Aberrant brain dynamics in neuroHIV: Evidence from magnetoencephalographic (MEG) imaging

Magnetoencephalography (MEG) is a noninvasive, silent, and totally passive neurophysiological imaging method with excellent temporal resolution (~1ms) and good spatial precision (~3-5mm). While MEG studies of neuroHIV remain relatively rare, the number of studies per year has sharply increased recently and this trend will likely continue into the foreseeable future. The current in-depth review focuses on the studies that have been conducted to date, which include investigations of somatosensory and visual modalities, resting-state, as well as motor control and higher-level functions such as working memory and visual attention. The review begins with an introduction to the principles and methods of MEG, and then transitions to a review of each of the empirical studies that have been conducted to date, separated by sensory modality for the basic studies and cognitive domain for the higher-level investigations. As such, this review attempts to be exhaustive in its coverage of empirical MEG studies of neuroHIV. Across studies major themes emerge including aberrant neural oscillatory activity in HIV-infected adults, both in primary sensory regions of the brain and higher-order executive regions. Many studies have also connected the amplitude of neural oscillations to behavioral and/or neuropsychological function in the study population, making a vital connection to performance and improving the veracity of the findings. One conspicuous emerging area is the use of MEG to distinguish cognitively-impaired from unimpaired HIV-infected adults, with major success reported and future studies sure to come. The review concludes with a summary of findings and suggested focus areas for future studies.

A conceptual model of the visual control of posture

In order to isolate the visual contribution to the control of postural balance, experiments in which subjects are exposed to large-field visual motion (optokinetic) stimuli are reviewed. In these situations, at motion onset, the visual stimulus signals subject self-motion but inertial (vestibulo-proprioceptive) cues do not. Visually evoked postural responses (VEPR) thus induced can be quickly suppressed by cognitive status or simple repetition of the stimulus, if the inertial self-motion cues available to the subject are reliable. In the conceptual model presented here, the process of assessing the reliability, and degree of matching, of visual and inertial signals is carried out by a General comparator; in turn able to access the Gain control mechanism of the visuo-postural system. Complexity and congruency in the visual stimulus itself are assessed by a Visual comparator, e.g., the presence of motion parallax in the visual stimulus can reverse the sway response direction. VEPR can also be re-oriented according to the position of the eyes in the head and the head on the trunk. This indicates that ocular and cervical proprioceptors must also access the gain control mechanism so that visual stimuli can recruit and silence different postural muscles appropriately. The overall gain of the visuo-postural system is also influenced by less easily defined idiosyncratic factors, such as visual dependence and psychological traits; interestingly both these factors have been found to be associated with poor long term outcome in vestibular disorders. The experimental results and model presented illustrate that the visuo-postural system is a wonderful example of interaction between physics (e.g., stimuli geometry, body dynamics), neuroscience and the border zone between neurology and psycho-somatic medicine.

Visual Hyper-vigilance But Insufficient Mental Representation in Children with Overweight/Obesity: Event-related Potential Study with Visual Go/NoGo Test

PURPOSE

The neural processing of children with overweight/obesity (CWO), may affect their eating behavior. We investigated the visual information processing of CWO under response control condition, by event-related potential (ERP) study, an electrophysiologic study for cognitive mechanism.

METHODS

Seventeen CWO (mean age: 10.6±1.9), and 17 age-matched non-obese children (NOC), participated in the study. Neurocognitive function tests and visual ERP under Go/NoGo conditions, were implemented. Area amplitudes of major ERP components (P1, N1, P2, N2, and P3) from four scalp locations (frontal, central, parietal, and occipital), were analyzed.

RESULTS

For Go and NoGo conditions, CWO had significantly greater occipital P1, fronto-central N1, and P2 amplitudes compared with NOC. P2 amplitude was significantly greater in CWO, than in NOC, at the frontal location. N2 amplitude was not significantly different, between CWO and NOC. For CWO and NOC, Go P3 amplitude was highest at the parietal location, and NoGo P3 amplitude was highest at the frontal location. In Go and NoGo conditions, P3 amplitude of CWO was significantly less than in NOC.

CONCLUSION

The greater P1, N1, and P2 suggested hyper-vigilance to visual stimuli of CWO, but the smaller P3 suggested insufficient mental representation of them. Such altered visual processing, may affect the eating behavior of CWO.

Visual and Action-control Expressway Associated with Efficient Information Transmission in Elite Athletes

Effective information transmission for open skill performance requires fine-scale coordination of distributed networks of brain regions linked by white matter tracts. However, how patterns of connectivity in these anatomical pathways may improve global efficiency remains unclear. In this study, we hypothesized that the feeder edges in visual and motor systems have the potential to become "expressways" that increase the efficiency of information communication across brain networks of open skill experts. Thirty elite athletes and thirty novice subjects were recruited to participate in visual tracking and motor imagery tasks. We collected structural imaging data from these subjects, and then resolved structural neural networks using deterministic tractography to identify streamlines connecting cortical and subcortical brain regions of each participant. We observed that superior skill performance in elite athletes was associated with increased information transmission efficiency in feeder edges distributed between orbitofrontal and basal ganglia modules, as well as among temporal, occipital, and limbic system modules. These findings suggest that there is an expressway linking visual and action-control system of skill experts that enables more efficient interactions of peripheral and central information in support of effective performance of an open skill.

Assessing motor, visual and language function using a single 5-minute fMRI paradigm: three birds with one stone

Clinical functional Magnetic Resonance Imaging (fMRI) requires inferences on localization of major brain functions at the individual subject level. We hypothesized that a single "triple use" task would satisfy sensitivity and reliability requirements for successfully assessing the motor, visual and language domain in this context. This was tested here by the application in a group of healthy adults, assessing sensitivity and reliability at the individual subject level, separately for each domain.Our "triple use" task consisted of 2 conditions (condition 1, assessing motor and visual domain, and condition 2, assessing the language domain), serving mutually as active/control. We included 20 healthy adult subjects. Random effect analyses showed activation in primary motor, visual and language regions, as expected. Less expected regions were activated both for the motor and visual domains. Further, reliability of primary activation patterns was very high across individual subjects, with activation seen in 70-100% of subjects in primary motor, visual, and left-lateralized language regions.These findings suggest the "triple use" task to be reliable at the individual subject's level to assess motor, visual and language domains in the clinical fMRI context. Benefits of such an approach include shortening of acquisition time, simplicity of the task for each domain, and using a visual stimulus. Following establishment of reliability in adults, the task may also be a valuable addition in the pediatric clinical fMRI context, where each of these factors is of high relevance.

Effect of range of heading differences on human visual-inertial heading estimation

Both visual and inertial cues are salient in heading determination. However, optic flow can ambiguously represent self-motion or environmental motion. It is unclear how visual and inertial heading cues are determined to have common cause and integrated vs perceived independently. In four experiments visual and inertial headings were presented simultaneously with ten subjects reporting visual or inertial headings in separate trial blocks. Experiment 1 examined inertial headings within 30° of straight-ahead and visual headings that were offset by up to 60°. Perception of the inertial heading was shifted in the direction of the visual stimulus by as much as 35° by the 60° offset, while perception of the visual stimulus remained largely uninfluenced. Experiment 2 used ± 140° range of inertial headings with up to 120° visual offset. This experiment found variable behavior between subjects with most perceiving the sensory stimuli to be shifted towards an intermediate heading but a few perceiving the headings independently. The visual and inertial headings influenced each other even at the largest offsets. Experiments 3 and 4 had similar inertial headings to experiments 1 and 2, respectively, except subjects reported environmental motion direction. Experiment 4 displayed similar perceptual influences as experiment 2, but in experiment 3 percepts were independent. Results suggested that perception of visual and inertial stimuli tend to be perceived as having common causation in most subjects with offsets up to 90° although with significant variation in perception between individuals. Limiting the range of inertial headings caused the visual heading to dominate the perception.

