Development of the mirror-image sensitivity for different object categories-Evidence from the mirror costs of object images in children and adults.

Object recognition relies on a multitude of factors, including size, orientation, and so on. Mirrored orientation, particularly due to children's mirror confusion in reading, holds special significance among various object orientations. Brain imaging studies suggest that the visual ventral and dorsal streams exhibit distinct orientation sensitivity across diverse object categories. Yet, it remains unclear whether mirror orientation sensitivity also varies among these categories during development at the behavioral level. Here, we explored the mirror sensitivity of children and adults across five distinct categories, which encompass tools that activate both the visual ventral stream for function information and the dorsal stream for manipulation information, and animals and faces that mainly activate the ventral stream. Two types of symbols, letters and Chinese characters, were also included. Mirror sensitivity was assessed through mirror costs-that is, the additional reaction time or error rate in the mirrored versus the same orientation condition when judging the identity of object pairs. The mirror costs in reaction times and error rates consistently revealed that children exhibited null mirror costs for tools, and the mirror costs for tools in adults were minimal, if any, and were smaller than those for letters and characters. The mirror costs reflected in absolute reaction time and error rate were similar across adults and children, but when the overall difference in reaction times was considered, adults showed a larger mirror cost than children. Overall, our investigation unveils categorical distinctions and development in mirror sensitivity of object recognition across the ventral and dorsal streams.

Web-based language production experiments: Semantic interference assessment is robust for spoken and typed response modalities.

For experimental research on language production, temporal precision and high quality of the recorded audio files are imperative. These requirements are a considerable challenge if language production is to be investigated online. However, online research has huge potential in terms of efficiency, ecological validity and diversity of study populations in psycholinguistic and related research, also beyond the current situation. Here, we supply confirmatory evidence that language production can be investigated online and that reaction time (RT) distributions and error rates are similar in written naming responses (using the keyboard) and typical overt spoken responses. To assess semantic interference effects in both modalities, we performed two pre-registered experiments (n = 30 each) in online settings using the participants' web browsers. A cumulative semantic interference (CSI) paradigm was employed that required naming several exemplars of semantic categories within a seemingly unrelated sequence of objects. RT is expected to increase linearly for each additional exemplar of a category. In Experiment 1, CSI effects in naming times described in lab-based studies were replicated. In Experiment 2, the responses were typed on participants' computer keyboards, and the first correct key press was used for RT analysis. This novel response assessment yielded a qualitatively similar, very robust CSI effect. Besides technical ease of application, collecting typewritten responses and automatic data preprocessing substantially reduce the work load for language production research. Results of both experiments open new perspectives for research on RT effects in language experiments across a wide range of contexts. JavaScript- and R-based implementations for data collection and processing are available for download.

Effects of horizontal displacement and inter-character spacing on transposed-character effects in same-different matching.

In two same-different matching experiments we investigated whether transposed-character effects can be modulated by the horizontal displacement or inter-character spacing of target stimuli (strings of 6 consonants, digits, or symbols). Reference and target stimuli could be identical or differed either by transposing or substituting two characters. Transposition costs (greater difficulty in detecting a difference with transpositions compared with substitutions) were greater for letter stimuli compared to both digit and symbol stimuli in both experiments. In Experiment 1, half of the targets were displayed at the center of the screen and the other half were shifted by two character-positions to the left or to the right, whereas the reference was always presented at the center of the screen. Target displacement made the task harder and caused an increase in transposition costs whatever the type of stimulus. In Experiment 2, all stimuli were presented at the center of the screen and the inter-character spacing of target stimuli was increased by one character space on half of the trials. Increased spacing made the task harder and paradoxically caused an increase in transposition costs, but only significantly so for letter stimuli, and only in the discriminability (d') measure. These results suggest that target location and inter-character spacing manipulations caused an increase in positional uncertainty during the processing of location-specific complex features prior to activation of a location-invariant representation of character-in-string order. The hypothesized existence of a letter-specific order encoding mechanism accounts for the greater transposition costs seen with letter stimuli, as well as the greater modulation of these effects by an increase in inter-character spacing seen in discriminability (d').

