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1.
Behav Neurol ; 2019: 1410425, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31565094

RESUMO

Previous studies have shown that the neural mechanisms underlying visual spatial attention rely on top-down control information from the frontal and parietal cortexes, which ultimately amplifies sensory processing of stimulus occurred at the attended location relative to those at unattended location. However, the modulations of effective brain networks in response to stimulus at attended and unattended location are not yet clear. In present study, we collected event-related potentials (ERPs) from 15 subjects during a visual spatial attention task, and a partial directed coherence (PDC) method was used to construct alpha-band effective brain networks of two conditions (targets at attended and nontargets at unattended location). Flow gain mapping, effective connectivity pattern, and graph measures including clustering coefficient (C), characteristic path length (L), global efficiency (E global), and local efficiency (E local) were compared between two conditions. Flow gain mapping showed that the frontal region seemed to serve as the main source of information transmission in response to targets at attended location while the parietal region served as the main source in nontarget condition. Effective connectivity pattern indicated that in response to targets, there existed obvious top-down connections from the frontal, temporal, and parietal cortexes to the visual cortex compared with in response to nontargets. Graph theory analysis was used to quantify the topographical properties of the brain networks, and results revealed that in response to targets, the brain networks were characterized by significantly smaller characteristic path length and larger global efficiency than in response to nontargets. Our findings suggested that smaller characteristic path length and larger global efficiency could facilitate global integration of information and provide a substrate for more efficient perceptual processing of targets at attended location compared with processing of nontargets at ignored location, which revealed the neural mechanisms underlying visual spatial attention from the perspective of effective brain networks and graph theory for the first time and opened new vistas to interpret a cognitive process.


Assuntos
Ritmo alfa/fisiologia , Processamento Espacial/fisiologia , Percepção Visual/fisiologia , Atenção/fisiologia , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Eletroencefalografia/métodos , Potenciais Evocados/fisiologia , Feminino , Lobo Frontal/fisiologia , Humanos , Masculino , Rede Nervosa/fisiologia , Lobo Parietal/fisiologia , Estimulação Luminosa , Adulto Jovem
2.
World Neurosurg ; 131: 364-370, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31658579

RESUMO

In recent years, advances in cortical-subcortical mapping, intraoperative neurophysiology, and neuropsychology have increased the ability to remove intrinsic brain tumors, expanding indications and maximizing the extent of resection. This has provided a significant improvement in progression-free survival, time of malignant transformation (in low-grade gliomas), and overall survival. Although current techniques enable preservation of language and motor functions during surgery, the maintenance of a complex set of functions defined with the term cognition is not always achievable. Cognition is defined as every neural process underlying a high human function and includes motor haptic and visuospatial functions, memory, social interactions, empathy, and emotions. In this regard, an extensive preoperative and postoperative neuropsychological evaluation is strongly suggested to assess cognitive impairment due to tumor growth, to assess surgical result, and to plan cognitive rehabilitation. This article discusses the main recent innovations introduced for cognitive mapping with the aim to preserve cognitive functions, which are essential to maintain a high quality of life.


Assuntos
Mapeamento Encefálico/métodos , Neoplasias Encefálicas/terapia , Transtornos Cognitivos/prevenção & controle , Terapia por Estimulação Elétrica/métodos , Glioma/terapia , Procedimentos Neurocirúrgicos/métodos , Neoplasias Encefálicas/psicologia , Função Executiva/fisiologia , Glioma/psicologia , Humanos , Margens de Excisão , Testes Neuropsicológicos , Tratamentos com Preservação do Órgão/métodos , Complicações Pós-Operatórias/prevenção & controle , Semântica , Processamento Espacial/fisiologia
3.
Am J Audiol ; 28(2S): 437-449, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31461328

