Mikkel Wallentin

Working memory (WM) evoked by linguistic cues for allocentric spatial and egocentric spatial aspects of a visual scene was investigated by correlating fMRI BOLD signal (or “activation”) with performance on a spatial-relations task. Subjects indicated the relative positions of a person or object (referenced by the personal pronouns “he/she/it”) in a previously shown image relative to either themselves (egocentric reference frame) or shifted to a reference frame anchored in another person or object in the image (allocentric reference frame), e.g. “Was he
in front of you/her?” Good performers had both shorter response time and more correct responses than poor performers in both tasks. These behavioural variables were entered into a principal component analysis. The first component reflected generalised performance level. We found that the frontal eye fields (FEF), bilaterally, had a higher BOLD response during recall involving allocentric compared to egocentric spatial reference frames, and that this difference was larger in good performers than in poor performers as measured by the first behavioral principal component. The frontal eye fields may be used when subjects move their internal gaze during shifting reference frames in representational space. Analysis of actual eye movements in three subjects revealed no difference between egocentric and allocentric recall tasks where visual stimuli were also absent. Thus, the FEF machinery for directing eye movements may also be involved in changing reference frames within WM.

The left posterior middle temporal region, anterior to V5/MT, has been shown to be responsive both to images with implied motion, to simulated motion, and to motion verbs. In this study, we investigated whether sentence context alters the response of the left posterior middle temporal region. 'Fictive motion' sentences are sentences in which an inanimate subject noun, semantically incapable of self movement, is coupled with a motion verb, yielding an apparent semantic contradiction (e.g. 'The path comes into the garden.'). However, this context yields no less activation in the left posterior middle temporal region than sentences in which the motion can be applied to the subject noun. We speculate that the left posterior middle temporal region activity in fictive motion sentences reflects the fact that the hearer applies motion to the depicted scenario by scanning it egocentrically.

Using functional magnetic resonance imaging, we contrasted major and minor mode melodies controlled for liking to study the neural basis of musical mode perception. To examine the influence of the larger dissonance in minor melodies on neural activation differences, we further introduced a strongly dissonant stimulus, in the form of a chromatic scale. Minor mode melodies were evaluated as sadder than major melodies, and in comparison they caused increased activity in limbic structures, namely left parahippocampal gyrus, bilateral ventral anterior cingulate, and in left medial prefrontal cortex. Dissonance explained some, but not all, of the heightened activity in the limbic structures when listening to minor mode music.

High sensitivity to magnetic susceptibility changes and accurate localization of functional activations are key requisites for pulse sequences used for BOLD fMRI. This paper seeks to develop a framework for analysing the performance of various k-space sampling techniques in this respect, with special emphasis on spiral EPI (spiral) and cartesian EPI (EPI) and their performance under influence of induced field gradients (SFGs) and stochastic noise. A numerical method for calculating synthetic MR images is developed and used to simulate BOLD fMRI experiments using EPI and spirals. The data is then examined for activation using a pixel-wise t test. Nine subjects are scanned with both techniques while performing a motor task. SPM99 is used for analysing the experimental data. The simulated spirals provide generally higher t scores at low SFGs but lose more strength than EPI at higher SFGs, where EPI activation is offset from the true position. In the primary motor area spirals provide significantly higher t scores (P < 0.0002). In-plane variation of EPI is higher in phase-encoding direction than in frequency-encoding direction (P < 0.003). In the low SFG areas spirals provide stronger activation than EPI and less spatial variability. Thus, spirals are recommended for fMRI in motor area and language areas.

This experiment tests how people produce and detect deception while playing a computerized version of the dice game, Meyer. Deception is an integral part of this game, and the participants played it as in real life, without constraints on whether or when to attempt to deceive their opponent, and whether or when to accuse them of deception. We stress that deception is a complex act that cannot be exclusively associated with telling a falsehood, and that it is facilitated by hierarchical decision-making and risk evaluation. In comparison with a non-competitive control condition, both claiming truthfully and claiming falsely were associated with activity in fronto-polar cortex (BA10). However, relative to true claims, false claims were associated with greater activity in the premotor and parietal cortices. We speculate that the activity in BA10 is associated with the development of high-level executive strategies involved in both types of claim, while the premotor and parietal activity is associated with the need to select which particular claim to make.

Abstract: It is widely assumed that human learning and the structure of human languages are intimately related. This relationship is frequently suggested to derive from a language-specific biological endowment, which encodes universal, but communicatively arbitrary, principles ...

ABSTRACT Nearly all neuroimaging studies of creative behavior investigate verbal associations. These studies find an involvement of the left dorsolateral prefrontal cortex (DLPFC). In contrast, two recent studies of pianists found the right DLPFC to be linked ...

1Le présent chapitre passe en revue les études d'imagerie par résonance magnétique fonctionnelle (IRMf) relatives au rappel, indicé verbalement, des propriétés spatiales d'images vues ; ou de phrases lues précédemment. La mise en place de références contextuelles durant un ...