolescent , Female , Retina/pathology , Retina/diagnostic imaging , Magnetic Resonance Imaging/methods , Visual Cortex/diagnostic imaging , Visual Cortex/pathology
2.
Cereb Cortex ; 34(13): 30-39, 2024 May 02.
Article in English | MEDLINE | ID: mdl-38696599

ABSTRACT

The amygdala undergoes a period of overgrowth in the first year of life, resulting in enlarged volume by 12 months in infants later diagnosed with ASD. The overgrowth of the amygdala may have functional consequences during infancy. We investigated whether amygdala connectivity differs in 12-month-olds at high likelihood (HL) for ASD (defined by having an older sibling with autism), compared to those at low likelihood (LL). We examined seed-based connectivity of left and right amygdalae, hypothesizing that the HL and LL groups would differ in amygdala connectivity, especially with the visual cortex, based on our prior reports demonstrating that components of visual circuitry develop atypically and are linked to genetic liability for autism. We found that HL infants exhibited weaker connectivity between the right amygdala and the left visual cortex, as well as between the left amygdala and the right anterior cingulate, with evidence that these patterns occur in distinct subgroups of the HL sample. Amygdala connectivity strength with the visual cortex was related to motor and communication abilities among HL infants. Findings indicate that aberrant functional connectivity between the amygdala and visual regions is apparent in infants with genetic liability for ASD and may have implications for early differences in adaptive behaviors.


Subject(s)
Amygdala , Magnetic Resonance Imaging , Visual Cortex , Humans , Amygdala/diagnostic imaging , Amygdala/physiopathology , Male , Female , Infant , Visual Cortex/diagnostic imaging , Visual Cortex/physiopathology , Visual Cortex/growth & development , Neural Pathways/physiopathology , Neural Pathways/diagnostic imaging , Autistic Disorder/genetics , Autistic Disorder/physiopathology , Autistic Disorder/diagnostic imaging , Autism Spectrum Disorder/genetics , Autism Spectrum Disorder/physiopathology , Autism Spectrum Disorder/diagnostic imaging , Genetic Predisposition to Disease/genetics
3.
Cereb Cortex ; 34(5)2024 May 02.
Article in English | MEDLINE | ID: mdl-38752980

ABSTRACT

The effects of hypoxia on brain function remain largely unknown. This study aimed to clarify this issue by visual-stimulated functional magnetic resonance imaging design. Twenty-three college students with a 30-d high-altitude exposure were tested before, 1 week and 3 months after returning to sea level. Brain functional magnetic resonance imaging and retinal electroretinogram were acquired. One week after returning to sea level, decreased blood oxygenation level dependent in the right lingual gyrus accompanied with increased blood oxygenation level dependent in the frontal cortex and insular cortex, and decreased amplitude of electroretinogram a-wave in right eye; moreover, the bilateral lingual gyri showed increased functional connectivity within the dorsal visual stream pathway, and the blood oxygenation level dependent signals in the right lingual gyrus showed positive correlation with right retinal electroretinogram a-wave. Three months after returning to sea level, the blood oxygenation level dependent signals recovered to normal level, while intensively increased blood oxygenation level dependent signals in a broad of brain regions and decreased retinal electroretinogram were also existed. In conclusion, hypoxic exposure has long-term effects on visual cortex, and the impaired retinal electroretinogram may contribute to it. The increased functional connectivity of dorsal stream may compensate for the decreased function of retinal photoreceptor cells to maintain normal visual function.


Subject(s)
Electroretinography , Magnetic Resonance Imaging , Neuronal Plasticity , Visual Pathways , Humans , Male , Young Adult , Female , Neuronal Plasticity/physiology , Visual Pathways/physiology , Visual Pathways/diagnostic imaging , Hypoxia/physiopathology , Adult , Oxygen/blood , Visual Cortex/diagnostic imaging , Visual Cortex/physiology , Brain/physiology , Brain/diagnostic imaging , Photic Stimulation/methods , Retina/physiology , Retina/diagnostic imaging , Brain Mapping/methods
4.
Sci Rep ; 14(1): 11376, 2024 05 18.
Article in English | MEDLINE | ID: mdl-38762549

