Comment on "Modafinil shifts human locus coeruleus to low-tonic, high-phasic activity during functional MRI" and "Homeostatic sleep pressure and responses to sustained attention in the suprachiasmatic area"

Abstract

Minzenberg et al. (Reports, 12 December 2008, p. 1700) and Schmidt et al. (Reports, 24 April 2009, p. 516) reported blood oxygen level-dependent (BOLD) responses in the human locus coeruleus (LC). Here, we show that these LC responses do not correspond to the anatomical location of the LC and present cautionary data concerning the quality of BOLD signals measured from the LC using standard functional magnetic resonance imaging acquisition parameters.

Figure 1

A: The localization of the human LC in neuromelanin scans of 10 subjects. B: High contrast LC voxels from the group-averaged neuromelanin image in atlas space (see Supplementary Figure 2) are colored in red on the group-averaged anatomical image in atlas space. The location of the LC in this atlas-space image can be compared with the atlas-space activations of Minzenberg et al. (1), which is shown in C: Adapted version of Fig. 1 from Minzenberg et al, 2008 (1). Reprinted with permission from AAAS.

Figure 2

A: Average time course from 10 subjects extracted from individually defined ROIs in the right LC and the IV ventricle. B: average magnitudes from the same subjects extracted from the same regions. Cue: response to an informative peripheral cue that either shifted attention or maintained attention at the current location; target: response to correct detection of a target, which required a key press (13). rLC: right LC, IV vent.: IV ventricle. Error bars represent SEM.