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1.
Int J Mol Sci ; 22(15)2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34361009

RESUMO

The parietal cortex of rodents participates in sensory and spatial processing, movement planning, and decision-making, but much less is known about its role in associative learning and memory formation. The present study aims to examine the involvement of the parietal association cortex (PtA) in associative fear memory acquisition and retrieval in mice. Using ex vivo c-Fos immunohistochemical mapping and in vivo Fos-EGFP two-photon imaging, we show that PtA neurons were specifically activated both during acquisition and retrieval of cued fear memory. Fos immunohistochemistry revealed specific activation of the PtA neurons during retrieval of the 1-day-old fear memory. In vivo two-photon Fos-EGFP imaging confirmed this result and in addition detected specific c-Fos responses of the PtA neurons during acquisition of cued fear memory. To allow a more detailed study of the long-term activity of such PtA engram neurons, we generated a Fos-Cre-GCaMP transgenic mouse line that employs the Targeted Recombination in Active Populations (TRAP) technique to detect calcium events specifically in cells that were Fos-active during conditioning. We show that gradual accumulation of GCaMP3 in the PtA neurons of Fos-Cre-GCaMP mice peaks at the 4th day after fear learning. We also describe calcium transients in the cell bodies and dendrites of the TRAPed neurons. This provides a proof-of-principle for TRAP-based calcium imaging of PtA functions during memory processes as well as in experimental models of fear- and anxiety-related psychiatric disorders and their specific therapies.


Assuntos
Medo , Memória , Lobo Parietal/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Animais , Aprendizagem por Associação , Sinalização do Cálcio , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Lobo Parietal/citologia , Lobo Parietal/fisiologia , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
2.
Neuron ; 109(16): 2519-2534, 2021 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-34293296

RESUMO

Developing sensory circuits exhibit different patterns of spontaneous activity, patterns that are related to the construction and refinement of functional networks. During the development of different sensory modalities, spontaneous activity originates in the immature peripheral sensory structures and in the higher-order central structures, such as the thalamus and cortex. Certainly, the perinatal thalamus exhibits spontaneous calcium waves, a pattern of activity that is fundamental for the formation of sensory maps and for circuit plasticity. Here, we review our current understanding of the maturation of early (including embryonic) patterns of spontaneous activity and their influence on the assembly of thalamic and cortical sensory networks. Overall, the data currently available suggest similarities between the developmental trajectory of brain activity in experimental models and humans, which in the future may help to improve the early diagnosis of developmental disorders.


Assuntos
Potenciais de Ação/fisiologia , Córtex Cerebral/fisiologia , Plasticidade Neuronal/fisiologia , Córtex Somatossensorial/fisiologia , Animais , Humanos , Neurônios/fisiologia , Lobo Parietal/fisiologia
3.
Nat Commun ; 12(1): 3261, 2021 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-34059682

RESUMO

A fundamental scientific question concerns the neural basis of perceptual consciousness and perceptual monitoring resulting from the processing of sensory events. Although recent studies identified neurons reflecting stimulus visibility, their functional role remains unknown. Here, we show that perceptual consciousness and monitoring involve evidence accumulation. We recorded single-neuron activity in a participant with a microelectrode in the posterior parietal cortex, while they detected vibrotactile stimuli around detection threshold and provided confidence estimates. We find that detected stimuli elicited neuronal responses resembling evidence accumulation during decision-making, irrespective of motor confounds or task demands. We generalize these findings in healthy volunteers using electroencephalography. Behavioral and neural responses are reproduced with a computational model considering a stimulus as detected if accumulated evidence reaches a bound, and confidence as the distance between maximal evidence and that bound. We conclude that gradual changes in neuronal dynamics during evidence accumulation relates to perceptual consciousness and perceptual monitoring in humans.


