PurposePrevious studies have shown high reproducibility of population receptive field (pRF) mapping in young, healthy individuals. The present study examines whether such a level of reproducibility can also be achieved in patients suffering from retinal disease.MethodsEleven patients with Stargardt disease and eleven patients with geographic atrophy (GA) secondary to age-related macular degeneration (AMD) were examined in up to four sessions using high-resolution ultra-high field fMRI (Siemens Magnetom 7 T) and microperimetry (MP, Nidek MP-3). Reproducibility of the pRF parameters within and between sessions was assessed using Spearman's correlation coefficient.ResultsRetinotopic maps calculated from ultra-high field MRI had excellent intra- and intersession reproducibility for pRF center position (median correlation between sessions for pRF center eccentricity: r = 0.91; polar angle: r = 0.90), but only modest reproducibility for pRF size (average correlation r = 0.39). Reproducibility was constant across sessions multiple weeks apart, indicating a long-term stability of the method. In addition, the results show that reproducibility is not related to the severity of retinal disease.ConclusionThe data demonstrate that retinotopic mapping of the primary visual cortex using ultra-high field MRI is a highly reproducible technique for the assessment of macular function in patients with retinal disease. The technique provides an unbiased quantification of retinal function adjunct to conventional clinical assessments and may assist the early diagnosis of retinal disease. In addition, it may be a valuable objective method for monitoring visual deficits during long-term therapeutic interventions or disease progression.

The claustrum is a thin, bilateral sheet of grey matter between the insula and putamen that stands out by its high interconnectivity with almost the entire cortex. Despite continuing research in humans and animals, its functional role remains largely unknown. In the present study, we explored the topographic organization of the recently described human visual claustrum zone. We performed a population receptive field (pRF) analysis on the 7T retinotopy dataset of the Young Adult Human Connectome Project (N = 181, 109 female) comparing the visual claustrum with established visual field properties of the lateral geniculate nucleus, the primary visual cortex, and higher-level topographic maps of the dorsal and the ventral stream. Our results demonstrate for the first time that the human visual claustrum showed several topographic properties typical for visual areas, including a representational bias towards the contralateral visual field, and a pRF size increase with increasing eccentricity. At the same time, the claustrum also exhibited a positive eccentricity gradient along the posterior-anterior axis, an extended representation of the visual periphery compared to other areas and a lack of horizontal meridian bias. These latter two properties highlight the claustrums role as a higher-level nucleus which is less dependent on sensory input. This study is the first to characterize the topographic organization of the visual claustrum zone in humans, highlighting its uniqueness among the known visually responsive regions. ### Competing Interest Statement The authors have declared no competing interest. FWF Austrian Science Fund, https://ror.org/013tf3c58, 10.55776/PAT8722623, 10.55776/P35583

Abstract Population receptive field (pRF) mapping is widely used to characterize retinotopic organization based on functional magnetic resonance imaging (fMRI) data. Despite its broad adoption, the factors governing intra- and inter-subject variability in pRF estimates remain incompletely understood, limiting the ability to evaluate and optimize visual stimulation paradigms prior to data collection. Here, we investigate whether large-scale simulations can reproduce in vivo run-to-run variability patterns observed in pRF mapping and provide mechanistic insight into their origins. With GEMSim-pRF, our newly proposed computational framework for large-scale simulation and estimation of pRF responses, we generated millions of synthetic fMRI time courses across a wide range of receptive field parameters and noise conditions. We analyzed the variability of pRF estimation results derived from simulations and compared them with in vivo data from the publicly available NYU Retinotopy Dataset. Here we show that our simulation results matched the characteristic eccentricity-dependent variability observed in empirical pRF estimates. These findings show that key variability patterns observed in empirical pRF mapping can be successfully reproduced in large-scale simulations, establishing simulation-based analysis as a practical approach for understanding, predicting, evaluating and ultimately improving the behaviour of retinotopic mapping paradigms before empirical data collection.

The human claustrum is a small bilateral grey matter structure that is highly interconnected with cortical and subcortical regions. It has been implicated in different functions including sleep, multisensory integration, consciousness and attention, yet its exact function remains unclear. The primate claustrum is known to have distinct sensory regions, with the visual zone recently demonstrated in humans using high-resolution fMRI. In this study, we investigated stimulus properties that drive human visual claustrum activity. First, we tested the association of its response with various low- and mid-level physical stimulus features, including temporal and spatial contrast, color and motion. Second, we tested the association with subjective ratings of arousal, valence and interest. To compare the claustrum's responses with visual cortical regions, we performed the same analysis with the hV4 and hMT/V5+ complex. We found that the claustrum's visual response was associated with motion, as well as with arousal, interest and valence. The pattern of claustrum responses was similar to hMT/V5+. Given the well-established link between arousal and attentional allocation, as well as between saliency and motion, our results suggest that the visual claustrum may contribute to saliency detection and attention modulation during the sensory input.

