Visual Processing Areas Research Articles

Progressive visual loss in Retinitis Pigmentosa leads to cortical and subcortical reorganization of the human brain

AbstractPurpose Retinitis Pigmentosa (RP) is a retinal disease characterized by photoreceptor degeneration. Usually, symptoms are early onset night blindness followed by progressive peripheral vision loss, with central vision being later affected. Some patients become blind after several years of disease. We studied the consequences of this progressive loss of visual input in the human brain using Magnetic Resonance Imaging.Methods 13 RP patients (8M, 5F; mean age 47±13yrs; range:23‐66yrs) and 24 age‐matched controls (10M, 14F; mean age 44±13yrs; range 22‐69yrs) were scanned in a 3T Siemens scanner. Cortical thickness (CT), surface area (SA) and subcortical volumes were obtained with Freesurfer.Results Patients’ visual field ranged from 22deg to almost blindness. Self‐reported symptoms’ onset ranged from birth to 45 years of age (mean symptoms’ duration: 30yrs; range 6‐51). Patients showed decreased CT in pericalcarine(p=0.002); cuneus(p<0.001); lingual(p=0.02) and lateral occipital(p=0.007) regions and increased CT in supramarginal(p=0.02), superior frontal(p=0.02) and the parahippocampal(p=<0.02) gyri. Also, cortical SA was decreased only in superior parietal cortex(p<0.009,) and increased in inferior temporal gyrus(p=0.03), isthmus cingulate(p=0.02), banks of superior temporal sulcus(p=0.007), pars orbitalis(p=0.02) and transverse temporal sulcus(p=0.002). Also, the caudate nucleus was increased in RP(p=0.003).Conclusion We conclude that visual input deprivation in RP leads to a large scale subcortical and cortical reorganization of brain resources, with loss in visual processing areas and changes in multimodal integration areas that may compensate for this sensory input loss.

A 58-year-old female with blurred vision and apraxia

A 58-year-old right handed woman, with 12 years of formal education, had a five-year history of slowly progressive blurred vision and apraxia. Five years before the examination she gradually became blurred vision and had difficulties identifying static objects within the visual field. Then she went to an ophthalmologist and received cataract surgery. However, the symptoms were not improved after surgery. Two years later, she had difficulty doing household chores and was unable to dress herself. She developed an anxiety disorder in the absence of prominent language or memory deficits. Five years after onset, she showed global cognitive decline and abilities of daily life decline. On neurological examination she was alert. Neuropsychological testing revealed a mini-mental state examination (MMSE) score of 20/30 with anomia, agraphia, alexia and partial impairment on time orientation. Biochemical investigations for disorders involving thyroid function, vitamin B 12 , and folate were unremarkable. A brain MRI showed diffuse cortical atrophy and hippocampus atrophy. An 18 F-FDG PET scan showed bilateral hypometabolism at the frontal lobes, tempoparietooccipital adjunction, posterior cingulate cortices and precuneus, insular lobes, caudate nuclei and right thalamus. An 11 C-PIB PET scan showed bilateral amyloid deposits at bilateral frontal lobes and occipital lobes, left temporal lobe and insular, basal ganglia, bilateral cingulate cortices and precuneus. No PSEN1, PSEN2 or APP mutations were identified. This early-onset patient had an unusual cognitive complaint, including visual agnosia and apraxia. The clinical features, structural and functional imaging findings of this case were compatible with the diagnosis of Posterior Cortical Atrophy (PCA). PCA is a neurodegenerative condition characterized by a progressive, often dramatic and relatively selective decline in visual processing skills and other functions subserved by parietal, occipital and occipito-temporal regions, relatively intact memory and language in the early stages, and atrophy of posterior brain regions. Often considered as an atypical or variant form of Alzheimer’s disease (AD), PCA typically presents in the mid-50s or early 60s with a variety of unusual symptoms, such as difficulty in interpreting, locating, or reaching for objects under visual guidance or difficulty in navigating. Understanding numbers and reading and writing or spelling may also be affected and, as the disease progresses, patients often develop a more diffuse pattern of cognitive dysfunction, ultimately leading to dementia. The vast majority (>80%) of PCA patients are found to have AD pathology as the cause of dementia at autopsy. Both PCA and AD patients show a similar pattern of high cortical binding on amyloid positron emission tomography (PET) imaging, and analogous changes in cerebrospinal fluid (CSF) level of Aβ42, total tau, and phosphorylated tau. PCA and AD show overlapping atrophy and hypometabolism/hypoperfusion in temporoparietal regions, suggesting a common anatomic focus of neurodegeneration. Structural neuroimaging with either MRI or CT initially shows greater atrophy of visual processing areas in parietotemporo-occipital cortex and relative sparing of critical memory regions in the medial temporal lobe. Over time, the neuroimaging profile of PCA may also merge with that of typical AD. This patient has five-year history of blurred vision and apraxia. At the time of examination, she has been in the stage of global cognitive declining. Diffuse cortical atrophy and hippocampus atrophy in MRI is very difficult to distinguish from typical AD. Hypometabolism and amyloid deposits from PET scan also showed overlapping with typical AD. doi: 10.3969/j.issn.1672-6731.2014.07.018

