Mental rotation meets the motion aftereffect: the role of hV5/MT+ in visual mental imagery

A growing number of studies show that visual mental imagery recruits the same brain areas as visual perception. Although the necessity of hV5/MT+ for motion perception has been revealed by means of TMS, its relevance for motion imagery remains unclear. We induced a direction-selective adaptation in hV5/MT+ by means of an MAE while subjects performed a mental rotation task that elicits imagined motion. We concurrently measured behavioral performance and neural activity with fMRI, enabling us to directly assess the effect of a perturbation of hV5/MT+ on other cortical areas involved in the mental rotation task. The activity in hV5/MT+ increased as more mental rotation was required, and the perturbation of hV5/MT+ affected behavioral performance as well as the neural activity in this area. Moreover, several regions in the posterior parietal cortex were also affected by this perturbation. Our results show that hV5/MT+ is required for imagined visual motion and engages in an interaction with parietal cortex during this cognitive process

The Timecourse of Activation Within the Cortical Network Associated with Visual Imagery

The current study examined the hemodynamic timecourse of activation within a network of regions that is thought to be associated with visual imagery. Two experimental conditions were examined that were designed to place differential demands on specific nodes within the visual imagery network. The two tasks were an object inspection task and a mental rotation task. The two conditions recruited overlapping cortical regions; however several regions revealed a differential response to object inspection and mental rotation. The mental rotation condition elicited greater activation in parietal cortex, lateral occipital/temporal regions, and bilateral prefrontal cortex. Conversely, the object inspection condition elicited greater activation in inferior extrastriate cortex, the inferior frontal gyrus, and the right cerebellum. When examining the timecourse of activation three different timecourse patterns were observed across cortical regions and conditions. The shape of the hemodynamic timecourse appears to correspond strongly with the cognitive processing taking place within the region, not the stimulus paradigm. The paper discusses the significance of those varying timecourse shapes and has implications for the appropriateness of using the canonical hrf during fMRI data analysis

Working memory encoding delays top-down attention to visual cortex

The encoding of information from one event into working memory can delay high-level, central decision-making processes for subsequent events [e.g., Jolicoeur, P., & Dell'Acqua, R. The demonstration of short-term consolidation. Cognitive Psychology, 36, 138-202, 1998, doi:10.1006/cogp.1998.0684]. Working memory, however, is also believed to interfere with the deployment of top-down attention [de Fockert, J. W., Rees, G., Frith, C.D., &Lavie, N. The role ofworking memory in visual selective attention. Science, 291, 1803-1806, 2001, doi:10.1126/science.1056496]. It is, therefore, possible that, in addition to delaying central processes, the engagement of working memory encoding (WME) also postpones perceptual processing as well. Here, we tested this hypothesis with time-resolved fMRI by assessing whether WME serially postpones the action of top-down attention on low-level sensory signals. In three experiments, participants viewed a skeletal rapid serial visual presentation sequence that contained two target items (T1 and T2) separated by either a short (550 msec) or long (1450 msec) SOA. During single-target runs, participants attended and responded only to T1, whereas in dual-target runs, participants attended and responded to both targets. To determine whether T1 processing delayed top-down attentional enhancement of T2, we examined T2 BOLD response in visual cortex by subtracting the single-task waveforms from the dualtask waveforms for each SOA. When the WME demands of T1 were high (Experiments 1 and 3), T2 BOLD response was delayed at the short SOA relative to the long SOA. This was not the case when T1 encoding demands were low (Experiment 2). We conclude that encoding of a stimulus into working memory delays the deployment of attention to subsequent target representations in visual cortex

Entwicklungsbedingte morphologische Gehirnveränderungen und ihre funktionellen Auswirkungen auf die räumliche Zahlenverarbeitung

This study examines age-related changes in grey and white matter in subjects aged eight to 20 years and their consequences on skills required at school. Therefore, 137 children underwent an MRI scan during which VBM as well as fMRI data were acquired. I expected a grey matter reduction with increasing age especially in frontal and parietal regions, activation in these areas induced by school exercises and an impact of anatomic changes on exercise performance. Results showed grey matter reduction in favour of white matter with increasing age in inferior frontal gyrus, superior parietal lobule, intraparietal sulcus and middle temporal gyrus closely to superior and middle temporal sulcus. Activation induced by school exercises was found especially in superior parietal lobule and frontal and occipital areas. Linking morphology and function, the following correlations emerged: A reduction of grey matter in left superior parietal lobule had a functional impact on mental rotation performance, whereas similar right-hemispheric changes affected number processing.Diese Studie untersucht die altersabhängigen Veränderungen der grauen und weißen Gehirnsubstanz im Altersgefüge von acht bis 20 Jahren und deren Auswirkungen auf die schulische Performanz. Zu diesem Zweck nahmen 137 Kinder an einer MRT-Messung teil, bei der sowohl VBM- als auch fMRI-Daten erhoben wurden. Ich erwartete eine Reduktion der grauen Substanz mit zunehmendem Alter vor allem in frontalen und parietalen Arealen, eine Aktivierung innerhalb dieser Areale durch schulische Aufgaben und eine Auswirkung der anatomischen Veränderungen auf die Performanz bei diesen Aufgaben. Die Ergebnisse zeigten eine Abnahme der grauen bei gleichzeitiger Zunahme der weißen Substanz mit voranschreitendem Alter vorwiegend im Inferioren Frontalgyrus, im Superioren Parietallappen, im Intraparietalsulcus sowie im mittleren Temporalgyrus in unmittelbarer Nähe zum Superioren und Mittleren Temporalsulcus. Eine Aktivierung durch schulische Aufgaben war insbesondere im Superioren Parietallappen und in frontalen und okzipitalen Arealen zu verzeichnen. Bei der Verknüpfung zwischen Morphologie und Funktion stellten sich folgende Zusammenhänge heraus: Eine Reduktion der grauen Substanz im linken Superioren Parietallappen wirkt sich funktionell auf die Performanz bei der mentalen Rotation aus, während sich entsprechende Veränderungen rechtshemisphärisch auf die Performanz bei der Zahlenverarbeitung auswirkten