Population receptive field (pRF) mapping is a fundamental technique for understanding retinotopic organisation of the human visual system. Since its introduction in 2008, however, its scalability has been severely hindered by the computational bottleneck of iterative parameter refinement. Current state-of-the-art implementations either sacrifice precision for speed or rely on slow iterative parameter updates, limiting their applicability to large-scale datasets. Here, we present a novel mathematical reformulation of the General Linear Model (GLM), wrapped in a GPU-Empowered Mapping of population Receptive Fields (GEM-pRF) software implementation. By orthogonalizing the design matrix, our approach enables the direct and fast computation of the objective function's derivatives, which are used to eliminate the iterative refinement process. This approach dramatically accelerates pRF estimation with high accuracy. Validation using empirical and simulated data confirms GEM-pRF's accuracy, and benchmarking against established tools demonstrates a reduction in computation time of almost two orders of magnitude. With its modular and extensible design, GEM-pRF provides a critical advancement for large-scale fMRI retinotopic mapping. Furthermore, our reformulated GLM approach in combination with GPU-based implementation offers a broadly applicable solution that may extend beyond visual neuroscience, accelerating computational modelling across various domains in neuroimaging and beyond.

Concurrent transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (TMS-fMRI) provides a step-change in the toolkit of neuroscience research. TMS enables the noninvasive perturbation of ongoing human brain activity, and when coupled to fMRI for the simultaneous read-out of its effects across the brain, concurrent TMS-fMRI enables studies aimed at determining the causal inference of human brain–behavior relationships, with implications for both fundamental research and clinical application. Many of the technical barriers to TMS-fMRI implementation, such as hardware design and setups, have now been overcome, and the research community in the field is rapidly growing. Here, we present the guidelines set by an international consensus, from researchers at all levels and across the fields of cognitive and applied human neuroscience, for the experimental design and practical considerations of concurrent TMS-fMRI via 12 detailed use cases. These guidelines may facilitate the uptake of this approach and simplify the experimental design and planning stages. We present best practice guidelines for the use of concurrent TMS-fMRI, experimental design, technical requirements and data interpretation, illustrated via 12 use cases.

INTRODUCTION:Precise targeting and dosing are critical for neurophysiological effectivity of repetitive transcranial magnetic stimulation (rTMS), particularly in clinical applications such as treating major depressive disorder (MDD). While neuronavigation enables accurate, individualized coil positioning, even small deviations in coil placement, e.g. during extended stimulation protocols, can significantly alter the induced electric field (E-field). In this study, we use continuous neuronavigational monitoring during stimulation to quantify motion-induced E-field variability at the target and introduce a novel methodology for compensating it. METHODS:We analyzed coil-target movement parameters in a sample of 200 rTMS sessions conducted in 20 adults with MDD, evaluating position, rotation and main axes of movement. In addition, we simulated induced E-fields within a target-ROI and quantified variability within- and across-sessions. To mitigate movement-related variability, we developed an algorithm which enables real-time adjustment of stimulator output based on current coil position and interpolation of precomputed E-fields. RESULTS:Our results show that E-field variability in this sample was primarily driven by coil displacement along the scalp-normal and rotation. Lateral movement played a minor role. Using the new stimulation amplitude adjustment strongly reduced target E-field variability. Mean E-field coefficient of variation was reduced within-session by 41% (2.85%-1.67%) and across-sessions by 74% (6.77%-1.73%). DISCUSSION:This study presents the first quantitative analysis of motion during rTMS treatment sessions and a practical method to compensate for it. Given its low computational cost, the proposed approach is well suited for clinical implementation, potentially enhancing treatment reliability, particularly in individuals prone to motion.

Population receptive field (pRF) mapping is a quantitative functional MRI (fMRI) analysis method that links visual field positions with specific locations in the visual cortex. A common preprocessing step in pRF analyses involves projecting volumetric fMRI data onto the cortical surface, typically leading to upsampling of the data. This process may introduce biases in the resulting pRF parameters. Using publicly available analysis containers, we compared pRF maps generated from the original volumetric with those from upsampled surface data. Our results show substantial increases in pRF coverage in the central visual field of upsampled datasets. These effects were consistent across early visual cortex areas V1-3. Further analysis indicates that this bias is primarily driven by the nonlinear relationship between cortical distance and visual field eccentricity, known as cortical magnification. Our results underscore the importance of understanding and addressing biases introduced by processing steps to ensure accurate interpretation of pRF mapping data, particularly in cross-study comparisons.

dMRI is a promising imaging technique for examining the human brain. Validation of dMRI is challenging, and specialized test samples, so-called brain phantoms, that mimic the tissue microstructure authentically, are needed. High-resolution 3D printing by means of 2-Photon Polymerization allows for the manufacturing of such novel brain phantoms. (e-mail: franziska.gantner@tuwien.ac.at). (c) 2025 The Author(s).

Rewards are a broad category of stimuli inducing approach behavior to aid survival. Extensive evidence from animal research has shown that wanting (the motivation to pursue a reward) and liking (the pleasure associated with its consumption) are mostly regulated by dopaminergic and opioidergic activity in dedicated brain areas. However, less is known about the neuroanatomy of dopaminergic and opioidergic regulation of reward processing in humans, especially when considering different types of rewards (i.e., social and non-social). To fill this gap of knowledge, we combined dopaminergic and opioidergic antagonism (via amisulpride and naltrexone administration) with functional neuroimaging to investigate the neurochemical and neuroanatomical bases of wanting and liking of matched non-social (food) and social (interpersonal touch) rewards, using a randomized, between-subject, placebo-controlled, double-blind design. While at the behavioral level no drug effect was observed, brain activity was modulated by the administered compounds. In particular, opioid antagonism, compared to placebo, was associated with reduced activity in the medial orbitofrontal cortex during consumption of the most valued social and non-social rewards. Dopamine antagonism, however, had no clear effects on brain activity in response to rewards anticipation. These findings provide insights into the neurobiology of human reward processing and suggest a similar opioidergic regulation of the neural responses to social and non-social reward consumption.