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1.
eNeuro ; 11(4)2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38580452

RESUMO

This systematic review presented a comprehensive survey of studies that applied transcranial magnetic stimulation and transcranial electrical stimulation to parietal and nonparietal areas to examine the neural basis of symbolic arithmetic processing. All findings were compiled with regard to the three assumptions of the triple-code model (TCM) of number processing. Thirty-seven eligible manuscripts were identified for review (33 with healthy participants and 4 with patients). Their results are broadly consistent with the first assumption of the TCM that intraparietal sulcus both hold a magnitude code and engage in operations requiring numerical manipulations such as subtraction. However, largely heterogeneous results conflicted with the second assumption of the TCM that the left angular gyrus subserves arithmetic fact retrieval, such as the retrieval of rote-learned multiplication results. Support is also limited for the third assumption of the TCM, namely, that the posterior superior parietal lobule engages in spatial operations on the mental number line. Furthermore, results from the stimulation of brain areas outside of those postulated by the TCM show that the bilateral supramarginal gyrus is involved in online calculation and retrieval, the left temporal cortex in retrieval, and the bilateral dorsolateral prefrontal cortex and cerebellum in online calculation of cognitively demanding arithmetic problems. The overall results indicate that multiple cortical areas subserve arithmetic skills.


Assuntos
Encéfalo , Imageamento por Ressonância Magnética , Humanos , Imageamento por Ressonância Magnética/métodos , Encéfalo/fisiologia , Aprendizagem/fisiologia , Estimulação Magnética Transcraniana , Lobo Parietal/fisiologia , Mapeamento Encefálico
2.
Behav Brain Funct ; 20(1): 8, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38637870

RESUMO

One important role of the TPJ is the contribution to perception of the global gist in hierarchically organized stimuli where individual elements create a global visual percept. However, the link between clinical findings in simultanagnosia and neuroimaging in healthy subjects is missing for real-world global stimuli, like visual scenes. It is well-known that hierarchical, global stimuli activate TPJ regions and that simultanagnosia patients show deficits during the recognition of hierarchical stimuli and real-world visual scenes. However, the role of the TPJ in real-world scene processing is entirely unexplored. In the present study, we first localized TPJ regions significantly responding to the global gist of hierarchical stimuli and then investigated the responses to visual scenes, as well as single objects and faces as control stimuli. All three stimulus classes evoked significantly positive univariate responses in the previously localized TPJ regions. In a multivariate analysis, we were able to demonstrate that voxel patterns of the TPJ were classified significantly above chance level for all three stimulus classes. These results demonstrate a significant involvement of the TPJ in processing of complex visual stimuli that is not restricted to visual scenes and that the TPJ is sensitive to different classes of visual stimuli with a specific signature of neuronal activations.


Assuntos
Imageamento por Ressonância Magnética , Lobo Parietal , Humanos , Lobo Parietal/fisiologia , Reconhecimento Psicológico , Neuroimagem , Análise Multivariada , Estimulação Luminosa , Reconhecimento Visual de Modelos/fisiologia , Percepção Visual/fisiologia , Mapeamento Encefálico/métodos
3.
Elife ; 122024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38656279

RESUMO

The central tendency bias, or contraction bias, is a phenomenon where the judgment of the magnitude of items held in working memory appears to be biased toward the average of past observations. It is assumed to be an optimal strategy by the brain and commonly thought of as an expression of the brain's ability to learn the statistical structure of sensory input. On the other hand, recency biases such as serial dependence are also commonly observed and are thought to reflect the content of working memory. Recent results from an auditory delayed comparison task in rats suggest that both biases may be more related than previously thought: when the posterior parietal cortex (PPC) was silenced, both short-term and contraction biases were reduced. By proposing a model of the circuit that may be involved in generating the behavior, we show that a volatile working memory content susceptible to shifting to the past sensory experience - producing short-term sensory history biases - naturally leads to contraction bias. The errors, occurring at the level of individual trials, are sampled from the full distribution of the stimuli and are not due to a gradual shift of the memory toward the sensory distribution's mean. Our results are consistent with a broad set of behavioral findings and provide predictions of performance across different stimulus distributions and timings, delay intervals, as well as neuronal dynamics in putative working memory areas. Finally, we validate our model by performing a set of human psychophysics experiments of an auditory parametric working memory task.