Assuntos
Estado de Consciência/fisiologia , Neurônios/fisiologia , Lobo Parietal/fisiologia , Percepção/fisiologia , Adulto , Animais , Tomada de Decisões , Epilepsia Resistente a Medicamentos/terapia , Eletrodos Implantados , Eletroencefalografia , Voluntários Saudáveis , Humanos , Microeletrodos , Lobo Parietal/citologia , Estimulação Física/métodos , Análise de Célula Única , Adulto Jovem
4.
Commun Biol ; 4(1): 768, 2021 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-34158579

RESUMO

To optimize visual search, humans attend to objects with the expected size of the sought target relative to its surrounding scene (object-scene scale consistency). We investigate how the human brain responds to variations in object-scene scale consistency. We use functional magnetic resonance imaging and a voxel-wise feature encoding model to estimate tuning to different object/scene properties. We find that regions involved in scene processing (transverse occipital sulcus) and spatial attention (intraparietal sulcus) have the strongest responsiveness and selectivity to object-scene scale consistency: reduced activity to mis-scaled objects (either unusually smaller or larger). The findings show how and where the brain incorporates object-scene size relationships in the processing of scenes. The response properties of these brain areas might explain why during visual search humans often miss objects that are salient but at atypical sizes relative to the surrounding scene.


Assuntos
Lobo Occipital/fisiologia , Lobo Parietal/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino
5.
Nat Neurosci ; 24(7): 975-986, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33986549

RESUMO

Noise correlations (that is, trial-to-trial covariations in neural activity for a given stimulus) limit the stimulus information encoded by neural populations, leading to the widely held prediction that they impair perceptual discrimination behaviors. However, this prediction neglects the effects of correlations on information readout. We studied how correlations affect both encoding and readout of sensory information. We analyzed calcium imaging data from mouse posterior parietal cortex during two perceptual discrimination tasks. Correlations reduced the encoded stimulus information, but, seemingly paradoxically, were higher when mice made correct rather than incorrect choices. Single-trial behavioral choices depended not only on the stimulus information encoded by the whole population, but unexpectedly also on the consistency of information across neurons and time. Because correlations increased information consistency, they enhanced the conversion of sensory information into behavioral choices, overcoming their detrimental information-limiting effects. Thus, correlations in association cortex can benefit task performance even if they decrease sensory information.


Assuntos
Comportamento de Escolha/fisiologia , Neurônios/fisiologia , Lobo Parietal/fisiologia , Animais , Camundongos , Modelos Neurológicos
6.
Elife ; 102021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33942722

RESUMO

Paying attention to one speaker in a noisy place can be extremely difficult, because to-be-attended and task-irrelevant speech compete for processing resources. We tested whether this competition is restricted to acoustic-phonetic interference or if it extends to competition for linguistic processing as well. Neural activity was recorded using Magnetoencephalography as human participants were instructed to attend to natural speech presented to one ear, and task-irrelevant stimuli were presented to the other. Task-irrelevant stimuli consisted either of random sequences of syllables, or syllables structured to form coherent sentences, using hierarchical frequency-tagging. We find that the phrasal structure of structured task-irrelevant stimuli was represented in the neural response in left inferior frontal and posterior parietal regions, indicating that selective attention does not fully eliminate linguistic processing of task-irrelevant speech. Additionally, neural tracking of to-be-attended speech in left inferior frontal regions was enhanced when competing with structured task-irrelevant stimuli, suggesting inherent competition between them for linguistic processing.


Assuntos
Lobo Frontal/fisiologia , Idioma , Lobo Parietal/fisiologia , Fala , Adolescente , Adulto , Atenção , Feminino , Humanos , Linguística , Magnetoencefalografia/métodos , Masculino , Análise e Desempenho de Tarefas , Adulto Jovem
7.
Nat Commun ; 12(1): 2514, 2021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33947840

RESUMO

Primates use their arms in complex ways that frequently require coordination between the two arms. Yet the planning of bimanual movements has not been well-studied. We recorded spikes and local field potentials (LFP) from the parietal reach region (PRR) in both hemispheres simultaneously while monkeys planned and executed unimanual and bimanual reaches. From analyses of interhemispheric LFP-LFP and spike-LFP coherence, we found that task-specific information is shared across hemispheres in a frequency-specific manner. This shared information could arise from common input or from direct communication. The population average unit activity in PRR, representing PRR output, encodes only planned contralateral arm movements while beta-band LFP power, a putative PRR input, reflects the pattern of planned bimanual movement. A parsimonious interpretation of these data is that PRR integrates information about the movement of the left and right limbs, perhaps in service of bimanual coordination.