Age-related behavioural and neurofunctional patterns of second language word learning: Different ways of being successful

This study aimed at investigating the neural basis of word learning as a function of age and word type. Ten young and ten elderly French-speaking participants were trained by means of a computerized Spanish word program. Both age groups reached a similar naming accuracy, but the elderly required significantly more time. Despite equivalent performance, distinct neural networks characterized the ceiling. While the young cohort showed subcortical activations, the elderly recruited the left inferior frontal gyrus, the left lingual gyrus and the precuneus. The learning trajectory of the elderly, the neuroimaging findings together with their performance on the Stroop suggest that the young adults relied on control processing areas whereas the elderly relied on episodic memory circuits, which may reflect resorting to better preserved cognitive resources. Finally, the recruitment of visual processing areas by the elderly may reflect the impact of the language training method used.

Shutting down sensorimotor interference unblocks the networks for stimulus processing: An SMR neurofeedback training study

ObjectiveIn the present study, we investigated how the electrical activity in the sensorimotor cortex contributes to improved cognitive processing capabilities and how SMR (sensorimotor rhythm, 12–15Hz) neurofeedback training modulates it. Previous evidence indicates that higher levels of SMR activity reduce sensorimotor interference and thereby promote cognitive processing. MethodsParticipants were randomly assigned to two groups, one experimental (N=10) group receiving SMR neurofeedback training, in which they learned to voluntarily increase SMR, and one control group (N=10) receiving sham feedback. Multiple cognitive functions and electrophysiological correlates of cognitive processing were assessed before and after 10 neurofeedback training sessions. ResultsThe experimental group but not the control group showed linear increases in SMR power over training runs, which was associated with behavioural improvements in memory and attentional performance. Additionally, increasing SMR led to a more salient stimulus processing as indicated by increased N1 and P3 event-related potential amplitudes after the training as compared to the pre-test. Finally, functional brain connectivity between motor areas and visual processing areas was reduced after SMR training indicating reduced sensorimotor interference. ConclusionsThese results indicate that SMR neurofeedback improves stimulus processing capabilities and consequently leads to improvements in cognitive performance. SignificanceThe present findings contribute to a better understanding of the mechanisms underlying SMR neurofeedback training and cognitive processing and implicate that SMR neurofeedback might be an effective cognitive training tool.

