[Show abstract][Hide abstract] ABSTRACT: Single-dose administration of selective serotonin and noradrenaline reuptake blockers has been shown to alter emotional processing in both behavioral and fMRI studies in healthy volunteers. Mirtazapine is a clinically established antidepressant with different pharmacological actions from monoamine reuptake inhibitors, involving blockade of noradrenaline α(2)-adrenoceptors and multiple 5-HT receptor subtypes. The aim of this study was to investigate the effect of a single dose of mirtazapine on the neural processing of emotional faces in healthy volunteers.
Twenty-eight participants were randomized to receive either a single dose of mirtazapine (15 mg) or placebo. Two hours later, participants underwent an fMRI scan, in which they classified fearful and happy faces on the basis of gender. Mood and subjective experience were also measured.
Whole-brain analysis showed significant group × emotion interactions in a right amygdala-hippocampal region and left fronto-striatal cortex. Post hoc analyses revealed significantly reduced activation to fear and greater activation to happy faces in both regions under mirtazapine.
Our findings indicate that a single dose of mirtazapine modulates neural activity to affective stimuli. Mirtazapine was found to decrease neural responses to fear and increase responses to happy facial expressions in regions implicated in the processing of emotional faces. These effects may be important for our understanding of the neural mechanisms of antidepressant action in anxiety and depression.
Full-text · Article · Dec 2010 · Psychopharmacology
[Show abstract][Hide abstract] ABSTRACT: The capacity to stabilize the content of attention over time varies among individuals, and its impairment is a hallmark of several mental illnesses. Impairments in sustained attention in patients with attention disorders have been associated with increased trial-to-trial variability in reaction time and event-related potential deficits during attention tasks. At present, it is unclear whether the ability to sustain attention and its underlying brain circuitry are transformable through training. Here, we show, with dichotic listening task performance and electroencephalography, that training attention, as cultivated by meditation, can improve the ability to sustain attention. Three months of intensive meditation training reduced variability in attentional processing of target tones, as indicated by both enhanced theta-band phase consistency of oscillatory neural responses over anterior brain areas and reduced reaction time variability. Furthermore, those individuals who showed the greatest increase in neural response consistency showed the largest decrease in behavioral response variability. Notably, we also observed reduced variability in neural processing, in particular in low-frequency bands, regardless of whether the deviant tone was attended or unattended. Focused attention meditation may thus affect both distracter and target processing, perhaps by enhancing entrainment of neuronal oscillations to sensory input rhythms, a mechanism important for controlling the content of attention. These novel findings highlight the mechanisms underlying focused attention meditation and support the notion that mental training can significantly affect attention and brain function.
Full-text · Article · Oct 2009 · The Journal of Neuroscience : The Official Journal of the Society for Neuroscience
[Show abstract][Hide abstract] ABSTRACT: Practitioners understand "meditation," or mental training, to be a process of familiarization with one's own mental life leading to long-lasting changes in cognition and emotion. Little is known about this process and its impact on the brain. Here we find that long-term Buddhist practitioners self-induce sustained electroencephalographic high-amplitude gamma-band oscillations and phase-synchrony during meditation. These electroencephalogram patterns differ from those of controls, in particular over lateral frontoparietal electrodes. In addition, the ratio of gamma-band activity (25-42 Hz) to slow oscillatory activity (4-13 Hz) is initially higher in the resting baseline before meditation for the practitioners than the controls over medial frontoparietal electrodes. This difference increases sharply during meditation over most of the scalp electrodes and remains higher than the initial baseline in the postmeditation baseline. These data suggest that mental training involves temporal integrative mechanisms and may induce short-term and long-term neural changes.
Preview · Article · Dec 2004 · Proceedings of the National Academy of Sciences