Acupuncture using laser needles is a new totally painless stimulation method which has been described for the first time. This paper presents an experimental double-blind study in acupuncture research in healthy volunteers using a new optical stimulation method. We investigated 18 healthy volunteers (mean age +/- SD: 25.4 +/- 4.3 years; range: 21-30 years; 11 female, 7 male) in a randomized controlled cross-over trial using functional multidirectional transcranial ultrasound Doppler sonography (fTCD; n = 17) and performed functional magnetic resonance imaging (fMRI) in one volunteer. Stimulation of vision-related acupoints resulted in an increase of mean blood flow velocity in the posterior cerebral artery measured by fTCD [before stimulation (mean +/- SE): 42.2 +/- 2.5; during stimulation: 44.2 +/- 2.6; after stimulation: 42.3 +/- 2.4 cm/s, n.s.]. Mean blood flow velocity in the middle cerebral artery decreased insignificantly. Significant changes (p < 0.05) of brain activity were demonstrated in the occipital and frontal gyrus by fMRI. Optical stimulation using properly adjusted laser needles has the advantage that the stimulation cannot be felt by the patient (painless and no tactile stimulation) and the operator may also be unaware of whether the stimulation system is active. Therefore true double-blind studies in acupuncture research can be performed.

The present study was aimed at simultaneously determining on the same subject, the effects of stress on retrieval of flexible (contextual or temporal) or stable (spatial) information. Three behavioral paradigms carried out in a four-hole board were designed as follows: (1) Simple Discrimination (SD), in which mice learned a single discrimination; (2) Contextual and Serial Discriminations (CSD), in which mice learned two successive discriminations on two different internal contexts; (3) Spatial Serial Discriminations (SSD), in which mice learned two successive discriminations on an identical internal context. The stressor (three inescapable electric footshocks) was delivered 5 min before retention, occurring 5 min or 24 h after acquisition. Results showed that this stressor increased plasmatic corticosterone levels and fear reactivity in an elevated-plus-maze, as compared with nonstressed mice. The stressor reversed the normal pattern of retrieval observed in nonstressed controls in the CSD task, this effect being context dependent, as it was not observed in the SSD task. Overall, our study shows that stress affected the retrieval of flexible and old information, but spared the retrieval of stable or recent ones. Therefore, these behavioral paradigms allow us to study simultaneously, on the same animal, the effects of stress on distinct forms of memory retrieval.Extensive evidence indicates that stress or pharmacologically induced modifications of the emotional state can influence cognitive function (Kirschbaum et al. 1996;Lupien and McEwen 1997;Belanoff et al. 2001;Wolf et al. 2001). It has been demonstrated that the stress-induced release of glucocorticoids is one of the main factors responsible for these effects. However, glucocorticoids have differential effects depending on the memory phase or the memory system concerned in animal and human subjects (Roozendaal 2002). Glucocorticoids enhance the consolidation of new memories for emotionally arousing experiences (Kovacs et al. 1977;Buchanan and Lovallo 2001), whereas glucocorticoids impair retrieval of long-term spatial memory in rats (De Quervain et al. 1998) and free recall of verbal material in humans (De Quervain et al. 2000;Wolf et al. 2001). Interestingly, even though the modification of the affective state can act on different memory and neurobiological systems (Packard and Cahill 2001), it has been shown that working and declarative memory retrieval are particularly sensitive to glucocorticoids' administration (Lupien et al. 1999;De Quervain et al. 2003).Animal studies have focused mainly on the effects of stress on acquisition, consolidation, and long-term storage of newly acquired information (Lupien and McEwen 1997). Only a few studies have been carried out in animals to determine the effects of stress on retrieval processes (De Quervain et al. 1998;Bats et al. 2001). More specifically, De Quervain et al. (1998) have shown that stress and glucocorticoids impaired retention performance in a water-maze spatial task, as a function of the time interval...

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