Assuntos
Potenciais de Ação/fisiologia , Movimento/fisiologia , Lobo Parietal/fisiologia , Desempenho Psicomotor/fisiologia , Animais , Escala de Avaliação Comportamental , Eletrofisiologia , Lateralidade Funcional/fisiologia , Macaca mulatta , Masculino , Córtex Motor/fisiologia , Neurônios/fisiologia , Movimentos Sacádicos/fisiologia , Transdução de Sinais/fisiologia
8.
Neuroimage ; 235: 118016, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-33819609

RESUMO

When primates (both human and non-human) learn to categorize simple visual or acoustic stimuli by means of non-verbal matching tasks, two types of changes occur in their brain: early sensory cortices increase the precision with which they encode sensory information, and parietal and lateral prefrontal cortices develop a categorical response to the stimuli. Contrary to non-human animals, however, our species mostly constructs categories using linguistic labels. Moreover, we naturally tend to define categories by means of multiple sensory features of the stimuli. Here we trained adult subjects to parse a novel audiovisual stimulus space into 4 orthogonal categories, by associating each category to a specific symbol. We then used multi-voxel pattern analysis (MVPA) to show that during a cross-format category repetition detection task three neural representational changes were detectable. First, visual and acoustic cortices increased both precision and selectivity to their preferred sensory feature, displaying increased sensory segregation. Second, a frontoparietal network developed a multisensory object-specific response. Third, the right hippocampus and, at least to some extent, the left angular gyrus, developed a shared representational code common to symbols and objects. In particular, the right hippocampus displayed the highest level of abstraction and generalization from a format to the other, and also predicted symbolic categorization performance outside the scanner. Taken together, these results indicate that when humans categorize multisensory objects by means of language the set of changes occurring in the brain only partially overlaps with that described by classical models of non-verbal unisensory categorization in primates.


Assuntos
Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica , Adulto , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Feminino , Hipocampo/fisiologia , Humanos , Idioma , Imageamento por Ressonância Magnética , Masculino , Lobo Parietal/fisiologia , Estimulação Luminosa , Córtex Pré-Frontal/fisiologia , Lobo Temporal/fisiologia
9.
Neuroimage ; 235: 118021, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-33836266

RESUMO

Although behavioral studies show large improvements in arithmetic skills in elementary school, we do not know how brain structure supports math gains in typically developing children. While some correlational studies have investigated the concurrent association between math performance and brain structure, such as gray matter volume (GMV), longitudinal studies are needed to infer if there is a causal relation. Although discrepancies in the literature on the relation between GMV and math performance have been attributed to the different demands on quantity vs. retrieval mechanisms, no study has experimentally tested this assumption. We defined regions of interests (ROIs) associated with quantity representations in the bilateral intraparietal sulcus (IPS) and associated with the storage of arithmetic facts in long-term memory in the left middle and superior temporal gyri (MTG/STG), and studied associations between GMV in these ROIs and children's performance on operations having greater demands on quantity vs. retrieval mechanisms, namely subtraction vs. multiplication. The aims of this study were threefold: First, to study concurrent associations between GMV and math performance, second, to investigate the role of GMV at the first time-point (T1) in predicting longitudinal gains in math skill to the second time-point (T2), and third, to study whether changes in GMV over time were associated with gains in math skill. Results showed no concurrent association between GMV in IPS and math performance, but a concurrent association between GMV in left MTG/STG and multiplication skill at T1. This association showed that the higher the GMV in this ROI, the higher the children's multiplication skill. Results also revealed that GMV in left IPS and left MTG/STG predicted longitudinal gains in subtraction skill only for younger children (approximately 10 years old). Whereas higher levels of GMV in left IPS at T1 predicted larger subtraction gains, higher levels of GMV in left MTG/STG predicted smaller gains. GMV in left MTG/STG did not predict longitudinal gains in multiplication skill. No significant association was found between changes in GMV over time and longitudinal gains in math. Our findings support the early importance of brain structure in the IPS for mathematical skills that rely on quantity mechanisms.


