Showing papers by "Diego A. Pizzagalli published in 2007"

Electroencephalography and high-density electrophysiological source localization

Abstract: In 1924, Hans Berger, a German psychiatrist, performed the first electroencephalographic (EEG) recording in humans (Berger, 1929), a discovery that was initially greeted with great skepticism by the scientific community. By recording from one electrode placed over the forehead and one over the occipital cortex, Berger discovered the existence of rhythmic activity oscillating at approximately 10 Hz, particularly during relaxed wakefulness and in the absence of sensory stimulation or mental activity. In this landmark discovery, Berger described for the first time what would become known as alpha waves. As a result, Berger was among the first to suggest that the periodic fluctuations of the human EEG may be associated with mental processes, including arousal, memory, and consciousness. Over the years, developments in data collection and analyses transformed EEG into one of the prime techniques for studying the human brain. Table 3.1 summarizes selected landmark discoveries and developments that have contributed shaping the EEG field throughout the century. The past two decades in particular have witnessed unparalleled progress in our ability to image human brain function noninvasively. Different imaging techniques are currently available to investigate brain function based on hemodynamic (functional magnetic resonance imaging, fMRI), metabolic (positron emission tomography, PET), or electromagnetic (electroencephalography, EEG; magnetoencephalography, MEG) measurements. In order to investigate spatiotemporal dynamics of brain activity, methods that directly assess neural activity are required. By measuring electrical activity of neuronal assemblies with millisecond temporal resolution, EEG and MEG, unlike hemodynamic techniques, offer the possibility of studying brain function in real time. Unfortunately, as will be discussed in this chapter, the spatial resolution afforded by EEG/MEG is constrained by several factors. The most important of these factors are the distorting effects of the head volume conductor,1 low signal-to-noise

Inhibition of Action, Thought, and Emotion: A Selective Neurobiological Review.

Abstract: The neural bases of inhibitory function are reviewed, covering data from paradigms assessing inhibition of motor responses (antisaccade, go/nogo, stop-signal), cognitive sets (e.g., Wisconsin Card Sort Test), and emotion (fear extinction). The frontal cortex supports performance on these paradigms, but the specific neural circuitry varies: response inhibition depends upon fronto-basal ganglia networks, inhibition of cognitive sets is supported by orbitofrontal cortex, and retention of fear extinction reflects ventromedial prefrontal cortex–amygdala interactions. Inhibition is thus neurobiologically heterogeneous, although right ventrolateral prefrontal cortex may support a general inhibitory process. Dysfunctions in these circuits may contribute to psychopathological conditions marked by inhibitory deficits.

Dissociation of neural regions associated with anticipatory versus consummatory phases of incentive processing

Abstract: Incentive delay tasks implicate the striatum and medial frontal cortex in reward processing. However, prior studies delivered more rewards than penalties, possibly leading to unwanted differences in signal-to-noise ratio. Also, whether particular brain regions are specifically involved in anticipation or consumption is unclear. We used a task featuring balanced incentive delivery and an analytic strategy designed to identify activity specific to anticipation or consumption. Reaction time data in two independent samples (n=13 and n=8) confirmed motivated responding. Functional magnetic resonance imaging revealed regions activated by anticipation (anterior cingulate) versus consumption (orbital and medial frontal cortex). Ventral striatum was active during reward anticipation but not significantly more so than during consumption. Although the study features several methodological improvements and helps clarify the neural basis of incentive processing, replications in larger samples are needed.

Task feedback effects on conflict monitoring and executive control: Relationship to subclinical measures of depression.

Abstract: Emerging evidence suggests that depression is associated with executive dysfunction, particularly after committing errors or receiving negative performance feedback. To test this hypothesis, 57 participants performed two executive tasks known to elicit errors (the Simon and Stroop Tasks) during positive or negative performance feedback. Participants with elevated depressive symptoms (Beck Depression Inventory scores >or= 13) were characterized by impaired posterror and postconflict performance adjustments, especially during emotionally negative task-related feedback. Additionally, for both tasks, depressive symptoms were inversely related to postconflict reaction time adjustments following negative, but not positive, feedback. These findings suggest that subclinical depression is associated with impairments in behavioral adjustments after internal (perceived failure) and external feedback about deficient task performance.

Perceived stress and cognitive vulnerability mediate the effects of personality disorder comorbidity on treatment outcome in major depressive disorder: a path analysis study.

Abstract: Although personality disorder (PD) comorbidity has been associated with poor treatment outcome in major depressive disorder (MDD), little is known about mechanisms mediating this link. Converging evidence suggests that maladaptive cognitive patterns, particularly in interaction with stressors, might lead to poor treatment outcome in MDD subjects with PD pathology. The goal of this study was to test the role of PD comorbidity, cognitive vulnerability, and perceived stress in treatment outcome in MDD. Three hundred eighty-four MDD outpatients were enrolled in an 8-week open-label treatment of fluoxetine. Structural equation modeling and path analyses revealed that the effect of PD vulnerability on treatment outcome was fully mediated by increased pretreatment cognitive vulnerability and depression severity, which led to increased stress perception after treatment and poorer antidepressant response. Depressogenic cognitions might be continuously activated by chronic distress in MDD subjects reporting axis II pathology, leading to stress exacerbation and eventually poorer treatment outcome.

Systems and methods for predicting effectiveness in the treatment of psychiatric disorders, including depression

Abstract: The present invention pertains to the evaluation and/or treatment of psychopathological diseases. In one aspect, information regarding brain activity, coupled with behavior tests (e.g., determining performance in a computer-based task), may be used to predict the response of a subject to psychological treatment, e.g., with a psychoactive drug. For example, the subject may be one suffering from depression, or other disturbances of the rostral anterior cingulate cortex. Another aspect of the present invention is directed to methods for analyzing neurobiological predictors through integration of information gathered from one or more levels of analyses: (1) behavior, (2) brain function, and/or (3) genes. In one aspect, the methods of the present invention can comprise any one of these components (i.e., behavior, brain function, and genes), or a combination of two or more of these components, and/or other components. Through these methods, development of novel algorithms for improving the ability to identify biological surrogate markers of treatment response are disclosed, according to certain embodiments of the invention. Still other aspects of the present invention are directed to systems and methods for implementing such evaluation techniques, analyzing such evaluation techniques, promotion of such evaluation techniques, and the like.