Similarities and disparities between visual analysis and high-resolution electromyography of facial expressions.

Computer vision (CV) is widely used in the investigation of facial expressions. Applications range from psychological evaluation to neurology, to name just two examples. CV for identifying facial expressions may suffer from several shortcomings: CV provides indirect information about muscle activation, it is insensitive to activations that do not involve visible deformations, such as jaw clenching. Moreover, it relies on high-resolution and unobstructed visuals. High density surface electromyography (sEMG) recordings with soft electrode array is an alternative approach which provides direct information about muscle activation, even from freely behaving humans. In this investigation, we compare CV and sEMG analysis of facial muscle activation. We used independent component analysis (ICA) and multiple linear regression (MLR) to quantify the similarity and disparity between the two approaches for posed muscle activations. The comparison reveals similarity in event detection, but discrepancies and inconsistencies in source identification. Specifically, the correspondence between sEMG and action unit (AU)-based analyses, the most widely used basis of CV muscle activation prediction, appears to vary between participants and sessions. We also show a comparison between AU and sEMG data of spontaneous smiles, highlighting the differences between the two approaches. The data presented in this paper suggests that the use of AU-based analysis should consider its limited ability to reliably compare between different sessions and individuals and highlight the advantages of high-resolution sEMG for facial expression analysis.

Rapid online assessment of reading ability.

An accurate model of the factors that contribute to individual differences in reading ability depends on data collection in large, diverse and representative samples of research participants. However, that is rarely feasible due to the constraints imposed by standardized measures of reading ability which require test administration by trained clinicians or researchers. Here we explore whether a simple, two-alternative forced choice, time limited lexical decision task (LDT), self-delivered through the web-browser, can serve as an accurate and reliable measure of reading ability. We found that performance on the LDT is highly correlated with scores on standardized measures of reading ability such as the Woodcock-Johnson Letter Word Identification test (r = 0.91, disattenuated r = 0.94). Importantly, the LDT reading ability measure is highly reliable (r = 0.97). After optimizing the list of words and pseudowords based on item response theory, we found that a short experiment with 76 trials (2-3 min) provides a reliable (r = 0.95) measure of reading ability. Thus, the self-administered, Rapid Online Assessment of Reading ability (ROAR) developed here overcomes the constraints of resource-intensive, in-person reading assessment, and provides an efficient and automated tool for effective online research into the mechanisms of reading (dis)ability.

Parafoveal degradation during reading reduces preview costs only when it is not perceptually distinct.

There is a growing understanding that the parafoveal preview effect during reading may represent a combination of preview benefits and preview costs due to interference from parafoveal masks. It has been suggested that visually degrading the parafoveal masks may reduce their costs, but adult readers were later shown to be highly sensitive to degraded display changes. Four experiments examined how preview benefits and preview costs are influenced by the perception of distinct parafoveal degradation at the target word location. Participants read sentences with four preview types (identity, orthographic, phonological, and letter-mask preview) and two levels of visual degradation (0% vs. 20%). The distinctiveness of the target word degradation was either eliminated by degrading all words in the sentence (Experiments 1a-2a) or remained present, as in previous research (Experiments 1b-2b). Degrading the letter masks resulted in a reduction in preview costs, but only when all words in the sentence were degraded. When degradation at the target word location was perceptually distinct, it induced costs of its own, even for orthographically and phonologically related previews. These results confirm previous reports that traditional parafoveal masks introduce preview costs that overestimate the size of the true benefit. However, they also show that parafoveal degradation has the unintended consequence of introducing additional costs when participants are aware of distinct degradation on the target word. Parafoveal degradation appears to be easily perceived and may temporarily orient attention away from the reading task, thus delaying word processing.

The differential impact of viewing fitspiration and thinspiration images on men's body image concerns: An experimental ecological momentary assessment study.

