Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 1.714
Filter
1.
Nat Commun ; 15(1): 7196, 2024 Aug 21.
Article in English | MEDLINE | ID: mdl-39169024

ABSTRACT

Distinguishing faces requires well distinguishable neural activity patterns. Contextual information may separate neural representations, leading to enhanced identity recognition. Here, we use functional magnetic resonance imaging to investigate how predictions derived from contextual information affect the separability of neural activity patterns in the macaque face-processing system, a 3-level processing hierarchy in ventral visual cortex. We find that in the presence of predictions, early stages of this hierarchy exhibit well separable and high-dimensional neural geometries resembling those at the top of the hierarchy. This is accompanied by a systematic shift of tuning properties from higher to lower areas, endowing lower areas with higher-order, invariant representations instead of their feedforward tuning properties. Thus, top-down signals dynamically transform neural representations of faces into separable and high-dimensional neural geometries. Our results provide evidence how predictive context transforms flexible representational spaces to optimally use the computational resources provided by cortical processing hierarchies for better and faster distinction of facial identities.


Subject(s)
Facial Recognition , Macaca mulatta , Magnetic Resonance Imaging , Visual Cortex , Animals , Visual Cortex/physiology , Visual Cortex/diagnostic imaging , Magnetic Resonance Imaging/methods , Male , Facial Recognition/physiology , Brain Mapping/methods , Photic Stimulation , Pattern Recognition, Visual/physiology , Face , Female
2.
Nat Commun ; 15(1): 7185, 2024 Aug 21.
Article in English | MEDLINE | ID: mdl-39169063

ABSTRACT

The consolidation of discrete experiences into a coherent narrative shapes the cognitive map, providing structured mental representations of our experiences. In this process, past memories are reactivated and replayed in sequence, fostering hippocampal-cortical dialogue. However, brain-wide engagement coinciding with sequential reactivation (or replay) of memories remains largely unexplored. In this study, employing simultaneous EEG-fMRI, we capture both the spatial and temporal dynamics of memory replay. We find that during mental simulation, past memories are replayed in fast sequences as detected via EEG. These transient replay events are associated with heightened fMRI activity in the hippocampus and medial prefrontal cortex. Replay occurrence strengthens functional connectivity between the hippocampus and the default mode network, a set of brain regions key to representing the cognitive map. On the other hand, when subjects are at rest following learning, memory reactivation of task-related items is stronger than that of pre-learning rest, and is also associated with heightened hippocampal activation and augmented hippocampal connectivity to the entorhinal cortex. Together, our findings highlight a distributed, brain-wide engagement associated with transient memory reactivation and its sequential replay.


Subject(s)
Brain , Electroencephalography , Hippocampus , Magnetic Resonance Imaging , Humans , Male , Hippocampus/physiology , Hippocampus/diagnostic imaging , Female , Adult , Young Adult , Brain/physiology , Brain/diagnostic imaging , Prefrontal Cortex/physiology , Prefrontal Cortex/diagnostic imaging , Brain Mapping , Learning/physiology , Memory/physiology , Entorhinal Cortex/physiology , Entorhinal Cortex/diagnostic imaging
3.
J Headache Pain ; 25(1): 136, 2024 Aug 21.
Article in English | MEDLINE | ID: mdl-39169303

ABSTRACT

BACKGROUND: Migraine is a neurological disorder characterized by complex, widespread, and sudden attacks with an unclear pathogenesis, particularly in chronic migraine (CM). Specific brain regions, including the insula, amygdala, thalamus, and cingulate, medial prefrontal, and anterior cingulate cortex, are commonly activated by pain stimuli in patients with CM and animal models. This study employs fluorescence microscopy optical sectioning tomography (fMOST) technology and AAV-PHP.eB whole-brain expression to map activation patterns of brain regions in CM mice, thus enhancing the understanding of CM pathogenesis and suggesting potential treatment targets. METHODS: By repeatedly administering nitroglycerin (NTG) to induce migraine-like pain in mice, a chronic migraine model (CMM) was established. Olcegepant (OLC) was then used as treatment and its effects on mechanical pain hypersensitivity and brain region activation were observed. All mice underwent mechanical withdrawal threshold, light-aversive, and elevated plus maze tests. Viral injections were administered to the mice one month prior to modelling, and brain samples were collected 2 h after the final NTG/vehicle control injection for whole-brain imaging using fMOST. RESULTS: In the NTG-induced CMM, mechanical pain threshold decreased, photophobia, and anxiety-like behavior were observed, and OLC was found to improve these manifestations. fMOST whole-brain imaging results suggest that the isocortex-cerebral cortex plate region, including somatomotor areas (MO), somatosensory areas (SS), and main olfactory bulb (MOB), appears to be the most sensitive area of activation in CM (P < 0.05). Other brain regions such as the inferior colliculus (IC) and intermediate reticular nucleus (IRN) were also exhibited significant activation (P < 0.05). The improvement in migraine-like symptoms observed with OLC treatment may be related to its effects on these brain regions, particularly SS, MO, ansiform lobule (AN), IC, spinal nucleus of the trigeminal, caudal part (Sp5c), IRN, and parvicellular reticular nucleus (PARN) (P < 0.05). CONCLUSIONS: fMOST whole-brain imaging reveals c-Fos + cells in numerous brain regions. OLC improves migraine-like symptoms by modulating brain activity in some brain regions. This study demonstrates the activation of the specific brain areas in NTG-induced CMM and suggests some regions as a potential treatment mechanism according to OLC.