Comparative efficacy and safety of multiple antiplatelet therapies for secondary prevention of ischemic stroke or transient ischemic attack: A network meta-analysis

BACKGROUND

Antiplatelet therapies for secondary prevention of ischemic stroke or transient ischemic attack (TIA) is a highly active research topic with five critical drugs obtained by visual analysis. We aimed to compare and rank multiple antiplatelet therapies using a network meta-analysis.

METHODS

Relevant medical databases were searched. Eligible randomized controlled trials (RCTs) which examined any comparisons involving mono- or dual antiplatelet therapies, based on aspirin, clopidogrel, dipyridamole, ticlopidine, cilostazol and placebo for patients with noncardioembolic ischemic stroke or TIA, were included. 14 outcomes were assessed. Primary outcomes were stroke recurrence, composite events (stroke recurrence, myocardial infarction and vascular death), and intracranial hemorrhage. PROSPERO registered number CRD42017069728.

RESULTS

45 RCTs with 173,131 patients were included in network meta-analysis, involving eight antiplatelet therapies. Cilostazol and clopidogrel were statistically more efficacious than aspirin (odds ratio (OR) = 0.64, 95% confidence interval (CI) = 0.47-0.88; OR = 0.77, 95%CI = 0.62-0.95) and dipyridamole (OR = 0.64, 95%CI = 0.44-0.93; OR = 0.76, 95%CI = 0.58-0.99) in reducing stroke recurrence, and showed significant benefits in reducing composite events compared with aspirin (OR = 0.63, 95%CI = 0.45-0.89; OR = 0.90, 95%CI = 0.83-0.97). No significant difference was found between cilostazol and clopidogrel in intracranial hemorrhage. Weighted regression suggested cilostazol was hierarchically the optimum treatment in consideration of both efficacy and safety, followed by clopidogrel.

CONCLUSION

Cilostazol and clopidogrel are probably promising options for secondary prevention of ischemic stroke or TIA. Both of them reduce stroke recurrence similarly compared with aspirin or dipyridamole, and reduce composite events compared with aspirin. Further studies are needed to confirm this finding.

MEGALEX: A megastudy of visual and auditory word recognition

Using the megastudy approach, we report a new database (MEGALEX) of visual and auditory lexical decision times and accuracy rates for tens of thousands of words. We collected visual lexical decision data for 28,466 French words and the same number of pseudowords, and auditory lexical decision data for 17,876 French words and the same number of pseudowords (synthesized tokens were used for the auditory modality). This constitutes the first large-scale database for auditory lexical decision, and the first database to enable a direct comparison of word recognition in different modalities. Different regression analyses were conducted to illustrate potential ways to exploit this megastudy database. First, we compared the proportions of variance accounted for by five word frequency measures. Second, we conducted item-level regression analyses to examine the relative importance of the lexical variables influencing performance in the different modalities (visual and auditory). Finally, we compared the similarities and differences between the two modalities. All data are freely available on our website ( https://sedufau.shinyapps.io/megalex/ ) and are searchable at www.lexique.org , inside the Open Lexique search engine.

Metacognition across sensory modalities: Vision, warmth, and nociceptive pain

The distinctive experience of pain, beyond mere processing of nociceptive inputs, is much debated in psychology and neuroscience. One aspect of perceptual experience is captured by metacognition—the ability to monitor and evaluate one’s own mental processes. We investigated confidence in judgements about nociceptive pain (i.e. pain that arises from the activation of nociceptors by a noxious stimulus) to determine whether metacognitive processes contribute to the distinctiveness of the pain experience. Our participants made intensity judgements about noxious heat, innocuous warmth, and visual contrast (first-order, perceptual decisions) and rated their confidence in those judgements (second-order, metacognitive decisions). First-order task performance between modalities was balanced using adaptive staircase procedures. For each modality, we quantified metacognitive efficiency (meta-d’/d’)—the degree to which participants’ confidence reports were informed by the same evidence that contributed to their perceptual judgements—and metacognitive bias (mean confidence)—the participant’s tendency to report higher or lower confidence overall. We found no overall differences in metacognitive efficiency or mean confidence between modalities. Mean confidence ratings were highly correlated between all three tasks, reflecting stable inter-individual variability in metacognitive bias. However, metacognitive efficiency for pain varied independently of metacognitive efficiency for warmth and visual perception. That is, those participants who had higher metacognitive efficiency in the visual task also tended to have higher metacognitive efficiency in the warmth task, but not necessarily in the pain task. We thus suggest that some distinctive and idiosyncratic aspects of the pain experience may stem from additional variability at a metacognitive level. We further speculate that this additional variability may arise from the affective or arousal aspects of pain.

Three-dimensional versus two-dimensional high-definition laparoscopy in cholecystectomy: a prospective randomized controlled study

BACKGROUND

While 3D laparoscopy increases surgical performance under laboratory conditions, it is unclear whether it improves outcomes in real clinical scenarios. The aim of this trial was to determine whether the 3D laparoscopy can enhance surgical efficacy in laparoscopic cholecystectomy (LCC).

METHOD

This prospective randomized controlled study was conducted between February 2015 and April 2017 in a day case unit of an academic teaching hospital. Patients scheduled for elective LCC were assessed for eligibility. The exclusion criteria were: (1) planned secondary operation in addition to LCC, (2) predicted to be high-risk for conversion, and (3) surgeons with less than five previous 3D laparoscopic procedures. Patients were operated on by 12 residents and 3 attendings. The primary endpoint was operation time. All surgeons were tested for stereoaquity (Randot® stereotest). The study was registered in ClinicalTrials.gov (NCT02357589).

RESULTS

A total of 210 patients were randomized; 105 to 3D laparoscopy and 104 to 2D laparoscopy. Median operation time as similar in the 3D and 2D laparoscopy groups (49 min vs. 48 min, p = 0.703). Operation times were similar in subgroup analyses for surgeon's sex (male vs. female), surgeon's status (resident vs. attending), surgeon's stereovision (stereopsis 10 vs. less than 10), surgeon's experience (performed 200 LCCs or below versus over 200 LCCs), or patient's BMI (≤ 25 vs. 25-30 vs. > 30). No differences in intra- or postoperative complications were noted between the 3D and 2D groups.

CONCLUSION

3D laparoscopy did not show any advantages over 2D laparoscopy in LCC.

An epidemiological study on the prevalence of hallucinations in a general-population sample: Effects of age and sensory modality

Epidemiological studies have repeatedly shown that a significant minority of the general population have experienced hallucinations, however, a potential effect of age on the prevalence of hallucinations in the general population has never been previously examined in a specific study. The aim of the present study was thus to examine the effects of age and sensory modality on hallucination prevalence in a general population sample. A large, randomly selected and representative sample of the Norwegian population completed measures assessing different hallucination modalities (auditory, visual, olfactory, and tactile) and types (sensed presence and hypnagogic/hypnopompic hallucinations). Three age groups were identified and compared: young (19-30 years), middle (31-60) and old (61-96). There was a significant main-effect of age for all hallucination modalities and types, whereby hallucination prevalence significantly decreased with age. We also found that anxiety partially mediated the effect of age on hallucinations whilst depression was a partial suppressor. Concerning the co-occurrence of hallucination modalities, there was very little co-occurrence of auditory and visual hallucinations in all three age groups. In summary, a main-effect of age for hallucination prevalence was observed. Furthermore, individuals reported a more diverse variety of hallucination modalities compared to what is commonly reported in clinical populations.