ABSTRACT

The ventral visual stream is organized into units, or functional regions of interest (fROIs), specialized for processing high-level visual categories. Task-based fMRI scans ("localizers") are typically used to identify each individual's nuanced set of fROIs. The unique landscape of an individual's functional activation may rely in large part on their specialized connectivity patterns; recent studies corroborate this by showing that connectivity can predict individual differences in neural responses. We focus on the ventral visual stream and ask: how well can an individual's resting state functional connectivity localize their fROIs for face, body, scene, and object perception? And are the neural processors for any particular visual category better predicted by connectivity than others, suggesting a tighter mechanistic relationship between connectivity and function? We found, among 18 fROIs predicted from connectivity for each subject, all but one were selective for their preferred visual category. Defining an individual's fROIs based on their connectivity patterns yielded regions that were more selective than regions identified from previous studies or atlases in nearly all cases. Overall, we found that in the absence of a domain-specific localizer task, a 10-min resting state scan can be reliably used for defining these fROIs.


Subject(s)
Brain Mapping , Magnetic Resonance Imaging , Visual Cortex , Humans , Magnetic Resonance Imaging/methods , Male , Female , Brain Mapping/methods , Adult , Visual Cortex/physiology , Visual Cortex/diagnostic imaging , Visual Perception/physiology , Young Adult , Photic Stimulation , Visual Pathways/physiology , Visual Pathways/diagnostic imaging
5.
Neurorehabil Neural Repair ; 38(6): 437-446, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38659366

ABSTRACT

BACKGROUND AND OBJECTIVE: Homonymous hemianopia caused by cerebrovascular disease may improve over time. This study investigated whether functional neuroimaging can predict the prognosis of hemianopia due to cerebral infarction. METHODS: We studied 19 patients (10 men and 9 women) with homonymous hemianopia and compared them with 34 healthy subjects (20 men and 14 women). Cerebral glucose metabolism was measured by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), 1 to 6 months after the onset. Bilateral regions of interest (ROIs) were selected from the posterior and, anterior striate cortices, extrastriate cortex, and thalamus. Furthermore, semi-quantitative data on cerebral glucose metabolism were obtained for ROIs and compared with the data obtained for homologous regions in the contralateral hemisphere by calculating the ipsilateral/contralateral (I/C) ratio. RESULTS: The I/C ratio for the cerebral glucose metabolism in the posterior striate cortex was high (>0.750) in 8 patients, and the central visual field of these patients improved or showed macular sparing. The I/C ratio for cerebral glucose metabolism in the anterior striate cortex was high (>0.830) in 7 patients, and the peripheral visual field of these patients improved. However, no improvement was observed in 9 patients with a low I/C ratio for cerebral glucose metabolism in both the posterior and anterior striate cortices. CONCLUSION: Measurement of cerebral glucose metabolism in the striate cortex is useful for estimating visual field prognosis. Furthermore, FDG-PET is useful in predicting the prognosis of hemianopia.


Subject(s)
Fluorodeoxyglucose F18 , Glucose , Hemianopsia , Positron-Emission Tomography , Visual Cortex , Humans , Male , Female , Hemianopsia/metabolism , Hemianopsia/diagnostic imaging , Hemianopsia/physiopathology , Middle Aged , Visual Cortex/metabolism , Visual Cortex/diagnostic imaging , Glucose/metabolism , Aged , Prognosis , Adult
6.
Neuroreport ; 35(9): 568-576, 2024 Jun 05.
Article in English | MEDLINE | ID: mdl-38652513