Subject(s)
Brain , Disease Models, Animal , Migraine Disorders , Nitroglycerin , Animals , Nitroglycerin/toxicity , Nitroglycerin/pharmacology , Nitroglycerin/administration & dosage , Migraine Disorders/chemically induced , Migraine Disorders/diagnostic imaging , Migraine Disorders/metabolism , Migraine Disorders/drug therapy , Mice , Brain/diagnostic imaging , Brain/drug effects , Brain/metabolism , Male , Proto-Oncogene Proteins c-fos/metabolism , Mice, Inbred C57BL , Brain Mapping , Vasodilator Agents/pharmacology , Vasodilator Agents/administration & dosage , Pain Threshold/drug effects
4.
PLoS One ; 19(8): e0299091, 2024.
Article in English | MEDLINE | ID: mdl-39172913

ABSTRACT

Interoception plays an important role in emotion processing. However, the neurobiological substrates of the relationship between visceral responses and emotional experiences remain unclear. In the present study, we measured interoceptive sensitivity using the heartbeat discrimination task and investigated the effects of individual differences in interoceptive sensitivity on changes in pulse rate and insula activity in response to subjective emotional intensity. We found a positive correlation between heart rate and valence level when listening to music only in the high interoceptive sensitivity group. The valence level was also positively correlated with music-elicited anterior insula activity. Furthermore, a region of interest analysis of insula subregions revealed significant activity in the left dorsal dysgranular insula for individuals with high interoceptive sensitivity relative to individuals with low interoceptive sensitivity while listening to the high-valence music pieces. Our results suggest that individuals with high interoceptive sensitivity use their physiological responses to assess their emotional level when listening to music. In addition, insula activity may reflect the use of interoceptive signals to estimate emotions.


Subject(s)
Emotions , Heart Rate , Interoception , Music , Humans , Music/psychology , Heart Rate/physiology , Male , Interoception/physiology , Female , Young Adult , Adult , Emotions/physiology , Magnetic Resonance Imaging , Insular Cortex/physiology , Auditory Perception/physiology , Cerebral Cortex/physiology , Brain Mapping
5.
PLoS One ; 19(8): e0306538, 2024.
Article in English | MEDLINE | ID: mdl-39172991

ABSTRACT

To investigate changes in brain network organization and possible neurobehavioral similarities to attention-deficit hyperactivity disorder (ADHD), we measured changes in brain resting-state functional connectivity (rs-fMRI) and cognitive domains in patients with resistance to thyroid hormone ß (RTHß) and compared them with those in healthy control subjects. In this prospective case-control study, twenty-one participants with genetically confirmed RTHß were matched with 21 healthy controls. The Adult ADHD Self-Report Scale (ASRS-v1.1) and ADHD Rating Scale-IV were used to assess self-reported symptoms of ADHD. A voxel-wise and atlas-based approach was used to identify changes in the brain networks. The RTHß group reported behavioral symptoms similar to those of ADHD. We found evidence of weaker network integration of the lingual and fusiform gyri in the RTHß group, which was mainly driven by weaker connectivity to the bilateral insula and supplementary motor cortex. Functional connectivity between regions of the default mode network (angular gyrus/middle temporal gyrus) and regions of the cognitive control network (bilateral middle frontal gyrus) was increased in RTHß patients compared to healthy controls. Increased connectivity between regions of the default mode network and the dorsolateral prefrontal cortex is frequently reported in ADHD and is interpreted to be associated with deficits in attention. Our finding of weaker connectivity of the lingual gyrus to the bilateral insula (salience network) in RTHß patients has also been reported previously in ADHD and may reflect decreased habituation to visual stimuli and increased distractibility. Overall, our observations support the notion of neuropsychological similarities between RTHß and ADHD.