Assuntos
Substância Cinzenta/anatomia & histologia , Substância Cinzenta/fisiologia , Matemática , Lobo Parietal/anatomia & histologia , Lobo Parietal/fisiologia , Resolução de Problemas/fisiologia , Adolescente , Mapeamento Encefálico , Córtex Cerebral , Criança , Feminino , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Instituições Acadêmicas
10.
Sci Rep ; 11(1): 9060, 2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33907213

RESUMO

Although multisensory integration is crucial for sensorimotor function, it is unclear how visual and proprioceptive sensory cues are combined in the brain during motor behaviors. Here we characterized the effects of multisensory interactions on local field potential (LFP) activity obtained from the superior parietal lobule (SPL) as non-human primates performed a reaching task with either unimodal (proprioceptive) or bimodal (visual-proprioceptive) sensory feedback. Based on previous analyses of spiking activity, we hypothesized that evoked LFP responses would be tuned to arm location but would be suppressed on bimodal trials, relative to unimodal trials. We also expected to see a substantial number of recording sites with enhanced beta band spectral power for only one set of feedback conditions (e.g. unimodal or bimodal), as was previously observed for spiking activity. We found that evoked activity and beta band power were tuned to arm location at many individual sites, though this tuning often differed between unimodal and bimodal trials. Across the population, both evoked and beta activity were consistent with feedback-dependent tuning to arm location, while beta band activity also showed evidence of response suppression on bimodal trials. The results suggest that multisensory interactions can alter the tuning and gain of arm position-related LFP activity in the SPL.


Assuntos
Potenciais de Ação , Braço/fisiologia , Retroalimentação Sensorial/fisiologia , Movimento , Neurônios/fisiologia , Lobo Parietal/fisiologia , Percepção Visual/fisiologia , Animais , Braço/inervação , Mapeamento Encefálico , Macaca mulatta , Estimulação Luminosa
11.
Neuroimage ; 234: 117977, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-33757905

RESUMO

The brain hemispheres can be divided into an upper dorsal and a lower ventral system. Each system consists of distinct cortical regions connected via long association tracts. The tracts cross the central sulcus or the limen insulae to connect the frontal lobe with the posterior brain. The dorsal stream is associated with sensorimotor mapping. The ventral stream serves structural analysis and semantics in different domains, as visual, acoustic or space processing. How does the prefrontal cortex, regarded as the platform for the highest level of integration, incorporate information from these different domains? In the current view, the ventral pathway consists of several separate tracts, related to different modalities. Originally the assumption was that the ventral path is a continuum, covering all modalities. The latter would imply a very different anatomical basis for cognitive and clinical models of processing. To further define the ventral connections, we used cutting-edge in vivo global tractography on high-resolution diffusion tensor imaging (DTI) data from 100 normal subjects from the human connectome project and ex vivo preparation of fiber bundles in the extreme capsule of 8 humans using the Klingler technique. Our data showed that ventral stream tracts, traversing through the extreme capsule, form a continuous band of fibers that fan out anteriorly to the prefrontal cortex, and posteriorly to temporal, occipital and parietal cortical regions. Introduction of additional volumes of interest in temporal and occipital lobes differentiated between the inferior fronto-occipital fascicle (IFOF) and uncinate fascicle (UF). Unequivocally, in both experiments, in all subjects a connection between the inferior frontal and middle-to-posterior temporal cortical region, otherwise known as the temporo-frontal extreme capsule fascicle (ECF) from nonhuman primate brain-tracing experiments was identified. In the human brain, this tract connects the language domains of "Broca's area" and "Wernicke's area". The differentiation in the three tracts, IFOF, UF and ECF seems arbitrary, all three pass through the extreme capsule. Our data show that the ventral pathway represents a continuum. The three tracts merge seamlessly and streamlines showed considerable overlap in their anterior and posterior course. Terminal maps identified prefrontal cortex in the frontal lobe and association cortex in temporal, occipital and parietal lobes as streamline endings. This anatomical substrate potentially facilitates the prefrontal cortex to integrate information across different domains and modalities.