ABSTRACT

Our objective was to explore the disparities in the intrinsic functional connectivity (FC) patterns of primary visual cortex (V1) between patients with thyroid-associated ophthalmopathy (TAO) and healthy controls (HCs) utilizing resting-state functional MRI. Twenty-one patients with TAO (14 males and 7 females; mean age: 54.17 ±â€…4.83 years) and 21 well-matched HCs (14 males and 7 females; mean age: 55.17 ±â€…5.37 years) underwent functional MRI scans in the resting-state. We assessed modifications in the intrinsic FC patterns of the V1 in TAO patients using the FC method. Subsequently, the identified alterations in FC regions in the analysis were selected as classification features to distinguish TAO patients from HCs through the support vector machine (SVM) method. The results indicated that, in comparison to HCs, patients with TAO exhibited notably reduced FC values between the left V1 and the bilateral calcarine (CAL), lingual gyrus (LING) and superior occipital gyrus, as well as between the right V1 and the bilateral CAL/LING and the right cerebellum. Furthermore, the SVM classification model based on FC maps demonstrated effective performance in distinguishing TAO patients from HCs, achieving an accuracy of 61.9% using the FC of the left V1 and 64.29% using the FC of the right V1. Our study revealed that patients with TAO manifested disruptions in FC between the V1 and higher visual regions during rest. This might indicate that TAO patients could present with impaired top-down modulations, visual imagery and vision-motor function. These insights could be valuable in understanding the underlying neurobiological mechanisms of vision impairment in individuals with TAO.


Subject(s)
Graves Ophthalmopathy , Magnetic Resonance Imaging , Primary Visual Cortex , Humans , Male , Female , Middle Aged , Graves Ophthalmopathy/physiopathology , Graves Ophthalmopathy/diagnostic imaging , Magnetic Resonance Imaging/methods , Primary Visual Cortex/physiopathology , Primary Visual Cortex/diagnostic imaging , Primary Visual Cortex/physiology , Support Vector Machine , Brain Mapping/methods , Adult , Neural Pathways/physiopathology , Neural Pathways/diagnostic imaging , Visual Cortex/physiopathology , Visual Cortex/diagnostic imaging
7.
J Neurosci ; 44(17)2024 Apr 24.
Article in English | MEDLINE | ID: mdl-38438256

ABSTRACT

Recognizing faces regardless of their viewpoint is critical for social interactions. Traditional theories hold that view-selective early visual representations gradually become tolerant to viewpoint changes along the ventral visual hierarchy. Newer theories, based on single-neuron monkey electrophysiological recordings, suggest a three-stage architecture including an intermediate face-selective patch abruptly achieving invariance to mirror-symmetric face views. Human studies combining neuroimaging and multivariate pattern analysis (MVPA) have provided convergent evidence of view selectivity in early visual areas. However, contradictory conclusions have been reached concerning the existence in humans of a mirror-symmetric representation like that observed in macaques. We believe these contradictions arise from low-level stimulus confounds and data analysis choices. To probe for low-level confounds, we analyzed images from two face databases. Analyses of image luminance and contrast revealed biases across face views described by even polynomials-i.e., mirror-symmetric. To explain major trends across neuroimaging studies, we constructed a network model incorporating three constraints: cortical magnification, convergent feedforward projections, and interhemispheric connections. Given the identified low-level biases, we show that a gradual increase of interhemispheric connections across network-layers is sufficient to replicate view-tuning in early processing stages and mirror-symmetry in later stages. Data analysis decisions-pattern dissimilarity measure and data recentering-accounted for the inconsistent observation of mirror-symmetry across prior studies. Pattern analyses of human fMRI data (of either sex) revealed biases compatible with our model. The model provides a unifying explanation of MVPA studies of viewpoint selectivity and suggests observations of mirror-symmetry originate from ineffectively normalized signal imbalances across different face views.


Subject(s)
Facial Recognition , Humans , Male , Female , Facial Recognition/physiology , Adult , Neuroimaging/methods , Photic Stimulation/methods , Models, Neurological , Visual Cortex/physiology , Visual Cortex/diagnostic imaging , Magnetic Resonance Imaging/methods , Young Adult
8.
Sci Adv ; 10(9): eadi9294, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38427730

ABSTRACT

Previous research shows that the beauty of natural images is already determined during perceptual analysis. However, it is unclear which perceptual computations give rise to the perception of beauty. Here, we tested whether perceived beauty is predicted by spatial integration across an image, a perceptual computation that reduces processing demands by aggregating image parts into more efficient representations of the whole. We quantified integrative processing in an artificial deep neural network model, where the degree of integration was determined by the amount of deviation between activations for the whole image and its constituent parts. This quantification of integration predicted beauty ratings for natural images across four studies with different stimuli and designs. In a complementary functional magnetic resonance imaging study, we show that integrative processing in human visual cortex similarly predicts perceived beauty. Together, our results establish integration as a computational principle that facilitates perceptual analysis and thereby mediates the perception of beauty.