RESUMO

Purpose This study was carried out to understand the neural intricacies of auditory spatial processing in listeners with sensorineural hearing impairment (SNHI) and compare it with normal hearing (NH) listeners using both local and global measures of waveform analyses. Method A standard group comparison research design was adopted in this study. Participants were assigned to 2 groups. Group I consisted of 13 participants with mild-moderate flat or sloping SNHI, while Group II consisted of 13 participants with NH sensitivity. Electroencephalographic data using virtual acoustic stimuli (spatially loaded stimuli played in center, right, and left hemifields) were recorded from 64 electrode sites in passive oddball paradigm. Both local (electrode-wise waveform analysis) and global (dissimilarity index, electric field strength, and topographic pattern analyses) measures were performed on the electroencephalographic data. Results Results of local waveform analyses marked the appearance of mismatch negativity in an earlier time window, relative to those reported conventionally in both the groups. The global measures of electric field strength and topographic modulations (dissimilarity index) revealed differences between the 2 groups in different time periods, indicating multiphases (integration and consolidation) of spatial processing. Further, the topographic pattern analysis showed the emergence of different scalp maps for SNHI and NH in the time window corresponding to mismatch negativity (78-150 ms), suggestive of differential spatial processing between the groups at the cortical level. Conclusions The findings of this study highlights the differential allotment of neural generators, denoting variations in spatial processing between SNHI and NH individuals.


Assuntos
Encéfalo/fisiopatologia , Potenciais Evocados Auditivos/fisiologia , Perda Auditiva Neurossensorial/fisiopatologia , Processamento Espacial/fisiologia , Estimulação Acústica , Adulto , Idoso , Atenção , Estudos de Casos e Controles , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
4.
J Vis ; 19(7): 6, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31287860

RESUMO

Are people biologically prepared for the rapid detection of threat posed by an angry facial expression, even when it is conveyed in the form of a schematic line drawing? Based on visual search times, the current literature would suggest that the answer is yes. But are there low-level explanations for this effect? Here, we present visual search results for schematic faces using current best practice, based on a concentric search array and set size manipulation. Using this approach, we replicate the classic search advantage for angry over happy faces. However, we also report a comparable effect when abstract plus- and square-shaped stimuli-derived from the angry and happy schematic faces respectively-are used within the same paradigm. We then go on to demonstrate that, while reduced, the effect remains after removal of the circular surround, bringing us closer to the source of the effect. We explore the possibility that the source of this search asymmetry could be the iso-feature suppression and collinear facilitation model proposed in Li's (1999a, 1999b, and 2002) bottom-up model of saliency. Simulations with this model using the abstract stimuli align with the corresponding behavioral results (i.e., the plus shape was found to be more salient than the square). Given the deliberate similarities between these abstract shapes and the respective face stimuli, we propose that the underlying cause for the asymmetries typically found using schematic faces, may be more related to early visual processing of line orientation than threat detection.


Assuntos
Ira/fisiologia , Expressão Facial , Adolescente , Adulto , Cognição/fisiologia , Aglomeração/psicologia , Emoções/fisiologia , Medo/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Orientação/fisiologia , Estimulação Luminosa , Processamento Espacial/fisiologia , Adulto Jovem
5.
Optom Vis Sci ; 96(7): 484-491, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31274736

RESUMO

SIGNIFICANCE: Glaucoma has been shown to impair hazard detection ability and increase crash risk compared to controls. Differences in visual search behavior of the driving scene may explain these differences; however, there has been limited investigation of this issue with inconsistent findings. PURPOSE: Through eye movement tracking of older drivers with glaucoma, we explored their visual search behavior in comparison with controls while performing the DriveSafe, a slide recognition test purported to predict fitness to drive. METHODS: Thirty-one drivers with glaucoma (mean age, 71.7 ± 6.3 years; average better-eye mean defect,-3 dB; average worse-eye mean defect,-12 dB) and 25 age-matched controls underwent measurements of their visual acuity, contrast sensitivity, visual fields, and useful field of view (visual processing speeds). Participants' eye movements were recorded while they completed the DriveSafe test, which consists of brief presentations of static, real-world driving scenes containing various road users (pedestrians, bicycles, vehicles). Participants reported the types, positions, and direction of travel of road users in each image; the score was the total number of correctly reported items (maximum, 128). RESULTS: Drivers with glaucoma had significantly worse DriveSafe scores (P = .03), fixated on road users for shorter durations (P < .001), and exhibited smaller saccades (P = .02) compared with controls. For all participants, longer fixation times on road users (P < .001) was the eye movement measure most strongly associated with better DriveSafe scores; this relationship was not significantly different between groups. Useful field-of-view divided attention was the strongest visual predictor of DriveSafe scores. CONCLUSIONS: Eye movement changes in the glaucoma group may reflect increased difficulty in identifying relevant objects in the visual scene, which may be related to their lower DriveSafe scores. Given the DriveSafe's potential utility in assessing drivers with visual impairment before on-road testing, further investigations on how DriveSafe performance and eye movement patterns compare to those during on-road driving are warranted.