Subject(s)
Attention Deficit Disorder with Hyperactivity , Brain , Magnetic Resonance Imaging , Thyroid Hormone Resistance Syndrome , Humans , Male , Female , Adult , Attention Deficit Disorder with Hyperactivity/physiopathology , Attention Deficit Disorder with Hyperactivity/diagnostic imaging , Case-Control Studies , Thyroid Hormone Resistance Syndrome/physiopathology , Brain/physiopathology , Brain/diagnostic imaging , Prospective Studies , Nerve Net/physiopathology , Nerve Net/diagnostic imaging , Middle Aged , Young Adult , Brain Mapping
6.
Sci Rep ; 14(1): 18756, 2024 08 13.
Article in English | MEDLINE | ID: mdl-39138266

ABSTRACT

Heart rate variability (HRV) has been linked to resilience and emotion regulation (ER). How HRV and brain processing interact during ER, however, has remained elusive. Sixty-two subjects completed the acquisition of resting HRV and task HRV while performing an ER functional Magnetic Resonance Imaging (fMRI) paradigm, which included the differential strategies of ER reappraisal and acceptance in the context of viewing aversive pictures. We found high correlations of resting and task HRV across all emotion regulation strategies. Furthermore, individuals with high levels of resting, but not task, HRV showed numerically lower distress during ER with acceptance. Whole-brain fMRI parametrical modulation analyses revealed that higher task HRV covaried with dorso-medial prefrontal activation for reappraisal, and dorso-medial prefrontal, anterior cingulate and temporo-parietal junction activation for acceptance. Subjects with high resting HRV, compared to subjects with low resting HRV, showed higher activation in the pre-supplementary motor area during ER using a region of interest approach. This study demonstrates that while resting and task HRV exhibit a positive correlation, resting HRV seems to be a better predictor of ER capacity. Resting and task HRV were associated with ER brain activation in mid-line frontal cortex (i.e. DMPFC).


Subject(s)
Brain , Emotional Regulation , Emotions , Heart Rate , Magnetic Resonance Imaging , Humans , Heart Rate/physiology , Male , Female , Adult , Brain/physiology , Brain/diagnostic imaging , Young Adult , Emotions/physiology , Emotional Regulation/physiology , Brain Mapping , Rest/physiology
7.
Sci Rep ; 14(1): 19483, 2024 08 22.
Article in English | MEDLINE | ID: mdl-39174562

ABSTRACT

Neuroimaging studies using functional magnetic resonance imaging (fMRI) have provided unparalleled insights into the fundamental neural mechanisms underlying human cognitive processing, such as high-level linguistic processes during reading. Here, we build upon this prior work to capture sentence reading comprehension outside the MRI scanner using functional near infra-red spectroscopy (fNIRS) in a large sample of participants (n = 82). We observed increased task-related hemodynamic responses in prefrontal and temporal cortical regions during sentence-level reading relative to the control condition (a list of non-words), replicating prior fMRI work on cortical recruitment associated with high-level linguistic processing during reading comprehension. These results lay the groundwork towards developing adaptive systems to support novice readers and language learners by targeting the underlying cognitive processes. This work also contributes to bridging the gap between laboratory findings and more real-world applications in the realm of cognitive neuroscience.


Subject(s)
Cognition , Reading , Spectroscopy, Near-Infrared , Humans , Spectroscopy, Near-Infrared/methods , Male , Female , Adult , Cognition/physiology , Young Adult , Magnetic Resonance Imaging/methods , Brain Mapping/methods , Comprehension/physiology , Prefrontal Cortex/physiology , Prefrontal Cortex/diagnostic imaging
8.
Nature ; 632(8027): 990-991, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39174630
9.
Mol Autism ; 15(1): 35, 2024 Aug 22.
Article in English | MEDLINE | ID: mdl-39175054

