Mathematics of the brain: a NeuroMat op-ed

What does Mathematics have to do with Brain Biology? This is the question that NeuroMat's director, Antonio Galves, asks on his first post as a contributor to the "Science & Mathematics" blog of the Brazilian newspaper

Reduced functional connectivity within the primary motor cortex of patients with brachial plexus injury

D. Fraiman, M. F. Miranda, F. Erthal, P. F. Buur, M. Elschot, L. Souza, S. A. R. B. Rombouts, C. A. Schimmelpenninck, D. G. Norris, M. J. A. Malessy, A. Galves and C. D. Vargas

This study aims at the effects of traumatic brachial plexus lesion with root avulsions (BPA) upon the organization of the primary motor cortex (M1). Nine right-handed patients with a right BPA in whom an intercostal to musculocutaneous (ICN-MC) nerve transfer was performed had post-operative resting state fMRI scanning. The analysis of empirical functional correlations between neighboring voxels revealed faster correlation decay as a function of distance in the M1 region corresponding to the arm in BPA patients as compared to the control group. No differences between the two groups were found in the face area. We also investigated whether such larger decay in patients could be attributed to a gray matter diminution in M1. Structural imaging analysis showed no difference in gray matter density between groups. Our findings suggest that the faster decay in neighboring functional correlations without significant gray matter diminution in BPA patients could be related to a reduced activity in intrinsic horizontal connections in M1 responsible for upper limb motor synergies.

D2 dopamine receptor regulation of learning, sleep and plasticity

A.S.C. França, B. Lobão-Soares, L. Muratori, G. Nascimento, J. Winne, C.M. Pereira, S.M.B. Jeronimo and S. Ribeiro

Dopamine and sleep have been independently linked with hippocampus-dependent learning. Since D2 dopaminergic transmission is required for the occurrence of rapid-eye-movement (REM) sleep, it is possible that dopamine affects learning by way of changes in post-acquisition REM sleep. To investigate this hypothesis, we first assessed whether D2 dopaminergic modulation in mice affects novel object preference, a hippocampus-dependent task. Animals trained in the dark period, when sleep is reduced, did not improve significantly in performance when tested 24 h after training. In contrast, animals trained in the sleep-rich light period showed significant learning after 24 h. When injected with the D2 inverse agonist haloperidol immediately after the exploration of novel objects, animals trained in the light period showed reduced novelty preference upon retesting 24 h later. Next we investigated whether haloperidol affected the protein levels of plasticity factors shown to be up-regulated in an experience-dependent manner during REM sleep. Haloperidol decreased post-exploration hippocampal protein levels at 3 h, 6 h and 12 h for phosphorylated Ca2+/calmodulin-dependent protein kinase II, at 6 h for Zif-268; and at 12 h for the brain-derived neurotrophic factor. Electrophysiological and kinematic recordings showed a significant decrease in the amount of REM sleep following haloperidol injection, while slow-wave sleep remained unaltered. Importantly, REM sleep decrease across animals was strongly correlated with deficits in novelty preference (Rho=0.56, p=0.012). Altogether, the results suggest that the dopaminergic regulation of REM sleep affects learning by modulating post-training levels of calcium-dependent plasticity factors.

Science in comics: comic books gain prominence in science dissemination

This month RIDC NeuroMat was covered by Pesquisa FAPESP magazine, this time on how comic books gain prominence in science dissemination. "The Arms of Nildo and Rony" is a NeuroMat HQ that guides patients with brachial plexus injury, which is a set of nerves responsible for the communication between the brain and the upper limbs. The story recounts the meeting of a biker, Nildo, who had a motorcycle accident, and a physician doctor, Rony, who was shot in an armed robbery. Both of them damage the brachial plexus and have partial loss of arm movements. "The goal is to inform patients and families about this disease, which leaves sequels even after surgery," explained Antonio Galves, NeuroMat coordinator and scriptwriter of the HQ. "We investigated this disease because it is a good model for studying the plasticity of the human brain." Pesquisa FAPESP magazine, 07/2018. (In Portuguese.)

The Goalkeeper Game, a tool for massive data collection and experiments

NeuroMat's Goalkeeper Game has evolved as two concomitant research, development directions. Firstly, the game, that had a first version launched in early 2016, is being developed as a tool for massive data collection. Secondly, the game remains a resource for efficient diagnosis and allows for changes in settings for experiments. Challenges in these two directions have been advanced by a multidisciplinary team within NeuroMat's innovation area.

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O Centro de Pesquisa, Inovação e Difusão em Neuromatemática está sediado na Universidade de São Paulo e é financiado pela FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo).

 

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