During cognitive tasks, our brain needs to temporarily hold and manipulate the information it is processing to decide how best to respond. This ability, known as working memory, is influenced by how the brain represents and processes the sensory world around us, which can lead to biases, such as 'central tendency'. Consider an experiment where you are presented with a metal bar and asked to recall how long it was after a few seconds. Typically, our memories, averaged over many trials of repeating this memory recall test, appear to skew towards an average length, leading to the tendency to mis-remember the bar as being shorter or longer than it actually was. This central tendency occurs in most species, and is thought to be the result of the brain learning which sensory input is the most likely to occur out of the range of possibilities. Working memory is also influenced by short-term history or recency bias, where a recent past experience influences a current memory. Studies have shown that 'turning off' a region of the rat brain called the posterior parietal cortex removes the effects of both recency bias and central tendency on working memory. Here, Boboeva et al. reveal that these two biases, which were thought to be controlled by separate mechanisms, may in fact be related. Building on the inactivation study, the team modelled a circuit of neurons that can give rise to the results observed in the rat experiments, as well as behavioural results in humans and primates. The computational model contained two modules: one of which represented a putative working memory, and another which represented the posterior parietal cortex which relays sensory information about past experiences. Boboeva et al. found that sensory inputs relayed from the posterior parietal cortex module led to recency biases in working memory. As a result, central tendency naturally emerged without needing to add assumptions to the model about which sensory input is the most likely to occur. The computational model was also able to replicate all known previous experimental findings, and made some predictions that were tested and confirmed by psychophysics tests on human participants. The findings of Boboeva et al. provide a new potential mechanism for how central tendency emerges in working memory. The model suggests that to achieve central tendency prior knowledge of how a sensory stimulus is distributed in an environment is not required, as it naturally emerges due to a volatile working memory which is susceptible to errors. This is the first mechanistic model to unify these two sources of bias in working memory. In the future, this could help advance our understanding of certain psychiatric conditions in which working memory and sensory learning are impaired.


Assuntos
Memória de Curto Prazo , Memória de Curto Prazo/fisiologia , Animais , Humanos , Ratos , Modelos Neurológicos , Lobo Parietal/fisiologia
4.
Sci Rep ; 14(1): 7865, 2024 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-38570619

RESUMO

Maintaining vigilance is essential for many everyday tasks, but over time, our ability to sustain it inevitably decreases, potentially entailing severe consequences. High-definition transcranial direct current stimulation (HD-tDCS) has proven to be useful for studying and improving vigilance. This study explores if/how cognitive load affects the mitigatory effects of HD-tDCS on the vigilance decrement. Participants (N = 120) completed a modified ANTI-Vea task (single or dual load) while receiving either sham or anodal HD-tDCS over the right posterior parietal cortex (rPPC). This data was compared with data from prior studies (N = 120), where participants completed the standard ANTI-Vea task (triple load task), combined with the same HD-tDCS protocol. Against our hypotheses, both the single and dual load conditions showed a significant executive vigilance (EV) decrement, which was not affected by the application of rPPC HD-tDCS. On the contrary, the most cognitively demanding task (triple task) showed the greatest EV decrement; importantly, it was also with the triple task that a significant mitigatory effect of the HD-tDCS intervention was observed. The present study contributes to a more nuanced understanding of the specific effects of HD-tDCS on the vigilance decrement considering cognitive demands. This can ultimately contribute to reconciling heterogeneous effects observed in past research and fine-tuning its future clinical application.


