Abstract: The challenge of unraveling the function of the human amygdala is attracting great interest. The major subregions of the human amygdala, the laterobasal group (LB), the superficial group (SF), and the centromedial group (CM), have been anatomically delineated, but little is known about the functional response properties of these amygdala subregions in humans. We combined functional magnetic resonance imaging (fMRI) with cyto-architectonically defined probabilistic maps to analyze the response characteris-tics of these amygdala subregions in healthy subjects presented with auditory stimuli. We acquired fMRI with high spatial resolution as this might be advantageous for subregional amygdala imaging. Here we report results obtained from spatially smoothed data because analysis of the unsmoothed high resolution data did not yield sufficient statistical power. We found positive auditory stimulation-related signal changes pre-dominantly in probabilistic defined LB. The peak amplitudes of the hemodynamic responses in the amygdala were however much smaller than in the auditory neocortex (approx. 10 % of the cortical responses). Finally, auditory responses in LB, and to a lesser degree also in SF, showed significant habituation across the time of the experiment. These findings likely reflect a predominance of auditory inputs to human LB, similar to many animal species in which the majority of sensory, including auditory, afferents project to this subregion of the amygdala. We argue that, taking into account the small response amplitudes in the amygdala region, high resolution acquisition may be advantageous even if spatial lowpass filtering is required and that high resolution fMRI thus may contribute to optimize subregional imaging of the human amygdala.

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{{Explor lien
   |wiki=    Wicri/Musique
   |area=    DebussyV1
   |flux=    Main
   |étape=   Exploration
   |type=    RBID
   |clé=     ISTEX:DA16E024FB3A66366AFEA776568B5476BC7D6DA8
   |texte=   Probabilistic Assignment of Brain Responses to the Human Amygdala and its Subregions using High Resolution Functional MRI
}}