Assuntos
Conectoma/métodos , Imagem de Tensor de Difusão/métodos , Lobo Frontal/diagnóstico por imagem , Lobo Occipital/diagnóstico por imagem , Lobo Parietal/diagnóstico por imagem , Lobo Temporal/diagnóstico por imagem , Adulto , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Feminino , Lobo Frontal/fisiologia , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Vias Neurais/diagnóstico por imagem , Vias Neurais/fisiologia , Lobo Occipital/fisiologia , Lobo Parietal/fisiologia , Lobo Temporal/fisiologia
12.
Neuroimage ; 234: 117982, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-33757908

RESUMO

Lesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also with impairments in the processing of objects presented under demanding viewing conditions. Evidence from neuroimaging studies and lesion patterns observed in patients with simultanagnosia and agnosia for object orientation suggest similar brain regions to be involved in perception of global shapes and processing of objects in atypical ('non-canonical') orientation. In a localizer experiment, we identified individual temporo-parietal brain areas involved in global shape perception and found significantly higher BOLD signals during the processing of non-canonical compared to canonical objects. In a multivariate approach, we demonstrated that posterior temporo-parietal brain areas show distinct voxel patterns for non-canonical and canonical objects and that voxel patterns of global shapes are more similar to those of objects in non-canonical compared to canonical viewing conditions. These results suggest that temporo-parietal brain areas are not only involved in global shape perception but might serve a more general mechanism of complex object perception. Our results challenge a strict attribution of object processing to the ventral visual stream by suggesting specific dorsal contributions in more demanding viewing conditions.


Assuntos
Imageamento por Ressonância Magnética/métodos , Lobo Parietal/fisiologia , Estimulação Luminosa/métodos , Reconhecimento Psicológico/fisiologia , Lobo Temporal/fisiologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Lobo Parietal/diagnóstico por imagem , Lobo Temporal/diagnóstico por imagem , Adulto Jovem
13.
Neuroimage ; 232: 117909, 2021 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-33652148

RESUMO

Humans and animals rely on accurate object size perception to guide behavior. Object size is judged from visual input, but the relationship between an object's retinal size and its real-world size varies with distance. Humans perceive object sizes to be relatively constant when retinal size changes. Such size constancy compensates for the variable relationship between retinal size and real-world size, using the context of recent retinal sizes of the same object to bias perception towards its likely real-world size. We therefore hypothesized that object size perception may be affected by the range of recently viewed object sizes, attracting perceived object sizes towards recently viewed sizes. We demonstrate two systematic biases: a central tendency attracting perceived size towards the average size across all trials, and a serial dependence attracting perceived size towards the size presented on the previous trial. We recently described topographic object size maps in the human parietal cortex. We therefore hypothesized that neural representations of object size here would be attracted towards recently viewed sizes. We used ultra-high-field (7T) functional MRI and population receptive field modeling to compare object size representations measured with small (0.05-1.4°diameter) and large objects sizes (0.1-2.8°). We found that parietal object size preferences and tuning widths follow this presented range, but change less than presented object sizes. Therefore, perception and neural representation of object size are attracted towards recently viewed sizes. This context-dependent object size representation reveals effects on neural response preferences that may underlie context dependence of object size perception.