Assuntos
Estimulação Transcraniana por Corrente Contínua , Humanos , Estimulação Transcraniana por Corrente Contínua/métodos , Tempo de Reação/fisiologia , Vigília , Lobo Parietal/fisiologia , Cognição/fisiologia
5.
Nat Commun ; 15(1): 3357, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38637493

RESUMO

Egocentric encoding is a well-known property of brain areas along the dorsal pathway. Different to previous experiments, which typically only demanded egocentric spatial processing during movement preparation, we designed a task where two male rhesus monkeys memorized an on-the-object target position and then planned a reach to this position after the object re-occurred at variable location with potentially different size. We found allocentric (in addition to egocentric) encoding in the dorsal stream reach planning areas, parietal reach region and dorsal premotor cortex, which is invariant with respect to the position, and, remarkably, also the size of the object. The dynamic adjustment from predominantly allocentric encoding during visual memory to predominantly egocentric during reach planning in the same brain areas and often the same neurons, suggests that the prevailing frame of reference is less a question of brain area or processing stream, but more of the cognitive demands.


Assuntos
Córtex Cerebral , Percepção Espacial , Masculino , Animais , Percepção Espacial/fisiologia , Córtex Cerebral/fisiologia , Lobo Parietal/fisiologia , Memória , Cognição , Desempenho Psicomotor/fisiologia
6.
Hum Brain Mapp ; 45(4): e26636, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38488458

RESUMO

Parietal alpha activity shows a specific pattern of phasic changes during working memory. It decreases during the encoding and recall phases but increases during the maintenance phase. This study tested whether online rTMS delivered to the parietal cortex during the maintenance phase of a working memory task would increase alpha activity and hence improve working memory. Then, 46 healthy volunteers were randomly assigned to two groups to receive 3-day parietal 10 Hz online rTMS (either real or sham, 3600 pulses in total) that were time-locked to the maintenance phase of a spatial span task (180 trials in total). Behavioral performance on another spatial span task and EEG signals during a change detection task were recorded on the day before the first rTMS (pretest) and the day after the last rTMS (posttest). We found that rTMS improved performance on both online and offline spatial span tasks. For the offline change detection task, rTMS enhanced alpha activity within the maintenance phase and improved interference control of working memory at both behavioral (K score) and neural (contralateral delay activity) levels. These results suggested that rTMS with alpha frequency time-locked to the maintenance phase is a promising way to boost working memory.


Assuntos
Memória de Curto Prazo , Estimulação Magnética Transcraniana , Humanos , Estimulação Magnética Transcraniana/métodos , Memória de Curto Prazo/fisiologia , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiologia , Rememoração Mental
7.
Comput Biol Med ; 172: 108188, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38492454

RESUMO

Deep neural networks (DNNs) are widely adopted to decode motor states from both non-invasively and invasively recorded neural signals, e.g., for realizing brain-computer interfaces. However, the neurophysiological interpretation of how DNNs make the decision based on the input neural activity is limitedly addressed, especially when applied to invasively recorded data. This reduces decoder reliability and transparency, and prevents the exploitation of decoders to better comprehend motor neural encoding. Here, we adopted an explainable artificial intelligence approach - based on a convolutional neural network and an explanation technique - to reveal spatial and temporal neural properties of reach-to-grasping from single-neuron recordings of the posterior parietal area V6A. The network was able to accurately decode 5 different grip types, and the explanation technique automatically identified the cells and temporal samples that most influenced the network prediction. Grip encoding in V6A neurons already started at movement preparation, peaking during movement execution. A difference was found within V6A: dorsal V6A neurons progressively encoded more for increasingly advanced grips, while ventral V6A neurons for increasingly rudimentary grips, with both subareas following a linear trend between the amount of grip encoding and the level of grip skills. By revealing the elements of the neural activity most relevant for each grip with no a priori assumptions, our approach supports and advances current knowledge about reach-to-grasp encoding in V6A, and it may represent a general tool able to investigate neural correlates of motor or cognitive tasks (e.g., attention and memory tasks) from single-neuron recordings.