Assuntos
Condução de Veículo , Movimentos Oculares/fisiologia , Glaucoma/fisiopatologia , Processamento Espacial/fisiologia , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Inquéritos e Questionários , Testes Visuais , Acuidade Visual/fisiologia , Testes de Campo Visual , Campos Visuais/fisiologia
6.
Biol Psychol ; 146: 107727, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31276757

RESUMO

Previous studies suggested that highly math-anxious (HMA) individuals invest more attentional resources than their low math-anxious (LMA) peers in numerical tasks, and have worse spatial skills. We aimed to explore whether they also need to apply more resources in spatial tasks. In this study, HMA and LMA individuals saw normal or mirror-reversed letters in six orientations and made mirror-normal decisions. In both groups, response times and errors increased with angular deviation from upright and the ERP mental rotation effect was found. However, HMAs were slower to respond than their LMA counterparts. Interestingly, the HMA group showed a larger P3b in greater deviations for normal letters and in all mirrored letters. Since P3b amplitude reflects the attentional resources invested in the categorization of relevant stimuli, HMA individuals may need to devote more processing effort than their LMA peers when performing mental rotation. This finding is consistent with the Attentional Control Theory.


Assuntos
Ansiedade/psicologia , Imaginação/fisiologia , Matemática , Processamento Espacial/fisiologia , Tomada de Decisões , Eletroencefalografia , Potenciais Evocados , Feminino , Humanos , Testes Neuropsicológicos , Tempo de Reação , Rotação , Adulto Jovem
7.
Ear Hear ; 40(4): 757-765, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31242136

RESUMO

OBJECTIVES: Hearing loss is considered an independent risk factor for dementia. Growing evidence in animal and human studies suggest that not only hearing loss but also vestibular loss might result in cognitive deficits. The objective of this study is to evaluate the presence of spatial and nonspatial cognitive deficits in patients with bilateral vestibulopathy. As different causes of bilateral vestibulopathy are associated with hearing loss, the objective is to evaluate if these cognitive deficits are due to the vestibular loss of the patients with bilateral vestibulopathy, or to their hearing loss, or both. DESIGN: We performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. (1) Data sources: MEDLINE and the Cochrane Library. (2) Study selection: Cross-sectional studies investigating cognitive performances in human patients with bilateral vestibulopathy confirmed by quantitative vestibular testing. (3) Data extraction: Independent extraction of articles by three authors using predefined data fields, including patient- and control characteristics and cognitive outcomes. RESULTS: Ten studies reporting on 126 patients with bilateral vestibulopathy matched the inclusion criteria. Cognitive domains evaluated in patients with bilateral vestibulopathy included visuospatial abilities, memory, language, attention, and executive function. In only three studies, hearing performance of the included patients was briefly described. Nearly all studies demonstrated a significant impairment of spatial cognition in patients with bilateral vestibulopathy. In the few papers investigating nonspatial cognition, worse outcome was demonstrated in patients with bilateral vestibular loss performing cognitive tasks assessing attentional performance, memory, and executive function. CONCLUSIONS: Strong evidence exists that patients with bilateral vestibulopathy suffer from impaired spatial cognition. Recent studies even suggest impairment in other cognitive domains than spatial cognition. However, in all previous studies, conclusions on the link between cognitive performance and vestibular loss were drawn without taken hearing loss into consideration as a possible cause of the cognitive impairment.