Magnetoencephalography and the infant brain

Magnetoencephalography (MEG) is a non-invasive neuroimaging technique that provides whole-head measures of neural activity with millisecond temporal resolution. Over the last three decades, MEG has been used for assessing brain activity, most commonly in adults. MEG has been used less often to examine neural function during early development, in large part due to the fact that infant whole-head MEG systems have only recently been developed. In this review, an overview of infant MEG studies is provided, focusing on the period from birth to three years. The advantages of MEG for measuring neural activity in infants are highlighted (See Box 1), including the ability to assess activity in brain (source) space rather than sensor space, thus allowing direct assessment of neural generator activity. Recent advances in MEG hardware and source analysis are also discussed. As the review indicates, efforts in this area demonstrate that MEG is a promising technology for studying the infant brain. As a noninvasive technology, with emerging hardware providing the necessary sensitivity, an expected deliverable is the capability for longitudinal infant MEG studies evaluating the developmental trajectory (maturation) of neural activity. It is expected that departures from neuro-typical trajectories will offer early detection and prognosis insights in infants and toddlers at-risk for neurodevelopmental disorders, thus paving the way for early targeted interventions.

Does dance training influence beat sensorimotor synchronization? Differences in finger-tapping sensorimotor synchronization between competitive ballroom dancers and nondancers

Sensorimotor synchronization is the coordination of rhythmic movement with an external beat. Dancers often synchronize each beat of their motion with an external rhythm. Compared with social dancing, competitive ballroom dancing requires a higher level of sensorimotor ability. Although previous studies have found that dance experience may facilitate sensorimotor synchronization, they did not examine this in competitive ballroom dancers. Thus, the present study compared sensorimotor synchronization in 41 nondancers and 41 skilled, competitive ballroom dancers as they performed a simple beat synchronization finger-tapping task. All participants finger-tapped freely at their preferred tempo before the formal experiments. Participants were then required to synchronize their finger-tapping with auditory, visual, or combined audiovisual signals in separate experiments and at varying tempos. To assess sensorimotor plasticity, the participants then repeated the free-tapping task after completing all three finger-tapping experiments. Compared with nondancers, dancers showed more accurate and stable beat synchronization. Dancers tapped before onset of all three types of sensorimotor stimulation, indicating a significant negative mean asynchrony and had a tendency to anticipate (predict) the stimuli. Dancers tended to auditory stimulation for beat sensorimotor synchronization, whereas nondancers tended to visual stimuli. Dancers had a faster tempo preference in the initial free-tapping task; however, the preferred tapping tempo increased in all participants in the second free-tapping task, suggesting that beat induction is affected by practice. Together these findings suggest that dance experience enhances sensorimotor synchronization and sensorimotor plasticity, with ballroom dancers tending to auditory stimulation for beat induction.

Prediction of individualized task activation in sensory modality-selective frontal cortex with 'connectome fingerprinting'

The human cerebral cortex is estimated to comprise 200-300 distinct functional regions per hemisphere. Identification of the precise anatomical location of an individual's unique set of functional regions is a challenge for neuroscience that has broad scientific and clinical utility. Recent studies have demonstrated the existence of four interleaved regions in lateral frontal cortex (LFC) that are part of broader visual attention and auditory attention networks (Michalka et al., 2015; Noyce et al., 2017; Tobyne et al., 2017). Due to a large degree of inter-subject anatomical variability, identification of these regions depends critically on within-subject analyses. Here, we demonstrate that, for both sexes, an individual's unique pattern of resting-state functional connectivity can accurately identify their specific pattern of visual- and auditory-selective working memory and attention task activation in lateral frontal cortex (LFC) using "connectome fingerprinting." Building on prior techniques (Saygin et al., 2011; Osher et al., 2016; Tavor et al., 2016; Smittenaar et al., 2017; Wang et al., 2017; Parker Jones et al., 2017), we demonstrate here that connectome fingerprint predictions are far more accurate than group-average predictions and match the accuracy of within-subject task-based functional localization, while requiring less data. These findings are robust across brain parcellations and are improved with penalized regression methods. Because resting-state data can be easily and rapidly collected, these results have broad implications for both clinical and research investigations of frontal lobe function. Our findings also provide a set of recommendations for future research.

Handedness modulates proprioceptive drift in the rubber hand illusion

Preference for use of either the left or right hand (‘handedness’) has been linked with modulations of perception and sensory processing—both of space and the body. Here we ask whether multisensory integration of bodily information also varies as a function of handedness. We created a spatial disparity between visual and somatosensory hand position information using the rubber hand illusion, and use the magnitude of illusory shifts in hand position (proprioceptive ‘drift’) as a tool to probe the weighted integration of multisensory information. First, we found drift was significantly reduced when the illusion was performed on the dominant vs. non-dominant hand. We suggest increased manual dexterity of the dominant hand causes greater representational stability and thus an increased resistance to bias by the illusion induction. Second, drift was generally greatest when the hand was in its habitual action space (i.e., near the shoulder of origin), compared to when it laterally displaced towards, or across the midline. This linear effect, however, was only significant for the dominant hand—in both left- and right-handed groups. Thus, our results reveal patterns of habitual hand action modulate drift both within a hand (drift varies with proximity to action space), and between hands (differences in drift between the dominant and non-dominant hands). In contrast, we were unable to find conclusive evidence to support, or contradict, an overall difference between left- and right-handers in susceptibility to RHI drift (i.e., total drift, collapsed across hand positions). In sum, our results provide evidence that patterns of daily activity—and the subsequent patterns of sensory input—shape multisensory integration across space.

Modulation of event-related potentials to food cues upon sensory-specific satiety

Tempting environmental food cues and metabolic signals are important factors in appetite regulation. Food intake reduces liking of food cues that are congruent to the food eaten (sensory-specific satiety). With this study we aimed to assess effects of sensory-specific satiety on neural processing (perceptual and evaluative) of visual and olfactory food cues. Twenty healthy female subjects (age: 20 ± 2 years; BMI: 22 ± 2 kg/m²) participated in two separate test sessions during which they consumed an ad libitum amount of a sweet or savoury meal. Before and after consumption, event-related potentials were recorded in response to visual and olfactory cues signalling high-energy sweet, high-energy savoury, low-energy sweet and low-energy savoury food and non-food items. In general, we observed that food intake led to event-related potentials with an increased negative and decreased positive amplitudes for food, but also non-food cues. Changes were most pronounced in response to high-energy sweet food pictures after a sweet meal, and occurred in early processes of perception (~80-150 ms) and later processes of cognitive evaluation (~300-700 ms). Food intake appears to lead to general changes in neural processing that are related to motivated attention, and sensory-specific changes that reflect decreased positive valence of the stimuli and/or modulation of top-down cognitive control over processing of cues congruent to the food eaten to satiety.

Prevalence and characteristics of multi-modal hallucinations in people with psychosis who experience visual hallucinations

Hallucinations can occur in single or multiple sensory modalities. Historically, greater attention has been paid to single sensory modality experiences with a comparative neglect of hallucinations that occur across two or more sensory modalities (multi-modal hallucinations). With growing evidence suggesting that visual hallucinations may be experienced along with other hallucinations, this study aimed to explore multi-modal hallucinations in a sample of people with psychotic disorders who reported visual hallucinations (n = 22). No participants reported just visual hallucinations i.e. all reported related or unrelated auditory hallucinations. Twenty-one participants reported multi-modal hallucinations that were serial in nature, whereby they saw visual hallucinations and heard unrelated auditory hallucinations at other times. Nineteen people out of the twenty two also reported simultaneous multi-modal hallucinations, with the most common being an image that talked to and touched them. Multi-modal related and simultaneous hallucinations appeared to be associated with greater conviction that the experiences were real, and greater distress. Theoretical and clinical implications of multi-modal hallucinations are discussed.