Assuntos
Imageamento por Ressonância Magnética/métodos , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiologia , Estimulação Luminosa/métodos , Percepção de Tamanho/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Psicofísica , Adulto Jovem
14.
Neuroimage ; 235: 118019, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-33789132

RESUMO

How does the human brain support reasoning about social relations (e.g., social status, friendships)? Converging theories suggest that navigating knowledge of social relations may co-opt neural circuitry with evolutionarily older functions (e.g., shifting attention in space). Here, we analyzed multivoxel response patterns of fMRI data to examine the neural mechanisms for shifting attention in knowledge of a social hierarchy. The "directions" in which participants mentally navigated social knowledge were encoded in multivoxel patterns in superior parietal cortex, which also encoded directions of attentional shifts in space. Exploratory analyses implicated additional regions of posterior parietal and occipital cortex in encoding analogous mental operations in space and social knowledge. However, cross-domain analyses suggested that attentional shifts in space and social knowledge are likely encoded in functionally independent response patterns. Additionally, cross-participant multivoxel pattern similarity analyses indicated that "directions'' of mental navigation in social knowledge are signaled consistently across participants and across different social hierarchies in a set of brain regions, including the right superior parietal lobule. Taken together, these results elucidate the neural basis of navigating abstract knowledge of social relations, and its connection to more basic mental operations.


Assuntos
Atenção/fisiologia , Encéfalo/fisiologia , Relações Interpessoais , Cognição Social , Percepção Espacial , Adulto , Mapeamento Encefálico , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Lobo Occipital/fisiologia , Lobo Parietal/fisiologia , Reconhecimento Visual de Modelos/fisiologia
15.
Neuron ; 109(9): 1554-1566.e4, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33756104

RESUMO

New technologies are key to understanding the dynamic activity of neural circuits and systems in the brain. Here, we show that a minimally invasive approach based on ultrasound can be used to detect the neural correlates of movement planning, including directions and effectors. While non-human primates (NHPs) performed memory-guided movements, we used functional ultrasound (fUS) neuroimaging to record changes in cerebral blood volume with 100 µm resolution. We recorded from outside the dura above the posterior parietal cortex, a brain area important for spatial perception, multisensory integration, and movement planning. We then used fUS signals from the delay period before movement to decode the animals' intended direction and effector. Single-trial decoding is a prerequisite to brain-machine interfaces, a key application that could benefit from this technology. These results are a critical step in the development of neuro-recording and brain interface tools that are less invasive, high resolution, and scalable.


Assuntos
Intenção , Neuroimagem/métodos , Lobo Parietal/fisiologia , Desempenho Psicomotor/fisiologia , Ultrassonografia/métodos , Animais , Mapeamento Encefálico/métodos , Interfaces Cérebro-Computador , Macaca mulatta , Masculino , Movimento , Neuroimagem/instrumentação , Ultrassonografia/instrumentação
16.
J Neurosci ; 41(14): 3204-3221, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33648956

RESUMO

Learning the spatial layout of a novel environment is associated with dynamic activity changes in the hippocampus and in medial parietal areas. With advancing age, the ability to learn spatial environments deteriorates substantially but the underlying neural mechanisms are not well understood. Here, we report findings from a behavioral and a fMRI experiment where healthy human older and younger adults of either sex performed a spatial learning task in a photorealistic virtual environment (VE). We modeled individual learning states using a Bayesian state-space model and found that activity in retrosplenial cortex (RSC)/parieto-occipital sulcus (POS) and anterior hippocampus did not change systematically as a function learning in older compared with younger adults across repeated episodes in the environment. Moreover, effective connectivity analyses revealed that the age-related learning deficits were linked to an increase in hippocampal excitability. Together, these results provide novel insights into how human aging affects computations in the brain's navigation system, highlighting the critical role of the hippocampus.SIGNIFICANCE STATEMENT Key structures of the brain's navigation circuit are particularly vulnerable to the deleterious consequences of aging, and declines in spatial navigation are among the earliest indicators for a progression from healthy aging to neurodegenerative diseases. Our study is among the first to provide a mechanistic account about how physiological changes in the aging brain affect the formation of spatial knowledge. We show that neural activity in the aging hippocampus and medial parietal areas is decoupled from individual learning states across repeated episodes in a novel spatial environment. Importantly, we find that increased excitability of the anterior hippocampus might constitute a potential neural mechanism for cognitive mapping deficits in old age.