Subject(s)
Visual Cortex , Visual Perception , Humans , Vision, Ocular , Visual Cortex/diagnostic imaging , Magnetic Resonance Imaging , Judgment , Brain Mapping
9.
Brain Behav ; 14(3): e3462, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38468484

ABSTRACT

INTRODUCTION: The objective of this study was to investigate changes in vision-related resting-state activity in patients with suprasellar tumors (ST) who experienced vision deterioration after surgery. METHODS: Twelve patients with ST and vision deterioration after surgery were included in the study. Resting-state functional connectivity (FC) was compared before and after surgery using a seed-based analysis with a priori specified regions of interest (ROIs) within the visual areas. The differences between the two groups were identified using a paired t-test. RESULTS: The data showed a decrease in FC within and between the dorsal and ventral pathways, as well as in the third pathway in ST patients. The middle temporal visual cortex (MT+) showed a decreased FC with more regions than other visual ROIs. The data also revealed an increase in FC between the visual ROIs and higher-order cortex. The superior frontal gyrus/BA8 showed an increased FC with more ROIs than other high-order regions, and the hOC4d was involved in an increased FC with more high-order regions than other ROIs. CONCLUSIONS: The study results indicate significant neural reorganization in the vision-related cortex of ST patients with postoperative vision damage. Most subareas within the visual cortex showed remarkable neural dysfunction, and some highe-order cortex may be primarily involved in top-down control of the subareas within the visual cortex. The hot zones may arise in the processing of "top-down" influence.


Subject(s)
Neoplasms , Visual Cortex , Humans , Magnetic Resonance Imaging/methods , Vision, Ocular , Visual Cortex/diagnostic imaging , Temporal Lobe , Brain
10.
Brain Connect ; 14(3): 189-197, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38386496

ABSTRACT

Introduction: The mental load caused by simultaneous multitasking can affect visual information processing and reduce its ability. This study investigated the effect of mental load caused by cognitive tasks simultaneously with visual task on the number of active voxels in the visual cortex. Methods: This study recruited 22 individuals with a mean age of 24.72 ± 5.47 years. 3-Tesla functional magnetic resonance imaging (fMRI) was used to examine the functions of the visual cortex and amygdala region during three different task conditions: visual task alone, visual task with an auditory n-back task, and visual task with an arithmetic task. The visual stimuli consisted of Gabor patches with a contrast of 55% at spatial frequencies of 0.25, 4, and 9 cycles per degree (cpd). These were presented in three trials of eight blocks with a stimulation time of 12 sec and a rest time of 14 sec. Results: Activated brain voxels in the primary, secondary, and associated visual cortex areas were reduced in response to the mental load imposed by the n-back and arithmetic tasks. This reduction was greater for a spatial frequency of 0.25 cpd in the n-back task condition and spatial frequency of 9 cpd in the arithmetic task condition. In addition, the amygdala was stimulated in 2-back task and arithmetic task conditions. Conclusions: This study revealed a decline in the number of activated voxels of the visual cortex due to the mental load caused by simultaneous cognitive tasks, confirming the findings of previous psychophysical studies.


