The neural correlates of statistical learning in a word segmentation task: An fMRI study

Functional magnetic resonance imaging (fMRI) was used to assess neural activation as participants learned to segment continuous streams of speech containing syllable sequences varying in their transitional probabilities. Speech streams were presented in four runs, each followed by a behavioral test to measure the extent of learning over time. Behavioral performance indicated that participants could discriminate statistically coherent sequences (words) from less coherent sequences (partwords). Individual rates of learning, defined as the difference in ratings for words and partwords, were used as predictors of neural activation to ask which brain areas showed activity associated with these measures. Results showed significant activity in the pars opercularis and pars triangularis regions of the left inferior frontal gyrus (LIFG). The relationship between these findings and prior work on the neural basis of statistical learning is discussed, and parallels to the frontal/subcortical network involved in other forms of implicit sequence learning are considered.     

Visual image retention does not contribute to modulation of event-related potentials by mental rotation

Rotation of a visual image in mind is associated with a slow posterior negative deflection of the event-related potential (ERP), termed rotation-related negativity (RRN). Retention of a visual image in short-term memory is also associated with a slow posterior negative ERP, termed negative slow wave (NSW). We tested whether short-term memory retention, indexed by the NSW, contributes to the RRN. ERPs were recorded in the same subjects in two tasks, a mental rotation task, eliciting the RRN, and a visual short-term memory task, eliciting the NSW. Over both right and left parietal scalp, no association was found between the NSW and the RRN amplitudes. Furthermore, adjusting for the effect of the NSW had no influence on a significant association between the RRN amplitude and response time, an index of mental rotation performance. Our data indicate that the RRN reflects manipulation of a visual image but not its retention in short-term memory.     

Behavioral assessment of emotional and motivational appraisal during visual processing of emotional scenes depending on spatial frequencies

Previous studies performed on visual processing of emotional stimuli have revealed preference for a specific type of visual spatial frequencies (high spatial frequency, HSF; low spatial frequency, LSF) according to task demands. The majority of studies used a face and focused on the appraisal of the emotional state of others. The present behavioral study investigates the relative role of spatial frequencies on processing emotional natural scenes during two explicit cognitive appraisal tasks, one emotional, based on the self-emotional experience and one motivational, based on the tendency to action. Our results suggest that HSF information was the most relevant to rapidly identify the self-emotional experience (unpleasant, pleasant, and neutral) while LSF was required to rapidly identify the tendency to action (avoidance, approach, and no action). The tendency to action based on LSF analysis showed a priority for unpleasant stimuli whereas the identification of emotional experience based on HSF analysis showed a priority for pleasant stimuli. The present study confirms the interest of considering both emotional and motivational characteristics of visual stimuli.     

Inter-hemispheric remapping between arm proprioception and vision of the hand is disrupted by single pulse TMS on the left parietal cortex

Parietal cortical areas are involved in sensori-motor transformations for their respective contralateral hemifield/body. When arms of the subjects are crossed while their gaze is fixed straight ahead, vision of the hand is processed by the hemisphere ipsilateral to the arm position and proprioception of the arm by the contralateral hemisphere. It induces interhemispheric transfer and remapping. Our objective was to investigate whether a single pulse TMS applied to the left parietal cortical area would disturb interhemispheric remapping in a similar case, and would increase a simple reaction time (RT) with respect to a control single pulse TMS applied to the frontal cortical area. Two LED were superimposed and located in front of the subjects on the saggital axis. Subjects were asked to carefully fixate on these LED during each trial. The lighting of the red LED was used as a warning signal. Following the green one was illuminated after a variable delay and served as a go-signal. The hand for the response was determined before the start of each trial. TMS was applied to the left parietal, the left frontal cortical areas, or not applied to the subject. Results revealed that: (1) Irrespective of its location, single pulse TMS induced a non-specific effect similar to a startle reflex and reduced RT substantially (15 ms on average) with respect to a control condition without TMS (mean value = 153 ms). (2) Irrespective of TMS, RT were shorter when the right or the left hand was positioned in the right visual hemi-field (i.e. normal and crossed positions respectively). (3) Finally, RT increased when single pulse TMS was applied to the left parietal area and when hands were crossed irrespective of which hand was used. We concluded that interhemispheric sensori-motor remapping was disrupted by a single pulse TMS that was applied to the left parietal cortex. This effect was also combined with some visual attention directed towards the hand located on the right visual hemi-field.     