ABSTRACT

BACKGROUND: Autism spectrum disorder (ASD), a neurodevelopmental disorder defined by social communication deficits plus repetitive behaviors and restricted interests, currently affects 1/36 children in the general population. Recent advances in functional brain imaging show promise to provide useful biomarkers of ASD diagnostic likelihood, behavioral trait severity, and even response to therapeutic intervention. However, current gold-standard neuroimaging methods (e.g., functional magnetic resonance imaging, fMRI) are limited in naturalistic studies of brain function underlying ASD-associated behaviors due to the constrained imaging environment. Compared to fMRI, high-density diffuse optical tomography (HD-DOT), a non-invasive and minimally constraining optical neuroimaging modality, can overcome these limitations. Herein, we aimed to establish HD-DOT to evaluate brain function in autistic and non-autistic school-age children as they performed a biological motion perception task previously shown to yield results related to both ASD diagnosis and behavioral traits. METHODS: We used HD-DOT to image brain function in 46 ASD school-age participants and 49 non-autistic individuals (NAI) as they viewed dynamic point-light displays of coherent biological and scrambled motion. We assessed group-level cortical brain function with statistical parametric mapping. Additionally, we tested for brain-behavior associations with dimensional metrics of autism traits, as measured with the Social Responsiveness Scale-2, with hierarchical regression models. RESULTS: We found that NAI participants presented stronger brain activity contrast (coherent > scrambled) than ASD children in cortical regions related to visual, motor, and social processing. Additionally, regression models revealed multiple cortical regions in autistic participants where brain function is significantly associated with dimensional measures of ASD traits. LIMITATIONS: Optical imaging methods are limited in depth sensitivity and so cannot measure brain activity within deep subcortical regions. However, the field of view of this HD-DOT system includes multiple brain regions previously implicated in both task-based and task-free studies on autism. CONCLUSIONS: This study demonstrates that HD-DOT is sensitive to brain function that both differentiates between NAI and ASD groups and correlates with dimensional measures of ASD traits. These findings establish HD-DOT as an effective tool for investigating brain function in autistic and non-autistic children. Moreover, this study established neural correlates related to biological motion perception and its association with dimensional measures of ASD traits.


Subject(s)
Autism Spectrum Disorder , Brain Mapping , Motion Perception , Tomography, Optical , Humans , Tomography, Optical/methods , Male , Child , Female , Motion Perception/physiology , Brain Mapping/methods , Autism Spectrum Disorder/diagnostic imaging , Autism Spectrum Disorder/physiopathology , Brain/diagnostic imaging , Brain/physiopathology , Autistic Disorder/physiopathology , Autistic Disorder/diagnostic imaging , Magnetic Resonance Imaging/methods , Adolescent
10.
Cell Syst ; 15(8): 770-786.e5, 2024 Aug 21.
Article in English | MEDLINE | ID: mdl-39142285

ABSTRACT

Functional magnetic resonance imaging (fMRI) provides insights into cognitive processes with significant clinical potential. However, delays in brain region communication and dynamic variations are often overlooked in functional network studies. We demonstrate that networks extracted from fMRI cross-correlation matrices, considering time lags between signals, show remarkable reliability when focusing on statistical distributions of network properties. This reveals a robust brain functional connectivity pattern, featuring a sparse backbone of strong 0-lag correlations and weaker links capturing coordination at various time delays. This dynamic yet stable network architecture is consistent across rats, marmosets, and humans, as well as in electroencephalogram (EEG) data, indicating potential universality in brain dynamics. Second-order properties of the dynamic functional network reveal a remarkably stable hierarchy of functional correlations in both group-level comparisons and test-retest analyses. Validation using alcohol use disorder fMRI data uncovers broader shifts in network properties than previously reported, demonstrating the potential of this method for identifying disease biomarkers.


Subject(s)
Brain , Electroencephalography , Magnetic Resonance Imaging , Brain/physiology , Brain/diagnostic imaging , Magnetic Resonance Imaging/methods , Animals , Humans , Rats , Electroencephalography/methods , Male , Nerve Net/physiology , Nerve Net/diagnostic imaging , Brain Mapping/methods , Callithrix/physiology , Adult
11.
Sci Rep ; 14(1): 19232, 2024 08 20.
Article in English | MEDLINE | ID: mdl-39164353