Neural substrates of visual masking by object substitution in schizophrenia

Despite a well-known behavioral finding of visual backward masking impairment in schizophrenia, its underlying neural mechanism remains obscure. This study examined neural correlates of a distinct type of visual backward masking, object substitution masking (OSM), in schizophrenia. Twenty schizophrenia patients and 26 healthy controls completed a 4-Dot OSM task and three functional localizer tasks for the lateral occipital (LO), human motion-sensitive (hMT+), and retinotopic areas in the scanner. In 4-dot masking, subjects detected a target that was followed by a mask consisting of 4 dots that surrounded a target. Stimulus-onset asynchrony (SOA) between target and mask was varied to examine the modulation of masking: (1) within three visual processing areas regions of interest (ROI) (i.e., ROI analysis) and (2) in brain regions outside the three visual processing areas (i.e., whole brain analysis). In the ROI analyses, LO and retinotopic areas showed increased peak amplitude when SOA become longer in both patients and controls. There was also an effect of ROI in that both groups showed higher activation in LO and hMT+ compared with the retinotopic areas. The whole brain analyses revealed a significantly activated area for longer SOAs vs. a short SOA in the occipital cortex in controls only, but the group contrast was not significant. Overall, this study did not find strong evidence for neural abnormalities of OSM in schizophrenia, suggesting that neural substrates of OSM in schizophrenia are not as compromised as those involved in the more common masking methods that rely on disruption of object formation.

Posterior P1 and early frontal negativity reflect developmental changes in attentional distraction during adolescence

Previous studies in adults have revealed that attentional distraction modulates the late positive potential (LPP) during emotion regulation. To determine whether early visual components reflect developmental changes in attentional distraction during adolescence, we collected event-related potentials from 20 young adolescents, 18 older adolescents, and 18 young adults as they performed a distraction task (counting) while viewing affective images. Consistent with previous findings obtained in distraction studies, the distraction task (counting) reduced emotional modulation of the LPP. At an early stage of processing, counting reduced emotional modulation of P1 and increased the negativity bias of early frontal negativity (eFN) for negatively valenced pictures compared to simple viewing with no distraction. sLORETA analyses further revealed eFN indexing of rostral prefrontal cortical activation, a cortical area that has been shown in recent fMRI studies to be activated by distraction. Moreover, P1 amplitudes in young and older adolescents did not differ but were both larger than the P1s in young adults. In addition, eFN amplitudes significantly decreased with age. The dissociable distraction patterns between the posterior P1 and eFN provide evidence not only for the timing hypothesis of emotion regulation but also for different developmental trajectories of visual processing areas and the prefrontal cortex during affective processing in adolescence.

Specific brain morphometric changes in spinal cord injury with and without neuropathic pain.

Why only certain patients develop debilitating pain after spinal chord injury and whether structural brain changes are implicated remain unknown. The aim of this study was to determine if patients with chronic, neuropathic below-level pain have specific cerebral changes compared to those who remain pain-free. Voxel-based morphometry of high resolution, T1-weighted images was performed on three subject groups comprising patients with pain (SCI-P, n = 18), patients without pain (SCI-N, n = 12) and age- and sex-matched controls (n = 18). The SCI-P group was first compared directly with the SCI-N group and then subsequently with controls. Overall, grey and white matter changes dependent on the presence of pain were revealed. Significant changes were found within the somatosensory cortex and also in corticospinal tracts and visual-processing areas. When the SCI-P group was directly compared with the SCI-N group, reduced grey matter volume was found in the deafferented leg area of the somatosensory cortex bilaterally. This region negatively correlated with pain intensity. Relative to controls, grey matter in this paracentral primary sensory cortex was decreased in SCI-P but conversely increased in SCI-N. When compared with controls, discrepant corticospinal tract white matter reductions were found in SCI-P and in SCI-N. In the visual cortex, SCI-N showed increased grey matter, whilst the SCI-N showed reduced white matter. In conclusion, structural changes in SCI are related to the presence and degree of below-level pain and involve but are not limited to the sensorimotor cortices. Pain-related structural plasticity may hold clinical implications for the prevention and management of refractory neuropathic pain.