Visual biofeedback training reduces quantitative drugs index scores associated with fall risk

OBJECTIVE

Drugs increase fall risk and decrease performance on balance and mobility tests. Conversely, whether biofeedback training to reduce fall risk also decreases scores on a published drug-based fall risk index has not been documented. Forty-eight community-dwelling older adults underwent either treadmill gait training plus visual feedback (+VFB), or walked on a treadmill without feedback. The Quantitative Drug Index (QDI) was derived from each participant's drug list and is based upon all cause drug-associated fall risk. Analysis of covariance assessed changes in the QDI during the study, and data is presented as mean ± standard error of the mean.

RESULTS

The QDI scores decreased significantly (p = 0.031) for participants receiving treadmill gait training +VFB (- 0.259 ± 0.207), compared to participants who walked on the treadmill without VFB (0.463 ± 0.246). Changes in participants QDI scores were dependent in part upon their age, which was a significant covariate (p = 0.007). These preliminary results demonstrate that rehabilitation to reduce fall risk may also decrease use of drugs associated with falls. Determination of which drugs or drug classes that contribute to the reduction in QDI scores for participants receiving treadmill gait training +VFB, compared to treadmill walking only, will require a larger participant investigation. Trial Registration ISRNCT01690611, ClinicalTrials.gov #366151-1, initial 9/24/2012, completed 4/21/2016.

How would you describe a familiar route or put in order the landmarks along it? It depends on your cognitive style!

Cognitive style refers to the preference in perceiving, organizing and remembering information. Different cognitive styles have been identified across the years. Amongst others, field-dependence/independence cognitive style is the extent to which the person perceives part of a field as discrete from the surrounding environment as a whole, rather than embedded in the field. Instead, visualizer/verbalizer cognitive style involves the preference in processing visual versus verbal information. Both cognitive styles can influence navigational behaviour. The present study aimed at clarifying the extent to which field-dependence/independence and visualizer/verbalizer cognitive styles affect route-based navigational tasks. Therefore, 44 healthy participants from L'Aquila City were assessed for their cognitive styles and were asked to perform two different navigational tasks: reorder paths using a series of photos depicting landmarks from L'Aquila (visually presented task, visual path task-VisPT); orally describe specific paths of L'Aquila (verbally presented task, verbal path task-VerPT). Results showed that the field-independence cognitive style predicted response times of VisPT, whereas the visualizer/verbalizer cognitive style predicted the instructions given when performing the VerPT, namely, the number of metrical distance indicators provided by participants. By investigating two different cognitive styles, the study clarifies that field-dependence/independence and visualizer/verbalizer cognitive styles can play a different role in spatial navigation and suggests that the material by which a navigational task is presented affects its performance.

Altered neural responsivity to food cues in relation to food preferences, but not appetite-related hormone concentrations after RYGB-surgery

BACKGROUND

After Roux-en-Y gastric bypass (RYGB) surgery, patients report a shift in food preferences away from high-energy foods.

OBJECTIVE

We aimed to elucidate the potential mechanisms underlying this shift in food preferences by assessing changes in neural responses to food pictures and odors before and after RYGB. Additionally, we investigated whether altered neural responsivity was associated with changes in plasma endocannabinoid and ghrelin concentrations.

DESIGN

19 RYGB patients (4 men; age 41 ± 10 years; BMI 41 ± 1 kg/m² before; BMI 36 ± 1 kg/m² after) participated in this study. Before and two months after RYGB surgery, they rated their food preferences using the Macronutrient and Taste Preference Ranking Task and BOLD fMRI responses towards pictures and odors of high-, and low-energy foods and non-food items were measured. Blood samples were taken to determine plasma endocannabinoid and ghrelin concentrations pre- and post-surgery.

RESULTS

Patients demonstrated a shift in food preferences away from high-fat/sweet and towards low-energy/savory food products, which correlated with decreased superior parietal lobule responsivity to high-energy food odor and a reduced difference in precuneus responsivity to high-energy versus low-energy food pictures. In the anteroventral prefrontal cortex (superior frontal gyrus) the difference in deactivation towards high-energy versus non-food odors reduced. The precuneus was less deactivated in response to all cues. Plasma concentrations of anandamide were higher after surgery, while plasma concentrations of other endocannabinoids and ghrelin did not change. Alterations in appetite-related hormone concentrations did not correlate with changes in neural responsivity.

CONCLUSIONS

RYGB leads to changed responsivity of the frontoparietal control network that orchestrates top-down control to high-energy food compared to low-energy food and non-food cues, rather than in reward related brain regions, in a satiated state. Together with correlations with the shift in food preference from high- to low-energy foods this indicates a possible role in new food preference formation.

Effects of early eye removal on the morphology of a multisensory neuron in the chicken optic tectum

The midbrain is a subcortical area involved in central functions such as integrating sensory modalities, movement initiation and bottom-up and top-down attention. In chicken, the midbrain roof is termed optic tectum (TeO) and consists of 15 layers with distinct in- and output regions. Visual input targets the superficial layers, while auditory input terminates in deeper layers. It has been shown that ablation of sensory epithelia leads to changes in the cellular patterning and structural organization of the sensory pathways. For the tectum, ablation of the eye anlagen was shown to affect retinorecipient neurons. While the gross morphology remained intact after enucleation, the shape of dendritic endings was changed presumably due to missing presynaptic input during synaptic pruning. We investigated the effect of deafferentation in a multisensory cell type, the Shepherd's crook neuron (SCN) in the TeO. SCNs have distinct dendritic branches in retinorecipient layers (superficial layers 1 to 5 and 7) and in layers where auditory input terminates. To assess whether removal of a single sensory input only affects the dendrites recipient for that input, we removed the eye anlagen and retrogradely labeled SCNs later in embryogenesis to visualize the morphology in lesioned and non-lesioned embryos. We found no changes in the gross morphology or in the basal dendrites, but an altered growth of the fine structures at the apical dendrite of SCNs in the retinorecipient layers. Our data indicate that the neuronal morphology of SCNs is mostly predefined before retinal innervation affect the fine structure.

Analysis of sensory system aspects of postural stability during quiet standing in adolescent idiopathic scoliosis patients

Background

The aim of this study was to quantitatively analyze quite standing postural stability of adolescent idiopathic scoliosis (AIS) patients in respect to three sensory systems (visual, vestibular, and somatosensory).

Method

In this study, we analyzed the anterior-posterior center of pressure (CoP) signal using discrete wavelet transform (DWT) between AIS patients (n = 32) and normal controls (n = 25) during quiet standing.

Result

The energy rate (∆E_EYE%) of the CoP signal was significantly higher in the AIS group than that in the control group at levels corresponding to vestibular and somatosensory systems (p < 0.01).

Conclusions

This implies that AIS patients use strategies to compensate for possible head position changes and spinal asymmetry caused by morphological deformations of the spine through vestibular and somatosensory systems. This could be interpreted that such compensation could help them maintain postural stability during quiet standing. The interpretation of CoP signal during quiet standing in AIS patients will improve our understanding of changes in physical exercise ability due to morphological deformity of the spine. This result is useful for evaluating postural stability before and after treatments (spinal fusion, bracing, rehabilitation, and so on).