ABSTRACT

Acceptance and reappraisal are considered adaptive emotion regulation strategies. While previous studies have explored the neural underpinnings of these strategies using task-based fMRI and sMRI, a gap exists in the literature concerning resting-state functional brain networks' contributions to these abilities, especially regarding acceptance. Another intriguing question is whether these strategies rely on similar or different neural mechanisms. Building on the well-known improved emotion regulation and increased cognitive flexibility of individuals who rely on acceptance, we expected to find decreased activity inside the affective network and increased activity inside the executive and sensorimotor networks to be predictive of acceptance. We also expect that these networks may be associated at least in part with reappraisal, indicating a common mechanism behind different strategies. To test these hypotheses, we conducted a functional connectivity analysis of resting-state data from 134 individuals (95 females; mean age: 30.09 ± 12.87 years, mean education: 12.62 ± 1.41 years). To assess acceptance and reappraisal abilities, we used the Cognitive Emotion Regulation Questionnaire (CERQ) and a group-ICA unsupervised machine learning approach to identify resting-state networks. Subsequently, we conducted backward regression to predict acceptance and reappraisal abilities. As expected, results indicated that acceptance was predicted by decreased affective, and executive, and increased sensorimotor networks, while reappraisal was predicted by an increase in the sensorimotor network only. Notably, these findings suggest both distinct and overlapping brain contributions to acceptance and reappraisal strategies, with the sensorimotor network potentially serving as a core common mechanism. These results not only align with previous findings but also expand upon them, illustrating the complex interplay of cognitive, affective, and sensory abilities in emotion regulation.


Subject(s)
Brain , Magnetic Resonance Imaging , Humans , Female , Male , Adult , Magnetic Resonance Imaging/methods , Brain/physiology , Brain/diagnostic imaging , Young Adult , Nerve Net/physiology , Nerve Net/diagnostic imaging , Emotional Regulation/physiology , Emotions/physiology , Rest/physiology , Brain Mapping/methods , Cognition/physiology
12.
Sci Rep ; 14(1): 19334, 2024 08 20.
Article in English | MEDLINE | ID: mdl-39164440

ABSTRACT

Restoring motor function after stroke necessitates involvement of numerous cognitive systems. However, the impact of damage to motor and cognitive network organization on recovery is not well understood. To discover correlates of successful recovery, we explored imaging characteristics in chronic stroke subjects by combining noninvasive brain stimulation and fMRI. Twenty stroke survivors (6 months or more after stroke) were randomly assigned to a single session of transcranial direct current stimulation (tDCS) or sham during image acquisition. Twenty healthy subjects were included as controls. tDCS was limited to 10 min at 2 mA to serve as a mode of network modulation rather than therapeutic delivery. Fugl-Meyer Assessments (FMA) revealed significant motor improvement in the chronic stroke group receiving active stimulation (p = 0.0005). Motor changes in this group were correlated in a data-driven fashion with imaging features, including functional connectivity (FC), surface-based morphometry, electric field modeling and network topology, focusing on relevant regions of interest. We observed stimulation-related changes in FC in supplementary motor (p = 0.0029), inferior frontal gyrus (p = 0.0058), and temporo-occipital (p = 0.0095) areas, though these were not directly related to motor improvement. The feature most strongly associated with FMA improvement in the chronic stroke cohort was graph topology of the dorsal attention network (DAN), one of the regions surveyed and one with direct connections to each of the areas with FC changes. Chronic stroke subjects with a greater degree of motor improvement had lower signal transmission cost through the DAN (p = 0.029). While the study was limited by a small stroke cohort with moderate severity and variable lesion location, these results nevertheless suggest a top-down role for higher order areas such as attention in helping to orchestrate the stroke recovery process.


Subject(s)
Magnetic Resonance Imaging , Stroke Rehabilitation , Stroke , Transcranial Direct Current Stimulation , Humans , Magnetic Resonance Imaging/methods , Male , Female , Stroke/physiopathology , Stroke/diagnostic imaging , Stroke/therapy , Stroke/complications , Middle Aged , Transcranial Direct Current Stimulation/methods , Aged , Stroke Rehabilitation/methods , Attention/physiology , Recovery of Function , Adult , Brain/diagnostic imaging , Brain/physiopathology , Motor Cortex/physiopathology , Motor Cortex/diagnostic imaging , Brain Mapping/methods
13.
Sci Rep ; 14(1): 19070, 2024 08 17.
Article in English | MEDLINE | ID: mdl-39154133