Assuntos
Vestibulopatia Bilateral/fisiopatologia , Vestibulopatia Bilateral/psicologia , Cognição/fisiologia , Memória Espacial/fisiologia , Processamento Espacial/fisiologia , Humanos , Testes de Estado Mental e Demência , Navegação Espacial/fisiologia , Escala de Memória de Wechsler
8.
Int J Neurosci ; 129(11): 1119-1132, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31232638

RESUMO

Objective: Recognition of target signal improves when the target and distracted sources are spatially separated, an effect defined as 'spatial release from masking' (SRM). The neural mechanisms underpinning SRM are complicated and still need to be identified. The aim of this study was to identify whether objective correlates of SRM can be recorded in either the brainstem or cortex (or both). Materials and methods: In response to 200 target stimulus blocks, auditory brainstem responses (ABRs), frequency-following responses (FFRs) and cortical auditory evoked potentials (CAEPs) were recorded concurrently from 13 normally hearing adults utilizing two stimulus patterns, flat and staircase, in the presence of randomized distractors at -5, 0, 5, 10 and 15 dB SNR, and in co-located and separated spatial locations. Results: FFR F0 amplitude increased for the flat stimuli at -5 dB SNR, ABR wave V latency decreased for both flat and staircase stimuli in all SNRs and for P1 and N1 latencies due to the noisy CAEPs, drawing any significant conclusion could be subject to further investigation. Conclusion: These findings suggest that SRM can be objectively recorded concurrently in both the brainstem and auditory cortex. It is speculated that the central auditory system can suppress background noise based on spatial information commencing from the brainstem and that this capability is remarkable in more difficulty listing situations. This study may pave the way to evaluate spatial processing electrophysiologically utilizing FFR amplitude, ABR and CAEPs latencies condition to confirmation of the results of this study, at least at the level of the cortex in future investigation.


Assuntos
Atenção/fisiologia , Percepção Auditiva/fisiologia , Córtex Cerebral/fisiologia , Potenciais Evocados Auditivos/fisiologia , Processamento Espacial/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
9.
PLoS One ; 14(6): e0219005, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31247002

RESUMO

Level-2 visuo-spatial perspective-taking is an embodied process during which the perspective-taker mentally simulates a movement of his or her body into the location of the target. Evidence for the embodiment of this process so far exclusively stems from congruency effects in visuo-spatial perspective-taking experiments. Here, additional triangulation for the embodiment of this process is provided from an interindividual differences perspective. In a cross-sectional observational study, participants completed a behavioral level-2 visuo-spatial perspective-taking task and the heartbeat tracking task, which measures interoceptive accuracy and sensibility. Interoceptive accuracy is the objective ability to accurately perceive signals from within the body. In the present study, interoceptive accuracy was quantified by comparing the number of actual heartbeats observed via electrocardiographic recording to subjectively perceived heartbeats during that time. This measure was related to faster perspective-taking and better overall perspective-taking performance. Interoceptive sensibility refers to subjective beliefs about interoceptive abilities. Here, confidence in the estimated number of heartbeats served as a measure if interoceptive sensibility. Finally, the correspondence between interoceptive accuracy and sensibility is referred to as interoceptive awareness. Interoceptive sensibility and awareness were unrelated to perspective-taking. The study is a demonstration of the role interindividual differences in different facets of interoception play for embodied cognition. Implications for future research on links between embodied cognition and interoception are outlined and critically discussed.