Subject(s)
Brain Mapping , Cognition , Magnetic Resonance Imaging , Visual Cortex , Humans , Magnetic Resonance Imaging/methods , Visual Cortex/physiology , Visual Cortex/diagnostic imaging , Male , Female , Adult , Cognition/physiology , Young Adult , Brain Mapping/methods , Amygdala/diagnostic imaging , Amygdala/physiology , Photic Stimulation/methods , Visual Perception/physiology
11.
eNeuro ; 11(2)2024 Feb.
Article in English | MEDLINE | ID: mdl-38336475

ABSTRACT

Content-to-context binding is crucial for working memory performance. Using a dual-serial retrocueing (DSR) task on oriented gratings, Yu et al. (2020) found that content (orientation) of both prioritized and unprioritized memory items (PMI; UMI) was represented simultaneously in visual cortex, while their context (location) was represented in intraparietal sulcus (IPS), with a priority-based remapping of the representation of content and context of the UMI in each region, respectively. This registered report acquired fMRI of 24 healthy adults while they performed a DSR task with location as the to-be-reported content and orientation as the task-relevant context. We contrasted three accounts: domain-dependent, the engagement of visual and parietal regions depends on the feature domain (orientation vs location); functional, the engagement of these regions depends on their function (content vs context); and hybrid-a combination of the domain-dependent account and the additional stipulation that IPS encodes context regardless of domain. Delay-period activity in early visual cortex conformed most closely with functional predictions: robust priority-sensitive representation of stimulus location (content), but no evidence for the active representation of stimulus orientation (context). Delay-period activity in IPS, in contrast, conformed most closely to predictions of the hybrid account: active representation of content (location) and of prioritized context (orientation). Exploratory analyses further supported the hybrid account of IPS, revealing univariate sensitivity to variation in both content and context load, the latter in a manner that predicted individual differences in behavior. The representation of visual information in working memory is highly dependent on behavioral context.


Subject(s)
Memory, Short-Term , Visual Cortex , Adult , Humans , Visual Perception , Parietal Lobe/diagnostic imaging , Visual Cortex/diagnostic imaging , Cognition , Magnetic Resonance Imaging , Brain Mapping
12.
Sci Rep ; 14(1): 3247, 2024 02 08.
Article in English | MEDLINE | ID: mdl-38332042

ABSTRACT

A reciprocal relationship between perceptual learning and functional brain changes towards perceptual learning effectiveness has been demonstrated previously; however, the underlying neural correlates remain unclear. Further, visual perceptual learning (VPL) is implicated in visual field defect (VFD) recovery following chronic stroke. We investigated resting-state functional connectivity (RSFC) in the visual cortices associated with mean total deviation (MTD) scores for VPL-induced VFD recovery in chronic stroke. Patients with VFD due to chronic ischemic stroke in the visual cortex received 24 VPL training sessions over 2 months, which is a dual discrimination task of orientation and letters. At baseline and two months later, the RSFC in the ipsilesional, interhemispheric, and contralesional visual cortices and MTD scores in the affected hemi-field were assessed. Interhemispheric visual RSFC at baseline showed the strongest correlation with MTD scores post-2-month VPL training. Notably, only the subgroup with high baseline interhemispheric visual RSFC showed significant VFD improvement following the VPL training. The interactions between the interhemispheric visual RSFC at baseline and VPL led to improvement in MTD scores and largely influenced the degree of VFD recovery. The interhemispheric visual RSFC at baseline could be a promising brain biomarker for the effectiveness of VPL-induced VFD recovery.


Subject(s)
Stroke , Visual Cortex , Humans , Visual Fields , Spatial Learning , Brain , Visual Cortex/diagnostic imaging , Brain Damage, Chronic , Magnetic Resonance Imaging
13.
Hum Brain Mapp ; 45(3): e26616, 2024 Feb 15.
Article in English | MEDLINE | ID: mdl-38379465