Assuntos
Envelhecimento/fisiologia , Mapeamento Encefálico/métodos , Cognição/fisiologia , Hipocampo/fisiologia , Aprendizagem Espacial/fisiologia , Realidade Virtual , Adulto , Idoso , Envelhecimento/psicologia , Feminino , Hipocampo/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiologia , Desempenho Psicomotor/fisiologia , Navegação Espacial/fisiologia , Adulto Jovem
17.
Commun Biol ; 4(1): 405, 2021 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-33767350

RESUMO

Efficient memory-based problem-solving strategies are a cardinal feature of expertise across a wide range of cognitive domains in childhood. However, little is known about the neurocognitive mechanisms that underlie the acquisition of efficient memory-based problem-solving strategies. Here we develop, to the best of our knowledge, a novel neurocognitive process model of latent memory processes to investigate how cognitive training designed to improve children's problem-solving skills alters brain network organization and leads to increased use and efficiency of memory retrieval-based strategies. We found that training increased both the use and efficiency of memory retrieval. Functional brain network analysis revealed training-induced changes in modular network organization, characterized by increase in network modules and reorganization of hippocampal-cortical circuits. Critically, training-related changes in modular network organization predicted performance gains, with emergent hippocampal, rather than parietal cortex, circuitry driving gains in efficiency of memory retrieval. Our findings elucidate a neurocognitive process model of brain network mechanisms that drive learning and gains in children's efficient problem-solving strategies.


Assuntos
Cognição/fisiologia , Hipocampo/fisiologia , Aprendizagem/fisiologia , Memória/fisiologia , Lobo Parietal/fisiologia , Criança , Feminino , Humanos , Masculino , Rememoração Mental , Testes de Estado Mental e Demência , Modelos Psicológicos , Resolução de Problemas
18.
Neurosci Lett ; 750: 135805, 2021 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-33705926

RESUMO

Research has confirmed that the visual working memory representation of objects' roughness is robust against illumination changes in the human ventral visual cortex and intraparietal sulcus, but not yet against visual distractors during memory maintenance. Thus, this study investigated the effects of visual distractors on roughness-related brain regions during the maintenance phase using multi-voxel pattern analysis (MVPA). We conducted an fMRI experiment in which participants were asked to memorize a sphere's roughness against visual distractors, presented during the delay period in random trials. Region of interest-based MVPA showed no contribution of the ventral visual cortex and intraparietal sulcus to the roughness memory, regardless of behavioral performance. Post hoc searchlight MVPA revealed an above-chance decoding performance level in the brain regions presumably related to haptic processing when no visual distractors were shown. In contrast, when visual distractors appeared in the delay period, decoding performance exceeded the chance level in the ventral visual cortex. These results suggest that when visual distractors are presented during the memory phase, both visual and haptic processing are related to visual working memory for roughness, and the weighting of modality changes depending on the presence of visual distractors.


Assuntos
Memória de Curto Prazo , Percepção do Tato , Córtex Visual/fisiologia , Percepção Visual , Atenção , Conectoma , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Lobo Parietal/fisiologia , Adulto Jovem
19.
Neuroimage ; 231: 117869, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33607279