To date, little is known about the impact of fitspiration and thinspiration exposure on men, as previous studies on these social media trends were primarily conducted on women. Male participants (n = 223) completed baseline measures of trait body image, then used a smartphone application to complete up to six state-based assessments daily for seven days. In each assessment, participants were randomly assigned to one of three image conditions (fitspiration, thinspiration, or neutral). Before and after viewing each image, they reported state body fat dissatisfaction, muscularity dissatisfaction, negative mood, and urge to engage in behaviours to reduce body fat and increase muscularity. Multi-level analyses revealed that compared to viewing neutral images, viewing fitspiration images increased men's body dissatisfaction, whereas viewing thinspiration images decreased body dissatisfaction. Viewing either fit- or thinspiration images also led to lower mood and greater urges to increase muscularity, whereas only fitspiration images increased urges to reduce body fat. Men with greater baseline muscularity dissatisfaction and higher appearance comparison were most vulnerable to muscularity dissatisfaction after viewing fitspiration images. Findings suggest the importance of limiting exposure to fitspiration imagery and implementing social media literacy programmes for men and well as women.

Vision for the blind: visual psychophysics and blinded inference for decision models.

Evidence accumulation models like the diffusion model are increasingly used by researchers to identify the contributions of sensory and decisional factors to the speed and accuracy of decision-making. Drift rates, decision criteria, and nondecision times estimated from such models provide meaningful estimates of the quality of evidence in the stimulus, the bias and caution in the decision process, and the duration of nondecision processes. Recently, Dutilh et al. (Psychonomic Bulletin & Review 26, 1051-1069, 2019) carried out a large-scale, blinded validation study of decision models using the random dot motion (RDM) task. They found that the parameters of the diffusion model were generally well recovered, but there was a pervasive failure of selective influence, such that manipulations of evidence quality, decision bias, and caution also affected estimated nondecision times. This failure casts doubt on the psychometric validity of such estimates. Here we argue that the RDM task has unusual perceptual characteristics that may be better described by a model in which drift and diffusion rates increase over time rather than turn on abruptly. We reanalyze the Dutilh et al. data using models with abrupt and continuous-onset drift and diffusion rates and find that the continuous-onset model provides a better overall fit and more meaningful parameter estimates, which accord with the known psychophysical properties of the RDM task. We argue that further selective influence studies that fail to take into account the visual properties of the evidence entering the decision process are likely to be unproductive.

Multi-domain cognitive assessment of male mice shows space radiation is not harmful to high-level cognition and actually improves pattern separation.

Astronauts on interplanetary missions - such as to Mars - will be exposed to space radiation, a spectrum of highly-charged, fast-moving particles that includes 56Fe and 28Si. Earth-based preclinical studies show space radiation decreases rodent performance in low- and some high-level cognitive tasks. Given astronaut use of touchscreen platforms during training and space flight and given the ability of rodent touchscreen tasks to assess functional integrity of brain circuits and multiple cognitive domains in a non-aversive way, here we exposed 6-month-old C57BL/6J male mice to whole-body space radiation and subsequently assessed them on a touchscreen battery. Relative to Sham treatment, 56Fe irradiation did not overtly change performance on tasks of visual discrimination, reversal learning, rule-based, or object-spatial paired associates learning, suggesting preserved functional integrity of supporting brain circuits. Surprisingly, 56Fe irradiation improved performance on a dentate gyrus-reliant pattern separation task; irradiated mice learned faster and were more accurate than controls. Improved pattern separation performance did not appear to be touchscreen-, radiation particle-, or neurogenesis-dependent, as 56Fe and 28Si irradiation led to faster context discrimination in a non-touchscreen task and 56Fe decreased new dentate gyrus neurons relative to Sham. These data urge revisitation of the broadly-held view that space radiation is detrimental to cognition.

Assessment tool for visual perception deficits in cerebral visual impairment: development and normative data of typically developing children.

