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International audience; The standard technique for brain activation functional MRI (fMRI) is the BOLD sequence. Two new techniques have emerged: arterial spin labeling (ASL) MRI and diffusion MRI. Both have the theoretical advantage of more accurately directly demonstrating neuronal activation compared to BOLD imaging, resulting in improved spatial and temporal resolution. ASL is a perfusion sequence using labeled arterial protons as an endogenous perfusion agent. In spite of methodological difficulties, quantitative CBF measurements are possible. ASL is less susceptible to venous contamination than BOLD and more reproducible. Diffusion MRI evaluates neuronal activation at the cellular level with the prospect of excellent spatial resolution. The main limitations for both techniques are the technical difficulties in the acquisition and the low SNR. AS such, ASL is not widely used clinically and diffusion remains in the field of research. However, the increasing availability of 3T MR systems coupled with multi-channel surface coils and improved postprocessing techniques should improve the detection of the brain activation signal. It is thus possible that these techniques could become clinically available either in complement to or as a replacement for BOLD imaging.

International audience

International audience; For now several years, the growing developement of neuroimaging techniques such as Positron Emission Tomography (PET) or functional Magnetic Resonance Imaging (fMRI) allowed a better understanding of neural processes involved in human emotions and goal-directed behaviors. In particular, several studies are now available on the neural correlates of male sexual arousal. A neurobehavioral model of neural processes involved in sexual arousal has been proposed (Redout?t al., 2000) comprising: i) a cognitive component; ii) an emotional component; iii) a motivational component and iv) an autonomic component. Among other regions, several cerebral areas have been found to be linked to: 1) the cognitive component which comprises: i) the orbitofrontal cortex involved in attentional processes directed toward the target and the superior parietal lobules; ii) the inferior parietal lobules involved in motor imagery processes; 2) the motivational component which involves the caudal part of the anterior cingulate cortex, related to motor preparation processes; 3) the autonomic component: concurrent measures of cerebral activations by functional neuroimaging and of erectile response by penile plethysmography allow the demonstration of the involvement of the hypothalamus, the insula, and the rostral part of the anterior cingulate cortex in this component.

International audience; Many groups are trying out functional MRI (fMRI) to study normal and diseased brain function. FMRI is a technique that images intrinsic blood signal changes accompanying variations of cerebral blood flow (CBF), cerebral blood volume (CBV) and oxygenation during mental activity. The main advantages which account for fMRI's increasing popularity are its time resolution (less than 1 second), a fine spatial resolution (on the scale of 1 mm), and the ability to acquire, within the same individual, repeated, multiple scans in a non-invasive manner. While the basic design of most studies centers on comparison of baseline to an active (test) condition, as the Positron Emission Tomography (PET), fMRI allows an important departure from the single scan per condition study-design, into more flexible paradigms of multiple scans over varying time intervals and multiple conditions. Although the technique is only a few years old, a large volume of experimental data have already been published. In this presentation we would like to provide potential users with a short overview of the basic principles and the main applications in cognitive neuroscience, as well as potential clinical applications.

International audience; Many groups are trying out functional MRI (fMRI) to study normal and diseased brain function. FMRI is a technique that images intrinsic blood signal changes accompanying variations of cerebral blood flow (CBF), cerebral blood volume (CBV) and oxygenation during mental activity. The main advantages which account for fMRI's increasing popularity are its time resolution (less than 1 second), a fine spatial resolution (on the scale of 1 mm), and the ability to acquire, within the same individual, repeated, multiple scans in a non-invasive manner. While the basic design of most studies centers on comparison of baseline to an active (test) condition, as the Positron Emission Tomography (PET), fMRI allows an important departure from the single scan per condition study-design, into more flexible paradigms of multiple scans over varying time intervals and multiple conditions. Although the technique is only a few years old, a large volume of experimental data have already been published. In this presentation we would like to provide potential users with a short overview of the basic principles and the main applications in cognitive neuroscience, as well as potential clinical applications.

International audience; Clinical research may be seen in the context of the more general problem of an exchange of knowledge between psychopathology and neurosciences. While this interaction is not contested by the specialists in either field, we cannot, nonetheless, ignore the question of their various levels of congruence. More generally, we are increasingly aware of a need for enhanced formalization of the models derived from the two disciplines with a view to setting up transpositions or even cross fertilizations. The two communities, that of psychiatrists and that of neurobiologists, while they fascinate each other, have rarely been able to produce joint findings. The psychopathologist expects a positive validation of his clinical concepts from the neurobiologist, while the neurobiologist, who has frequently not resisted the etiological temptation, wants the clinician to give him pointers to enable him to refine his own experimental models. What is required, however, is that both the psychopathologist and the neurobiologist reduce their expectations and agree to move outside of their respective disciplinary autarkies. This would avoid two traps: that of the homological temptation which leads both to graft an experimental model onto clinical entities without checking the levels of congruence or non-congruence, making do with a simple behavioral similarity; the second error consists in using the complexity of the clinical picture as an unavoidable obstacle to any coming-together of the two disciplines. These two traps have not always been avoided, in particular in the context of the use of cognitive paradigms in nosographic clinical models.

International audience; Many groups are trying out functional MRI (fMRI) to study normal and diseased brain function. FMRI is a technique that images intrinsic blood signal changes accompanying variations of cerebral blood flow (CBF), cerebral blood volume (CBV) and oxygenation during mental activity. The main advantages which account for fMRI's increasing popularity are its time resolution (less than 1 second), a fine spatial resolution (on the scale of 1 mm), and the ability to acquire, within the same individual, repeated, multiple scans in a non-invasive manner. While the basic design of most studies centers on comparison of baseline to an active (test) condition, as the Positron Emission Tomography (PET), fMRI allows an important departure from the single scan per condition study-design, into more flexible paradigms of multiple scans over varying time intervals and multiple conditions. Although the technique is only a few years old, a large volume of experimental data have already been published. In this presentation we would like to provide potential users with a short overview of the basic principles and the main applications in cognitive neuroscience, as well as potential clinical applications.