Assuntos
Inteligência Artificial , Desempenho Psicomotor , Reprodutibilidade dos Testes , Desempenho Psicomotor/fisiologia , Lobo Parietal/fisiologia , Redes Neurais de Computação , Força da Mão/fisiologia , Movimento/fisiologia
8.
Neurosci Biobehav Rev ; 160: 105622, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38490498

RESUMO

The present review examined the consequences of focal brain injury on spatial attention studied with cueing paradigms, with a particular focus on the disengagement deficit, which refers to the abnormal slowing of reactions following an ipsilesional cue. Our review supports the established notion that the disengagement deficit is a functional marker of spatial neglect and is particularly pronounced when elicited by peripheral cues. Recent research has revealed that this deficit critically depends on cues that have task-relevant characteristics or are associated with negative reinforcement. Attentional capture by task-relevant cues is contingent on damage to the right temporo-parietal junction (TPJ) and is modulated by functional connections between the TPJ and the right insular cortex. Furthermore, damage to the dorsal premotor or prefrontal cortex (dPMC/dPFC) reduces the effect of task-relevant cues. These findings support an interactive model of the disengagement deficit, involving the right TPJ, the insula, and the dPMC/dPFC. These interconnected regions play a crucial role in regulating and adapting spatial attention to changing intrinsic values of stimuli in the environment.


Assuntos
Lesões Encefálicas , Transtornos da Percepção , Humanos , Córtex Pré-Frontal , Transtornos da Percepção/etiologia , Sinais (Psicologia) , Percepção Espacial/fisiologia , Lobo Parietal/fisiologia , Lateralidade Funcional/fisiologia , Tempo de Reação/fisiologia
9.
Elife ; 122024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38478405

RESUMO

Previous research has found that prolonged eye-based attention can bias ocular dominance. If one eye long-termly views a regular movie meanwhile the opposite eye views a backward movie of the same episode, perceptual ocular dominance will shift towards the eye previously viewing the backward movie. Yet it remains unclear whether the role of eye-based attention in this phenomenon is causal or not. To address this issue, the present study relied on both the functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) techniques. We found robust activation of the frontal eye field (FEF) and intraparietal sulcus (IPS) when participants were watching the dichoptic movie while focusing their attention on the regular movie. Interestingly, we found a robust effect of attention-induced ocular dominance shift when the cortical function of vertex or IPS was transiently inhibited by continuous theta burst stimulation (cTBS), yet the effect was significantly attenuated to a negligible extent when cTBS was delivered to FEF. A control experiment verified that the attenuation of ocular dominance shift after inhibitory stimulation of FEF was not due to any impact of the cTBS on the binocular rivalry measurement of ocular dominance. These findings suggest that the fronto-parietal attentional network is involved in controlling eye-based attention in the 'dichoptic-backward-movie' adaptation paradigm, and in this network, FEF plays a crucial causal role in generating the attention-induced ocular dominance shift.


Assuntos
Dominância Ocular , Estimulação Magnética Transcraniana , Humanos , Estimulação Magnética Transcraniana/métodos , Atenção/fisiologia , Lobo Frontal/fisiologia , Lobo Parietal/fisiologia , Estimulação Luminosa/métodos
10.
Nature ; 627(8003): 367-373, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38383788

RESUMO

The posterior parietal cortex exhibits choice-selective activity during perceptual decision-making tasks1-10. However, it is not known how this selective activity arises from the underlying synaptic connectivity. Here we combined virtual-reality behaviour, two-photon calcium imaging, high-throughput electron microscopy and circuit modelling to analyse how synaptic connectivity between neurons in the posterior parietal cortex relates to their selective activity. We found that excitatory pyramidal neurons preferentially target inhibitory interneurons with the same selectivity. In turn, inhibitory interneurons preferentially target pyramidal neurons with opposite selectivity, forming an opponent inhibition motif. This motif was present even between neurons with activity peaks in different task epochs. We developed neural-circuit models of the computations performed by these motifs, and found that opponent inhibition between neural populations with opposite selectivity amplifies selective inputs, thereby improving the encoding of trial-type information. The models also predict that opponent inhibition between neurons with activity peaks in different task epochs contributes to creating choice-specific sequential activity. These results provide evidence for how synaptic connectivity in cortical circuits supports a learned decision-making task.