RESUMO

Previous neuroimaging studies have extensively evaluated the structural and functional connectivity of the Ventral Attention Network (VAN) and its role in reorienting attention in the presence of a salient (pop-out) stimulus. However, a detailed understanding of the "directed" functional connectivity within the VAN during the process of reorientation remains elusive. Functional magnetic resonance imaging (fMRI) studies have not adequately addressed this issue due to a lack of appropriate temporal resolution required to capture this dynamic process. The present study investigates the neural changes associated with processing salient distractors operating at a slow and a fast time scale using custom-designed experiment involving visual search on static images and dynamic motion tracking, respectively. We recorded high-density scalp electroencephalography (EEG) from healthy human volunteers, obtained saliency-specific behavioral and spectral changes during the tasks, localized the sources underlying the spectral power modulations with individual-specific structural MRI scans, reconstructed the waveforms of the sources and finally, investigated the causal relationships between the sources using spectral Granger-Geweke Causality (GGC). We found that salient stimuli processing, across tasks with varying spatio-temporal complexities, involves a characteristic modulation in the alpha frequency band which is executed primarily by the nodes of the VAN constituting the temporo-parietal junction (TPJ), the insula and the lateral prefrontal cortex (lPFC). The directed functional connectivity results further revealed the presence of bidirectional interactions among prominent nodes of right-lateralized VAN, corresponding only to the trials with saliency. Thus, our study elucidates the invariant network mechanisms for processing saliency in visual attention tasks across diverse time-scales.


Assuntos
Atenção/fisiologia , Imageamento por Ressonância Magnética/métodos , Rede Nervosa/fisiologia , Lobo Parietal/fisiologia , Córtex Pré-Frontal/fisiologia , Lobo Temporal/fisiologia , Adulto , Mapeamento Encefálico/métodos , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Rede Nervosa/diagnóstico por imagem , Lobo Parietal/diagnóstico por imagem , Estimulação Luminosa/métodos , Córtex Pré-Frontal/diagnóstico por imagem , Tempo de Reação/fisiologia , Lobo Temporal/diagnóstico por imagem , Adulto Jovem
20.
J Neurosci ; 41(14): 3254-3265, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33622780

RESUMO

Perceptual decision-making is increasingly being understood to involve an interaction between bottom-up sensory-driven signals and top-down choice-driven signals, but how these signals interact to mediate perception is not well understood. The parieto-insular vestibular cortex (PIVC) is an area with prominent vestibular responsiveness, and previous work has shown that inactivating PIVC impairs vestibular heading judgments. To investigate the nature of PIVC's contribution to heading perception, we recorded extracellularly from PIVC neurons in two male rhesus macaques during a heading discrimination task, and compared findings with data from previous studies of dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas using identical stimuli. By computing partial correlations between neural responses, heading, and choice, we find that PIVC activity reflects a dynamically changing combination of sensory and choice signals. In addition, the sensory and choice signals are more balanced in PIVC, in contrast to the sensory dominance in MSTd and choice dominance in VIP. Interestingly, heading and choice signals in PIVC are negatively correlated during the middle portion of the stimulus epoch, reflecting a mismatch in the polarity of heading and choice signals. We anticipate that these results will help unravel the mechanisms of interaction between bottom-up sensory signals and top-down choice signals in perceptual decision-making, leading to more comprehensive models of self-motion perception.SIGNIFICANCE STATEMENT Vestibular information is important for our perception of self-motion, and various cortical regions in primates show vestibular heading selectivity. Inactivation of the macaque vestibular cortex substantially impairs the precision of vestibular heading discrimination, more so than inactivation of other multisensory areas. Here, we record for the first time from the vestibular cortex while monkeys perform a forced-choice heading discrimination task, and we compare results with data collected previously from other multisensory cortical areas. We find that vestibular cortex activity reflects a dynamically changing combination of sensory and choice signals, with both similarities and notable differences with other multisensory areas.


Assuntos
Comportamento de Escolha/fisiologia , Movimentos da Cabeça/fisiologia , Percepção de Movimento/fisiologia , Lobo Parietal/fisiologia , Córtex Somatossensorial/fisiologia , Vestíbulo do Labirinto/fisiologia , Animais , Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/fisiologia , Aprendizagem por Discriminação/fisiologia , Macaca mulatta , Imageamento por Ressonância Magnética/métodos , Masculino , Lobo Parietal/diagnóstico por imagem , Estimulação Luminosa/métodos , Córtex Somatossensorial/diagnóstico por imagem , Vestíbulo do Labirinto/diagnóstico por imagem
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