AIM: To develop an assessment tool that measures a wide range of visual perceptual deficits common in cerebral visual impairment (CVI) and to provide normative data from typically developing children between 3 and 6 years of age. METHOD: Test development reflected cross-talk between vision research and clinical relevance for CVI. The Children's Visual Impairment Test for 3- to 6-year-olds (CVIT 3-6) includes 14 subtests covering four domains of visual perception: Object Recognition, Degraded Object Recognition, Motion Perception, and Global-Local Processing. Normative data were collected from 301 typically developing children (mean age 4y 8mo [SD 9.7mo]; 148 females, 153 males). A questionnaire was administered to parents about pregnancy duration, birth, and developmental problems. RESULTS: Average total CVIT 3-6 performance was 60.1 (SD 5.5) out of 70. The cut-off score for normal visual perception (53) was set at the 10th centile of scores in typically developing children. Multiple regression indicated CVIT 3-6 visual perception scores increase with age for children born at 36 weeks' gestational age or later (ß=-18.03, 95% confidence interval -31.31 to -4.75). INTERPRETATION: CVIT 3-6 is a tool to assess a wide range of visual perceptual deficits common in CVI. Age-dependent normative data are available because we found performance increased with age. WHAT THE PAPER ADDS: A test for visual perceptual deficits common in cerebral visual impairment. Visual perceptual functions improve with age in full-term typically developing children.

HERRAMIENTA DE EVALUACIÓN PARA LAS DEFICIENCIAS DE LA PERCEPCIÓN VISUAL EN LA DISCAPACIDAD VISUAL CEREBRAL: DESARROLLO Y DATOS NORMATIVOS DE NIÑOS CON DESARROLLO TÍPICO: OBJETIVO: Desarrollar una herramienta de evaluación que mida una amplia gama de déficits de percepción visual comunes en la discapacidad visual cerebral (CVI) y proporcionar datos normativos de niños con un desarrollo típico entre los 3 y los 6 años de edad. MÉTODO: El desarrollo de la prueba reflejó la alineación de contenidos entre la investigación de la visión y la relevancia clínica para la CVI. La prueba de discapacidad visual para niños de 3 a 6 años (CVIT 3-6) incluye 14 subpruebas que cubren cuatro dominios de la percepción visual: reconocimiento de objetos, reconocimiento de objetos con fondos borrosos, percepción de movimiento y procesamiento global y local. Se recopilaron datos normativos de 301 niños con desarrollo típico (edad promedio 4 años y 8 meses [DS 9,7 meses]; 148 mujeres, 153 varones). Se administró un cuestionario a los padres sobre la duración del embarazo, el parto y los problemas de desarrollo. RESULTADOS: El rendimiento promedio total de CVIT 3-6 fue de 60,1 (DS 5,5) sobre 70. El puntaje límite para la percepción visual normal (53) se estableció en el décimo centil de puntajes en niños con un desarrollo típico. La regresión múltiple indicó que las puntuaciones de percepción visual CVIT 3-6 aumentan con la edad para los niños nacidos a las 36 semanas de edad gestacional o más tarde (ß = -18,03, intervalo de confianza del 95% -31,31 a -4,75). INTERPRETACIÓN: CVIT 3-6 es una herramienta para evaluar una amplia gama de déficits de percepción visual comunes en la CVI. Los datos normativos que dependen de la edad están disponibles porque encontramos que el rendimiento aumentó con la edad.

INSTRUMENTO DE AVALIAÇÃO PARA DÉFICITS DE PERCEPÇÃO VISUAL NA DEFICIÊNCIA VISUAL CEREBRAL: DESENVOLVIMENTO E DADOS NORMATIVOS DE CRIANÇAS COM DESENVOLVIMENTO TÍPICO: OBJETIVO: Desenvolver um instrumento de avaliação que mensure uma variedade de déficits de percepção visual comuns na deficiência visual cerebral (DVC) e fornecer dados normativos de crianças com desenvolvimento típcico entre 3 e 6 anos de idade. MÉTODO: O desenvolvimento do teste refletiu a comunicação entre pesquisas relacionadas à visão e a relevância clínica para a DVC. O Teste da Deficiência Visual para Crianças direcionado para a população de 3 a 6 anos de idade (TDVC-3-6) inclui 14 subtestes que cobrem quatro domínios da percepção visual: reconhecimento de objetos, reconhecimento de objetos diminuída, percepção de movimento, e processamento global-local. Dados normativos foram coletados em 301 crianças com desenvolvimento típico (média de idade 4a 8m [DP 9,7 m]; 148 do sexo feminino, 153 do sexo masculino). Um questionário foi administrado aos pais sobre a duração da gestação, nascimento e problemas relacionados ao desenvolvimento. RESULTADOS: O desempenho médio total no TDVC 3-6 foi 60,1 (DP 5,5) em um total de 70. O escore de corte para percepção visual normal (53) foi estabelecido como o 10o. percentil de escores em crianças com desenvolvimento típico. Regressão múltipla indicou que escores de percepção do TDVC 3-6 aumentam com a idade para crianças nascidas com 36 semanas de idade gestacional ou mais (ß=-18,03, 95% intervalo de confiança -31,31 a -4,75). INTERPRETAÇÃO: O TDVC 3-6 é um instrumento para avaliar uma variedade de déficits da percepção visual comuns em DVC. Dados normativos relacionados à idade estão disponíveis, pois observamos que o desempenho aumentou com a idade.

