Biology subjects

Manea, A. M. G.

Publications and source records attributed to Manea, A. M. G..

4 recordsLinked to original sources

bioRxiv2025

An RF coil array system for in vivo & ex vivo non-human primate brain studies at 10.5 Tesla

PurposeWe aimed to develop an innovative RF coil toolset for high resolution in vivo and ex vivo non-human primate neuroimaging applications at 10.5T MRI. The main goal was to improve our multimodal neural connectivity pipeline through the improved SNR, CNR, and spatial resolution that result from utilizing high-density RF coil arrays in combination with ultra-high field MRI. MethodsTwo RF coil arrays, both comprising 8 transmit and 40 receive channels, were designed and built for in vivo and ex vivo NHP imaging at 10.5 T. Experimental data was collected on multiple in vivo and ex vivo specimens, showing the utility UHF MRI for NHP neuroscience. ResultsExperimental results demonstrate uniform whole-brain coverage within both in vivo--which included the cerebellar, and spinal cord regions--and ex vivo specimens. High spatial resolutions (in vivo: 0.1x0.1x0.5 mm, ex vivo: 120 micron isotropic) were achieved, revealing detailed anatomical structures throughout. High temporal stability allowed for EPI and dMRI applications. ConclusionAn RF coil toolset comprising two 8ch transmit/40ch receive arrays was successfully designed for both in vivo and ex vivo NHP brain applications at 10.5 T. Both high-density RF coil arrays coupled with the SNR and CNR benefits available at UHF supported unmatched anatomical, functional, and diffusion applications at some of the highest spatial resolutions to date. Additionally, the combined capability of both in vivo and ex vivo MRI with the same brain specimen allows for tighter control for experimental-paradigm multistage studies examining translation between in vivo and ex vivo methodologies.

neuroscience↗

bioRxiv2025

Convergent and divergent neural and behavioral responses to chronic cocaine use in macaques

Chronic cocaine use leads to physical dependence, psychological addiction, and various health problems such as cardiovascular issues and cognitive impairments. This condition continues to be extremely difficult to treat, as we grapple with its neural and behavioral complexities. What we are missing is a comprehensive account on how naive brains react to occasional and chronic cocaine use, abstinence and re-exposure within subject. We tracked naive macaques using precision functional mapping before, during and after chronic cocaine self-administration over a period of nine months. We analyzed the entire brain to illustrate the pervasive impact of chronic cocaine use on overall function. Although we set out to map the "addiction" connectome, we found that the neural correlates of chronic drug use and recovery are more complex that can be captured by a singular, canonical connectome. We provide a preclinical model that maps the progression of the macaque functional connectome from a naive state through chronic cocaine use, recovery and re-exposure. We demonstrate that the "addiction" connectome is dynamic and is characterized by the interaction of subject by drug by time. Occasional cocaine use, whether initial or re-exposure, overrides individual differences, leading to a strong homogenous effect across subjects, or convergence. However, the brains response to prolonged cocaine use becomes more individualized, resulting in the divergence of effects across subjects. This can be explained by heterogeneity in cocaine-induced effects and in their associated timescales. Abstinence-induced neural alterations converged across subjects after 1-month, but by 2 months, individual trajectories revealed heterogeneity, possibly indicating differences in recovery.

neuroscience↗

bioRxiv2023

Neural timescales reflect behavioral demands in freely moving rhesus macaques

Previous work has demonstrated remarkably reproducible and consistent hierarchies of neural timescales across cortical areas at rest. The question arises how such stable hierarchies give rise to adaptive behavior that requires flexible adjustment of temporal coding and integration demands. Potentially, this previously found lack of variability in the hierarchical organization of neural timescales could be a reflection of the structure of the laboratory contexts in which they were measured. Indeed, computational work demonstrates the existence of multiple temporal hierarchies within the same anatomical network when the input structure is altered. We posit that unconstrained behavioral environments where relatively little temporal demands are imposed from the experimenter are an ideal test bed to address the question of whether the hierarchical organization and the magnitude of neural timescales reflect ongoing behavioral demands. To tackle this question, we measured timescales of local field potential activity while rhesus macaques were foraging freely in a large open space. We find a hierarchy of neural timescales that is unique to this foraging environment. Importantly, although the magnitude of neural timescales generally expanded with task engagement, the brain areas relative position in the hierarchy was stable across the recording sessions. Notably, the magnitude of neural timescales monotonically expanded with task engagement across a relatively long temporal scale spanning the duration of the recording session. Over shorter temporal scales, the magnitude of neural timescales changed dynamically around foraging events. Moreover, the change in the magnitude of neural timescales contained functionally relevant information, differentiating between seemingly similar events in terms of motor demands and associated reward. That is, the patterns of change were associated with the cognitive and behavioral meaning of these events. Finally, we demonstrated that brain areas were differentially affected by these behavioral demands - i.e., the expansion of neural timescales was not the same across all areas. Together, these results demonstrate that the observed hierarchy of neural timescales is context-dependent and that changes in the magnitude of neural timescales are closely related to overall task engagement and behavioral demands.

neuroscience↗

bioRxiv2021

Intrinsic timescales as an organizational principle of neural processing across the whole rhesus macaque brain

Hierarchical temporal dynamics are a fundamental computational property of the brain; however, there are no whole-brain, noninvasive investigations into timescales of neural processing in animal models. To that end, we used the spatial resolution and sensitivity of ultrahigh field fMRI performed at 10.5 Tesla to probe timescales across the whole macaque brain. We uncovered within-species consistency between timescales estimated from fMRI and electrophysiology. Crucially, we extended existing electrophysiological hierarchies to whole brain topographies. Our results validate the complementary use of hemodynamic and electrophysiological intrinsic timescales, establishing a basis for future translational work. Further, with these results in hand, we were able to show that one facet of the high-dimensional functional connectivity topography of any region in the brain is closely related to hierarchical temporal dynamics. We demonstrated that intrinsic timescales are organized along spatial gradients that closely match functional connectivity gradient topographies across the whole brain. We conclude that intrinsic timescales are a unifying organizational principle of neural processing across the whole brain. Declaration of InterestsThe authors declare no competing interests.

neuroscience↗