ABSTRACT

The center-periphery visual field axis guides early visual system organization with enhanced resources devoted to central vision leading to reduced peripheral performance relative to that of central vision (i.e., behavioral eccentricity effect) for many visual functions. The center-periphery organization extends to high-order visual cortex where, for example, the well-studied face-sensitive fusiform face area (FFA) shows sensitivity to central vision and the place-sensitive parahippocampal place area (PPA) shows sensitivity to peripheral vision. As we have recently found that face perception is more sensitive to eccentricity than place perception, here we examined whether these behavioral findings reflect differences in FFA's and PPA's sensitivities to eccentricity. We assumed FFA would show higher sensitivity to eccentricity than PPA would, but that both regions' modulation by eccentricity would be invariant to the viewed category. We parametrically investigated (fMRI, n = 32) how FFA's and PPA's activations are modulated by eccentricity (≤8°) and category (upright/inverted faces/houses) while keeping stimulus size constant. As expected, FFA showed an overall higher sensitivity to eccentricity than PPA. However, both regions' activation modulations by eccentricity were dependent on the viewed category. In FFA, a reduction of activation with growing eccentricity ("BOLD eccentricity effect") was found (with different amplitudes) for all categories. In PPA however, qualitatively different BOLD eccentricity effect modulations were found (e.g., at 8° mild BOLD eccentricity effect for houses but a reverse BOLD eccentricity effect for faces and no modulation for inverted faces). Our results emphasize that peripheral vision investigations are critical to further our understanding of visual processing.


Subject(s)
Facial Recognition , Visual Cortex , Humans , Brain Mapping , Visual Perception/physiology , Visual Cortex/diagnostic imaging , Visual Cortex/physiology , Visual Fields , Facial Recognition/physiology , Magnetic Resonance Imaging , Pattern Recognition, Visual/physiology , Photic Stimulation
14.
Prog Neurobiol ; 234: 102584, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38309458

ABSTRACT

In human and nonhuman primate brains, columnar (mesoscale) organization has been demonstrated to underlie both lower and higher order aspects of visual information processing. Previous studies have focused on identifying functional preferences of mesoscale domains in specific areas; but there has been little understanding of how mesoscale domains may cooperatively respond to single visual stimuli across dorsal and ventral pathways. Here, we have developed ultrahigh-field 7 T fMRI methods to enable simultaneous mapping, in individual macaque monkeys, of response in both dorsal and ventral pathways to single simple color and motion stimuli. We provide the first evidence that anatomical V2 cytochrome oxidase-stained stripes are well aligned with fMRI maps of V2 stripes, settling a long-standing controversy. In the ventral pathway, a systematic array of paired color and luminance processing domains across V4 was revealed, suggesting a novel organization for surface information processing. In the dorsal pathway, in addition to high quality motion direction maps of MT, MST and V3A, alternating color and motion direction domains in V3 are revealed. As well, submillimeter motion domains were observed in peripheral LIPd and LIPv. In sum, our study provides a novel global snapshot of how mesoscale networks in the ventral and dorsal visual pathways form the organizational basis of visual objection recognition and vision for action.


Subject(s)
Macaca , Visual Cortex , Animals , Humans , Visual Pathways/diagnostic imaging , Visual Pathways/physiology , Magnetic Resonance Imaging/methods , Visual Cortex/diagnostic imaging , Visual Cortex/physiology , Brain Mapping
15.
Hum Brain Mapp ; 45(3): e26590, 2024 Feb 15.
Article in English | MEDLINE | ID: mdl-38401134

ABSTRACT

It has been suggested that visual images are memorized across brief periods of time by vividly imagining them as if they were still there. In line with this, the contents of both working memory and visual imagery are known to be encoded already in early visual cortex. If these signals in early visual areas were indeed to reflect a combined imagery and memory code, one would predict them to be weaker for individuals with reduced visual imagery vividness. Here, we systematically investigated this question in two groups of participants. Strong and weak imagers were asked to remember images across brief delay periods. We were able to reliably reconstruct the memorized stimuli from early visual cortex during the delay. Importantly, in contrast to the prediction, the quality of reconstruction was equally accurate for both strong and weak imagers. The decodable information also closely reflected behavioral precision in both groups, suggesting it could contribute to behavioral performance, even in the extreme case of completely aphantasic individuals. Our data thus suggest that working memory signals in early visual cortex can be present even in the (near) absence of phenomenal imagery.