Assuntos
Interocepção/fisiologia , Processamento Espacial/fisiologia , Adulto , Conscientização/fisiologia , Cognição , Simulação por Computador , Estudos Transversais , Feminino , Frequência Cardíaca , Humanos , Masculino , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Adulto Jovem
10.
Funct Neurol ; 34(1): 7-13, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31172934

RESUMO

Many people who have suffered a stroke will experience sensorimotor impairments that disrupt their performance of motor skills, including balance and gait. Furthermore, stroke-induced brain damage can Result in visual disorders that may significantly impact performance of normal daily activities. The primary aim of this study was to investigate the effects, on balance, of visual-spatial training as an add-on intervention to conventional neurorehabilitation in patients with subacute stroke without neglect; secondarily, it aimed to assess the effects of this training on activities of daily living. Thirty inpatients (17 M, age: 57.3±12.9 years) with a diagnosis of subacute stroke (< 180 days) were enrolled in this study and randomized into two groups: the visual-spatial training group and a control group. All patients were evaluated, using the Tinetti Balance and Gait Scale (TBG), the Berg Balance Scale, computerized posturography, and the Barthel Index (BI), both before (T0) and after (T1) four weeks of training sessions. In addition to conventional neurorehabilitation, each group performed a total of twelve 20-minute rehabilitation sessions (3 times/week for 4 weeks). Significant TIME x GROUP interactions were recorded in the experimental group with respect to the control group for the TBG score [F (1,18) =15.59; p = 0.0004] and BI score [F (1,28) =6.35; p = 0.01]. Both groups recorded non-significant improvements on the instrumental postural assessment. These data suggest that visualspatial training as an add-on intervention to conventional neurorehabilitation could be an effective complementary strategy to improve balance and activities of daily living.


Assuntos
Estimulação Luminosa/métodos , Equilíbrio Postural/fisiologia , Processamento Espacial/fisiologia , Reabilitação do Acidente Vascular Cerebral/métodos , Acidente Vascular Cerebral/terapia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Método Simples-Cego , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/fisiopatologia , Resultado do Tratamento
11.
Atten Percept Psychophys ; 81(6): 1913-1925, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31124050

RESUMO

Alertness seems to influence selective attention processes underlying cognitive control in the flanker task, as indicated by previous findings of larger congruency effects on alert trials (in which task stimuli are preceded by alerting cues) than on no-alert trials. One hypothesis for the alerting-congruency interaction is that increased alertness promotes spatial grouping of the target and distractors. In the present study, the author tested the spatial grouping hypothesis in three experiments in which the spatial alignment (collinearity) of the target and distractors was manipulated. Reliable alerting-congruency interactions were obtained, and congruency effects on response times were smaller for misaligned stimuli than for aligned stimuli in all experiments. However, the alerting-congruency interactions were not consistently modulated by alignment, contrary to a prediction derived from the spatial grouping hypothesis. The results suggest that spatial grouping is not a viable mechanism for explaining the alerting-congruency interaction in the flanker task, helping to prune the space of theoretical possibilities for linking alertness to cognitive control.


Assuntos
Atenção/fisiologia , Cognição/fisiologia , Processamento Espacial/fisiologia , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia
12.
Behav Neurosci ; 133(3): 282-296, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31045393

RESUMO

Localizing the source of a signal is often as important as deciphering the signal's message. Localization mechanisms must cope with the challenges of representing the spatial information of weak, noisy signals. Comparing these strategies across modalities and model systems allows a broader understanding of the general principles shaping spatial processing. In this review we focus on the electrosensory system of knifefish and provide an overview of our current understanding of spatial processing in this system, in particular, localization of conspecific signals. We argue that many mechanisms observed in other sensory systems, such as the visual or auditory systems, have comparable implementations in the electrosensory system. Our review therefore describes a field of research with unique opportunities to provide new insights into the principles underlying spatial processing. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Assuntos
Fenômenos Eletrofisiológicos/fisiologia , Comportamento Espacial/fisiologia , Processamento Espacial/fisiologia , Animais , Peixes/fisiologia , Humanos , Modelos de Interação Espacial
13.
Atten Percept Psychophys ; 81(6): 1890-1900, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31054029

