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1.
Nat Commun ; 12(1): 4839, 2021 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-34376673

RESUMO

The ability to maintain a sequence of items in memory is a fundamental cognitive function. In the rodent hippocampus, the representation of sequentially organized spatial locations is reflected by the phase of action potentials relative to the theta oscillation (phase precession). We investigated whether the timing of neuronal activity relative to the theta brain oscillation also reflects sequence order in the medial temporal lobe of humans. We used a task in which human participants learned a fixed sequence of pictures and recorded single neuron and local field potential activity with implanted electrodes. We report that spikes for three consecutive items in the sequence (the preferred stimulus for each cell, as well as the stimuli immediately preceding and following it) were phase-locked at distinct phases of the theta oscillation. Consistent with phase precession, spikes were fired at progressively earlier phases as the sequence advanced. These findings generalize previous findings in the rodent hippocampus to the human temporal lobe and suggest that encoding stimulus information at distinct oscillatory phases may play a role in maintaining sequential order in memory.


Assuntos
Potenciais de Ação/fisiologia , Epilepsia/fisiopatologia , Aprendizagem/fisiologia , Neurônios/fisiologia , Ritmo Teta/fisiologia , Adolescente , Adulto , Epilepsia/diagnóstico , Feminino , Hipocampo/citologia , Hipocampo/fisiologia , Humanos , Masculino , Modelos Neurológicos , Neurônios/citologia , Estimulação Luminosa/métodos , Lobo Temporal/citologia , Lobo Temporal/fisiologia , Adulto Jovem
2.
Nat Commun ; 12(1): 4816, 2021 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-34376652

RESUMO

Remapping refers to a decorrelation of hippocampal representations of similar spatial environments. While it has been speculated that remapping may contribute to the resolution of episodic memory interference in humans, direct evidence is surprisingly limited. We tested this idea using high-resolution, pattern-based fMRI analyses. Here we show that activity patterns in human CA3/dentate gyrus exhibit an abrupt, temporally-specific decorrelation of highly similar memory representations that is precisely coupled with behavioral expressions of successful learning. The magnitude of this learning-related decorrelation was predicted by the amount of pattern overlap during initial stages of learning, with greater initial overlap leading to stronger decorrelation. Finally, we show that remapped activity patterns carry relatively more information about learned episodic associations compared to competing associations, further validating the learning-related significance of remapping. Collectively, these findings establish a critical link between hippocampal remapping and episodic memory interference and provide insight into why remapping occurs.


Assuntos
Potenciais de Ação/fisiologia , Região CA3 Hipocampal/fisiologia , Giro Denteado/fisiologia , Aprendizagem/fisiologia , Memória/fisiologia , Adolescente , Adulto , Mapeamento Encefálico/métodos , Região CA3 Hipocampal/diagnóstico por imagem , Giro Denteado/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Estimulação Luminosa/métodos , Adulto Jovem
3.
FASEB J ; 35(9): e21802, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34383984

RESUMO

Mutations in transcription factors often exhibit pleiotropic effects related to their complex expression patterns and multiple regulatory targets. One such mutation in the zinc finger homeobox 3 (ZFHX3) transcription factor, short circuit (Sci, Zfhx3Sci/+ ), is associated with significant circadian deficits in mice. However, given evidence of its retinal expression, we set out to establish the effects of the mutation on retinal function using molecular, cellular, behavioral and electrophysiological measures. Immunohistochemistry confirms the expression of ZFHX3 in multiple retinal cell types, including GABAergic amacrine cells and retinal ganglion cells including intrinsically photosensitive retinal ganglion cells (ipRGCs). Zfhx3Sci/+ mutants display reduced light responsiveness in locomotor activity and circadian entrainment, relatively normal electroretinogram and optomotor responses but exhibit an unexpected pupillary reflex phenotype with markedly increased sensitivity. Furthermore, multiple electrode array recordings of Zfhx3Sci/+ retina show an increased sensitivity of ipRGC light responses.