Reading without words or target detection? A re-analysis and replication fMRI study of the Landolt paradigm

The Landolt paradigm is a visual scanning task intended to evoke reading-like eye-movements in the absence of orthographic or lexical information, thus allowing the dissociation of (sub-) lexical vs. visual processing. To that end, all letters in real word sentences are exchanged for closed Landolt rings, with 0, 1, or 2 open Landolt rings as targets in each Landolt sentence. A preliminary fMRI block-design study (Hillen et al. in Front Hum Neurosci 7:1-14, 2013) demonstrated that the Landolt paradigm has a special neural signature, recruiting the right IPS and SPL as part of the endogenous attention network. However, in that analysis, the brain responses to target detection could not be separated from those involved in processing Landolt stimuli without targets. The present study presents two fMRI experiments testing the question whether targets or the Landolt stimuli per se, led to the right IPS/SPL activation. Experiment 1 was an event-related re-analysis of the Hillen et al. (Front Hum Neurosci 7:1-14, 2013) data. Experiment 2 was a replication study with a new sample and identical procedures. In both experiments, the right IPS/SPL were recruited in the Landolt condition as compared to orthographic stimuli even in the absence of any target in the stimulus, indicating that the properties of the Landolt task itself trigger this right parietal activation. These findings are discussed against the background of behavioural and neuroimaging studies of healthy reading as well as developmental and acquired dyslexia. Consequently, this neuroimaging evidence might encourage the use of the Landolt paradigm also in the context of examining reading disorders, as it taps into the orientation of visual attention during reading-like scanning of stimuli without interfering sub-lexical information.

Modality-dependent effect of motion information in sensory-motor synchronised tapping

Synchronised action is important for everyday life. Generally, the auditory domain is more sensitive for coding temporal information, and previous studies have shown that auditory-motor synchronisation is much more precise than visuo-motor synchronisation. Interestingly, adding motion information improves synchronisation with visual stimuli and the advantage of the auditory modality seems to diminish. However, whether adding motion information also improves auditory-motor synchronisation remains unknown. This study compared tapping accuracy with a stationary or moving stimulus in both auditory and visual modalities. Participants were instructed to tap in synchrony with the onset of a sound or flash in the stationary condition, while these stimuli were perceived as moving from side to side in the motion condition. The results demonstrated that synchronised tapping with a moving visual stimulus was significantly more accurate than tapping with a stationary visual stimulus, as previous studies have shown. However, tapping with a moving auditory stimulus was significantly poorer than tapping with a stationary auditory stimulus. Although motion information impaired audio-motor synchronisation, an advantage of auditory modality compared to visual modality still existed. These findings are likely the result of higher temporal resolution in the auditory domain, which is likely due to the physiological and structural differences in the auditory and visual pathways in the brain.

Romberg ratio coefficient in quiet stance and postural control in Parkinson's disease

The aim of this study was to determine the function of visual afference in postural control in Parkinson patients. We enrolled 29 patients and 30 healthy controls. The stabilometry test was performed for posture and balance and Romberg ratio coefficients were calculated. In addition, the Berg Balance Scale and the 6-Minute Walking Test were administered to assess balance and functional exercise capacity; the Unified Parkinson's Disease Rating Scale was used to determine the stage of the disease; and the Short Form (SF)-36 Health Survey was given to collect information on quality of life.

RESULTS

significantly longer Center of Pressure (CoP) sway lengths were observed in the parkinson group. The Romberg index for CoP length of sway in parkinson patients was 94.3 ± 19.3%, versus 147.4 ± 120.6% for the control group. (p = 0.025).

CONCLUSION

Parkinson patients use the increase in CoP sway length and ellipse area to stabilize their balance and sight does not facilitate static postural control as in healthy subjects.

Using proprioception to control ongoing actions: dominance of vision or altered proprioceptive weighing?

Visual feedback is crucial for movement accuracy (e.g., Keele and Posner, J Exp Psychol 77:155-158, 1968). As well, proprioception has been argued to be important for the control of voluntary movements (e.g., Bagesteiro et al., Exp Brain Res 171:358-370, 2006; Rossetti et al., J Neurophysiol 74:457-463, 1995). While tendon vibration (TVib) has been used to perturb proprioceptive information during limb matching tasks (Goodwin et al., Science 175:1382-1384, 1972), the current study employed between-trial dual-muscle TVib, coupled with vision occlusion, to assess the use of vision and proprioception for the online control of voluntary movements. Participants (n = 17) performed an upper-limb reaching task (30 cm). TVib influenced both accuracy and precision of movement endpoint. Critically, variability analyses showed that participant's performance was most affected by TVib at 75% of the movement duration, even in the presence of vision. These findings demonstrate that between-trial dual-muscle tendon vibration can perturb proprioceptive feedback, and further, suggest that proprioception can be important for the online control of reaches, even when vision is available.

The mouse pulvinar nucleus: Organization of the tectorecipient zones

Comparative studies have greatly contributed to our understanding of the organization and function of visual pathways of the brain, including that of humans. This comparative approach is a particularly useful tactic for studying the pulvinar nucleus, an enigmatic structure which comprises the largest territory of the human thalamus. This review focuses on the regions of the mouse pulvinar that receive input from the superior colliculus, and highlights similarities of the tectorecipient pulvinar identified across species. Open questions are discussed, as well as the potential contributions of the mouse model for endeavors to elucidate the function of the pulvinar nucleus.

Individual differences in nonverbal prediction and vocabulary size in infancy

Children who generate and update verbal predictions have larger vocabularies, suggesting that prediction may be a mechanism that supports language learning. We hypothesize that this relation is not confined to the domain of language, but instead signals a broader individual difference in information processing. To investigate this possibility, we tested infants (n = 50) in the early stages of vocabulary development (12-24 months) on their ability to generate and update nonverbal, visual predictions. In an eye-tracking task, a central fixation reliably preceded a peripheral target. Then, halfway through the experiment, the peripheral target began appearing on the opposite side. We assessed infants' proficiency in initiating anticipatory eye movements before and after the switch, and found that infants with larger vocabularies did not generate more predictions overall, but were more efficient in updating predictions to the new target side. These findings establish a link between nonverbal prediction and vocabulary in infancy, and suggest a promising means of addressing whether or not prediction abilities are causally related to language learning.

Effects of modality and repetition in a continuous recognition memory task: Repetition has no effect on auditory recognition memory

Previous research has shown that auditory recognition memory is poorer compared to visual and cross-modal (visual and auditory) recognition memory. The effect of repetition on memory has been robust in showing improved performance. It is not clear, however, how auditory recognition memory compares to visual and cross-modal recognition memory following repetition. Participants performed a recognition memory task, making old/new discriminations to new stimuli, stimuli repeated for the first time after 4-7 intervening items (R1), or repeated for the second time after 36-39 intervening items (R2). Depending on the condition, participants were either exposed to visual stimuli (2D line drawings), auditory stimuli (spoken words), or cross-modal stimuli (pairs of images and associated spoken words). Results showed that unlike participants in the visual and cross-modal conditions, participants in the auditory recognition did not show improvements in performance on R2 trials compared to R1 trials. These findings have implications for pedagogical techniques in education, as well as for interventions and exercises aimed at boosting memory performance.

Sensory and motor differences in Autism Spectrum Conditions and developmental coordination disorder in children: A cross-syndrome study

Recent research has shown that Developmental coordination disorder (DCD) can present with some similar symptomology as Autism Spectrum Conditions (ASC). This paper therefore explored the similarities and differences in coordination and sensory responsivity between DCD and ASC. 77 children took part: 42 (35 male, 7 female) with ASC (ages 7-21: mean age 12.23 years), 26 (19 male, 7 female) with DCD (ages 7-21; mean age 11.07 years) and 9 (2 male, 7 female) with ASC and DCD (ages 8-15; mean age 12.27). All groups completed a battery of validated parent report measures online that included motor coordination (DCDQ), sensory responsivity (SPC-R) and social communication measures (AQ). Results showed no significant differences in coordination, and some significant differences in sensory responsivity between ASC and DCD (increased visual and auditory responsivity and decreased proprioception). Exploratory analysis showed that these differences showed good validity in identifying the diagnosis of ASC and DCD. These results elucidate the underlying causes of motor coordination difficulties in both conditions. Specifically, ASC coordination difficulties appear linked to visual processing impairments, whilst DCD coordination difficulties appear to be linked to spatial processing. This may aid better diagnosis and intervention for these conditions.

