Functional reorganization during the recovery of contralesional target selection deficits after prefrontal cortex lesions in macaque monkeys

© 2019 The Authors Visual extinction has been characterized by the failure to respond to a visual stimulus in the contralesional hemifield when presented simultaneously with an ipsilesional stimulus (Corbetta and Shulman, 2011). Unilateral damage to the macaque frontoparietal cortex commonly leads to deficits in contralesional target selection that resemble visual extinction. Recently, we showed that macaque monkeys with unilateral lesions in the caudal prefrontal cortex (PFC) exhibited contralesional target selection deficits that recovered over 2–4 months (Adam et al., 2019). Here, we investigated the longitudinal changes in functional connectivity (FC) of the frontoparietal network after a small or large right caudal PFC lesion in four macaque monkeys. We collected ultra-high field resting-state fMRI at 7-T before the lesion and at weeks 1–16 post-lesion and compared the functional data with behavioural performance on a free-choice saccade task. We found that the pattern of frontoparietal network FC changes depended on lesion size, such that the recovery of contralesional extinction was associated with an initial increase in network FC that returned to baseline in the two small lesion monkeys, whereas FC continued to increase throughout recovery in the two monkeys with a larger lesion. We also found that the FC between contralesional dorsolateral PFC and ipsilesional parietal cortex correlated with behavioural recovery and that the contralesional dorsolateral PFC showed increasing degree centrality with the frontoparietal network. These findings suggest that both the contralesional and ipsilesional hemispheres play an important role in the recovery of function. Importantly, optimal compensation after large PFC lesions may require greater recruitment of distant and intact areas of the frontoparietal network, whereas recovery from smaller lesions was supported by a normalization of the functional network

Structural alterations in cortical and thalamocortical white matter tracts after recovery from prefrontal cortex lesions in macaques

Unilateral damage to the frontoparietal network typically impairs saccade target selection within the contralesional visual hemifield. Severity of deficits and the degree of recovery have been associated with widespread network dysfunction, yet it is not clear how these behavioural and functional brain changes relate with the underlying structural white matter tracts. Here, we investigated whether recovery after unilateral prefrontal cortex (PFC) lesions was associated with changes in white matter microstructure across large-scale frontoparietal cortical and thalamocortical networks. Diffusion-weighted imaging was acquired in four male rhesus macaques at pre-lesion, week 1, and week 8-16 post-lesion when target selection deficits largely recovered. Probabilistic tractography was used to reconstruct cortical frontoparietal fiber tracts, including the superior longitudinal fasciculus (SLF) and transcallosal fibers connecting the PFC or posterior parietal cortex (PPC), as well as thalamocortical fiber tracts connecting the PFC and PPC to thalamic nuclei. We found that the two animals with small PFC lesions showed increased fractional anisotropy in both cortical and thalamocortical fiber tracts when behaviour had recovered. However, we found that fractional anisotropy decreased in cortical frontoparietal tracts after larger PFC lesions yet increased in some thalamocortical tracts at the time of behavioural recovery. These findings indicate that behavioural recovery after small PFC lesions may be supported by both cortical and subcortical areas, whereas larger PFC lesions may have induced widespread structural damage and hindered compensatory remodeling in the cortical frontoparietal network

Intrinsic functional boundaries of lateral frontal cortex in the common marmoset monkey

© 2019 the authors. The common marmoset (Callithrix jacchus) is a small New World primate species that has been recently targeted as a potentially powerful preclinical model of human prefrontal cortex dysfunction. Although the structural boundaries of frontal cortex were described in marmosets at the start of the 20th century (Brodmann, 1909) and refined more recently (Paxinos et al., 2012), the broad functional boundaries of marmoset frontal cortex have yet to be established. In this study, we sought to functionally derive boundaries of the marmoset lateral frontal cortex (LFC) using ultra-high field (9.4 T) resting-state functional magnetic resonance imaging (RS-fMRI). We collectedRS-fMRIdatainseven(fourfemales,threemales)lightlyanesthetizedmarmosetsandusedadata-drivenhierarchicalclustering approach to derive subdivisions of the LFC based on intrinsic functional connectivity. We then conducted seed-based analyses to assess the functional connectivity between these clusters and the rest of the brain. The results demonstrated seven distinct functional clusters withintheLFC.Thefunctionalconnectivitypatternsoftheseclusterswiththerestofthebrainwerealsofoundtobedistinctandorganized along a rostrocaudal gradient, consonant with those found in humans and macaques. Overall, these results support the view that marmosets are a promising preclinical modeling species for studying LFC dysfunction related to neuropsychiatric or neurodegenerative human brain diseases

Face selective patches in marmoset frontal cortex

© 2020, The Author(s). In humans and macaque monkeys, socially relevant face processing is accomplished via a distributed functional network that includes specialized patches in frontal cortex. It is unclear whether a similar network exists in New World primates, who diverged ~35 million years from Old World primates. The common marmoset is a New World primate species ideally placed to address this question given their complex social repertoire. Here, we demonstrate the existence of a putative high-level face processing network in marmosets. Like Old World primates, marmosets show differential activation in anterior cingulate and lateral prefrontal cortices while they view socially relevant videos of marmoset faces. We corroborate the locations of these frontal regions by demonstrating functional and structural connectivity between these regions and temporal lobe face patches. Given the evolutionary separation between macaques and marmosets, our results suggest this frontal network specialized for social face processing predates the separation between Platyrrhini and Catarrhini