ABSTRACT

Independent component analysis (ICA) and dictionary learning (DL) are the most successful blind source separation (BSS) methods for functional magnetic resonance imaging (fMRI) data analysis. However, ICA to higher and DL to lower extent may suffer from performance degradation by the presence of anomalous observations in the recovered time courses (TCs) and high overlaps among spatial maps (SMs). This paper addressed both problems using a novel three-layered sparse DL (TLSDL) algorithm that incorporated prior information in the dictionary update process and recovered full-rank outlier-free TCs from highly corrupted measurements. The associated sequential DL model involved factorizing each subject's data into a multi-subject (MS) dictionary and MS sparse code while imposing a low-rank and a sparse matrix decomposition restriction on the dictionary matrix. It is derived by solving three layers of feature extraction and component estimation. The first and second layers captured brain regions with low and moderate spatial overlaps, respectively. The third layer that segregated regions with significant spatial overlaps solved a sequence of vector decomposition problems using the proximal alternating linearized minimization (PALM) method and solved a decomposition restriction using the alternating directions method (ALM). It learned outlier-free dynamics that integrate spatiotemporal diversities across brains and external information. It differs from existing DL methods owing to its unique optimization model, which incorporates prior knowledge, subject-wise/multi-subject representation matrices, and outlier handling. The TLSDL algorithm was compared with existing dictionary learning algorithms using experimental and synthetic fMRI datasets to verify its performance. Overall, the mean correlation value was found to be 26 % higher for the TLSDL than for the state-of-the-art subject-wise sequential DL (swsDL) technique.


Subject(s)
Algorithms , Brain , Magnetic Resonance Imaging , Humans , Magnetic Resonance Imaging/methods , Brain/diagnostic imaging , Brain/physiology , Image Processing, Computer-Assisted/methods , Brain Mapping/methods , Nerve Net/physiology , Nerve Net/diagnostic imaging , Machine Learning
14.
Sci Rep ; 14(1): 17859, 2024 08 01.
Article in English | MEDLINE | ID: mdl-39090239

ABSTRACT

Recent research shows that emotional facial expressions impact behavioral responses only when their valence is relevant to the task. Under such conditions, threatening faces delay attentional disengagement, resulting in slower reaction times and increased omission errors compared to happy faces. To investigate the neural underpinnings of this phenomenon, we used functional magnetic resonance imaging to record the brain activity of 23 healthy participants while they completed two versions of the go/no-go task. In the emotion task (ET), participants responded to emotional expressions (fearful or happy faces) and refrained from responding to neutral faces. In the gender task (GT), the same images were displayed, but participants had to respond based on the posers' gender. Our results confirmed previous behavioral findings and revealed a network of brain regions (including the angular gyrus, the ventral precuneus, the left posterior cingulate cortex, the right anterior superior frontal gyrus, and two face-responsive regions) displaying distinct activation patterns for the same facial emotional expressions in the ET compared to the GT. We propose that this network integrates internal representations of task rules with sensory characteristics of facial expressions to evaluate emotional stimuli and exert top-down control, guiding goal-directed actions according to the context.


Subject(s)
Brain Mapping , Brain , Emotions , Facial Expression , Magnetic Resonance Imaging , Reaction Time , Humans , Male , Female , Emotions/physiology , Adult , Young Adult , Brain/physiology , Brain/diagnostic imaging , Reaction Time/physiology
15.
Sci Rep ; 14(1): 17830, 2024 08 01.
Article in English | MEDLINE | ID: mdl-39090331

ABSTRACT

Olfactory dysfunction is associated with aging and the earliest stages of neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases; it is thought to be an early biomarker of cognitive decline. In marmosets, a small non-human primate model used in brain research, olfactory pathway activity during olfactory stimulation has not been well studied because of the difficulty in clearly switching olfactory stimuli inside a narrow MRI. Here, we developed an olfactory-stimulated fMRI system using a small-aperture MRI machine. The olfactory presentation system consisted of two tubes, one for supply and one for suction of olfactory stimulants and a balloon valve. A balloon valve installed in the air supply tube controlled the presentation of the olfactory stimulant, which enabled sharp olfactory stimulation within MRI, such as 30 s of stimulation repeated five times at five-minute intervals. The olfactory stimulation system was validated in vivo and in a simulated system. fMRI analysis showed a rapid increase in signal values within 30 s of olfactory stimulation in eight regions related to the sense of smell. As these regions include those associated with Alzheimer's and Parkinson's diseases, olfactory stimulation fMRI may be useful in clarifying the relationship between olfactory dysfunction and dementia in non-human primates.


