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1.
Proc Natl Acad Sci U S A ; 118(37)2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34507986

RESUMO

The origins of oscillatory activity in the brain are currently debated, but common to many hypotheses is the notion that they reflect interactions between brain areas. Here, we examine this possibility by manipulating the strength of coupling between two human brain regions, ventral premotor cortex (PMv) and primary motor cortex (M1), and examine the impact on oscillatory activity in the motor system measurable in the electroencephalogram. We either increased or decreased the strength of coupling while holding the impact on each component area in the pathway constant. This was achieved by stimulating PMv and M1 with paired pulses of transcranial magnetic stimulation using two different patterns, only one of which increases the influence exerted by PMv over M1. While the stimulation protocols differed in their temporal patterning, they were comprised of identical numbers of pulses to M1 and PMv. We measured the impact on activity in alpha, beta, and theta bands during a motor task in which participants either made a preprepared action (Go) or withheld it (No-Go). Augmenting cortical connectivity between PMv and M1, by evoking synchronous pre- and postsynaptic activity in the PMv-M1 pathway, enhanced oscillatory beta and theta rhythms in Go and No-Go trials, respectively. Little change was observed in the alpha rhythm. By contrast, diminishing the influence of PMv over M1 decreased oscillatory beta and theta rhythms in Go and No-Go trials, respectively. This suggests that corticocortical communication frequencies in the PMv-M1 pathway can be manipulated following Hebbian spike-timing-dependent plasticity.

2.
Neuron ; 109(14): 2353-2361.e11, 2021 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-34171289

RESUMO

To navigate social environments, people must simultaneously hold representations about their own and others' abilities. During self-other mergence, people estimate others' abilities not only on the basis of the others' past performance, but the estimates are also influenced by their own performance. For example, if we perform well, we overestimate the abilities of those with whom we are co-operating and underestimate competitors. Self-other mergence is associated with specific activity patterns in the dorsomedial prefrontal cortex (dmPFC). Using a combination of non-invasive brain stimulation, functional magnetic resonance imaging, and computational modeling, we show that dmPFC neurostimulation silences these neural signatures of self-other mergence in relation to estimation of others' abilities. In consequence, self-other mergence behavior increases, and our assessments of our own performance are projected increasingly onto other people. This suggests an inherent tendency to form interdependent social representations and a causal role of the dmPFC in separating self and other representations.


Assuntos
Modelos Neurológicos , Córtex Pré-Frontal/fisiologia , Percepção Social , Adolescente , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Córtex Pré-Frontal/diagnóstico por imagem , Tempo de Reação/fisiologia , Comportamento Social , Estimulação Magnética Transcraniana , Adulto Jovem
3.
Neuron ; 109(8): 1396-1408.e7, 2021 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-33730554

RESUMO

More than one type of probability must be considered when making decisions. It is as necessary to know one's chance of performing choices correctly as it is to know the chances that desired outcomes will follow choices. We refer to these two choice contingencies as internal and external probability. Neural activity across many frontal and parietal areas reflected internal and external probabilities in a similar manner during decision-making. However, neural recording and manipulation approaches suggest that one area, the anterior lateral prefrontal cortex (alPFC), is highly specialized for making prospective, metacognitive judgments on the basis of internal probability; it is essential for knowing which decisions to tackle, given its assessment of how well they will be performed. Its activity predicted prospective metacognitive judgments, and individual variation in activity predicted individual variation in metacognitive judgments. Its disruption altered metacognitive judgments, leading participants to tackle perceptual decisions they were likely to fail.