Cross‐modal reorganization of cortical afferents to dorsal auditory cortex following early‐ and late‐onset deafness

Cat auditory cortex is known to undergo cross-modal reorganization following deafness, such that behavioral advantages in visual motion detection are abolished when a specific region of deaf auditory cortex, the dorsal zone (DZ), is deactivated. The purpose of the present investigation was to examine the connectional adaptations that might subserve this plasticity. We deposited biotinylated dextran amine (BDA; 3,000 MW), a retrograde tracer, unilaterally into the posterior portion of the suprasylvian fringe, corresponding to area DZ of hearing, early-deafened (onset <1 month), and late-deafened (onset >3 months) cats to reveal cortical afferent projections. Overall, the pattern of cortical projections to DZ was similar in both hearing and deafened animals. However, there was a progressive increase in projection strength among hearing and late- and early-deafened cats from an extrastriate visual cortical region known to be involved in the processing of visual motion, the posterolateral lateral suprasylvian area (PLLS). Additionally, although no such change was documented for the posteromedial lateral suprasylvian area (PMLS), labeled neurons were present within a subregion of PMLS devoted to foveal vision in both late- and early-deafened animals but not in hearing controls. PMLS is also an extrastriate visual motion processing area and is widely considered to be the homolog of primate middle temporal area. No changes in auditory cortical connectivity were observed among groups. These observations suggest that amplified cortical projections from extrastriate visual areas involved in visual motion processing to DZ may contribute to the cross-modal reorganization that functionally manifests as superior visual motion detection ability in the deaf animal.

Diagnosing Developmental Dyscalculia on the Basis of Reliable Single Case FMRI Methods: Promises and Limitations

FMRI-studies are mostly based on a group study approach, either analyzing one group or comparing multiple groups, or on approaches that correlate brain activation with clinically relevant criteria or behavioral measures. In this study we investigate the potential of fMRI-techniques focusing on individual differences in brain activation within a test-retest reliability context. We employ a single-case analysis approach, which contrasts dyscalculic children with a control group of typically developing children. In a second step, a support-vector machine analysis and cluster analysis techniques served to investigate similarities in multivariate brain activation patterns. Children were confronted with a non-symbolic number comparison and a non-symbolic exact calculation task during fMRI acquisition. Conventional second level group comparison analysis only showed small differences around the angular gyrus bilaterally and the left parieto-occipital sulcus. Analyses based on single-case statistical procedures revealed that developmental dyscalculia is characterized by individual differences predominantly in visual processing areas. Dyscalculic children seemed to compensate for relative under-activation in the primary visual cortex through an upregulation in higher visual areas. However, overlap in deviant activation was low for the dyscalculic children, indicating that developmental dyscalculia is a disorder characterized by heterogeneous brain activation differences. Using support vector machine analysis and cluster analysis, we tried to group dyscalculic and typically developing children according to brain activation. Fronto-parietal systems seem to qualify for a distinction between the two groups. However, this was only effective when reliable brain activations of both tasks were employed simultaneously. Results suggest that deficits in number representation in the visual-parietal cortex get compensated for through finger related aspects of number representation in fronto-parietal cortex. We conclude that dyscalculic children show large individual differences in brain activation patterns. Nonetheless, the majority of dyscalculic children can be differentiated from controls employing brain activation patterns when appropriate methods are used.

A ladder of lies: the adaptive advantages of deception

The Folly of Fools: The Logic of Deceit and Self-Deception in Human Life, by Robert Trivers. Philadelphia, PA: Basic Books, 2011. ‘The ultimate effect of shielding men from the effects of their folly is to fill the world with fools’. Herbert Spencer Largely through historical examples and personal anecdotes, Robert Trivers builds the foundation for an evolutionary theory of self-deception and deceit in his recent book, The Folly of Fools: The Logic of Deceit and Self-Deception in Human Life. Beginning with the evolutionary roots and logic of our unrivaled ability to hide the truth from ourselves and others, Trivers then explores phylogenetic, psychological, anthropological, and historical examples of deception, its consequences, and its propagation. Perhaps the most thought-provoking aspect of The Folly of Fools is Trivers visiting, and revisiting of the (seemingly) incompatible notions that: (1) of the most complex creatures that have ever evolved, we have a sensory system that provides us with an incredibly rich image of the world around us; yet (2) our brains swiftly bend, distort, or ignore this information. In other words, why, at the expense of valuable energetic resources, has evolution favored such sensitive truth-detecting and truth-dispensing processes? It is worth noting that this stark truth/lie dichotomy is likely a bit of an exaggeration; for example, visual perception does not have to wait for processing in visual areas of the brain to be distorted. The bending and aggregating of visual information begins as early in sensory processing as retinal ganglion cells. This relative lack of ‘truth’ in our sensory experience is, later in the text, addressed by Trivers: ‘At every single stage from its biased arrival, to its biased encoding, to organizing it around false logic, to misremembering and then misrepresenting it to others, the mind continually acts to distort information flow...’ (p. 139).