Assuntos
Tomada de Decisões , Vias Neurais , Lobo Parietal , Sinapses , Cálcio/análise , Cálcio/metabolismo , Tomada de Decisões/fisiologia , Interneurônios/metabolismo , Interneurônios/ultraestrutura , Aprendizagem/fisiologia , Microscopia Eletrônica , Inibição Neural , Vias Neurais/fisiologia , Vias Neurais/ultraestrutura , Lobo Parietal/citologia , Lobo Parietal/fisiologia , Lobo Parietal/ultraestrutura , Células Piramidais/metabolismo , Células Piramidais/ultraestrutura , Sinapses/metabolismo , Sinapses/ultraestrutura , Realidade Virtual , Modelos Neurológicos
11.
Sci Rep ; 14(1): 4632, 2024 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-38409306

RESUMO

The brain can adapt its expectations about the relative timing of actions and their sensory outcomes in a process known as temporal recalibration. This might occur as the recalibration of timing between the sensory (e.g. visual) outcome and (1) the motor act (sensorimotor) or (2) tactile/proprioceptive information (inter-sensory). This fMRI recalibration study investigated sensorimotor contributions to temporal recalibration by comparing active and passive conditions. Subjects were repeatedly exposed to delayed (150 ms) or undelayed visual stimuli, triggered by active or passive button presses. Recalibration effects were tested in delay detection tasks, including visual and auditory outcomes. We showed that both modalities were affected by visual recalibration. However, an active advantage was observed only in visual conditions. Recalibration was generally associated with the left cerebellum (lobules IV, V and vermis) while action related activation (active > passive) occurred in the right middle/superior frontal gyri during adaptation and test phases. Recalibration transfer from vision to audition was related to action specific activations in the cingulate cortex, the angular gyrus and left inferior frontal gyrus. Our data provide new insights in sensorimotor contributions to temporal recalibration via the middle/superior frontal gyri and inter-sensory contributions mediated by the cerebellum.


Assuntos
Imageamento por Ressonância Magnética , Desempenho Psicomotor , Humanos , Desempenho Psicomotor/fisiologia , Retroalimentação Sensorial/fisiologia , Encéfalo/diagnóstico por imagem , Lobo Parietal/fisiologia
12.
Cereb Cortex ; 34(2)2024 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-38300180

RESUMO

Psychophysical observations indicate that the spatial profile of visuospatial attention includes a central enhancement around the attentional focus, encircled by a narrow zone of reduced excitability in the immediate surround. This inhibitory ring optimally amplifies relevant target information, likely stemming from top-down frontoparietal recurrent activity modulating early visual cortex activations. However, the mechanisms through which neural suppression gives rise to the surrounding attenuation and any potential hemispheric specialization remain unclear. We used transcranial magnetic stimulation to evaluate the role of two regions of the dorsal attention network in the center-surround profile: the frontal eye field and the intraparietal sulcus. Participants performed a psychophysical task that mapped the entire spatial attentional profile, while transcranial magnetic stimulation was delivered either to intraparietal sulcus or frontal eye field on the right (Experiment 1) and left (Experiment 2) hemisphere. Results showed that stimulation of right frontal eye field and right intraparietal sulcus significantly changed the center-surround profile, by widening the inhibitory ring around the attentional focus. The stimulation on the left frontal eye field, but not left intraparietal sulcus, induced a general decrease in performance but did not alter the center-surround profile. Results point to a pivotal role of the right dorsal attention network in orchestrating inhibitory spatial mechanisms required to limit interference by surrounding distractors.