Assuntos
Ritmo Circadiano/fisiologia , Proteínas de Homeodomínio/metabolismo , Retina/metabolismo , Células Amácrinas/metabolismo , Animais , Luz , Locomoção/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estimulação Luminosa/métodos , Células Ganglionares da Retina/metabolismo , Visão Ocular/fisiologia
4.
Neuron ; 109(16): 2616-2626.e6, 2021 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-34228960

RESUMO

Vision develops rapidly during infancy, yet how visual cortex is organized during this period is unclear. In particular, it is unknown whether functional maps that organize the mature adult visual cortex are present in the infant striate and extrastriate cortex. Here, we test the functional maturity of infant visual cortex by performing retinotopic mapping with functional magnetic resonance imaging (fMRI). Infants aged 5-23 months had retinotopic maps, with alternating preferences for vertical and horizontal meridians indicating the boundaries of visual areas V1 to V4 and an orthogonal gradient of preferences from high to low spatial frequencies. The presence of multiple visual maps throughout visual cortex in infants indicates a greater maturity of extrastriate cortex than previously appreciated. The areas showed subtle age-related fine-tuning, suggesting that early maturation undergoes continued refinement. This early maturation of area boundaries and tuning may scaffold subsequent developmental changes.


Assuntos
Encéfalo/crescimento & desenvolvimento , Córtex Visual/crescimento & desenvolvimento , Campos Visuais/fisiologia , Vias Visuais/crescimento & desenvolvimento , Mapeamento Encefálico/métodos , Feminino , Humanos , Lactente , Imageamento por Ressonância Magnética/métodos , Masculino , Estimulação Luminosa/métodos
5.
Nat Commun ; 12(1): 3374, 2021 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-34099735

RESUMO

Numerosity, the set size of a group of items, helps guide behaviour and decisions. Non-symbolic numerosities are represented by the approximate number system. However, distinct behavioural performance suggests that small numerosities, i.e. subitizing range, are implemented differently in the brain than larger numerosities. Prior work has shown that neural populations selectively responding (i.e. hemodynamic responses) to small numerosities are organized into a network of topographical maps. Here, we investigate how neural populations respond to large numerosities, well into the ANS. Using 7 T fMRI and biologically-inspired analyses, we found a network of neural populations tuned to both small and large numerosities organized within the same topographic maps. These results demonstrate a continuum of numerosity preferences that progressively cover both the subitizing range and beyond within the same numerosity map, suggesting a single neural mechanism. We hypothesize that differences in map properties, such as cortical magnification and tuning width, underlie known differences in behaviour.


Assuntos
Mapeamento Encefálico/métodos , Encéfalo/fisiologia , Rede Nervosa/fisiologia , Percepção Visual/fisiologia , Adulto , Encéfalo/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Rede Nervosa/diagnóstico por imagem , Estimulação Luminosa/métodos , Reprodutibilidade dos Testes
6.
PLoS Biol ; 19(5): e3001241, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33951043

RESUMO

The study of unconscious processing requires a measure of conscious awareness. Awareness measures can be either subjective (based on participant's report) or objective (based on perceptual performance). The preferred awareness measure depends on the theoretical position about consciousness and may influence conclusions about the extent of unconscious processing and about the neural correlates of consciousness. We obtained functional magnetic resonance imaging (fMRI) measurements from 43 subjects while they viewed masked faces and houses that were either subjectively or objectively invisible. Even for objectively invisible (perceptually indiscriminable) stimuli, we found significant category information in both early, lower-level visual areas and in higher-level visual cortex, although representations in anterior, category-selective ventrotemporal areas were less robust. For subjectively invisible stimuli, similar to visible stimuli, there was a clear posterior-to-anterior gradient in visual cortex, with stronger category information in ventrotemporal cortex than in early visual cortex. For objectively invisible stimuli, however, category information remained virtually unchanged from early visual cortex to object- and category-selective visual areas. These results demonstrate that although both objectively and subjectively invisible stimuli are represented in visual cortex, the extent of unconscious information processing is influenced by the measurement approach. Furthermore, our data show that subjective and objective approaches are associated with different neural correlates of consciousness and thus have implications for neural theories of consciousness.


Assuntos
Conscientização/fisiologia , Visão Ocular/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Córtex Cerebral/fisiologia , Estado de Consciência/fisiologia , Feminino , Substância Cinzenta/fisiologia , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Estimulação Luminosa/métodos , Córtex Visual/fisiologia , Adulto Jovem
7.
Commun Biol ; 4(1): 559, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33976360

RESUMO

The brain naturally resolves the challenge of integrating auditory and visual signals produced by the same event despite different physical propagation speeds and neural processing latencies. Temporal recalibration manifests in human perception to realign incoming signals across the senses. Recent behavioral studies show it is a fast-acting phenomenon, relying on the most recent exposure to audiovisual asynchrony. Here we show that the physiological mechanism of rapid, context-dependent recalibration builds on interdependent pre-stimulus cortical rhythms in sensory brain regions. Using magnetoencephalography, we demonstrate that individual recalibration behavior is related to subject-specific properties of fast oscillations (>35 Hz) nested within a slower alpha rhythm (8-12 Hz) in auditory cortex. We also show that the asynchrony of a previously presented audiovisual stimulus pair alters the preferred coupling phase of these fast oscillations along the alpha cycle, with a resulting phase-shift amounting to the temporal recalibration observed behaviorally. These findings suggest that cross-frequency coupled oscillations contribute to forming unified percepts across senses.