Comparison of the Computer and Hand Administered Versions of the Brown Location Test (BLT)

Objective

The Brown Location Test (BLT) was developed to remedy some of the problems in existing visual-based memory tests. The hand version has demonstrated good psychometric properties, the ability to provide lateralization information for mesial temporal lobe epilepsy patients, and has normative data. The purpose of this study was to compare the hand administered format to the more recently developed computer administered format.

Methods

We used Generalizability Theory analyses to assess the degree of variability in scores across the hand and computer versions of the test, and across alternate test forms, A and B. We also compared the means and standard deviations for the different versions and forms using paired t-tests, and Pearson correlation coefficients.

Results

There was minimal variability and high levels of score similarity across the various test administration formats and forms.

Conclusions

The high degree of comparability between versions allows one to apply the validity findings and normative data collected using the hand administered version to the computer version of the BLT.

Optic flow is calibrated to walking effort

Through experience, people learn that a given magnitude of walking produces an associated magnitude of optic flow. Artificially altering this relationship has both behavioral and perceptual consequences: walking on a treadmill results in zero translational optic flow and causes people to subsequently drift forward when attempting to walk in place while blindfolded (they have learned that forward walking is required to remain stationary). Similarly, after walking on a treadmill people perceive the walking distance to targets to be greater (they have recalibrated the magnitude of walking required to reach the target). While the measurement unit for walking magnitude in this relationship has been treated as walking speed (stride length * [steps / time]), recent experiments suggest that walkable distances may instead be measured in bioenergetic units (i.e., the magnitude of energy required to produce a given magnitude of optic flow). In the first experiment, zero translational optic flow was paired with a constant walking speed, and walking energy was manipulated by varying the incline of the treadmill. Participants who walked on an inclined treadmill drifted farther while attempting to walk in place than participants who walked on a flat treadmill. A follow-up experiment presented optic flow via an immersive virtual environment, and no difference between flat and inclined treadmill walking was found, thereby showing that the effect found in the first experiment was not an artifact of biomechanical differences associated with flat versus inclined treadmill walking. The results support the hypothesis that walking magnitude is scaled by bioenergetic units.

Multisensory enhancement elicited by unconscious visual stimuli

The merging of information from different senses (i.e., multisensory integration) can facilitate information processing. Processing enhancements have been observed with signals that are irrelevant to the task at hand, and with cues that are non-predictive. Such findings are consistent with the notion that multiple sensory signals are sometimes integrated automatically. Multisensory enhancement has even been reported with stimuli that have been presented subliminally, though only with meaningful multisensory relations that have already been learned. The question of whether there exist cases where multisensory effects occur without either learning or awareness has, though, not been clearly established in the literature to date. Here, we present a case study of a patient with Posterior Cortical Atrophy, who was unable to consciously perceive visual stimuli with our task parameters, yet who nevertheless still exhibited signs of multisensory enhancement even with unlearned relations between audiovisual stimuli. In a simple speeded detection task, both response speed, and the variability of reaction times, decreased in a similar manner to controls for multisensory stimuli. These results are consistent with the view that the conscious perception of stimuli and prior learning are not always a prerequisite for multisensory integration to enhance human performance.

Rapid temporal recalibration to visuo-tactile stimuli

For a comprehensive understanding of the environment, the brain must constantly decide whether the incoming information originates from the same source and needs to be integrated into a coherent percept. This integration process is believed to be mediated by temporal integration windows. If presented with temporally asynchronous stimuli for a few minutes, the brain adapts to this new temporal relation by recalibrating the temporal integration windows. Such recalibration can occur even more rapidly after exposure to just a single trial of asynchronous stimulation. While rapid recalibration has been demonstrated for audio-visual stimuli, evidence for rapid recalibration of visuo-tactile stimuli is lacking. Here, we investigated rapid recalibration in the visuo-tactile domain. Subjects received visual and tactile stimuli with different stimulus onset asynchronies (SOA) and were asked to report whether the visuo-tactile stimuli were presented simultaneously. Our results demonstrate visuo-tactile rapid recalibration by revealing that subjects' simultaneity reports were modulated by the temporal order of stimulation in the preceding trial. This rapid recalibration effect, however, was only significant if the SOA in the preceding trial was smaller than 100 ms, while rapid recalibration could not be demonstrated for SOAs larger than 100 ms. Since rapid recalibration in the audio-visual domain has been demonstrated for SOAs larger than 100 ms, we propose that visuo-tactile recalibration works at shorter SOAs, and thus faster time scales than audio-visual rapid recalibration.

Visual outcomes after progressive apodized diffractive intraocular lens implantation

PURPOSE

To assess photopic and mesopic vision in patients implanted with the Bi-Flex® M 677 MY bifocal intraocular lens (IOL).

METHODS

In this prospective clinical study, 25 patients with cataract in both eyes were subjected to cataract surgery and bilateral implantation of the Bi-Flex® M 677MY (Medicontur, Hungary) IOL. Three months after surgery, high-contrast photopic uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were determined. Intermediate at 65 cm (DCIVA) and near at 40 cm (DCNVA) visual acuity were also measured, both with best distance correction. The CSV-1000 test chart was used to assess contrast sensitivity (CS). Defocus curves were constructed under photopic and mesopic conditions, determining binocular best-corrected visual acuity over the range +1.50 D to -4.00 D in 0.50-D steps. A KR-1W Wavefront Analyzer was used to measure pupil size and aberrometric outcomes. Presence and type of dysphotopsia were evaluated with the Likert scale.

RESULTS

Mesopic mean pupil diameter was 4.58 ± 0.73 mm. The mean values at 3 months were UDVA 0.03 ± 0.09, CDVA -0.05 ± 0.06, DCIVA 0.20 ± 0.07, and DCNVA 0.11 ± 0.08. Mean CS for the 4 frequencies examined were 1.66 ± 0.16, 1.75 ± 0.14, 1.39 ± 0.22, and 0.96 ± 0.19. Significant differences were observed in defocus curves for photopic and mesopic conditions. A significant correlation between pupil diameter and the dysphotopic photopic was found (r = 0.62; p = 0.02).

CONCLUSIONS

The evaluated progressive apodized diffractive design IOL provides effective restoration of visual function in far and near vision distance with an adequate intermediate visual quality between -1.00 and -1.50 focus.

Multisensory integration of redundant trisensory stimulation

Integration of sensory information across modalities can confer behavioral advantages by decreasing perceptual ambiguity, increasing reaction time, and increasing detection accuracy relative to unisensory stimuli. We asked how combinations of auditory, visual, and somatosensory events alter response time. Participants detected stimulation on one side of space (right or left) while ignoring stimulation on the other side of space. There were seven types of suprathreshold stimuli: auditory (tones from speakers), visual (sinusoidal contrast gratings), somatosensory (fingertip vibrations), audio-visual, somato-visual, audio-somatosensory, and audio-somato-visual. Response enhancement and race model analysis confirmed that bisensory and trisensory trials enhanced response time relative to unisensory trials. Exploratory analysis of individual differences in intersensory facilitation revealed that participants fit into one of two groups: those who benefitted from trisensory information and those who did not.

A multisensory perspective on object memory

Traditional studies of memory and object recognition involved objects presented within a single sensory modality (i.e., purely visual or purely auditory objects). However, in naturalistic settings, objects are often evaluated and processed in a multisensory manner. This begets the question of how object representations that combine information from the different senses are created and utilised by memory functions. Here we review research that has demonstrated that a single multisensory exposure can influence memory for both visual and auditory objects. In an old/new object discrimination task, objects that were presented initially with a task-irrelevant stimulus in another sense were better remembered compared to stimuli presented alone, most notably when the two stimuli were semantically congruent. The brain discriminates between these two types of object representations within the first 100ms post-stimulus onset, indicating early "tagging" of objects/events by the brain based on the nature of their initial presentation context. Interestingly, the specific brain networks supporting the improved object recognition vary based on a variety of factors, including the effectiveness of the initial multisensory presentation and the sense that is task-relevant. We specify the requisite conditions for multisensory contexts to improve object discrimination following single exposures, and the individual differences that exist with respect to these improvements. Our results shed light onto how memory operates on the multisensory nature of object representations as well as how the brain stores and retrieves memories of objects.