Assuntos
Lateralidade Funcional , Estimulação Magnética Transcraniana , Humanos , Lateralidade Funcional/fisiologia , Lobo Parietal/fisiologia , Lobo Frontal/fisiologia , Estimulação Luminosa/métodos , Imageamento por Ressonância Magnética , Mapeamento Encefálico
13.
Cortex ; 173: 138-149, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38394974

RESUMO

Although behavioral evidence has shown that postural changes influence the ability to localize or detect tactile stimuli, little is known regarding the brain areas that modulate these effects. This 7T functional magnetic resonance imaging (fMRI) study explores the effects of touch of the hand as a function of hand location (right or left side of the body) and hand configuration (open or closed). We predicted that changes in hand configuration would be represented in contralateral primary somatosensory cortex (S1) and the anterior intraparietal area (aIPS), whereas change in position of the hand would be associated with alterations in activation in the superior parietal lobule. Multivoxel pattern analysis and a region of interest approach partially supported our predictions. Decoding accuracy for hand location was above chance level in superior parietal lobule (SPL) and in the anterior intraparietal (aIPS) area; above chance classification of hand configuration was observed in SPL and S1. This evidence confirmed the role of the parietal cortex in postural effects on touch and the possible role of S1 in coding the body form representation of the hand.


Assuntos
Mapeamento Encefálico , Lobo Parietal , Humanos , Mapeamento Encefálico/métodos , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiologia , Postura , Imageamento por Ressonância Magnética/métodos , Encéfalo/diagnóstico por imagem , Mãos , Córtex Somatossensorial/diagnóstico por imagem , Córtex Somatossensorial/fisiologia
14.
J Neurosci ; 44(15)2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38395616

RESUMO

Control over internal representations requires the prioritization of relevant information and suppression of irrelevant information. The frontoparietal network exhibits prominent neural oscillations during these distinct cognitive processes. Yet, the causal role of this network-scale activity is unclear. Here, we targeted theta-frequency frontoparietal coherence and dynamic alpha oscillations in the posterior parietal cortex using online rhythmic transcranial magnetic stimulation (TMS) in women and men while they prioritized or suppressed internally maintained working memory (WM) representations. Using concurrent high-density EEG, we provided evidence that we acutely drove the targeted neural oscillation and TMS improved WM capacity only when the evoked activity corresponded with the desired cognitive process. To suppress an internal representation, we increased the amplitude of lateralized alpha oscillations in the posterior parietal cortex contralateral to the irrelevant visual field. For prioritization, we found that TMS to the prefrontal cortex increased theta-frequency connectivity in the prefrontoparietal network contralateral to the relevant visual field. To understand the spatial specificity of these effects, we administered the WM task to participants with implanted electrodes. We found that theta connectivity during prioritization was directed from the lateral prefrontal to the superior posterior parietal cortex. Together, these findings provide causal evidence in support of a model where a frontoparietal theta network prioritizes internally maintained representations and alpha oscillations in the posterior parietal cortex suppress irrelevant representations.


Assuntos
Eletroencefalografia , Estimulação Magnética Transcraniana , Masculino , Humanos , Feminino , Ritmo Teta/fisiologia , Lobo Parietal/fisiologia , Córtex Pré-Frontal/fisiologia , Memória de Curto Prazo/fisiologia
15.
Neuroimage ; 289: 120541, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38360384

RESUMO

Our everyday activities require the maintenance and continuous updating of information in working memory (WM). To control this dynamic, WM gating mechanisms have been suggested to be in place, but the neurophysiological mechanisms behind these processes are far from being understood. This is especially the case when it comes to the role of oscillatory neural activity. In the current study we combined EEG recordings, and anodal transcranial direct current stimulation (atDCS) and pupil diameter recordings to triangulate neurophysiology, functional neuroanatomy and neurobiology. The results revealed that atDCS, compared to sham stimulation, affected the WM gate opening mechanism, but not the WM gate closing mechanism. The altered behavioral performance was associated with specific changes in alpha band activities (reflected by alpha desynchronization), indicating a role for inhibitory control during WM gate opening. Functionally, the left superior and inferior parietal cortices, were associated with these processes. The findings are the first to show a causal relevance of alpha desynchronization processes in WM gating processes. Notably, pupil diameter recordings as an indirect index of the norepinephrine (NE) system activity revealed that individuals with stronger inhibitory control (as indexed through alpha desynchronization) showed less pupil dilation, suggesting they needed less NE activity to support WM gate opening. However, when atDCS was applied, this connection disappeared. The study suggests a close link between inhibitory controlled WM gating in parietal cortices, alpha band dynamics and the NE system.