The development and validation of the Self-Report Measure of Cognitive Abilities: A multitrait–multimethod study

The expansion in our understanding of the structure of differential cognitive abilities afforded by the Cattell–Horn–Carroll (CHC) model has brought with it the need to provide practitioners with efficient and effective methods for screening which abilities most critically require assessment. A Self-Report Measure of Cognitive Abilities could assist practitioners with this process. This article outlines the development and initial validation of the Self-Report Measure of Cognitive Abilities (SRMCA), a multi-item measure designed to indicate cognitive functioning in the CHC ability areas of Fluid reasoning (Gf), Comprehension-knowledge (Gc), and Visual processing (Gv). Validity was initially investigated and supported using exploratory factor analysis, and then cross-validated on a second sample using structural equation modelling (SEM). Subsequently, SEM based multitrait–multimethod analysis of the second sample confirmed convergent validity for the Gc and Gv subscales, but not the Gf subscale. The extent of method variance influence on the SRMCA was found to be non-existent, a markedly different result to that found for the single-item self-estimates of cognitive abilities. Results thus indicate that the use of multiple and specific items allows for self-ratings of distinct cognitive ability areas to be independent of one another. Suggestions for future research aimed at extending the current study are provided.

Perception-Based Media Processing [Scanning the Issue

The articles in this special issue provide a timely reviewof the state of the art in the areas of perception-based audio, visual, and haptic processing.

Basic Instinct Undressed: Early Spatiotemporal Processing for Primary Sexual Characteristics

This study investigates the spatiotemporal dynamics associated with conscious and non-conscious processing of naked and dressed human bodies. To this effect, stimuli of naked men and women with visible primary sexual characteristics, as well as dressed bodies, were presented to 20 heterosexual male and female participants while acquiring high resolution EEG data. The stimuli were either consciously detectable (supraliminal presentations) or were rendered non-conscious through backward masking (subliminal presentations). The N1 event-related potential component was significantly enhanced in participants when they viewed naked compared to dressed bodies under supraliminal viewing conditions. More importantly, naked bodies of the opposite sex produced a significantly greater N1 component compared to dressed bodies during subliminal presentations, when participants were not aware of the stimulus presented. A source localization algorithm computed on the N1 showed that the response for naked bodies in the supraliminal viewing condition was stronger in body processing areas, primary visual areas and additional structures related to emotion processing. By contrast, in the subliminal viewing condition, only visual and body processing areas were found to be activated. These results suggest that naked bodies and primary sexual characteristics are processed early in time (i.e., <200 ms) and activate key brain structures even when they are not consciously detected. It appears that, similarly to what has been reported for emotional faces, sexual features benefit from automatic and rapid processing, most likely due to their high relevance for the individual and their importance for the species in terms of reproductive success.

A survey of perceptual image processing methods

Perceptual approaches have been widely used in many areas of visual information processing. This paper presents an overview of perceptual based approaches for image enhancement, segmentation and coding. The paper also provides a brief review of image quality assessment (IQA) methods, which are used to evaluate the performance of visual information processing techniques. The intent of this paper is not to review all the relevant works that have appeared in the literature, but rather to focus on few topics that have been extensively researched and developed over the past few decades. The goal is to present a perspective as broad as possible on this actively evolving domain due to relevant advances in vision research and signal processing. Therefore, for each topic, we identify the main contributions of perceptual approaches and their limitations, and outline how perceptual vision has influenced current state-of-the-art techniques in image enhancement, segmentation, coding and visual information quality assessment.