Assuntos
Percepção Auditiva/fisiologia , Sincronização Cortical/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica/métodos , Adaptação Fisiológica/fisiologia , Adulto , Córtex Auditivo/fisiologia , Encéfalo/fisiologia , Ondas Encefálicas/fisiologia , Feminino , Humanos , Julgamento/fisiologia , Magnetoencefalografia/métodos , Masculino , Estimulação Luminosa/métodos , Fatores de Tempo , Córtex Visual/fisiologia
8.
Medicine (Baltimore) ; 100(21): e25823, 2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34032696

RESUMO

ABSTRACT: Sexual dysfunction is a common problem after cerebral infarction; however, little is known about sexual arousal in poststroke patients. Thus, this study aimed to investigate brain activation in response to visual sexual stimuli in patients with right middle cerebral artery (MCA) territory infarction using functional magnetic resonance imaging (fMRI). Using fMRI in 20 participants (11 right MCA infarction patients and 9 age-matched healthy controls), we assessed brain activation elicited by visual sexual stimuli (erotic images) and visual nonsexual stimuli (landscape images). In right MCA infarction patients, the left dorsolateral prefrontal cortex and the left frontal subgyral area were more strongly activated by visual sexual stimuli than by nonvisual sexual stimuli. Brain areas that were more activated by visual sexual stimuli in right MCA infarction patients than in controls included the right parahippocampal gyrus and the bilateral frontal subgyral area. These fMRI results suggest that brain activation patterns in response to visual sexual stimuli might be influenced by right MCA infarction. Further research is needed to explore the association between sexual dysfunction and brain activation in poststroke patients.


Assuntos
Encéfalo/fisiopatologia , Infarto da Artéria Cerebral Média/complicações , Comportamento Sexual/fisiologia , Disfunções Sexuais Fisiológicas/fisiopatologia , Percepção Visual/fisiologia , Adulto , Idoso , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Estudos de Casos e Controles , Literatura Erótica , Humanos , Infarto da Artéria Cerebral Média/fisiopatologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Disfunções Sexuais Fisiológicas/etiologia
9.
Nat Commun ; 12(1): 2930, 2021 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-34006884

RESUMO

The neural mechanisms underlying conscious recognition remain unclear, particularly the roles played by the prefrontal cortex, deactivated brain areas and subcortical regions. We investigated neural activity during conscious object recognition using 7 Tesla fMRI while human participants viewed object images presented at liminal contrasts. Here, we show both recognized and unrecognized images recruit widely distributed cortical and subcortical regions; however, recognized images elicit enhanced activation of visual, frontoparietal, and subcortical networks and stronger deactivation of the default-mode network. For recognized images, object category information can be decoded from all of the involved cortical networks but not from subcortical regions. Phase-scrambled images trigger strong involvement of inferior frontal junction, anterior cingulate cortex and default-mode network, implicating these regions in inferential processing under increased uncertainty. Our results indicate that content-specific activity in both activated and deactivated cortical networks and non-content-specific subcortical activity support conscious recognition.


Assuntos
Encéfalo/fisiologia , Córtex Cerebral/fisiologia , Estado de Consciência/fisiologia , Reconhecimento Psicológico/fisiologia , Córtex Visual/fisiologia , Adulto , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Córtex Cerebral/diagnóstico por imagem , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Rede Nervosa/diagnóstico por imagem , Rede Nervosa/fisiologia , Estimulação Luminosa/métodos , Córtex Visual/diagnóstico por imagem , Adulto Jovem
10.
PLoS One ; 16(4): e0234219, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33852575