Assuntos
Memória de Curto Prazo , Estimulação Transcraniana por Corrente Contínua , Humanos , Memória de Curto Prazo/fisiologia , Norepinefrina , Lobo Parietal/fisiologia
16.
J Neurosci Res ; 102(2): e25304, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38361404

RESUMO

Neuromodulation with transcranial direct current stimulation (tDCS) is an increasingly popular research tool to experimentally manipulate cortical areas and probe their causal involvements in behavior, but its replicability and regional specificity are not clear. This registered report investigated cathodal tDCS effects on spatial-numerical associations (i.e., the SNARC effect), the numerical distance effect (NDE), and inhibitory control (i.e., stop-signal reaction time; SSRT). Healthy adults (N = 160) were randomly assigned to one of five groups to receive sham tDCS or 1 mA cathodal tDCS to one of four stimulation sites (left/right prefrontal cortex [PFC], left/right posterior parietal cortex) with extracephalic return. We replicated that cathodal tDCS over the left PFC reduced the SNARC effect compared to sham tDCS and to tDCS over the left parietal cortex. However, neither NDE nor SSRT were modulated in the main analyses. Post hoc contrasts and exploratory analyses showed that cathodal tDCS over the right PFC had a time-dependent effect by delayed practice-related improvements in SSRT. Math anxiety moderated changes in the NDE in the groups receiving tDCS to the right parietal cortex. With few exceptions, the replicability and regional specificity of tDCS effects on behavior were weak and partially moderated by individual differences. Future research needs to characterize the parameter settings for effective neuromodulation.


Assuntos
Estimulação Transcraniana por Corrente Contínua , Adulto , Humanos , Tempo de Reação , Lobo Parietal/fisiologia , Eletrodos , Córtex Pré-Frontal/fisiologia
17.
Cereb Cortex ; 34(2)2024 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-38185997

RESUMO

Semantic knowledge includes understanding of objects and their features and also understanding of the characteristics of events. The hub-and-spoke theory holds that these conceptual representations rely on multiple information sources that are integrated in a central hub in the ventral anterior temporal lobes. The dual-hub theory expands this framework with the claim that the ventral anterior temporal lobe hub is specialized for object representation, while a second hub in angular gyrus is specialized for event representation. To test these ideas, we used representational similarity analysis, univariate and psychophysiological interaction analyses of fMRI data collected while participants processed object and event concepts (e.g. "an apple," "a wedding") presented as images and written words. Representational similarity analysis showed that angular gyrus encoded event concept similarity more than object similarity, although the left angular gyrus also encoded object similarity. Bilateral ventral anterior temporal lobes encoded both object and event concept structure, and left ventral anterior temporal lobe exhibited stronger coding for events. Psychophysiological interaction analysis revealed greater connectivity between left ventral anterior temporal lobe and right pMTG, and between right angular gyrus and bilateral ITG and middle occipital gyrus, for event concepts compared to object concepts. These findings support the specialization of angular gyrus for event semantics, though with some involvement in object coding, but do not support ventral anterior temporal lobe specialization for object concepts.