Subject(s)
Callithrix , Magnetic Resonance Imaging , Smell , Animals , Magnetic Resonance Imaging/methods , Smell/physiology , Olfactory Pathways/physiology , Olfactory Pathways/diagnostic imaging , Male , Brain Mapping/methods , Female , Odorants
16.
Sci Rep ; 14(1): 17943, 2024 08 02.
Article in English | MEDLINE | ID: mdl-39095418

ABSTRACT

A sensitive and efficient imaging technique is required to assess the subtle abnormalities occurring in the normal-appearing white matter (NAWM) and normal-appearing grey matter (NAGM) in patients with relapsing-remitting multiple sclerosis (RRMS). In this study, a fast 3D macromolecular proton fraction (MPF) quantification based on spin-lock (fast MPF-SL) sequence was proposed for brain MPF mapping. Thirty-four participants, including 17 healthy controls and 17 RRMS patients were prospectively recruited. We conducted group comparison and correlation between conventional MPF-SL, fast MPF-SL, and DWI, and compared differences in quantified parameters within MS lesions and the regional NAWM, NAGM, and normal-appearing deep grey matter (NADGN). MPF of MS lesions was significantly reduced (7.17% ± 1.15%, P < 0.01) compared to all corresponding normal-appearing regions. MS patients also showed significantly reduced mean MPF values compared with controls in NAGM (4.87% ± 0.38% vs 5.21% ± 0.32%, P = 0.01), NAWM (9.49% ± 0.69% vs 10.32% ± 0.59%, P < 0.01) and NADGM (thalamus 5.59% ± 0.67% vs 6.00% ± 0.41%, P = 0.04; caudate 5.10% ± 0.55% vs 5.53% ± 0.58%, P = 0.03). MPF and ADC showed abnormalities in otherwise normal appearing close to lesion areas (P < 0.01). In conclusion, time-efficient MPF mapping of the whole brain can be acquired efficiently (< 3 min) using fast MPF-SL. It offers a promising alternative way to detect white matter abnormalities in MS.


Subject(s)
Brain , Multiple Sclerosis, Relapsing-Remitting , White Matter , Humans , Female , Male , Adult , Multiple Sclerosis, Relapsing-Remitting/diagnostic imaging , Multiple Sclerosis, Relapsing-Remitting/pathology , White Matter/diagnostic imaging , White Matter/pathology , Brain/diagnostic imaging , Brain/pathology , Middle Aged , Protons , Gray Matter/diagnostic imaging , Gray Matter/pathology , Imaging, Three-Dimensional/methods , Magnetic Resonance Imaging/methods , Case-Control Studies , Brain Mapping/methods , Prospective Studies
17.
Sci Rep ; 14(1): 18298, 2024 08 07.
Article in English | MEDLINE | ID: mdl-39112629

ABSTRACT

Hand visibility affects motor control, perception, and attention, as visual information is integrated into an internal model of somatomotor control. Spontaneous brain activity, i.e., at rest, in the absence of an active task, is correlated among somatomotor regions that are jointly activated during motor tasks. Recent studies suggest that spontaneous activity patterns not only replay task activation patterns but also maintain a model of the body's and environment's statistical regularities (priors), which may be used to predict upcoming behavior. Here, we test whether spontaneous activity in the human somatomotor cortex as measured using fMRI is modulated by visual stimuli that display hands vs. non-hand stimuli and by the use/action they represent. A multivariate pattern analysis was performed to examine the similarity between spontaneous activity patterns and task-evoked patterns to the presentation of natural hands, robot hands, gloves, or control stimuli (food). In the left somatomotor cortex, we observed a stronger (multivoxel) spatial correlation between resting state activity and natural hand picture patterns compared to other stimuli. No task-rest similarity was found in the visual cortex. Spontaneous activity patterns in somatomotor brain regions code for the visual representation of human hands and their use.


Subject(s)
Brain Mapping , Hand , Magnetic Resonance Imaging , Visual Perception , Humans , Hand/physiology , Male , Female , Adult , Visual Perception/physiology , Young Adult , Brain/physiology , Brain/diagnostic imaging , Motor Cortex/physiology , Motor Cortex/diagnostic imaging , Rest/physiology , Photic Stimulation , Visual Cortex/physiology , Visual Cortex/diagnostic imaging
18.
Hum Brain Mapp ; 45(11): e26810, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39140847

ABSTRACT

Source analysis of magnetoencephalography (MEG) data requires the computation of the magnetic fields induced by current sources in the brain. This so-called MEG forward problem includes an accurate estimation of the volume conduction effects in the human head. Here, we introduce the Cut finite element method (CutFEM) for the MEG forward problem. CutFEM's meshing process imposes fewer restrictions on tissue anatomy than tetrahedral meshes while being able to mesh curved geometries contrary to hexahedral meshing. To evaluate the new approach, we compare CutFEM with a boundary element method (BEM) that distinguishes three tissue compartments and a 6-compartment hexahedral FEM in an n = 19 group study of somatosensory evoked fields (SEF). The neural generators of the 20 ms post-stimulus SEF components (M20) are reconstructed using both an unregularized and a regularized inversion approach. Changing the forward model resulted in reconstruction differences of about 1 centimeter in location and considerable differences in orientation. The tested 6-compartment FEM approaches significantly increase the goodness of fit to the measured data compared with the 3-compartment BEM. They also demonstrate higher quasi-radial contributions for sources below the gyral crowns. Furthermore, CutFEM improves source separability compared with both other approaches. We conclude that head models with 6 compartments rather than 3 and the new CutFEM approach are valuable additions to MEG source reconstruction, in particular for sources that are predominantly radial.