Direct Evidence for Attention-Dependent Influences of the Frontal Eye-Fields on Feature-Responsive Visual Cortex

Voluntary selective attention can prioritize different features in a visual scene. The frontal eye-fields (FEF) are one potential source of such feature-specific top-down signals, but causal evidence for influences on visual cortex (as was shown for “spatial” attention) has remained elusive. Here, we show that transcranial magnetic stimulation (TMS) applied to right FEF increased the blood oxygen level–dependent (BOLD) signals in visual areas processing “target feature” but not in “distracter feature”–processing regions. TMS-induced BOLD signals increase in motion-responsive visual cortex (MT+) when motion was attended in a display with moving dots superimposed on face stimuli, but in face-responsive fusiform area (FFA) when faces were attended to. These TMS effects on BOLD signal in both regions were negatively related to performance (on the motion task), supporting the behavioral relevance of this pathway. Our findings provide new causal evidence for the human FEF in the control of nonspatial “feature”-based attention, mediated by dynamic influences on feature-specific visual cortex that vary with the currently attended property.

Neural predictors and mechanisms of cognitive behavioral therapy on threat processing in social anxiety disorder

Cognitive behavioral therapy (CBT) is "gold standard" psychotherapy for social anxiety disorder (SAD). Cognitive models posit that preferential processing of threat mediates excessive forms of anxiety, which is supported by exaggerated amygdala, insula, and cortical reactivity to threatening socio-emotional signals in SAD. However, little is known about neural predictors of CBT success or the mechanisms by which CBT exerts its therapeutic effects. Functional magnetic resonance imaging (fMRI) was conducted during responses to social signals of threat (fearful/angry faces) against positive signals (happy faces) in 14 patients with SAD before and after 12 weeks of CBT. For comparison, 14 healthy control (HC) participants also underwent two fMRI scans, 12 weeks apart. Whole-brain voxel-wise analyses showed therapeutic success was predicted by enhanced pre-treatment activation to threatening faces in higher-order visual (superior and middle temporal gyrus), cognitive, and emotion processing areas (dorsal anterior cingulate cortex, dorsomedial prefrontal cortex). Moreover, a group by time interaction was revealed in prefrontal regions (dorsomedial, medial gyrus) and insula. The interaction was driven by relatively greater activity during threat processing in SAD, which significantly reduced after CBT but did not significantly predict response to CBT. Therefore, pre-treatment cortical hyperactivity to social threat signals may serve as a prognostic indicator of CBT success in SAD. Collectively, CBT-related brain changes involved a reduction in activity in insula, prefrontal, and extrastriate regions. Results are consistent with cognitive models, which associate decreases in threat processing bias with recovery.

A cortical pathway to olfactory naming: evidence from primary progressive aphasia

It is notoriously difficult to name odours. Without the benefit of non-olfactory information, even common household smells elude our ability to name them. The neuroscientific basis for this olfactory language 'deficit' is poorly understood, and even basic models to explain how odour inputs gain access to transmodal representations required for naming have not been put forward. This study used patients with primary progressive aphasia, a clinical dementia syndrome characterized by primary deficits in language, to investigate the interactions between olfactory inputs and lexical access by assessing behavioural performance of olfactory knowledge and its relationship to brain atrophy. We specifically hypothesized that the temporal pole would play a key role in linking odour object representations to transmodal networks, given its anatomical proximity to olfactory and visual object processing areas. Behaviourally, patients with primary progressive aphasia with non-semantic subtypes were severely impaired on an odour naming task, in comparison with an age-matched control group. However, with the availability of picture cues or word cues, odour matching performance approached control levels, demonstrating an inability to retrieve but not to recognize the name and nature of the odorant. The magnitude of cortical thinning in the temporal pole was found to correlate with reductions in odour familiarity and odour matching to visual cues, whereas the inferior frontal gyrus correlated with both odour naming and matching. Volumetric changes in the mediodorsal thalamus correlated with the proportion of categorical mismatch errors, indicating a possible role of this region in error-signal monitoring to optimize recognition of associations linked to the odour. A complementary analysis of patients with the semantic subtype of primary progressive aphasia, which is associated with marked temporopolar atrophy, revealed much more pronounced impairments of odour naming and matching. In identifying the critical role of the temporal pole and inferior frontal gyrus in transmodal linking and verbalization of olfactory objects, our findings provide a new neurobiological foundation for understanding why even common odours are hard to name.