Assuntos
Mapeamento Encefálico , Lobo Temporal , Humanos , Lobo Temporal/diagnóstico por imagem , Lobo Temporal/fisiologia , Lobo Parietal/fisiologia , Semântica , Imageamento por Ressonância Magnética/métodos
18.
Eur Neurol ; 87(1): 36-42, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38228099

RESUMO

INTRODUCTION: The integration of vestibular, visual, and somatosensory cues allows the perception of space through the orientation of our body and surrounding objects with respect to gravity. The main goal of this study was to identify the cortical networks recruited during the representation of body midline and the representation of verticality. METHODS: Thirty right-handed healthy participants were evaluated using fMRI. Brain networks activated during a subjective straight-ahead (SSA) task were compared to those recruited during a subjective vertical (SV) task. RESULTS: Different patterns of cortical activation were observed, with differential increases in the angular gyrus and left cerebellum posterior lobe during the SSA task, in right rolandic operculum and cerebellum anterior lobe during the SV task. DISCUSSION: The activation of these areas involved in visuo-spatial functions suggests that bodily processes of great complexity are engaged in body representation and vertical perception. Interestingly, the common brain networks involved in SSA and SV tasks were comprised of areas of vestibular projection that receive multisensory information (parieto-occipital areas) and the cerebellum, and reveal a predominance of the right cerebral and cerebellar hemispheres. The outcomes of this first fMRI study designed to unmask common and specific neural mechanisms at work in gravity- or body-referenced tasks pave a new way for the exploration of spatial cognitive impairment in patients with vestibular or cortical disorders.


Assuntos
Encéfalo , Percepção Espacial , Humanos , Percepção Espacial/fisiologia , Encéfalo/diagnóstico por imagem , Lobo Parietal/fisiologia , Mapeamento Encefálico/métodos , Ego
19.
Nat Commun ; 15(1): 572, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38233387

RESUMO

Much of human culture's advanced technology owes its existence to the ability to mentally manipulate quantities. Neuroscience has described the brain regions overall recruited by numerical tasks and the neuronal codes representing individual quantities during perceptual tasks. Nevertheless, it remains unknown how quantity representations are combined or transformed during mental computations and how specific quantities are coded in the brain when generated as the result of internal computations rather than evoked by a stimulus. Here, we imaged the brains of adult human subjects at 7 Tesla during an approximate calculation task designed to disentangle in- and outputs of the computation from the operation itself. While physically presented sample numerosities were distinguished in activity patterns along the dorsal visual pathway and within frontal and occipito-temporal regions, a representation of the internally generated result was most prominently detected in higher order regions such as angular gyrus and lateral prefrontal cortex. Behavioral precision in the task was related to cross-decoding performance between sample and result representations in medial IPS regions. This suggests the transformation of sample into result may be carried out within dorsal stream sensory-motor integration regions, and resulting outputs maintained for task purposes in higher-level regions in a format possibly detached from sensory-evoked inputs.


Assuntos
Mapeamento Encefálico , Imageamento por Ressonância Magnética , Adulto , Humanos , Mapeamento Encefálico/métodos , Imageamento por Ressonância Magnética/métodos , Encéfalo/diagnóstico por imagem , Lobo Parietal/fisiologia , Lobo Temporal , Estimulação Luminosa/métodos
20.
Nat Neurosci ; 27(2): 298-308, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38177341

RESUMO

Animals adapt to a constantly changing world by predicting their environment and the consequences of their actions. The predictive coding hypothesis proposes that the brain generates predictions and continuously compares them with sensory inputs to guide behavior. However, how the brain reconciles conflicting top-down predictions and bottom-up sensory information remains unclear. To address this question, we simultaneously imaged neuronal populations in the mouse somatosensory barrel cortex and posterior parietal cortex during an auditory-cued texture discrimination task. In mice that had learned the task with fixed tone-texture matching, the presentation of mismatched pairing induced conflicts between tone-based texture predictions and actual texture inputs. When decisions were based on the predicted rather than the actual texture, top-down information flow was dominant and texture representations in both areas were modified, whereas dominant bottom-up information flow led to correct representations and behavioral choice. Our findings provide evidence for hierarchical predictive coding in the mouse neocortex.


Assuntos
Percepção Auditiva , Neocórtex , Camundongos , Animais , Percepção Auditiva/fisiologia , Lobo Parietal/fisiologia , Córtex Somatossensorial/fisiologia , Discriminação Psicológica/fisiologia
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