Subject(s)
Evoked Potentials, Somatosensory , Finite Element Analysis , Magnetoencephalography , Humans , Magnetoencephalography/methods , Evoked Potentials, Somatosensory/physiology , Adult , Male , Female , Models, Neurological , Brain Mapping/methods , Somatosensory Cortex/physiology , Somatosensory Cortex/diagnostic imaging , Young Adult
19.
Nat Commun ; 15(1): 7002, 2024 Aug 14.
Article in English | MEDLINE | ID: mdl-39143147

ABSTRACT

Visual recognition is largely realized through neurons in the ventral stream, though recently, studies have suggested that ventrolateral prefrontal cortex (vlPFC) is also important for visual processing. While it is hypothesized that sensory and cognitive processes are integrated in vlPFC neurons, it is not clear how this mechanism benefits vision, or even if vlPFC neurons have properties essential for computations in visual cortex implemented via recurrence. Here, we investigated if vlPFC neurons in two male monkeys had functions comparable to visual cortex, including receptive fields, image selectivity, and the capacity to synthesize highly activating stimuli using generative networks. We found a subset of vlPFC sites show all properties, suggesting subpopulations of vlPFC neurons encode statistics about the world. Further, these vlPFC sites may be anatomically clustered, consistent with fMRI-identified functional organization. Our findings suggest that stable visual encoding in vlPFC may be a necessary condition for local and brain-wide computations.


Subject(s)
Macaca mulatta , Magnetic Resonance Imaging , Neurons , Prefrontal Cortex , Visual Cortex , Prefrontal Cortex/physiology , Prefrontal Cortex/cytology , Prefrontal Cortex/diagnostic imaging , Animals , Male , Visual Cortex/physiology , Visual Cortex/cytology , Visual Cortex/diagnostic imaging , Neurons/physiology , Photic Stimulation , Visual Perception/physiology , Brain Mapping
20.
Biomed Phys Eng Express ; 10(5)2024 Aug 19.
Article in English | MEDLINE | ID: mdl-39094595

ABSTRACT

Dynamic 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography (dFDG-PET) for human brain imaging has considerable clinical potential, yet its utilization remains limited. A key challenge in the quantitative analysis of dFDG-PET is characterizing a patient-specific blood input function, traditionally reliant on invasive arterial blood sampling. This research introduces a novel approach employing non-invasive deep learning model-based computations from the internal carotid arteries (ICA) with partial volume (PV) corrections, thereby eliminating the need for invasive arterial sampling. We present an end-to-end pipeline incorporating a 3D U-Net based ICA-net for ICA segmentation, alongside a Recurrent Neural Network (RNN) based MCIF-net for the derivation of a model-corrected blood input function (MCIF) with PV corrections. The developed 3D U-Net and RNN was trained and validated using a 5-fold cross-validation approach on 50 human brain FDG PET scans. The ICA-net achieved an average Dice score of 82.18% and an Intersection over Union of 68.54% across all tested scans. Furthermore, the MCIF-net exhibited a minimal root mean squared error of 0.0052. The application of this pipeline to ground truth data for dFDG-PET brain scans resulted in the precise localization of seizure onset regions, which contributed to a successful clinical outcome, with the patient achieving a seizure-free state after treatment. These results underscore the efficacy of the ICA-net and MCIF-net deep learning pipeline in learning the ICA structure's distribution and automating MCIF computation with PV corrections. This advancement marks a significant leap in non-invasive neuroimaging.


Subject(s)
Brain , Deep Learning , Fluorodeoxyglucose F18 , Positron-Emission Tomography , Humans , Positron-Emission Tomography/methods , Brain/diagnostic imaging , Brain/blood supply , Image Processing, Computer-Assisted/methods , Brain Mapping/methods , Neural Networks, Computer , Carotid Artery, Internal/diagnostic imaging , Male , Algorithms , Female , Radiopharmaceuticals
SELECTION OF CITATIONS
SEARCH DETAIL