RESUMO

An arrow marker appearing in a field of view shifts the observer's attention in its indicated direction. On the other hand, the gaze of another individual not only shifts the observer's attention but also increases the likability of objects in the direction of their gaze. These effects occur even when the arrow markers or gaze cues are presented for very short periods so that the observer is unaware of them. To expand on the findings of previous studies, we conducted two experiments. In the first we examined the changes in likability and attentional shift induced by supraliminal and subliminal arrow markers, using 40 male and 40 female participants. We found, contrary to previous findings, that supraliminal arrow markers not only shifted the observers' attention but slightly increased object likability. On the other hand, subliminal arrow markers only shifted the observers' attention. The attentional shift was stronger for female than for male participants in the case of supraliminal, but not of subliminal, markers. The second experiment verified the changes in likability induced by supraliminal arrow markers and compared the effects with those of supraliminal gaze cues among 40 female participants. We found that the liking effect was observed for both arrow markers and gaze cues. However, both effects were small, and no significant difference was found between them. Overall, these results show that gender and individual differences have considerable impacts on cueing effects.


Assuntos
Atenção/fisiologia , Emoções , Individualidade , Fatores Sexuais , Processamento Espacial/fisiologia , Adulto , Sinais (Psicologia) , Feminino , Fixação Ocular , Humanos , Masculino , Estimulação Luminosa/métodos , Tempo de Reação , Adulto Jovem
14.
Atten Percept Psychophys ; 81(6): 2026-2036, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31062299

RESUMO

Prior research has shown that readers may misread words by switching letters across words (e.g., the word sand in sand lane being recognized as land). These so-called letter migration errors have been observed using a divided attention paradigm whereby two words are briefly presented simultaneously, and one is postcued for identification. Letter migrations might therefore be due to a task-induced division of attention across the two words. Here, we show that a similar rate of migration errors is obtained in a flanker paradigm in which a central target word is flanked to the left and to the right by task-irrelevant flanking words. Three words were simultaneously presented for the same brief duration. Asked to type the target word postoffset, participants produced more migration errors when the migrating letter occupied the same position in the flanker and target words, with significantly fewer migrations occurring across adjacent positions, and the effect disappearing across nonadjacent positions. Our results provide further support for the hypothesis that orthographic information spanning multiple words is processed in parallel and spatially integrated (pooled) within a single channel. It is the spatial pooling of sublexical orthographic information that is thought to drive letter migration errors.


Assuntos
Atenção , Leitura , Processamento Espacial/fisiologia , Adulto , Dislexia/fisiopatologia , Dislexia/psicologia , Feminino , Humanos , Masculino , Semântica , Análise e Desempenho de Tarefas , Fatores de Tempo , Adulto Jovem
15.
J Vis ; 19(4): 4, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30943532

RESUMO

We almost never experience visual instability, despite retinal image instability induced by eye movements. How the stability of visual perception is maintained through spatiotopic representation remains a matter of debate. The discrepancies observed in the findings of existing neuroscience studies regarding spatiotopic representation partly originate from differences in regard to how attention is deployed to stimuli. In this study, we psychophysically examined whether spatial attention is needed to perceive spatiotopic visual motion. For this purpose, we used visual motion priming, which is a phenomenon in which a preceding priming stimulus modulates the perceived moving direction of an ambiguous test stimulus, such as a drifting grating that phase shifts by 180°. To examine the priming effect in different coordinates, participants performed a saccade soon after the offset of a primer. The participants were tasked with judging the direction of a subsequently presented test stimulus. To control the effect of spatial attention, the participants were asked to conduct a concurrent dot contrast-change detection task after the saccade. Positive priming was prominent in spatiotopic conditions, whereas negative priming was dominant in retinotopic conditions. At least a 600-ms interval between the priming and test stimuli was needed to observe positive priming in spatiotopic coordinates. When spatial attention was directed away from the location of the test stimulus, spatiotopic positive motion priming completely disappeared; meanwhile, the spatiotopic positive motion priming at shorter interstimulus intervals was enhanced when spatial attention was directed to the location of the test stimulus. These results provide evidence that an attentional resource is requisite for developing spatiotopic representation more quickly.