RESUMO

Category-specific impairments witnessed in patients with semantic deficits have broadly dissociated into natural and artificial kinds. However, how the category of food (more specifically, fruits and vegetables) fits into this distinction has been difficult to interpret, given a pattern of deficit that has inconsistently mapped onto either kind, despite its intuitive membership to the natural domain. The present study explores the effects of a manipulation of a visual sensory (i.e., color) or functional (i.e., orientation) feature on the consequential semantic processing of fruits and vegetables (and tools, by comparison), first at the behavioral and then at the neural level. The categorization of natural (i.e., fruits/vegetables) and artificial (i.e., utensils) entities was investigated via cross-modal priming. Reaction time analysis indicated a reduction in priming for color-modified natural entities and orientation-modified artificial entities. Standard event-related potentials (ERP) analysis was performed, in addition to linear classification. For natural entities, a N400 effect at central channel sites was observed for the color-modified condition compared relative to normal and orientation conditions, with this difference confirmed by classification analysis. Conversely, there was no significant difference between conditions for the artificial category in either analysis. These findings provide strong evidence that color is an integral property to the categorization of fruits/vegetables, thus substantiating the claim that feature-based processing guides as a function of semantic category.


Assuntos
Cognição/fisiologia , Semântica , Percepção Visual/fisiologia , Adolescente , Adulto , Mapeamento Encefálico/métodos , Cor , Eletroencefalografia , Potenciais Evocados/fisiologia , Potenciais Evocados Visuais/fisiologia , Feminino , Alimentos , Frutas , Humanos , Masculino , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Adulto Jovem
11.
Exp Eye Res ; 206: 108556, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33794198

RESUMO

PURPOSE: The macaque retina is often used as a model for the human retina. However, there are only a handful of direct in vivo comparisons of the retinal physiology in humans and macaques. In the current study, ERG responses to luminance, L-cone isolating and M-cone isolating stimuli with sinusoidal, sawtooth and square wave temporal profiles were measured. The results were compared with those obtained from human observers. METHODS: The responses from five anesthetized adult macaques were measured. Full field stimuli were created. L- and M-cone isolating stimuli were based on the triple silent substitution technique. Sinusoidal stimuli had temporal frequencies between 4 and 56 Hz in 4 Hz steps. Sawtooth stimuli with rapid-on ramp-off and with rapid-off ramp-on excitation profiles had a frequency of 4 Hz. Square stimuli were presented at 2 Hz. RESULTS: Macaque and human ERGs in response to L- and M-cone isolating stimuli reflect L/M opponency and luminance activity. In responses to sine waves, cone opponency dominates at low temporal frequencies (4-12 Hz); luminance dominates at high temporal frequencies. The responses to sawtooth and square wave stimuli reflect a mixture of chromatic and luminance activity. L:M response ratios vary between individuals both in macaques and humans. Macaques show more complex responses, including greater second harmonic contributions than those in humans. CONCLUSIONS: Macaque and human ERGs share basic underlying mechanisms reflecting L/M opponency and luminance activity. There may be quantitative differences possibly reflecting differences in contributions of inner retinal mechanisms to the ERGs.


Assuntos
Eletrorretinografia/métodos , Células Fotorreceptoras Retinianas Cones/fisiologia , Animais , Macaca , Modelos Animais , Estimulação Luminosa/métodos
12.
Elife ; 102021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33827753

RESUMO

Self-motion signals, distributed ubiquitously across parietal-temporal lobes, propagate to limbic hippocampal system for vector-based navigation via hubs including posterior cingulate cortex (PCC) and retrosplenial cortex (RSC). Although numerous studies have indicated posterior cingulate areas are involved in spatial tasks, it is unclear how their neurons represent self-motion signals. Providing translation and rotation stimuli to macaques on a 6-degree-of-freedom motion platform, we discovered robust vestibular responses in PCC. A combined three-dimensional spatiotemporal model captured data well and revealed multiple temporal components including velocity, acceleration, jerk, and position. Compared to PCC, RSC contained moderate vestibular temporal modulations and lacked significant spatial tuning. Visual self-motion signals were much weaker in both regions compared to the vestibular signals. We conclude that macaque posterior cingulate region carries vestibular-dominant self-motion signals with plentiful temporal components that could be useful for path integration.