Shared and Distinct Neural Bases of Large- and Small-Scale Spatial Ability: A Coordinate-Based Activation Likelihood Estimation Meta-Analysis

Background: Spatial ability is vital for human survival and development. However, the relationship between large-scale and small-scale spatial ability remains poorly understood. To address this issue from a novel perspective, we performed an activation likelihood estimation (ALE) meta-analysis of neuroimaging studies to determine the shared and distinct neural bases of these two forms of spatial ability.Methods: We searched Web of Science, PubMed, PsycINFO, and Google Scholar for studies regarding “spatial ability” published within the last 20 years (January 1988 through June 2018). A final total of 103 studies (Table 1) involving 2,085 participants (male = 1,116) and 2,586 foci were incorporated into the meta-analysis.Results: Large-scale spatial ability was associated with activation in the limbic lobe, posterior lobe, occipital lobe, parietal lobe, right anterior lobe, frontal lobe, and right sub-lobar area. Small-scale spatial ability was associated with activation in the parietal lobe, occipital lobe, frontal lobe, right posterior lobe, and left sub-lobar area. Furthermore, conjunction analysis revealed overlapping regions in the sub-gyrus, right superior frontal gyrus, right superior parietal lobule, right middle occipital gyrus, right superior occipital gyrus, left inferior occipital gyrus, and precuneus. The contrast analysis demonstrated that the parahippocampal gyrus, left lingual gyrus, culmen, right middle temporal gyrus, left declive, left superior occipital gyrus, and right lentiform nucleus were more strongly activated during large-scale spatial tasks. In contrast, the precuneus, right inferior frontal gyrus, right precentral gyrus, left inferior parietal lobule, left supramarginal gyrus, left superior parietal lobule, right inferior occipital gyrus, and left middle frontal gyrus were more strongly activated during small-scale spatial tasks. Our results further indicated that there is no absolute difference in the cognitive strategies associated with the two forms of spatial ability (egocentric/allocentric).Conclusion: The results of the present study verify and expand upon the theoretical model of spatial ability proposed by Hegarty et al. Our analysis revealed a shared neural basis between large- and small-scale spatial abilities, as well as specific yet independent neural bases underlying each. Based on these findings, we proposed a more comprehensive version of the behavioral model

Developing and Testing a Novel Neuroscience Hypothesis of Anorexia Nervosa

Eating disorders are difficult to treat: there is still no NICE-approved first-line treatment for anorexia nervosa. In part this could be due to a lack of a compelling theoretical model to account for the development and dogged persistence of the illness. Sociocultural factors implicating western preoccupation with thinness and attractiveness are likely to play a contributory role, but cannot be by themselves causal in societies where such ideals are dominant. Recent theoretical models in neuroscience predict that predisposing neurobiological factors in early brain development may render some young people more vulnerable than others to universal psychosocial pressures, especially during adolescence. This dissertation reviews the existing evidence for abnormal neurobiological functioning in eating disorders, acknowledging that it is difficult to distinguish between the acute effects of starvation on the brain and possibly pre-existing underlying factors. Nevertheless, such empirical studies do support the development of a novel hypothesis implicating abnormal functioning of a neural network centred on the insula cortex in anorexia nervosa. The insula hypothesis is tested in a series of functional imaging studies using Single Positron Emission Computed Tomography (SPECT) indicating focal abnormalities in the temporal region that persist following weight restoration treatment and correlate with neuropsychological deficits. A subsequent study using higher resolution functional Magnetic Resonance Imaging (fMRI) lends further partial support to the insula hypothesis (in three out of four tasks) and also implicates additional brain structures in the basal ganglia. These findings, if replicated, could contribute to the development of novel therapeutic approaches to the treatment of anorexia nervosa, including realtime fMRI and mindfulness-based approaches, both of which have been shown to modulate insula activation. The studies presented here could hopefully also help to reduce the stigma and shame so often associated with eating disorders, for the benefit of sufferers and their families.Helse Sør Øst, Norway