The Dynamic Neural Network and Its Development of Visual Word Processing

Investigating the dynamic neural network of cognitive processing is the new approach of cognitive neuroscience.This project proposes a series of fMRI experiments to investigate the function role of visual word form area(VWFA)at left middle part of fusiform gyrus,and further investigates the neural network of visual word processing and its development.Taking advantage of the specific properties of Chinese writing system,the first study will examine the activations of VWFA both under the task demands and the stimuli-driven.The interaction among VWFA,phonological and semantic areas will be tested to show the dynamic activation of brain regions involved in visual words processing.The second study investigates how the language experience shapes the development of brain network of visual words processing,by combining the experiments on English-speaker and Chinese Children.The third study conducts multivariate analysis on data from functional imaging,resting state and diffusion tensor imaging (DTI).The function and effective connectivity among visual,phonological and semantic processing areas will be used to construct the neurobiological model of visual words processing,and further to show the impact of language experience on its development.

Brain white matter microstructure is associated with susceptibility to motion‐induced nausea

Nausea is associated with significant morbidity, and there is a wide range in the propensity of individuals to experience nausea. The neural basis of the heterogeneity in nausea susceptibility is poorly understood. Our previous functional magnetic resonance imaging (fMRI) study in healthy adults showed that a visual motion stimulus caused activation in the right MT+/V5 area, and that increased sensation of nausea due to this stimulus was associated with increased activation in the right anterior insula. For the current study, we hypothesized that individual differences in visual motion-induced nausea are due to microstructural differences in the inferior fronto-occipital fasciculus (IFOF), the white matter tract connecting the right visual motion processing area (MT+/V5) and right anterior insula. To test this hypothesis, we acquired diffusion tensor imaging data from 30 healthy adults who were subsequently dichotomized into high and low nausea susceptibility groups based on the Motion Sickness Susceptibility Scale. We quantified diffusion along the IFOF for each subject based on axial diffusivity (AD); radial diffusivity (RD), mean diffusivity (MD) and fractional anisotropy (FA), and evaluated between-group differences in these diffusion metrics. Subjects with high susceptibility to nausea rated significantly (P < 0.001) higher nausea intensity to visual motion stimuli and had significantly (P < 0.05) lower AD and MD along the right IFOF compared to subjects with low susceptibility to nausea. This result suggests that differences in white matter microstructure within tracts connecting visual motion and nausea-processing brain areas may contribute to nausea susceptibility or may have resulted from an increased history of nausea episodes.

Age-related differences in agenda-driven monitoring of format and task information

Age-related source memory deficits may arise, in part, from changes in the agenda-driven processes that control what features of events are relevant during remembering. Using fMRI, we compared young and older adults on tests assessing source memory for format (picture, word) or encoding task (self-, other-referential), as well as on old–new recognition. Behaviorally, relative to old–new recognition, older adults showed disproportionate and equivalent deficits on both source tests compared to young adults. At encoding, both age groups showed expected activation associated with format in posterior visual processing areas, and with task in medial prefrontal cortex. At test, the groups showed similar selective, agenda-related activity in these representational areas. There were, however, marked age differences in the activity of control regions in lateral and medial prefrontal cortex and lateral parietal cortex. Results of correlation analyses were consistent with the idea that young adults had greater trial-by-trial agenda-driven modulation of activity (i.e., greater selectivity) than did older adults in representational regions. Thus, under selective remembering conditions where older adults showed clear differential regional activity in representational areas depending on type of test, they also showed evidence of disrupted frontal and parietal function and reduced item-by-item modulation of test-appropriate features. This pattern of results is consistent with an age-related deficit in the engagement of selective reflective attention.