Assuntos
Julgamento/fisiologia , Metacognição/fisiologia , Córtex Pré-Frontal/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Testes Neuropsicológicos , Córtex Pré-Frontal/diagnóstico por imagem , Estudos Prospectivos , Estimulação Magnética Transcraniana
4.
Nature ; 591(7849): 270-274, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33408410

RESUMO

Neural mechanisms that mediate the ability to make value-guided decisions have received substantial attention in humans and animals1-6. Experiments in animals typically involve long training periods. By contrast, choices in the real world often need to be made between new options spontaneously. It is therefore possible that the neural mechanisms targeted in animal studies differ from those required for new decisions, which are typical of human imaging studies. Here we show that the primate medial frontal cortex (MFC)7 is involved in making new inferential choices when the options have not been previously experienced. Macaques spontaneously inferred the values of new options via similarities with the component parts of previously encountered options. Functional magnetic resonance imaging (fMRI) suggested that this ability was mediated by the MFC, which is rarely investigated in monkeys3; MFC activity reflected different processes of comparison for unfamiliar and familiar options. Multidimensional representations of options in the MFC used a coding scheme resembling that of grid cells, which is well known in spatial navigation8,9, to integrate dimensions in this non-physical space10 during novel decision-making. By contrast, the orbitofrontal cortex held specific object-based value representations1,11. In addition, minimally invasive ultrasonic disruption12 of MFC, but not adjacent tissue, altered the estimation of novel choice values.


Assuntos
Comportamento de Escolha/fisiologia , Lobo Frontal/citologia , Lobo Frontal/fisiologia , Macaca mulatta/fisiologia , Neurônios/fisiologia , Adulto , Animais , Feminino , Células de Grade/fisiologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Córtex Pré-Frontal/citologia , Córtex Pré-Frontal/fisiologia , Navegação Espacial/fisiologia , Adulto Jovem
5.
Neuropsychopharmacology ; 46(2): 386-393, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33127993

RESUMO

Lithium is one of the most effective mood-stabilizing medications in bipolar disorder. This study was designed to test whether lithium administration may stabilize mood via effects on reward processing. It was hypothesized that lithium administration would modulate reward processing in the striatum and affect both anticipation and outcome computations. Thirty-seven healthy human participants (18 males, 33 with suitable fMRI data) received 11 (±1) days of lithium carbonate or placebo intervention (double-blind), after which they completed the monetary incentive delay task while fMRI data were collected. The monetary incentive delay task is a robust task with excellent test-retest reliability and is well suited to investigate different phases of reward processing within the caudate and nucleus accumbens. To test for correlations with prediction error signals a Rescorla-Wagner reinforcement-learning model was applied. Lithium administration enhanced activity in the caudate during reward anticipation compared to placebo. In contrast, lithium administration reduced caudate and nucleus accumbens activity during reward outcome. This latter effect seems related to learning as reward prediction errors showed a positive correlation with caudate and nucleus accumbens activity during placebo, which was absent after lithium administration. Lithium differentially modulates the anticipation relative to the learning of rewards. This suggests that lithium might reverse dampened reward anticipation while reducing overactive reward updating in patients with bipolar disorder. This specific effect of lithium suggests that a targeted modulation of reward learning may be a viable approach for novel interventions in bipolar disorder.


Assuntos
Lítio , Recompensa , Antecipação Psicológica , Método Duplo-Cego , Voluntários Saudáveis , Humanos , Imageamento por Ressonância Magnética , Masculino , Motivação , Reprodutibilidade dos Testes
6.
PLoS Biol ; 18(10): e3000899, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33125367

RESUMO

Animals learn from the past to make predictions. These predictions are adjusted after prediction errors, i.e., after surprising events. Generally, most reward prediction errors models learn the average expected amount of reward. However, here we demonstrate the existence of distinct mechanisms for detecting other types of surprising events. Six macaques learned to respond to visual stimuli to receive varying amounts of juice rewards. Most trials ended with the delivery of either 1 or 3 juice drops so that animals learned to expect 2 juice drops on average even though instances of precisely 2 drops were rare. To encourage learning, we also included sessions during which the ratio between 1 and 3 drops changed. Additionally, in all sessions, the stimulus sometimes appeared in an unexpected location. Thus, 3 types of surprising events could occur: reward amount surprise (i.e., a scalar reward prediction error), rare reward surprise, and visuospatial surprise. Importantly, we can dissociate scalar reward prediction errors-rewards that deviated from the average reward amount expected-and rare reward events-rewards that accorded with the average reward expectation but that rarely occurred. We linked each type of surprise to a distinct pattern of neural activity using functional magnetic resonance imaging. Activity in the vicinity of the dopaminergic midbrain only reflected surprise about the amount of reward. Lateral prefrontal cortex had a more general role in detecting surprising events. Posterior lateral orbitofrontal cortex specifically detected rare reward events regardless of whether they followed average reward amount expectations, but only in learnable reward environments.