Subject(s)
Memory, Short-Term , Visual Cortex , Humans , Visual Perception , Visual Cortex/diagnostic imaging , Imagery, Psychotherapy , Mental Recall , Imagination
16.
Nat Commun ; 15(1): 516, 2024 Jan 15.
Article in English | MEDLINE | ID: mdl-38225259

ABSTRACT

The coding privilege of end-spectral hues (red and blue) in the early visual cortex has been reported in primates. However, the origin of such bias remains unclear. Here, we provide a complete picture of the end-spectral bias in visual system by measuring fMRI signals and spiking activities in macaques. The correlated end-spectral biases between the LGN and V1 suggest a subcortical source for asymmetric coding. Along the ventral pathway from V1 to V4, red bias against green peaked in V1 and then declined, whereas blue bias against yellow showed an increasing trend. The feedforward and recurrent modifications of end-spectral bias were further revealed by dynamic causal modeling analysis. Moreover, we found that the strongest end-spectral bias in V1 was in layer 4C[Formula: see text]. Our results suggest that end-spectral bias already exists in the LGN and is transmitted to V1 mainly through the parvocellular pathway, then embellished by cortical processing.


Subject(s)
Visual Cortex , Visual Pathways , Animals , Visual Cortex/diagnostic imaging , Primates , Macaca , Magnetic Resonance Imaging/methods , Geniculate Bodies , Photic Stimulation/methods
17.
Int J Neural Syst ; 34(1): 2450002, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38084473

ABSTRACT

Functional MRI (fMRI) is a brain signal with high spatial resolution, and visual cognitive processes and semantic information in the brain can be represented and obtained through fMRI. In this paper, we design single-graphic and matched/unmatched double-graphic visual stimulus experiments and collect 12 subjects' fMRI data to explore the brain's visual perception processes. In the double-graphic stimulus experiment, we focus on the high-level semantic information as "matching", and remove tail-to-tail conjunction by designing a model to screen the matching-related voxels. Then, we perform Bayesian causal learning between fMRI voxels based on the transfer entropy, establish a hierarchical Bayesian causal network (HBcausalNet) of the visual cortex, and use the model for visual stimulus image reconstruction. HBcausalNet achieves an average accuracy of 70.57% and 53.70% in single- and double-graphic stimulus image reconstruction tasks, respectively, higher than HcorrNet and HcasaulNet. The results show that the matching-related voxel screening and causality analysis method in this paper can extract the "matching" information in fMRI, obtain a direct causal relationship between matching information and fMRI, and explore the causal inference process in the brain. It suggests that our model can effectively extract high-level semantic information in brain signals and model effective connections and visual perception processes in the visual cortex of the brain.


Subject(s)
Brain Mapping , Visual Cortex , Humans , Brain Mapping/methods , Bayes Theorem , Semantics , Brain , Magnetic Resonance Imaging/methods , Visual Cortex/diagnostic imaging
18.
J Neurosci ; 44(2)2024 Jan 10.
Article in English | MEDLINE | ID: mdl-37963768

ABSTRACT

The use of fMRI and computational modeling has advanced understanding of spatial characteristics of population receptive fields (pRFs) in human visual cortex. However, we know relatively little about the spatiotemporal characteristics of pRFs because neurons' temporal properties are one to two orders of magnitude faster than fMRI BOLD responses. Here, we developed an image-computable framework to estimate spatiotemporal pRFs from fMRI data. First, we developed a simulation software that predicts fMRI responses to a time-varying visual input given a spatiotemporal pRF model and solves the model parameters. The simulator revealed that ground-truth spatiotemporal parameters can be accurately recovered at the millisecond resolution from synthesized fMRI responses. Then, using fMRI and a novel stimulus paradigm, we mapped spatiotemporal pRFs in individual voxels across human visual cortex in 10 participants (both females and males). We find that a compressive spatiotemporal (CST) pRF model better explains fMRI responses than a conventional spatial pRF model across visual areas spanning the dorsal, lateral, and ventral streams. Further, we find three organizational principles of spatiotemporal pRFs: (1) from early to later areas within a visual stream, spatial and temporal windows of pRFs progressively increase in size and show greater compressive nonlinearities, (2) later visual areas show diverging spatial and temporal windows across streams, and (3) within early visual areas (V1-V3), both spatial and temporal windows systematically increase with eccentricity. Together, this computational framework and empirical results open exciting new possibilities for modeling and measuring fine-grained spatiotemporal dynamics of neural responses using fMRI.