The benefit (and cost) of drawing as an encoding strategy.

Drawing, as an encoding strategy for to-be-remembered words, has previously been shown to provide robust memory benefits. In the current study, we investigated the effect of drawing on false memory endorsements during a recognition test. We found that while drawing led to higher hit rates relative to writing (Experiment 1) and creating visual mental imagery (Experiment 2), it also led to higher false alarm (FA) rates to critical lures in a variant of the Deese-Roediger-McDermott (DRM) paradigm. When compared with an encoding strategy requiring listing of object features (Experiment 3), drawing led to a lower FA rate. We suggest that drawing enhances memory by promoting recollection of rich visual contextual information during retrieval, and this leads to the unintended side effect of increasing FA rates to related information.

Estimating statistical power for event-related potential studies using the late positive potential.

The late positive potential (LPP) is a common measurement used to study emotional processes of subjects in ERP paradigms. Despite its extensive use in affective neuroscience, there is presently no gold standard for how to appropriately power ERP studies using the LPP. The present study investigates how the number of trials, number of subjects, and magnitude of the effect size affect statistical power in analyses of the LPP. Using Monte Carlo simulations of ERP experiments with varying numbers of trials, subjects, and synthetic effects of known magnitude, we measured the probability of obtaining a statistically significant effect in 1,489 experiments repeated 1,000 times each. Predictably, our results showed that statistical power increases with increasing numbers of trials and subjects and at larger effect sizes. We also found that higher levels of statistical power can be achieved with lower numbers of subjects and trials and at lower effect sizes in within-subject than in between-subjects designs. Furthermore, we found that, as subjects are added to an experiment, the slope of the relationship between effect size and statistical power increased and shifted to the left until the power asymptoted to nearly 100% at higher effect sizes. This suggests that adding more subjects greatly increases statistical power at lower effect sizes (<1 µV) compared with more robust (>1.5 µV) effect sizes. We confirmed the results from the simulations based on the synthetic effects by running a new series of simulated experiments based on real data collected while participants looked at emotional images.

Attentional flexibility is imbalanced: Asymmetric cost for switches between external and internal attention.

Whereas the effects of attention switches occurring within perception or memory are relatively well understood, much less is known about switches of attention between them. We discuss the methodological limitations of initial research on this topic, which was never integrated with the broader cognitive literature. On the basis of this discussion, we present here a new paradigm, in which participants performed a simple probe-to-target matching task where targets were either perceived on screen or retrieved from memory. Across successive trials, repetitions or alternations (in both directions) between these 2 conditions were created, and eventually compared with each other. In line with our prediction, derived from the assumption of a top-down control mechanism, we found a cost for switching between external and internal attention in Experiment 1. Furthermore, this switch cost was asymmetric, being substantially larger when switching from (external) perception to (internal) memory than the other way around. In Experiments 2-4, we ruled out an imbalance in practice, learning, and preparation as confounds for this asymmetry. We propose that switches of attention between internal and external information are underpinned by a supervisory attention control mechanism, and that this asymmetry can be explained in terms of priming, associative interference or memory retrieval. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Cerebral cortical networking for mental workload assessment under various demands during dual-task walking.