Assuntos
Recompensa , Animais , Comportamento Animal , Encéfalo/fisiologia , Modelos Lineares , Macaca , Imageamento por Ressonância Magnética , Substância Negra/fisiologia , Análise e Desempenho de Tarefas , Área Tegmentar Ventral/fisiologia , Percepção Visual/fisiologia
7.
PLoS Biol ; 18(7): e3000810, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32735557

RESUMO

The temporal association cortex is considered a primate specialization and is involved in complex behaviors, with some, such as language, particularly characteristic of humans. The emergence of these behaviors has been linked to major differences in temporal lobe white matter in humans compared with monkeys. It is unknown, however, how the organization of the temporal lobe differs across several anthropoid primates. Therefore, we systematically compared the organization of the major temporal lobe white matter tracts in the human, gorilla, and chimpanzee great apes and in the macaque monkey. We show that humans and great apes, in particular the chimpanzee, exhibit an expanded and more complex occipital-temporal white matter system; additionally, in humans, the invasion of dorsal tracts into the temporal lobe provides a further specialization. We demonstrate the reorganization of different tracts along the primate evolutionary tree, including distinctive connectivity of human temporal gray matter.


Assuntos
Conectoma , Hominidae/anatomia & histologia , Macaca/anatomia & histologia , Lobo Temporal/anatomia & histologia , Substância Branca/anatomia & histologia , Animais , Humanos
8.
J Neurosci ; 40(14): 2925-2934, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32034069

RESUMO

Regulation of emotional behavior is essential for human social interactions. Recent work has exposed its cognitive complexity, as well as its unexpected reliance on portions of the anterior PFC (aPFC) also involved in exploration, relational reasoning, and counterfactual choice, rather than on dorsolateral and medial prefrontal areas involved in several forms of cognitive control. This study anatomically qualifies the contribution of aPFC territories to the regulation of prepotent approach-avoidance action tendencies elicited by emotional faces, and explores a possible structural pathway through which this emotional action regulation might be implemented. We provide converging evidence from task-based fMRI, diffusion-weighted imaging, and functional connectivity fingerprints for a novel neural element in emotional regulation. Task-based fMRI in human male participants (N = 40) performing an emotional approach-avoidance task identified aPFC territories involved in the regulation of action tendencies elicited by emotional faces. Connectivity fingerprints, based on diffusion-weighted imaging and resting-state connectivity, localized those task-defined frontal regions to the lateral frontal pole (FPl), an anatomically defined portion of the aPFC that lacks a homologous counterpart in macaque brains. Probabilistic tractography indicated that 10%-20% of interindividual variation in emotional regulation abilities is accounted for by the strength of structural connectivity between FPl and amygdala. Evidence from an independent replication sample (N = 50; 10 females) further substantiated this result. These findings provide novel neuroanatomical evidence for incorporating FPl in models of control over human action tendencies elicited by emotional faces.SIGNIFICANCE STATEMENT Successful regulation of emotional behaviors is a prerequisite for successful participation in human society, as is evidenced by the social isolation and loss of occupational opportunities often encountered by people suffering from emotion regulation disorders, such as social-anxiety disorder and psychopathy. Knowledge about the precise cortical regions and connections supporting this control is crucial for understanding both the nature of computations needed to successfully traverse the space of possible actions in social situations, and the potential interventions that might result in efficient treatment of social-emotional disorders. This study provides evidence for a precise cortical region (lateral frontal pole) and a structural pathway (the ventral amygdalofugal bundle) through which a cognitively complex form of emotional action regulation might be implemented in the human brain.