A biophysical model of decision making in an antisaccade task through variable climbing activity

We present a biophysical model of saccade initiation based on competitive integration of planned and reactive cortical saccade decision signals in the intermediate layer of the superior colliculus. In the model, the variable slopes of the climbing activities of the input cortical decision signals are produced from variability in the conductances of Na+, K+, Ca2+ activated K+, NMDA and GABA currents. These cortical decision signals are integrated in the activities of buildup neurons in the intermediate layer of the superior colliculus, whose activities grow nonlinearly towards a preset criterion level. When the level is crossed, a movement is initiated. The resultant model reproduces the unimodal distributions of saccade reaction times (SRTs) for correct antisaccades and erroneous prosaccades as well as the variability of SRTs (ranging from 80ms to 600ms) and the overall 25% of erroneous prosaccade responses in a large sample of 2006 young men performing an antisaccade task

Cortico-subcortical functional connectivity profiles of resting-state networks in marmosets and humans

Copyright © 2020 the authors Understanding the similarity of cortico-subcortical networks topologies between humans and nonhuman primate species is critical to study the origin of network alternations underlying human neurologic and neuropsychiatric diseases. The New World common marmoset (Callithrix jacchus) has become popular as a nonhuman primate model for human brain function. Most marmoset connectomic research, however, has exclusively focused on cortical areas, with connectivity to subcortical networks less extensively explored. Here, we aimed to first isolate patterns of subcortical connectivity with cortical resting-state networks in awake marmosets using resting-state fMRI, then to compare these networks with those in humans using connectivity fingerprinting. In this study, we used 5 marmosets (4 males, 1 female). While we could match several marmoset and human resting-state networks based on their functional fingerprints, we also found a few striking differences, for example, strong functional connectivity of the default mode network with the superior colliculus in marmosets that was much weaker in humans. Together, these findings demonstrate that many of the core cortico-subcortical networks in humans are also present in marmosets, but that small, potentially functionally relevant differences exist

Comparison of resting-state functional connectivity in marmosets with tracer-based cellular connectivity

© 2019 Elsevier Inc. Resting-state functional MRI (RS-fMRI) is widely used to assess how strongly different brain areas are connected. However, this connection obtained by RS-fMRI, which is called functional connectivity (FC), simply refers to the correlation of blood oxygen level-dependent (BOLD) signals across time it has yet to be quantified how accurately FC reflects cellular connectivity (CC). In this study, we elucidated this relationship using RS-fMRI and quantitative tracer data in marmosets. In addition, we also elucidated the effects of distance between two brain regions on the relationship between FC and CC across seed region. To calculate FC, we used full correlation approach that is considered to reflect not only direct (monosynaptic connections) but also indirect pathways (polysynaptic connections). Our main findings are that: (1) overall FC obtained by RS-fMRI was highly correlated with tracer-based CC, but correlation coefficients varied remarkably across seed regions; (2) the strength of FC decreased with increase in the distance between two regions; (3) correlation coefficients between FC and CC after regressing out the effects of the distance between two regions still varied across seed regions, but some regions have strong correlations. These findings suggest that although FC reflects the strength of monosynaptic pathways, it is strongly affected by the distance between regions

Looming and receding visual networks in awake marmosets investigated with fMRI

© 2020 The Author(s) An object that is looming toward a subject or receding away contains important information for determining if this object is dangerous, beneficial or harmless. This information (motion, direction, identity, time-to-collision, size, velocity) is analyzed by the brain in order to execute the appropriate behavioral responses depending on the context: fleeing, freezing, grasping, eating, exploring. In the current study, we performed ultra-high-field functional MRI (fMRI) at 9.4T in awake marmosets to explore the patterns of brain activation elicited by visual stimuli looming toward or receding away from the monkey. We found that looming and receding visual stimuli activated a large cortical network in frontal, parietal, temporal and occipital cortex in areas involved in the analysis of motion, shape, identity and features of the objects. Looming stimuli strongly activated a network composed of portions of the pulvinar, superior colliculus, putamen, parietal, prefrontal and temporal cortical areas. These activations suggest the existence of a network that processes visual stimuli looming toward peripersonal space to predict the consequence of these stimuli. Together with previous studies in macaque monkeys, these findings indicate that this network is preserved across Old and New World primates

Abordagem bayesiana multivariada para características de crescimento, fertilidade e escores visuais de rebanhos da raça Brangus.