Assuntos
Giro do Cíngulo/fisiologia , Percepção de Movimento , Propriocepção , Animais , Movimentos da Cabeça , Macaca mulatta , Masculino , Movimento (Física) , Neurônios/metabolismo , Estimulação Luminosa/métodos , Lobo Temporal/fisiologia , Vestíbulo do Labirinto/fisiologia , Realidade Virtual , Córtex Visual/fisiologia , Análise de Ondaletas
13.
Nat Neurosci ; 24(6): 843-850, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33875892

RESUMO

Decisions are held in memory until enacted, which makes them potentially vulnerable to distracting sensory input. Gating of information flow from sensory to motor areas could protect memory from interference during decision-making, but the underlying network mechanisms are not understood. Here, we trained mice to detect optogenetic stimulation of the somatosensory cortex, with a delay separating sensation and action. During the delay, distracting stimuli lost influence on behavior over time, even though distractor-evoked neural activity percolated through the cortex without attenuation. Instead, choice-encoding activity in the motor cortex became progressively less sensitive to the impact of distractors. Reverse engineering of neural networks trained to reproduce motor cortex activity revealed that the reduction in sensitivity to distractors was caused by a growing separation in the neural activity space between attractors that encode alternative decisions. Our results show that communication between brain regions can be gated via attractor dynamics, which control the degree of commitment to an action.


Assuntos
Atenção/fisiologia , Tomada de Decisões/fisiologia , Estimulação Luminosa/métodos , Filtro Sensorial/fisiologia , Córtex Somatossensorial/fisiologia , Potenciais de Ação/fisiologia , Animais , Camundongos , Camundongos Transgênicos
14.
Psychopharmacology (Berl) ; 238(8): 2179-2189, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33846866

RESUMO

RATIONALE: Alcohol use disorder is a common and devastating mental illness for which satisfactory treatments are still lacking. Nalmefene, as an opioid receptor modulator, could pharmacologically support the reduction of drinking by reducing the (anticipated) rewarding effects of alcohol and expanding the range of treatment options. It has been hypothesized that nalmefene acts via an indirect modulation of the mesolimbic reward system. So far, only a few imaging findings on the neuronal response to nalmefene are available. OBJECTIVES: We tested the effect of a single dose of 18 mg nalmefene on neuronal cue-reactivity in the ventral and dorsal striatum and subjective craving. METHODS: Eighteen non-treatment-seeking participants with alcohol use disorder (67% male, M = 50.3 ± 13.9 years) with a current high-risk drinking level (M = 76.9 ± 52 g of pure alcohol per day) were investigated using a cue-reactivity task during functional magnetic resonance imaging (fMRI) in a double-blind, placebo-controlled, cross-over study/design. In addition, self-reported craving was assessed before and after exposure to alcohol cues. RESULTS: An a priori defined region of interest (ROI) analysis of fMRI data from 15 participants revealed that nalmefene reduced alcohol cue-reactivity in the ventral, but not the dorsal striatum. Additionally, the subjective craving was significantly reduced after the cue-reactivity task under nalmefene compared to placebo. CONCLUSION: In the present study, reduced craving and cue-reactivity to alcohol stimuli in the ventral striatum by nalmefene indicates a potential anti-craving effect of this drug via attenuation of neural alcohol cue-reactivity.


Assuntos
Alcoolismo/tratamento farmacológico , Fissura/efeitos dos fármacos , Sinais (Psicologia) , Naltrexona/análogos & derivados , Estriado Ventral/efeitos dos fármacos , Adulto , Alcoolismo/diagnóstico por imagem , Alcoolismo/psicologia , Fissura/fisiologia , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Naltrexona/farmacologia , Naltrexona/uso terapêutico , Antagonistas de Entorpecentes/farmacologia , Antagonistas de Entorpecentes/uso terapêutico , Estimulação Luminosa/métodos , Estudos Prospectivos , Estriado Ventral/diagnóstico por imagem , Estriado Ventral/fisiologia , Adulto Jovem
15.
Nat Commun ; 12(1): 2003, 2021 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-33790282

RESUMO

Understanding how activity of visual neurons represents distinct components of attention and their dynamics that account for improved visual performance remains elusive because single-unit experiments have not isolated the intensive aspect of attention from attentional selectivity. We isolated attentional intensity and its single trial dynamics as determined by spatially non-selective attentional performance in an orientation discrimination task while recording from neurons in monkey visual area V4. We found that attentional intensity is a distinct cognitive signal that can be distinguished from spatial selectivity, reward expectations and motor actions. V4 spiking on single trials encodes a combination of sensory and cognitive signals on different time scales. Attentional intensity and the detection of behaviorally relevant sensory signals are well represented, but immediate reward expectation and behavioral choices are poorly represented in V4 spiking. These results provide a detailed representation of perceptual and cognitive signals in V4 that are crucial for attentional performance.