Assuntos
Aprendizagem da Esquiva/fisiologia , Emoções/fisiologia , Córtex Pré-Frontal/fisiologia , Autocontrole , Adolescente , Adulto , Mapeamento Encefálico/métodos , Imagem de Difusão por Ressonância Magnética , Humanos , Masculino , Comportamento Social , Adulto Jovem
9.
Neuron ; 105(2): 370-384.e8, 2020 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-31813653

RESUMO

The medial frontal cortex has been linked to voluntary action, but an explanation of why decisions to act emerge at particular points in time has been lacking. We show that, in macaques, decisions about whether and when to act are predicted by a set of features defining the animal's current and past context; for example, respectively, cues indicating the current average rate of reward and recent previous voluntary action decisions. We show that activity in two brain areas-the anterior cingulate cortex and basal forebrain-tracks these contextual factors and mediates their effects on behavior in distinct ways. We use focused transcranial ultrasound to selectively and effectively stimulate deep in the brain, even as deep as the basal forebrain, and demonstrate that alteration of activity in the two areas changes decisions about when to act.


Assuntos
Prosencéfalo Basal/fisiologia , Tomada de Decisões/fisiologia , Giro do Cíngulo/fisiologia , Estimulação Acústica , Animais , Sinais (Psicologia) , Estimulação Encefálica Profunda/métodos , Neuroimagem Funcional , Macaca , Imageamento por Ressonância Magnética , Masculino , Vias Neurais/fisiologia , Fatores de Tempo , Ondas Ultrassônicas
10.
Elife ; 82019 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-31689177

RESUMO

The interactions of anterior temporal structures, and especially the amygdala, with the prefrontal cortex are pivotal to learning, decision-making, and socio-emotional regulation. A clear anatomical description of the organization and dissociation of fiber bundles linking anterior temporal cortex/amygdala and prefrontal cortex in humans is still lacking. Using diffusion imaging techniques, we reconstructed fiber bundles between these anatomical regions in human and macaque brains. First, by studying macaques, we assessed which aspects of connectivity known from tracer studies could be identified with diffusion imaging. Second, by comparing diffusion imaging results in humans and macaques, we estimated the patterns of fibers coursing between human amygdala and prefrontal cortex and compared them with those in the monkey. In posterior prefrontal cortex, we observed a prominent and well-preserved bifurcation of bundles into primarily two fiber systems-an amygdalofugal path and an uncinate path-in both species. This dissociation fades away in more rostral prefrontal regions.


Assuntos
Tonsila do Cerebelo/anatomia & histologia , Rede Nervosa/anatomia & histologia , Vias Neurais/anatomia & histologia , Córtex Pré-Frontal/anatomia & histologia , Lobo Temporal/anatomia & histologia , Adulto , Tonsila do Cerebelo/fisiologia , Animais , Conectoma , Feminino , Humanos , Macaca mulatta , Masculino , Rede Nervosa/fisiologia , Vias Neurais/fisiologia , Córtex Pré-Frontal/fisiologia , Lobo Temporal/fisiologia , Adulto Jovem
11.
Acta Biomater ; 97: 116-140, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357005

RESUMO

The current understanding of the role of the cell membrane is in a state of flux. Recent experiments show that conventional models, considering only electrophysiological properties of a passive membrane, are incomplete. The neuronal membrane is an active structure with mechanical properties that modulate electrophysiology. Protein transport, lipid bilayer phase, membrane pressure and stiffness can all influence membrane capacitance and action potential propagation. A mounting body of evidence indicates that neuronal mechanics and electrophysiology are coupled, and together shape the membrane potential in tight coordination with other physical properties. In this review, we summarise recent updates concerning electrophysiological-mechanical coupling in neuronal function. In particular, we aim at making the link with two relevant yet often disconnected fields with strong clinical potential: the use of mechanical vibrations-ultrasound-to alter the electrophysiogical state of neurons, e.g., in neuromodulation, and the theories attempting to explain the action of general anaesthetics. STATEMENT OF SIGNIFICANCE: General anaesthetics revolutionised medical practice; now an apparently unrelated technique, ultrasound neuromodulation-aimed at controlling neuronal activity by means of ultrasound-is poised to achieve a similar level of impact. While both technologies are known to alter the electrophysiology of neurons, the way they achieve it is still largely unknown. In this review, we argue that in order to explain their mechanisms/effects, the neuronal membrane must be considered as a coupled mechano-electrophysiological system that consists of multiple physical processes occurring concurrently and collaboratively, as opposed to sequentially and independently. In this framework the behaviour of the cell membrane is not the result of stereotypical mechanisms in isolation but instead emerges from the integrative behaviour of a complexly coupled multiphysics system.