Assuntos
Atenção/fisiologia , Percepção de Movimento/fisiologia , Processamento Espacial/fisiologia , Adulto , Feminino , Humanos , Masculino , Psicofísica , Movimentos Sacádicos/fisiologia , Visão Ocular , Adulto Jovem
16.
Nat Neurosci ; 22(4): 609-617, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30911183

RESUMO

Continuous-attractor network models of grid formation posit that recurrent connectivity between grid cells controls their patterns of co-activation. Grid cells from a common module exhibit stable offsets in their periodic spatial tuning curves across environments, and this may reflect recurrent connectivity or correlated sensory inputs. Here we explore whether cell-cell relationships predicted by attractor models persist during sleep states in which spatially informative sensory inputs are absent. We recorded ensembles of grid cells in superficial layers of medial entorhinal cortex during active exploratory behaviors and overnight sleep. Per grid cell pair and collectively, and across waking, rapid eye movement sleep and non-rapid eye movement sleep, we found preserved patterns of spike-time correlations that reflected the spatial tuning offsets between these grid cells during active exploration. The preservation of cell-cell relationships across waking and sleep states was not explained by theta oscillations or activity in hippocampal subregion CA1. These results indicate that recurrent connectivity within the grid cell network drives grid cell activity across behavioral states.


Assuntos
Córtex Entorrinal/fisiologia , Células de Grade/fisiologia , Sono , Processamento Espacial/fisiologia , Potenciais de Ação , Animais , Região CA1 Hipocampal/fisiologia , Comportamento Exploratório , Masculino , Modelos Neurológicos , Atividade Motora , Ratos Long-Evans
17.
Nat Neurosci ; 22(4): 598-608, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30911185

RESUMO

The network of grid cells in the medial entorhinal cortex (MEC) forms a fixed reference frame for mapping physical space. The mechanistic origin of the grid representation is unknown, but continuous attractor network models explain multiple fundamental features of grid cell activity. An untested prediction of these models is that the grid cell network should exhibit an activity correlation structure that transcends behavioral states. By recording from MEC cell ensembles during navigation and sleep, we found that spatial phase offsets of grid cells predict arousal-state-independent spike rate correlations. Similarly, state-invariant correlations between conjunctive grid-head direction and pure head direction cells were predicted by their head direction tuning offsets during awake behavior. Grid cells were only weakly correlated across grid modules, and module scale relationships disintegrated during slow-wave sleep, suggesting that grid modules function as independent attractor networks. Collectively, our observations imply that network states in MEC are expressed universally across brain and behavior states.


Assuntos
Córtex Entorrinal/fisiologia , Células de Grade/fisiologia , Sono , Processamento Espacial/fisiologia , Potenciais de Ação , Animais , Hipocampo/fisiologia , Masculino , Ratos Long-Evans
18.
PLoS Comput Biol ; 15(2): e1006822, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30768590

RESUMO

Place cells in the mammalian hippocampus signal self-location with sparse spatially stable firing fields. Based on observation of place cell activity it is possible to accurately decode an animal's location. The precision of this decoding sets a lower bound for the amount of information that the hippocampal population conveys about the location of the animal. In this work we use a novel recurrent neural network (RNN) decoder to infer the location of freely moving rats from single unit hippocampal recordings. RNNs are biologically plausible models of neural circuits that learn to incorporate relevant temporal context without the need to make complicated assumptions about the use of prior information to predict the current state. When decoding animal position from spike counts in 1D and 2D-environments, we show that the RNN consistently outperforms a standard Bayesian approach with either flat priors or with memory. In addition, we also conducted a set of sensitivity analysis on the RNN decoder to determine which neurons and sections of firing fields were the most influential. We found that the application of RNNs to neural data allowed flexible integration of temporal context, yielding improved accuracy relative to the more commonly used Bayesian approaches and opens new avenues for exploration of the neural code.