Attention and sensation in functional motor disorder

Functional motor disorder (FMD), also called psychogenic motor disorder or conversion disorder, describes impairments of motor function where there is no evidence of organic disease. The diagnosis is usually confirmed by positive clinical signs, such as Hoover's sign, in which normal power returns when attention is diverted away from the affected limb. This suggests that selective attention is an important determinant of these functional symptoms. The present study is the first specifically to explore the shifting of spatial attention in relation to the side of FMD. We tested 14 patients with unilateral functional upper limb weakness on three tasks requiring detection of visual targets close to the affected or unaffected hand, or touches to the hand itself. Targets were preceded by central cues promoting voluntary shifts of attention, or peripheral cues promoting automatic shifts. We observed a reduced response to visual and/or tactile targets on the affected side in around half of the patients, by comparison with age-matched controls, indicating that some degree of detection cost often accompanies FMD. Additionally, although the patient group showed normal cueing effects on the visual tasks, they had a unilateral absence of cueing effect on the affected side in the tactile task. Consideration of the data in the context of recent theory suggests that the abnormality may be not in the shifting of attention itself, but rather in the consequences of attending to the affected side. Specifically, the expected cueing effects may be absent on the affected side, because attention to a functionally weak limb increases the perception of the symptom, including any reduced sensory response. This preliminary research suggests promising new lines of investigation into the role of attention, and particularly somatic attention, in FMD.

Appraisal of unimodal cues during agonistic interactions in Maylandia zebra

Communication is essential during social interactions including animal conflicts and it is often a complex process involving multiple sensory channels or modalities. To better understand how different modalities interact during communication, it is fundamental to study the behavioural responses to both the composite multimodal signal and each unimodal component with adequate experimental protocols. Here we test how an African cichlid, which communicates with multiple senses, responds to different sensory stimuli in a social relevant scenario. We tested Maylandia zebra males with isolated chemical (urine or holding water coming both from dominant males), visual (real opponent or video playback) and acoustic (agonistic sounds) cues during agonistic interactions. We showed that (1) these fish relied mostly on the visual modality, showing increased aggressiveness in response to the sight of a real contestant but no responses to urine or agonistic sounds presented separately, (2) video playback in our study did not appear appropriate to test the visual modality and needs more technical prospecting, (3) holding water provoked territorial behaviours and seems to be promising for the investigation into the role of the chemical channel in this species. Our findings suggest that unimodal signals are non-redundant but how different sensory modalities interplay during communication remains largely unknown in fish.

Differences between endogenous attention to spatial locations and sensory modalities

Vibell et al. (J Cogn Neurosci 19:109-120, 2007) reported that endogenously attending to a sensory modality (vision or touch) modulated perceptual processing, in part, by the relative speeding-up of neural activation (i.e., as a result of prior entry). However, it was unclear whether it was the fine temporal discrimination required by the temporal-order judgment task that was used, or rather, the type of attentional modulation (spatial locations or sensory modalities) that was responsible for the shift in latencies that they observed. The present study used a similar experimental design to evaluate whether spatial attention would also yield similar latency effects suggestive of prior entry in the early visual P1 potentials. Intriguingly, while the results demonstrate similar neural latency shifts attributable to spatial attention, they started at a somewhat later stage than seen in Vibell et al.'s study. These differences are consistent with different neural mechanisms underlying attention to a specific sensory modality versus to a spatial location.

Development of sensitivity versus specificity for print in the visual word form area

An area near the left lateral occipito-temporal sulcus that responds preferentially to print has been designated as the visual word form area (VWFA). Research suggests that specialization in this brain region increases as reading expertise is achieved. Here we aimed to characterize that development in terms of sensitivity (response to printed words relative to non-linguistic faces) versus specificity (response to printed words versus line drawings of nameable objects) in typically reading children ages 7-14 versus young adults as measured by functional magnetic resonance imaging (fMRI). Relative to adults, children displayed equivalent sensitivity but reduced specificity. These findings suggest that sensitivity for print relative to non-linguistic stimuli develops relatively early in the VWFA in the course of reading development, but that specificity for printed words in VWFA is still developing through at least age 14.

Occurrence and co-occurrence of hallucinations by modality in schizophrenia-spectrum disorders

It is not only unclear why hallucinations in schizophrenia occur with different prevalence by modality, but also to what extent they do. Reliable prevalence estimates of hallucinations by modality in schizophrenia are currently lacking, particularly for non-auditory hallucinations. Studies have also tended to report lifetime, not point prevalence by modality. This study assessed the prevalence and co-occurrence of hallucinations, for both lifetime and point prevalence, across the auditory, visual, olfactory, and tactile modalities, in people diagnosed with chronic schizophrenia-spectrum disorders in Ireland (N=693) and Australia (N=218). Lifetime prevalence was 64-80% auditory, 23-31% visual, 9-19% tactile, and 6-10% olfactory. Past month prevalence was 23-27% auditory, 5-8% visual, 4-7% tactile, and 2% olfactory. The majority of participants had only hallucinated in one modality, with this nearly always being the auditory. Approximately one-third had hallucinated in two modalities, most commonly the auditory and visual. Most currently hallucinating patients also hallucinated in a single modality, again, nearly always the auditory. Whereas 30-37% of patients with lifetime auditory hallucinations had experienced visual hallucinations, 83-97% of patients with experience of visual hallucinations had experienced auditory hallucinations. These findings help delineate the modality distribution of hallucinations in schizophrenia, and provide an explanatory target for theoretical models.

Temporal expectation weights visual signals over auditory signals

Temporal expectation is a process by which people use temporally structured sensory information to explicitly or implicitly predict the onset and/or the duration of future events. Because timing plays a critical role in crossmodal interactions, we investigated how temporal expectation influenced auditory-visual interaction, using an auditory-visual crossmodal congruity effect as a measure of crossmodal interaction. For auditory identification, an incongruent visual stimulus produced stronger interference when the crossmodal stimulus was presented with an expected rather than an unexpected timing. In contrast, for visual identification, an incongruent auditory stimulus produced weaker interference when the crossmodal stimulus was presented with an expected rather than an unexpected timing. The fact that temporal expectation made visual distractors more potent and visual targets less susceptible to auditory interference suggests that temporal expectation increases the perceptual weight of visual signals.

How do the two visual streams interact with each other?

The current consensus divides primate cortical visual processing into two broad networks or "streams" composed of highly interconnected areas (Milner and Goodale 2006, 2008; Goodale 2014). The ventral stream, passing from primary visual cortex (V1) through to inferior parts of the temporal lobe, is considered to mediate the transformation of the contents of the visual signal into the mental furniture that guides memory, recognition and conscious perception. In contrast the dorsal stream, passing from V1 through to various areas in the posterior parietal lobe, is generally considered to mediate the visual guidance of action, primarily in real time. The brain, however, does not work through mutually insulated subsystems, and indeed there are well-documented interconnections between the two streams. Evidence for contributions from ventral stream systems to the dorsal stream comes from human neuropsychological and neuroimaging research, and indicates a crucial role in mediating complex and flexible visuomotor skills. Complementary evidence points to a role for posterior dorsal-stream visual analysis in certain aspects of 3-D perceptual function in the ventral stream. A series of studies of a patient with visual form agnosia has been instrumental in shaping our knowledge of what each stream can achieve in isolation; but it has also helped us to tease apart the relative dependence of parietal visuomotor systems on direct bottom-up visual inputs versus inputs redirected via perceptual systems within the ventral stream.