While several studies have examined attentional reserve (via event-related potentials) and mental effort (via EEG spectral content) from various cortical regions during dual-task walking, none have assessed changes in the magnitude of interregional (cortico-cortical) communication as a measure of mental workload. Therefore, by deploying a traditional montage of electrode sites centered over the motor planning region as well as a more comprehensive graph theory-based approach encompassing the entire scalp, this study aimed to systematically examine changes in the magnitude of functional connectivity underlying cortico-cortical communication to assess changes in mental workload under various levels of challenge. Specifically, the Weighted Phase Lag Index (WPLI) was computed to assess the changes in magnitude of functional connectivity as participants performed a cognitive task under two demands (low and high) and two conditions (seated and walking). The results revealed enhanced fronto-centro-temporo-parietal theta connectivity during dual-task walking relative to being seated as well as a reduced inhibition of fronto-centro-temporo-parieto-occipital alpha networking as the demand on the secondary cognitive task increased. Collectively, these findings may reflect greater recruitment of task relevant processes to respond to increased cognitive-motor demands and thus an elevation of mental workload in an effort to maintain performance under varying levels of challenge. This work has the potential to inform future mental workload assessment applications in patient populations, including those who employ prostheses during cognitive-motor performance under various task demands.

Motion and binocular disparity processing: Two sides of two different coins.

From a mathematical point of view, extracting motion and disparity signals from a binocular visual stream requires very similar operations, applied over time for motion and across eyes for disparity. This similarity is reflected in the theories that have been proposed to describe the neural mechanisms used by the brain to extract these signals. At the behavioral level there are, however, several differences in how humans react to these stimuli, which presumably reflect differences in how these signals are processed by the brain. Here we highlight three such differences: the degree to which different axes of motion/disparity are treated isotropically, the importance of reference signals, and the rules that underlie the combination of 1D signals to extract 2D signals.

Dynamic Brain Interactions during Picture Naming.

Brain computations involve multiple processes by which sensory information is encoded and transformed to drive behavior. These computations are thought to be mediated by dynamic interactions between populations of neurons. Here, we demonstrate that human brains exhibit a reliable sequence of neural interactions during speech production. We use an autoregressive Hidden Markov Model (ARHMM) to identify dynamical network states exhibited by electrocorticographic signals recorded from human neurosurgical patients. Our method resolves dynamic latent network states on a trial-by-trial basis. We characterize individual network states according to the patterns of directional information flow between cortical regions of interest. These network states occur consistently and in a specific, interpretable sequence across trials and subjects: the data support the hypothesis of a fixed-length visual processing state, followed by a variable-length language state, and then by a terminal articulation state. This empirical evidence validates classical psycholinguistic theories that have posited such intermediate states during speaking. It further reveals these state dynamics are not localized to one brain area or one sequence of areas, but are instead a network phenomenon.

Flexibility in resizing attentional breadth: Asymmetrical versus symmetrical attentional contraction and expansion costs depends on context.

One of the core ways that attentional resources can be regulated is the breadth of attention: the tendency to concentrate one's attentional resources over a small region of space (i.e., "narrow scope"), or to spread them over a larger region of space (i.e., "broad scope"). It has long been understood that humans have a preference towards the broad or global level of processing. More recently, beyond any static preference, researchers have increasingly appreciated the importance of rapid rescaling of attentional breadth to meet task demands, especially for real-world tasks such as driving. Here, we examined whether there was any asymmetry in the human capacity to resize attention from a narrow to broad scale (expansion) versus a broad to narrow scale (contraction). In Experiment 1, we found remarkable symmetry in expansion and contraction efficiency, even under conditions where the global stimuli were demonstrably more salient. This indicates that humans can flexibly adapt to the attentional demands of the context. However, in Experiment 2, an asymmetry was revealed, whereby attentional expansion was more efficient than contraction. The key difference between Experiments 1 and 2 was whether or not the initial baseline block demanded frequent attentional resizing, suggesting that recent experience can impact attentional flexibility. We also found reliable individual differences in participants' ability to resize their attentional breadth, identifying a group of high-flexibility individuals who excelled at both attentional expansion and contraction.

Task-switching costs disappear if non-Chinese participants respond to Chinese characters.