Assuntos
Potenciais de Ação , Anestesia Geral , Encéfalo/fisiopatologia , Membrana Celular , Modelos Neurológicos , Neurônios , Ondas Ultrassônicas , Animais , Humanos
12.
Cogn Sci ; 43(5): e12733, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31087589

RESUMO

A long-standing debate in the study of human communication centers on the degree to which communicators tune their communicative signals (e.g., speech, gestures) for specific addressees, as opposed to taking a neutral or egocentric perspective. This tuning, called recipient design, is known to occur under special conditions (e.g., when errors in communication need to be corrected), but several researchers have argued that it is not an intrinsic feature of human communication, because that would be computationally too demanding. In this study, we contribute to this debate by studying a simple communicative behavior, communicative pointing, under conditions of successful (error-free) communication. Using an information-theoretic measure, called legibility, we present evidence of recipient design in communicative pointing. The legibility effect is present early in the movement, suggesting that it is an intrinsic part of the communicative plan. Moreover, it is reliable only from the viewpoint of the addressee, suggesting that the motor plan is tuned to the addressee. These findings suggest that recipient design is an intrinsic feature of human communication.


Assuntos
Comunicação , Gestos , Adolescente , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
13.
Nat Neurosci ; 22(5): 797-808, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30988525

RESUMO

The neural mechanisms mediating sensory-guided decision-making have received considerable attention, but animals often pursue behaviors for which there is currently no sensory evidence. Such behaviors are guided by internal representations of choice values that have to be maintained even when these choices are unavailable. We investigated how four macaque monkeys maintained representations of the value of counterfactual choices-choices that could not be taken at the current moment but which could be taken in the future. Using functional magnetic resonance imaging, we found two different patterns of activity co-varying with values of counterfactual choices in a circuit spanning the hippocampus, the anterior lateral prefrontal cortex and the anterior cingulate cortex. Anterior cingulate cortex activity also reflected whether the internal value representations would be translated into actual behavioral change. To establish the causal importance of the anterior cingulate cortex for this translation process, we used a novel technique, transcranial focused ultrasound stimulation, to reversibly disrupt anterior cingulate cortex activity.


Assuntos
Comportamento de Escolha/fisiologia , Giro do Cíngulo/fisiologia , Hipocampo/fisiologia , Córtex Pré-Frontal/fisiologia , Recompensa , Animais , Mapeamento Encefálico , Aprendizagem/fisiologia , Macaca mulatta , Imageamento por Ressonância Magnética , Masculino , Modelos Neurológicos , Vias Neurais/fisiologia
14.
J Neurosci ; 39(19): 3627-3639, 2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-30833514

RESUMO

The ventromedial prefrontal cortex (vmPFC), which comprises several distinct cytoarchitectonic areas, is a key brain region supporting decision-making processes, and it has been shown to be one of the main hubs of the Default Mode Network, a network classically activated during resting state. We here examined the interindividual variability in the vmPFC sulcal morphology in 57 humans (37 females) and demonstrated that the presence/absence of the inferior rostral sulcus and the subgenual intralimbic sulcus influences significantly the sulcal organization of this region. Furthermore, the sulcal organization influences the location of the vmPFC peak of the Default Mode Network, demonstrating that the location of functional activity can be affected by local sulcal patterns. These results are critical for the investigation of the function of the vmPFC and show that taking into account the sulcal variability might be essential to guide the interpretation of neuroimaging studies.SIGNIFICANCE STATEMENT The ventromedial prefrontal cortex (vmPFC) is one of the main hubs of the Default Mode Network and plays a central role in value coding and decision-making. The present study provides a complete description of the interindividual variability of anatomical morphology of this large portion of prefrontal cortex and its relation to functional organization. We have shown that two supplementary medial sulci predominantly determine the organization of the vmPFC, which in turn affects the location of the functional peak of activity in this region. Those results show that taking into account the variability in sulcal patterns might be essential to guide the interpretation of neuroimaging studies of the human brain and of the vmPFC in particular.