Assuntos
Algoritmos , Atenção/fisiologia , Macaca mulatta/fisiologia , Neurônios/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Animais , Fenômenos Eletrofisiológicos , Modelos Lineares , Masculino , Estimulação Luminosa/métodos , Pupila/fisiologia , Córtex Visual/citologia
16.
Nat Commun ; 12(1): 2315, 2021 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-33875667

RESUMO

The clustering of neurons with similar response properties is a conspicuous feature of neocortex. In primary visual cortex (V1), maps of several properties like orientation preference are well described, but the functional architecture of color, central to visual perception in trichromatic primates, is not. Here we used two-photon calcium imaging in macaques to examine the fine structure of chromatic representation and found that neurons responsive to spatially uniform, chromatic stimuli form unambiguous clusters that coincide with blobs. Further, these responsive groups have marked substructure, segregating into smaller ensembles or micromaps with distinct chromatic signatures that appear columnar in upper layer 2/3. Spatially structured chromatic stimuli revealed maps built on the same micromap framework but with larger subdomains that go well beyond blobs. We conclude that V1 has an architecture for color representation that switches between blobs and a combined blob/interblob system based on the spatial content of the visual scene.


Assuntos
Percepção de Cores/fisiologia , Macaca mulatta/fisiologia , Neurônios/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Animais , Cor , Feminino , Masculino , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Estimulação Luminosa/métodos , Córtex Visual/citologia
17.
J Alzheimers Dis ; 80(3): 1169-1183, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33646149

RESUMO

BACKGROUND: Alzheimer's disease (AD) is a chronic, neurodegenerative disease resulting in a progressive decline of autobiographical memories (AMs) which favors the development of psycho-behavioral disorders. One of the most popular psychosocial interventions in dementia care, Reminiscence Therapy, commonly uses sensory cueing to stimulate AMs retrieval. However, few empirical studies have investigated the impact of sensory stimulation on AMs retrieval in AD. OBJECTIVE: Our goal was to determine the most relevant cue for AMs retrieval in patients with early to mild AD when comparing odors, sounds and pictures. METHODS: Sixty AD patients, 60 healthy older adults (OA), and 60 healthy young adults (YA) participated in our study. Participants were presented with either 4 odors, 4 sounds, or 4 pictures. For each stimulus, they were asked to retrieve a personal memory, to rate it across 3 dimensions (emotionality, vividness, rarity) and then to date it. RESULTS: Overall, results showed no clear dominance of one sensory modality over the others in evoking higher-quality AMs. However, they show that using pictures is the better way to stimulate AD patients' AM, as it helps to retrieve a higher number of memories that are also less frequently retrieved, followed by odors. By contrast, auditory cueing with environmental sounds presented no true advantage. CONCLUSION: Our data should help dementia care professionals to increase the efficiency of Reminiscence Therapy using sensory elicitors. Other clinical implications and future directions are also discussed.


Assuntos
Estimulação Acústica/métodos , Doença de Alzheimer/fisiopatologia , Sinais (Psicologia) , Memória Episódica , Estimulação Luminosa/métodos , Olfato/fisiologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Envelhecimento Saudável , Humanos , Masculino , Odorantes , Percepção Olfatória/fisiologia , Adulto Jovem
18.
J Neurosci ; 41(14): 3180-3191, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33653697