Audio-visual temporal perception in children with restored hearing

It is not clear how audio-visual temporal perception develops in children with restored hearing. In this study we measured temporal discrimination thresholds with an audio-visual temporal bisection task in 9 deaf children with restored audition, and 22 typically hearing children. In typically hearing children, audition was more precise than vision, with no gain in multisensory conditions (as previously reported in Gori et al. (2012b)). However, deaf children with restored audition showed similar thresholds for audio and visual thresholds and some evidence of gain in audio-visual temporal multisensory conditions. Interestingly, we found a strong correlation between auditory weighting of multisensory signals and quality of language: patients who gave more weight to audition had better language skills. Similarly, auditory thresholds for the temporal bisection task were also a good predictor of language skills. This result supports the idea that the temporal auditory processing is associated with language development.

Brain activity associated with selective attention, divided attention and distraction

Top-down controlled selective or divided attention to sounds and visual objects, as well as bottom-up triggered attention to auditory and visual distractors, has been widely investigated. However, no study has systematically compared brain activations related to all these types of attention. To this end, we used functional magnetic resonance imaging (fMRI) to measure brain activity in participants performing a tone pitch or a foveal grating orientation discrimination task, or both, distracted by novel sounds not sharing frequencies with the tones or by extrafoveal visual textures. To force focusing of attention to tones or gratings, or both, task difficulty was kept constantly high with an adaptive staircase method. A whole brain analysis of variance (ANOVA) revealed fronto-parietal attention networks for both selective auditory and visual attention. A subsequent conjunction analysis indicated partial overlaps of these networks. However, like some previous studies, the present results also suggest segregation of prefrontal areas involved in the control of auditory and visual attention. The ANOVA also suggested, and another conjunction analysis confirmed, an additional activity enhancement in the left middle frontal gyrus related to divided attention supporting the role of this area in top-down integration of dual task performance. Distractors expectedly disrupted task performance. However, contrary to our expectations, activations specifically related to the distractors were found only in the auditory and visual cortices. This suggests gating of the distractors from further processing perhaps due to strictly focused attention in the current demanding discrimination tasks.

A pupil size response model to assess fear learning

During fear conditioning, pupil size responses dissociate between conditioned stimuli that are contingently paired (CS+) with an aversive unconditioned stimulus, and those that are unpaired (CS-). Current approaches to assess fear learning from pupil responses rely on ad hoc specifications. Here, we sought to develop a psychophysiological model (PsPM) in which pupil responses are characterized by response functions within the framework of a linear time-invariant system. This PsPM can be written as a general linear model, which is inverted to yield amplitude estimates of the eliciting process in the central nervous system. We first characterized fear-conditioned pupil size responses based on an experiment with auditory CS. PsPM-based parameter estimates distinguished CS+/CS- better than, or on par with, two commonly used methods (peak scoring, area under the curve). We validated this PsPM in four independent experiments with auditory, visual, and somatosensory CS, as well as short (3.5 s) and medium (6 s) CS/US intervals. Overall, the new PsPM provided equal or decisively better differentiation of CS+/CS- than the two alternative methods and was never decisively worse. We further compared pupil responses with concurrently measured skin conductance and heart period responses. Finally, we used our previously developed luminance-related pupil responses to infer the timing of the likely neural input into the pupillary system. Overall, we establish a new PsPM to assess fear conditioning based on pupil responses. The model has a potential to provide higher statistical sensitivity, can be applied to other conditioning paradigms in humans, and may be easily extended to nonhuman mammals.

The effects of task-relevant saccadic eye movements performed during the encoding of a serial sequence on visuospatial memory performance

Visuospatial working memory (VSWM) is a set of cognitive processes used to encode, maintain and manipulate spatial information. One important feature of VSWM is that it has a limited capacity such that only few items can be actively stored and manipulated simultaneously. Given the limited capacity, it is important to determine the conditions that affect memory performance as this will improve our understanding of the architecture and function of VSWM. Previous studies have shown that VSWM is disrupted when task-irrelevant eye movements are performed during the maintenance phase; however, relatively fewer studies examined the role of eye movements performed during the encoding phase. On one hand, performing eye movements during the encoding phase could result in a stronger memory trace because the memory formation is reinforced by the activation of the motor system. On the other hand, performing eye movements to each target could disrupt the configural processing of the spatial array because the spatial representation has to be updated with each movement to maintain perceptual stability. Therefore, this work was conducted to examine whether task-relevant saccadic eye movements performed during the encoding phase of a visuospatial working memory task affect the recall of serially presented targets. Results from two experiments showed that average recall accuracy was significantly higher when the spatial array (set size ≥ 7) was encoded using a covert strategy-that is, while participants fixated on a central target, in comparison to an overt strategy-that is, while participants moved their eyes to fixate on each target. Furthermore, the improvement in accuracy was evident only for targets presented in the first half of the sequence, suggesting that the primacy effect is modulated by the presence of eye movements. We propose that executing saccades during encoding could interfere with the ability to use a chunking strategy or disrupt active visualization of the configuration. In conclusion, this is the first study to show that task-relevant saccadic eye movements performed during encoding may actually reduce the spatial span of VSWM. These results extend the current knowledge about the role of eye movements in VSWM, and have implications for future studies investigating the VSWM.

Using fNIRS to examine occipital and temporal responses to stimulus repetition in young infants: Evidence of selective frontal cortex involvement

How does the developing brain respond to recent experience? Repetition suppression (RS) is a robust and well-characterized response of to recent experience found, predominantly, in the perceptual cortices of the adult brain. We use functional near-infrared spectroscopy (fNIRS) to investigate how perceptual (temporal and occipital) and frontal cortices in the infant brain respond to auditory and visual stimulus repetitions (spoken words and faces). In Experiment 1, we find strong evidence of repetition suppression in the frontal cortex but only for auditory stimuli. In perceptual cortices, we find only suggestive evidence of auditory RS in the temporal cortex and no evidence of visual RS in any ROI. In Experiments 2 and 3, we replicate and extend these findings. Overall, we provide the first evidence that infant and adult brains respond differently to stimulus repetition. We suggest that the frontal lobe may support the development of RS in perceptual cortices.

Circadian course of the P300 ERP in patients with amyotrophic lateral sclerosis - implications for brain-computer interfaces (BCI)

Background

Accidents or neurodegenerative diseases like amyotrophic lateral sclerosis (ALS) can lead to progressing, extensive, and complete paralysis leaving patients aware but unable to communicate (locked-in state). Brain-computer interfaces (BCI) based on electroencephalography represent an important approach to establish communication with these patients. The most common BCI for communication rely on the P300, a positive deflection arising in response to rare events. To foster broader application of BCIs for restoring lost function, also for end-users with impaired vision, we explored whether there were specific time windows during the day in which a P300 driven BCI should be preferably applied.

Methods

The present study investigated the influence of time of the day and modality (visual vs. auditory) on P300 amplitude and latency. A sample of 14 patients (end-users) with ALS and 14 healthy age matched volunteers participated in the study and P300 event-related potentials (ERP) were recorded at four different times (10, 12 am, 2, & 4 pm) during the day.

Results

Results indicated no differences in P300 amplitudes or latencies between groups (ALS patients v. healthy participants) or time of measurement. In the auditory condition, latencies were shorter and amplitudes smaller as compared to the visual condition.

Conclusion

Our findings suggest applicability of EEG/BCI sessions in patients with ALS throughout normal waking hours. Future studies using actual BCI systems are needed to generalize these findings with regard to BCI effectiveness/efficiency and other times of day.