Assuntos
Conectoma/métodos , Imageamento por Ressonância Magnética/métodos , Córtex Pré-Frontal/diagnóstico por imagem , Córtex Pré-Frontal/fisiologia , Feminino , Humanos , Masculino
15.
Elife ; 82019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30747105

RESUMO

To understand brain circuits it is necessary both to record and manipulate their activity. Transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation technique. To date, investigations report short-lived neuromodulatory effects, but to deliver on its full potential for research and therapy, ultrasound protocols are required that induce longer-lasting 'offline' changes. Here, we present a TUS protocol that modulates brain activation in macaques for more than one hour after 40 s of stimulation, while circumventing auditory confounds. Normally activity in brain areas reflects activity in interconnected regions but TUS caused stimulated areas to interact more selectively with the rest of the brain. In a within-subject design, we observe regionally specific TUS effects for two medial frontal brain regions - supplementary motor area and frontal polar cortex. Independently of these site-specific effects, TUS also induced signal changes in the meningeal compartment. TUS effects were temporary and not associated with microstructural changes.


Assuntos
Córtex Cerebral/fisiologia , Córtex Cerebral/efeitos da radiação , Ultrassonografia/métodos , Animais , Macaca , Imageamento por Ressonância Magnética
16.
Neuron ; 101(6): 1109-1116.e5, 2019 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-30765166

RESUMO

The causal role of an area within a neural network can be determined by interfering with its activity and measuring the impact. Many current reversible manipulation techniques have limitations preventing their application, particularly in deep areas of the primate brain. Here, we demonstrate that a focused transcranial ultrasound stimulation (TUS) protocol impacts activity even in deep brain areas: a subcortical brain structure, the amygdala (experiment 1), and a deep cortical region, the anterior cingulate cortex (ACC, experiment 2), in macaques. TUS neuromodulatory effects were measured by examining relationships between activity in each area and the rest of the brain using functional magnetic resonance imaging (fMRI). In control conditions without sonication, activity in a given area is related to activity in interconnected regions, but such relationships are reduced after sonication, specifically for the targeted areas. Dissociable and focal effects on neural activity could not be explained by auditory confounds.


Assuntos
Tonsila do Cerebelo/efeitos da radiação , Giro do Cíngulo/efeitos da radiação , Ondas Ultrassônicas , Tonsila do Cerebelo/diagnóstico por imagem , Tonsila do Cerebelo/fisiologia , Animais , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Encéfalo/efeitos da radiação , Mapeamento Encefálico , Neuroimagem Funcional , Giro do Cíngulo/diagnóstico por imagem , Giro do Cíngulo/fisiologia , Macaca , Imageamento por Ressonância Magnética , Vias Neurais/fisiologia , Vias Neurais/efeitos da radiação
17.
Brain Struct Funct ; 224(2): 681-697, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30470895

RESUMO

Resting state functional connectivity has been promoted as a promising tool for creating cortical maps that show remarkable similarity to those established by invasive histological methods. While this tool has been largely used to identify and map cortical areas, its true potential in the context of studying connectional architecture and in conducting comparative neuroscience has remained unexplored. Here, we employ widely used resting state connectivity and data-driven clustering methods to extend this approach for the study of the organizational principles of the macaque parietal-frontal system. We show multiple, overlapping principles of organization, including a dissociation between dorsomedial and dorsolateral pathways and separate parietal-premotor and parietal-frontal pathways. These results demonstrate the suitability of this approach for understanding the complex organizational principles of the brain and for large-scale comparative neuroscience.