RESUMO

Past work has demonstrated that active suppression of salient distractors is a critical part of visual selection. Evidence for goal-driven suppression includes below-baseline visual encoding at the position of salient distractors (Gaspelin and Luck, 2018) and neural signals such as the distractor positivity (Pd) that track how many distractors are presented in a given hemifield (Feldmann-Wüstefeld and Vogel, 2019). One basic question regarding distractor suppression is whether it is inherently spatial or nonspatial in character. Indeed, past work has shown that distractors evoke both spatial (Theeuwes, 1992) and nonspatial forms of interference (Folk and Remington, 1998), motivating a direct examination of whether space is integral to goal-driven distractor suppression. Here, we use behavioral and EEG data from adult humans (male and female) to provide clear evidence for a spatial gradient of suppression surrounding salient singleton distractors. Replicating past work, both reaction time and neural indices of target selection improved monotonically as the distance between target and distractor increased. Importantly, these target selection effects were paralleled by a monotonic decline in the amplitude of the Pd, an electrophysiological index of distractor suppression. Moreover, multivariate analyses revealed spatially selective activity in the θ-band that tracked the position of the target and, critically, revealed suppressed activity at spatial channels centered on distractor positions. Thus, goal-driven selection of relevant over irrelevant information benefits from a spatial gradient of suppression surrounding salient distractors.SIGNIFICANCE STATEMENT Past work has shown that distractor suppression is an important part of goal-driven attentional selection, but has not yet revealed whether suppression is spatially directed. Using behavioral data, event-related potentials (ERPs) of the EEG signal [N2pc and distractor positivity (Pd) component], as well as a multivariate model of EEG data [channel tuning functions (CTF)], we show that suppression-related neural activity increases monotonically as the distance between targets and distractors decreases, and that spatially-selective activity in the θ-band reveals depressed activity in spatial channels that index distractor positions. Thus, we provide robust evidence for spatially-guided distractor suppression, a result that has important implications for models of goal-driven attentional control.


Assuntos
Atenção/fisiologia , Potenciais Evocados Visuais/fisiologia , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Percepção Espacial/fisiologia , Adolescente , Adulto , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Percepção Visual/fisiologia , Adulto Jovem
19.
Nat Commun ; 12(1): 1900, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33772000

RESUMO

The computations performed by a neural circuit depend on how it integrates its input signals into an output of its own. In the retina, ganglion cells integrate visual information over time, space, and chromatic channels. Unlike the former two, chromatic integration is largely unexplored. Analogous to classical studies of spatial integration, we here study chromatic integration in mouse retina by identifying chromatic stimuli for which activation from the green or UV color channel is maximally balanced by deactivation through the other color channel. This reveals nonlinear chromatic integration in subsets of On, Off, and On-Off ganglion cells. Unlike the latter two, nonlinear On cells display response suppression rather than activation under balanced chromatic stimulation. Furthermore, nonlinear chromatic integration occurs independently of nonlinear spatial integration, depends on contributions from the rod pathway and on surround inhibition, and may provide information about chromatic boundaries, such as the skyline in natural scenes.


Assuntos
Potenciais de Ação/fisiologia , Retina/fisiologia , Células Ganglionares da Retina/fisiologia , Campos Visuais/fisiologia , Vias Visuais/fisiologia , Potenciais de Ação/efeitos dos fármacos , Algoritmos , Animais , Cor , Feminino , HEPES/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Dinâmica não Linear , Estimulação Luminosa/métodos , Piridazinas/farmacologia , Retina/citologia , Estricnina/farmacologia
20.
PLoS Comput Biol ; 17(3): e1007957, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33651790

RESUMO

There are two distinct classes of cells in the primary visual cortex (V1): simple cells and complex cells. One defining feature of complex cells is their spatial phase invariance; they respond strongly to oriented grating stimuli with a preferred orientation but with a wide range of spatial phases. A classical model of complete spatial phase invariance in complex cells is the energy model, in which the responses are the sum of the squared outputs of two linear spatially phase-shifted filters. However, recent experimental studies have shown that complex cells have a diverse range of spatial phase invariance and only a subset can be characterized by the energy model. While several models have been proposed to explain how complex cells could learn to be selective to orientation but invariant to spatial phase, most existing models overlook many biologically important details. We propose a biologically plausible model for complex cells that learns to pool inputs from simple cells based on the presentation of natural scene stimuli. The model is a three-layer network with rate-based neurons that describes the activities of LGN cells (layer 1), V1 simple cells (layer 2), and V1 complex cells (layer 3). The first two layers implement a recently proposed simple cell model that is biologically plausible and accounts for many experimental phenomena. The neural dynamics of the complex cells is modeled as the integration of simple cells inputs along with response normalization. Connections between LGN and simple cells are learned using Hebbian and anti-Hebbian plasticity. Connections between simple and complex cells are learned using a modified version of the Bienenstock, Cooper, and Munro (BCM) rule. Our results demonstrate that the learning rule can describe a diversity of complex cells, similar to those observed experimentally.


Assuntos
Aprendizagem , Neurônios/fisiologia , Córtex Visual/fisiologia , Animais , Comunicação Celular , Corpos Geniculados/citologia , Corpos Geniculados/fisiologia , Modelos Neurológicos , Plasticidade Neuronal , Estimulação Luminosa/métodos , Córtex Visual/citologia
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