O objetivo deste trabalho foi estimar parâmetros genéticos e tendências genéticas e fenotípicas de uma população da raça Brangus. As características peso, circunferência escrotal e escores visuais de conformação, precocidade, musculatura e umbigo, padronizadas para 550 dias de idade, foram avaliadas a partir de 6.789 registros de animais nascido de 288 touros e 5.949 vacas, entre 1991 e 2001, em 49 fazendas localizadas nas regiões Centro‑Oeste, Sudeste e Sul do Brasil. Para a estimação dos parâmetros, das correlações e das tendências genéticas, foi adotado o modelo animal linear‑limiar hexacaracterística. As estimativas de herdabilidade direta foram de 0,39 e 0,27, para peso e circunferência escrotal, respectivamente, e de 0,22, 0,20, 0,23 e 0,33 para conformação, precocidade, musculatura e umbigo, o que indica considerável variação genética aditiva e que é possível obter ganho genético por meio da seleção. As correlações genéticas entre peso e circunferência escrotal com os escores de conformação, precocidade e musculatura mostram a possibilidade de resposta correlacionada. As tendências genéticas estimadas indicam grande contribuição de fontes de variação não genéticas para todas as características no período estudado, e apontam a necessidade de melhoria das condições ambientais, para que os animais expressem todo seu potencial genético

Ver com as mãos e dar à luz um mundo: a Tecnologia 3D e suas possibilidades cognitivas para pessoas cegas

The HOMERO 3D Laboratory is linked to the Postgraduate Program in Design of Joinville University (PPGDesign / Univille), and to the IRIS Research group, which investigates methods of digital manufacturing and photographic proceedings attached to the design context along with teaching and learning processes. The Laboratory aims to foster technical-scientific research focusing on 3D printing and its potential as a teaching facilitator driven to blind people. The studies obtained so far, reinforce the perception that the popularization, improvement and cost reduction of the 3D printer expands the potential for the development of communication and educational activities aimed at blind people regarding: graphic-formal perception and memory; abstract concepts configuration; the change of textual printings into sound signals; and finally, the potential of learning and educational concepts in reducing the abstraction level. Throughout the report tactile sense, perception and cognition are discussed aiming the understanding of blind people learning process along with possible contributions of 3D printing in the dynamics of ‘seeing’ with the hands. The results will support research and teaching activities as well as the work of the research group associated with PPGDesign Univille, located in the city of Joinville, Santa Catarina.El Laboratorio HOMERO 3D está vinculado al Programa de Postgrado en Diseño de la Universidad de la Región de Joinville (PPGDesign/Univille), y al grupo de Investigación IRIS, que investiga métodos de fabricación digital y de la producción de imágenes fotográficas adscritas al contexto del artefacto tridimensional en las dimensiones de la concepción, desarrollo y la enseñanza y aprendizaje del diseño. El Laboratorio busca fomentar investigaciones técnico-científicas con foco en la impresión 3D y en su potencial como recurso facilitador de la enseñanza de personas ciegas. Los estudios obtenidos hasta entonces, fortalecen la percepción de que la popularización, mejora y la reducción de costo de la impresora 3D amplía la potencialidad para el desarrollo de actividades comunicacionales y educativas dirigidas a personas ciegas en lo que se refiere a: percepción gráficoformal y memoria; configuración de conceptos abstractos; la conversión de la impresión textual en las señales sonoras; y por último, la potenciación del aprendizaje de conceptos educativos, reduciendo el nivel de abstracción. A lo largo de este artículo se discute el sentido táctil, la percepción y la cognición, a fin de comprender el proceso de aprendizaje de personas ciegas, y de las posibles contribuciones de la impresión 3D en la educación gráfica y en la dinámica del ‘ver’ con las manos. Los resultados obtenidos apuntan a apoyar actividades de investigación, enseñanza y extensión, y la planificación de las acciones de los grupos de investigación asociados al PPGDesign Univille.O Laboratório HOMERO 3D é vinculado ao Programa de Pós-Graduação em Design da Universidade da Região de Joinville (PPGDesign/Univille), e ao grupo de Pesquisa ÍRIS, que investiga métodos de fabricação digital e da produção de imagens fotográficas adstritas ao contexto do artefato tridimensional nas dimensões da concepção, desenvolvimento e do ensino e aprendizagem do design. O Laboratório visa fomentar pesquisas técnico-científicas com foco na impressão 3D e no seu potencial como recurso facilitador do ensino de pessoas cegas. Os estudos obtidos até então, fortalecem a percepção de que, a popularização, aprimoramento e a redução de custo da impressora 3D amplia a potencialidade para o desenvolvimento de atividades comunicacionais e educacionais voltadas para pessoas cegas no que se refere a: percepção gráfico-formal e memória; configuração de conceitos abstratos; a conversão da impressão textual em sinais sonoros; e por fim, a potencialização da aprendizagem de conceitos educacionais, reduzindo o nível de abstração. Ao longo desse artigo discute-se o sentido tátil, a percepção e cognição, a fim de compreender o processo de aprendizagem de pessoas cegas, e das possíveis contribuições da impressão 3D na educação gráfica e na dinâmica do ‘ver’ com as mãos. Os resultados obtidos visam apoiar atividades de pesquisa, ensino e extensão, e o planejamento das ações dos grupos de pesquisas associados ao PPGDesign Univille