Deeper attentional masking by lateral objects in children with autism

Autism spectrum disorder (ASD) is often associated with a detail-oriented perception and overselective attention in visual tasks, such as visual search and crowding. These results were obtained manipulating exclusively the spatial properties of the stimuli: few is known about the spatio-temporal dynamics of visual processing in ASD. In this study we employed an attentional masking (AM) paradigm comparing children with ASD and IQ-matched typically developing (TD) controls. The AM effect refers to an impaired identification of a target followed by a competitive masking object at different proximities in space and time. We found that ASD and TD groups did not differ in the AM effect provoked by the competitive object displayed in the same position of the target. In contrast, children with ASD showed a deeper and prolonged interference than the TD group when the masking object was displayed in the lateral position. These psychophysical results suggest that the inefficient attentional selection in ASD depends on the spatio-temporal interaction between competitive visual objects. These evidence are discussed in the light of the ASD altered neural connectivity hypothesis and the reentrant theory of perception.     

Short-Term Memory and Working Memory in Children with Blindness: Support for a Domain General or Domain Specific System?

The study explored the contribution of two component processes (phonological and executive) to blind children's memory performance. Children with blindness and sight were matched on gender, chronological age, and verbal intelligence and compared on measures of short-term memory (STM) and working memory (WM). Although the measures were highly correlated, the results from two experiments indicated that the blind children were superior to sighted children on measures of STM, but not on measures of WM. The results supported the notion that children with blindness have advantages on memory tasks that draw upon resources from the phonological loop. However, comparable performance between the ability groups on WM measures suggests there are domain specific aspects in the executive system.     

Visual Perception and Memory Impairments in Children at Risk of Nonverbal Learning Disabilities

Visuospatial working memory (VSWM) and visual perception were examined in two groups aged 11–13, one with children displaying symptoms of nonverbal learning disability (NLD) (n = 18) and the other a control group without learning disabilities (n = 18). The two groups were matched for general verbal abilities, age, gender, and socioeconomic level. The children were presented with VSWM tests involving visual and spatial-simultaneous processes, and also with a classical visual illusion, a classical ambiguous figure, as well as visual perception tests specifically devised for the present study. Results revealed that performance of children at risk of NLD was worse than controls in some VSWM and in visual perception tests without memory involvement; these latter required comparisons of visual stimuli and locations in space with distractors. Moreover, the two groups differed in perceiving the classical ambiguous figure. Findings are discussed in the light of both theoretical and clinical implications.     

How semantic category modulates preschool children’s visual memory

The dynamic interplay between perception and memory has been explored in preschool children by presenting filtered stimuli regarding animals and artifacts. The identification of filtered images was markedly influenced by both prior exposure and the semantic nature of the stimuli. The identification of animals required less physical information than artifacts did. Our results corroborate the notion that the human attention system evolves to reliably develop definite category-specific selection criteria by which living entities are monitored in different ways.     

Charting the Developmental Trajectories of Attention and Executive Function in Chinese School-Aged Children

Attention is a complex domain that has reawakened research interest in recent years. There are relatively few studies that have examined age-related changes across different attention subcomponents, such as selection, maintenance, and control, using large samples covering a wide age range. The present study assessed performance in 466 participants in order to identify the ages at which mature performance was reached across differing attention subcomponents. Furthermore, we investigated whether the nature of the attentional demands or task difficulty predicted the age at which stable levels of performance were reached. The results supported the former rather than the latter alternative.     

An anxiety-induced bias in the perception of a bistable point-light walker

Human sensitivity for social cues is exquisite, as illustrated by the ease with which simplified point-light movements invoke social and emotional responses. Compared to faces, these biological motion stimuli only recently started to be used to explore questions regarding social cognition and anxiety. We presented human point-light walkers that could be perceived as facing towards or facing away from the observer, and tested whether participants with high social anxiety would perceive these bistable stimuli differently, because this type of stimuli has particular relevance for them. The results showed that observers with high social anxiety tended to see walkers as facing away more frequently than those with low social anxiety. This may mean that high socially anxious observers are biased towards the more positive perceptual alternative because they are motivated to protect themselves against threatening social experiences, but we also explore alternative explanations. The findings are in line with the evidence for a positivity bias in perception, also called wishful seeing, but in contrast with the attentional negativity bias often found in social anxiety. We discuss reasons for this divergence and possible limitations of the current study.