Subject(s)
Magnetic Resonance Imaging , Visual Cortex , Male , Female , Humans , Magnetic Resonance Imaging/methods , Brain Mapping/methods , Neurons , Visual Cortex/diagnostic imaging , Visual Cortex/physiology , Time , Photic Stimulation/methods
19.
CNS Neurosci Ther ; 30(3): e14427, 2024 03.
Article in English | MEDLINE | ID: mdl-37721197

ABSTRACT

AIMS: Neurodevelopmental impairments are closely linked to the basis of adolescent major psychiatric disorders (MPDs). The visual cortex can regulate neuroplasticity throughout the brain during critical periods of neurodevelopment, which may provide a promising target for neuromodulation therapy. This cross-species translational study examined the effects of visual cortex repetitive transcranial magnetic stimulation (rTMS) on neurodevelopmental impairments in MPDs. METHODS: Visual cortex rTMS was performed in both adolescent methylazoxymethanol acetate (MAM) rats and patients with MPDs. Functional magnetic resonance imaging (fMRI) and brain tissue proteomic data in rats and fMRI and clinical symptom data in patients were analyzed. RESULTS: The regional homogeneity (ReHo) analysis of fMRI data revealed an increase in the frontal cortex and a decrease in the posterior cortex in the MAM rats, representing the abnormal neurodevelopmental pattern in MPDs. In regard to the effects of rTMS, similar neuroimaging changes, particularly reduced frontal ReHo, were found both in MAM rats and adolescent patients, suggesting that rTMS may reverse the abnormal neurodevelopmental pattern. Proteomic analysis revealed that rTMS modulated frontal synapse-associated proteins, which may be the underpinnings of rTMS efficacy. Furthermore, a positive relationship was observed between frontal ReHo and clinical symptoms after rTMS in patients. CONCLUSION: Visual cortex rTMS was proven to be an effective treatment for adolescent MPDs, and the underlying neural and molecular mechanisms were uncovered. Our study provides translational evidence for therapeutics targeting the neurodevelopmental factor in MPDs.


Subject(s)
Mental Disorders , Visual Cortex , Humans , Adolescent , Animals , Rats , Transcranial Magnetic Stimulation/methods , Proteomics , Prefrontal Cortex , Visual Cortex/diagnostic imaging , Mental Disorders/diagnostic imaging , Mental Disorders/therapy , Magnetic Resonance Imaging
20.
Eur J Neurosci ; 59(3): 446-456, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38123158

ABSTRACT

The anterior cingulate cortex (ACC) and visual cortex are integral components of the neurophysiological mechanisms underlying migraine, yet the impact of altered connectivity patterns between these regions on migraine treatment remains unknown. To elucidate this issue, we investigated the abnormal causal connectivity between the ACC and visual cortex in patients with migraine without aura (MwoA), based on the resting-state functional magnetic resonance imaging data, and its predictive ability for the efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs). The results revealed increased causal connectivity from the bilateral ACC to the lingual gyrus (LG) and decreased connectivity in the opposite direction in nonresponders compared with the responders. Moreover, compared with the healthy controls, nonresponders exhibited heightened causal connectivity from the ACC to the LG, right inferior occipital gyrus (IOG) and left superior occipital gyrus, while connectivity patterns from the LG and right IOG to the ACC were diminished. Based on the observed abnormal connectivity patterns, the support vector machine (SVM) models showed that the area under the receiver operator characteristic curves for the ACC to LG, LG to ACC and bidirectional models were 0.857, 0.898, and 0.939, respectively. These findings indicate that neuroimaging markers of abnormal causal connectivity in the ACC-visual cortex circuit may facilitate clinical decision-making regarding NSAIDs administration for migraine management.


Subject(s)
Migraine without Aura , Visual Cortex , Humans , Gyrus Cinguli/diagnostic imaging , Magnetic Resonance Imaging/methods , Migraine without Aura/pathology , Visual Cortex/diagnostic imaging , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Anti-Inflammatory Agents , Brain
SELECTION OF CITATIONS
SEARCH DETAIL
...