Assuntos
Previsões/métodos , Hipocampo/fisiologia , Células de Lugar/fisiologia , Potenciais de Ação , Animais , Teorema de Bayes , Aprendizado de Máquina , Masculino , Memória , Modelos Neurológicos , Neurônios , Ratos , Ratos Endogâmicos/fisiologia , Processamento Espacial/fisiologia
19.
Vision Res ; 158: 31-39, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30721742

RESUMO

Glaucoma is traditionally considered an asymptomatic disease until later stages. However, questionnaire studies revealed visual complaints related to various tasks, especially under extreme luminance conditions (such as outdoor at night on an unlit road or outside in the sun). We measured contrast sensitivity (CS) over a luminance range of 6 log units spanning the scotopic to photopic range and we aimed (1) to determine whether Weber's law also holds under extremely high luminance conditions and (2) to compare CS as a function of spatial frequency and luminance between glaucoma patients and healthy subjects. We included 22 glaucoma patients and 51 controls, all with normal visual acuity. For the second aim, we used a subgroup of 22 age-similar controls. Vertically oriented sine-wave gratings were generated with a projector-based setup (stimulus size 8x5 degrees). CS was measured monocularly at 1, 3, and 10 cycles per degree (cpd); mean luminance ranged from 0.0085 to 8500 cd/m2. ANOVA was used to analyze the effect of glaucoma, luminance, and spatial frequency on logCS. In controls, Weber's law held for 3 and 10 cpd; for 1 cpd, CS dropped above 1000 cd/m2 (P = 0.003). The logCS versus log luminance curves did not differ grossly between patients and controls (P = 0.14; typically 0-0.2 log units); the difference became larger with decreasing luminance (P = 0.003) but did not depend clearly on spatial frequency (P = 0.27). We conclude that differences between glaucoma and healthy were relatively modest for the spatially redundant, static stimulus as used in the current study.


Assuntos
Visão de Cores/fisiologia , Sensibilidades de Contraste/fisiologia , Glaucoma de Ângulo Aberto/fisiopatologia , Visão Noturna/fisiologia , Retina/fisiologia , Processamento Espacial/fisiologia , Idoso , Estudos de Casos e Controles , Estudos Transversais , Feminino , Voluntários Saudáveis , Humanos , Pressão Intraocular/fisiologia , Masculino , Pessoa de Meia-Idade , Luz Solar , Acuidade Visual
20.
Nature ; 566(7745): 533-537, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30742074

RESUMO

Hippocampal place cells are spatially tuned neurons that serve as elements of a 'cognitive map' in the mammalian brain1. To detect the animal's location, place cells are thought to rely upon two interacting mechanisms: sensing the position of the animal relative to familiar landmarks2,3 and measuring the distance and direction that the animal has travelled from previously occupied locations4-7. The latter mechanism-known as path integration-requires a finely tuned gain factor that relates the animal's self-movement to the updating of position on the internal cognitive map, as well as external landmarks to correct the positional error that accumulates8,9. Models of hippocampal place cells and entorhinal grid cells based on path integration treat the path-integration gain as a constant9-14, but behavioural evidence in humans suggests that the gain is modifiable15. Here we show, using physiological evidence from rat hippocampal place cells, that the path-integration gain is a highly plastic variable that can be altered by persistent conflict between self-motion cues and feedback from external landmarks. In an augmented-reality system, visual landmarks were moved in proportion to the movement of a rat on a circular track, creating continuous conflict with path integration. Sustained exposure to this cue conflict resulted in predictable and prolonged recalibration of the path-integration gain, as estimated from the place cells after the landmarks were turned off. We propose that this rapid plasticity keeps the positional update in register with the movement of the rat in the external world over behavioural timescales. These results also demonstrate that visual landmarks not only provide a signal to correct cumulative error in the path-integration system4,8,16-19, but also rapidly fine-tune the integration computation itself.


Assuntos
Hipocampo/citologia , Plasticidade Neuronal/fisiologia , Células de Lugar/citologia , Células de Lugar/fisiologia , Processamento Espacial/fisiologia , Animais , Sinais (Psicologia) , Retroalimentação Fisiológica , Células de Grade/citologia , Células de Grade/fisiologia , Hipocampo/fisiologia , Masculino , Ratos , Ratos Long-Evans , Navegação Espacial/fisiologia
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