In experiments with univalent target stimuli, task-switching costs can be eliminated if participants are unaware of the task rules and apply cue-target-response associations. However, in experiments with bivalent target stimuli, participants show task-switching costs. Participants may exhibit switch costs even when no task rules are provided in the instructions because they can infer the task rules. We tested this prediction by controlling the meaningfulness of cues and targets and therefore the ability to apply the task rules in 2 groups of participants. We compared the performance of Chinese and non-Chinese participants, who responded to Chinese numerals in an odd/even and high/low number task. In Experiment 1, Chinese participants, who knew Chinese characters and understood the task rules, showed task-switching costs. Non-Chinese participants on the other hand, who did not know Chinese characters, exhibited no switch costs. They applied a "target-first" strategy which means that they processed the target stimulus before the cue. In Experiment 2, we confirmed the absence of task-switching costs in Chinese participants using traditional Chinese numerals as target stimuli. Further, to determine how the target-first strategy affects switch costs, we manipulated the sequence of cue and target presentations. We conclude that task-switching costs can be eliminated more easily than previously thought, even for bivalent stimuli. The occurrence of task-switching costs depends on the approach used by participants and this may answer the puzzling question why humans typically do show task-switching costs whereas pigeons and monkeys do not. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

A critical assessment of data quality and venous effects in sub-millimeter fMRI.

Advances in hardware, pulse sequences, and reconstruction techniques have made it possible to perform functional magnetic resonance imaging (fMRI) at sub-millimeter resolution while maintaining high spatial coverage and acceptable signal-to-noise ratio. Here, we examine whether sub-millimeter fMRI can be used as a routine method for obtaining accurate measurements of fine-scale local neural activity. We conducted fMRI in human visual cortex during a simple event-related visual experiment (7 T, gradient-echo EPI, 0.8-mm isotropic voxels, 2.2-s sampling rate, 84 slices), and developed analysis and visualization tools to assess the quality of the data. Our results fall along three lines of inquiry. First, we find that the acquired fMRI images, combined with appropriate surface-based processing, provide reliable and accurate measurements of fine-scale blood oxygenation level dependent (BOLD) activity patterns. Second, we show that the highly folded structure of cortex causes substantial biases on spatial resolution and data visualization. Third, we examine the well-recognized issue of venous contributions to fMRI signals. In a systematic assessment of large sections of cortex measured at a fine scale, we show that time-averaged T2*-weighted EPI intensity is a simple, robust marker of venous effects. These venous effects are unevenly distributed across cortex, are more pronounced in gyri and outer cortical depths, and are, to a certain degree, in consistent locations across subjects relative to cortical folding. Furthermore, we show that these venous effects are strongly correlated with BOLD responses evoked by the experiment. We conclude that sub-millimeter fMRI can provide robust information about fine-scale BOLD activity patterns, but special care must be exercised in visualizing and interpreting these patterns, especially with regards to the confounding influence of the brain's vasculature. To help translate these methodological findings to neuroscience research, we provide practical suggestions for both high-resolution and standard-resolution fMRI studies.

Disparity level identification using the voxel-wise Gabor model of fMRI data.

Perceiving disparities is the intuitive basis for our understanding of the physical world. Although many electrophysiology studies have revealed the disparity-tuning characteristics of the neurons in the visual areas of the macaque brain, neuron population responses to disparity processing have seldom been investigated. Many disparity studies using functional magnetic resonance imaging (fMRI) have revealed the disparity-selective visual areas in the human brain. However, it is unclear how to characterize neuron population disparity-tuning responses using fMRI technique. In the present study, we constructed three voxel-wise encoding Gabor models to predict the voxel responses to novel disparity levels and used a decoding method to identify the new disparity levels from population responses in the cortex. Among the three encoding models, the fine-coarse model (FCM) that used fine/coarse disparities to fit the voxel responses to disparities outperformed the single model and uncrossed-crossed model. Moreover, the FCM demonstrated high accuracy in predicting voxel responses in V3A complex and high accuracy in identifying novel disparities from responses in V3A complex. Our results suggest that the FCM can better characterize the voxel responses to disparities than the other two models and V3A complex is a critical visual area for representing disparity information.