Assuntos
Mapeamento Encefálico/métodos , Lobo Frontal/diagnóstico por imagem , Rede Nervosa/diagnóstico por imagem , Lobo Parietal/diagnóstico por imagem , Animais , Feminino , Lobo Frontal/fisiologia , Neuroimagem Funcional , Processamento de Imagem Assistida por Computador , Macaca mulatta , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/fisiologia , Lobo Parietal/fisiologia
18.
Cortex ; 118: 107-115, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-29937266

RESUMO

Evolutionary adaptations of the human brain are the basis for our unique abilities such as language. An expansion of the arcuate fasciculus (AF), the dorsal language tract, in the human lineage involving left lateralization is considered canonical, but this hypothesis has not been tested in relation to other architectural adaptations in the human brain. Using diffusion-weighted MRI, we examined AF in the human and macaque and quantified species differences in white matter architecture and surface representations. To compare surface results in the two species, we transformed macaque representations to human space using a landmark-based monkey-to-human cortical expansion model. We found that the human dorsal AF, but not the ventral inferior fronto-occipital fasciculus (IFO), is left-lateralized. In the monkey AF is not lateralized. Moreover, compared to the macaque, human AF is relatively increased with respect to IFO. A comparison of human and transformed macaque surface representations suggests that cortical expansion alone cannot account for the species differences in the surface representation of AF. Our results show that the human AF has undergone critical anatomical modifications in comparison with the macaque AF. More generally, this work demonstrates that studies on the human brain specializations underlying the language connectome can benefit from current methodological advances in comparative neuroanatomy.


Assuntos
Mapeamento Encefálico , Encéfalo/anatomia & histologia , Rede Nervosa/anatomia & histologia , Vias Neurais/anatomia & histologia , Animais , Imagem de Tensor de Difusão/métodos , Humanos , Idioma , Macaca , Fibras Nervosas/patologia
19.
Elife ; 72018 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-29749930

RESUMO

Comparing the brains of related species faces the challenges of establishing homologies whilst accommodating evolutionary specializations. Here we propose a general framework for understanding similarities and differences between the brains of primates. The approach uses white matter blueprints of the whole cortex based on a set of white matter tracts that can be anatomically matched across species. The blueprints provide a common reference space that allows us to navigate between brains of different species, identify homologous cortical areas, or to transform whole cortical maps from one species to the other. Specializations are cast within this framework as deviations between the species' blueprints. We illustrate how this approach can be used to compare human and macaque brains.


Assuntos
Anatomia Comparada/métodos , Encéfalo/anatomia & histologia , Conectoma , Vias Neurais/anatomia & histologia , Animais , Feminino , Humanos , Macaca , Imageamento por Ressonância Magnética , Masculino
20.
Brain Struct Funct ; 223(1): 31-46, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28702735

RESUMO

The extrastriate body area (EBA) processes visual information about body parts, and it is considered one among a series of category-specific perceptual modules distributed across the occipito-temporal cortex. However, recent evidence raises the possibility that EBA might also provide an interface between perception and action, linking the ventral and dorsal streams of visual information processing. Here, we assess anatomical evidence supporting this possibility. We localise EBA in individual subjects using a perceptual task and compare the characteristics of its functional and structural connectivity to those of two perceptual areas, the lateral occipital complex (LOC) and the fusiform body area (FBA), separately for each hemisphere. We apply complementary analyses of resting-state fMRI and diffusion-weighted MRI data in a group of healthy right-handed human subjects (N = 31). Functional and structural connectivity profiles indicate that EBA interacts more strongly with dorsal-stream regions compared to other portions of the occipito-temporal cortex involved in processing body parts (FBA) and object identification (LOC). These findings provide anatomical ground for a revision of the functional role of EBA. Building on a number of recent observations, we suggest that EBA contributes to planning goal-directed actions, possibly by specifying a desired postural configuration to parieto-frontal areas involved in computing movement parameters.


Assuntos
Mapeamento Encefálico , Lateralidade Funcional/fisiologia , Córtex Visual/diagnóstico por imagem , Vias Visuais/diagnóstico por imagem , Percepção Visual/fisiologia , Adulto , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Estimulação Luminosa , Descanso , Adulto Jovem
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