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ABSTRACT: Event-related potentials (31-channel ERPs) were recorded from 38 depressed, unmedicated outpatients and 26 healthy adults (all right-handed) in tonal and phonetic oddball tasks developed to exploit the perceptual challenge of a dichotic stimulation. Tonal nontargets were pairs of complex tones (corresponding to musical notes G and B above middle C) presented simultaneously to each ear (L/R) in an alternating series (G/B or B/G; 2-s fixed SOA). A target tone (note A) replaced one of the pair on 20% of the trials (A/B, G/A, B/A, A/G). Phonetic nontargets were L/R pairs of syllables (/ba/, /da/) with a short voice onset time (VOT), and targets contained a syllable (/ta/) with a long VOT. Subjects responded with a left or right button press to targets (counterbalanced across blocks). Target detection was poorer in patients than controls and for tones than syllables. Reference-free current source densities (CSDs; spherical spline Laplacian) derived from ERP waveforms were simplified and measured using temporal, covariance-based PCA followed by unrestricted Varimax rotation. Target-related N2 sinks and mid-parietal P3 sources were represented by CSD factors peaking at 245 and 440 ms. The P3 source topography included a secondary, left-lateralized temporal lobe maximum for both targets and nontargets. However, a subsequent hemispheric spatiotemporal PCA disentangled temporal lobe N1 and P3 sources as distinct factors. P3 sources were reduced in patients compared with controls, even after using performance as a covariate. Results are consistent with prior reports of P3 reduction in depression and implicate distinct parietal and temporal generators of P3 when using a dichotic oddball paradigm.
International Journal of Psychophysiology 02/2008; 67(1):1-16. · 2.14 Impact Factor
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ABSTRACT: Anxiety symptoms might be a vulnerability factor for the development of major depressive disorder (MDD). Because elevated startle magnitude in threatening contexts is a marker for anxiety disorder, the present study investigated the hypothesis that enhanced startle reactivity would also be found in children and grandchildren of individuals with MDD.
The magnitude of startle was investigated in two tests (anticipation of an unpleasant blast of air and during darkness) in children (second generation) and grandchildren (third generation) of probands with (high risk) or without (low risk) MDD (first generation).
Startle discriminated between the low- and high-risk groups. In the probands' children, the high-risk group showed increased startle magnitude throughout the fear-potentiated startle test. In the probands' grandchildren, a gender-specific abnormality was found in the high-risk group with high-risk girls, but not boys, exhibiting elevated startle magnitude throughout the procedure.
Increased startle reactivity in threatening contexts, previously found in patients with anxiety disorder and in children of parents with an anxiety disorder, might also constitute a vulnerability marker for MDD. These findings suggest that there might be common biologic diatheses underlying depression and anxiety.
Biological Psychiatry 06/2005; 57(9):953-60. · 8.28 Impact Factor
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ABSTRACT: Electroencephalographic (EEG) studies have found abnormal regional hemispheric asymmetries in depressive disorders, which have been hypothesized to be vulnerability markers for depression. In a longitudinal high-risk study, resting EEG was measured in primarily adult offspring of depressed or nondepressed probands.
Electroencephalograms from12 homologous sites over each hemisphere (digitally linked-ears reference) were analyzed in right-handed offspring for whom both parents (n = 18), one parent (n = 40), or neither parent (n = 29) had a major depressive disorder (MDD).
Offspring with both parents having MDD showed greater alpha asymmetry at medial sites, with relatively less activity (more alpha) over right central and parietal regions, compared with offspring having one or no parent with MDD. Relatively less left frontal activity at lateral sites was associated with lifetime MDD in offspring but not with parental MDD. Offspring with both parents having a MDD also showed markedly greater anterior-to- posterior increase in alpha with eyes closed compared with those with one or no parent with a MDD.
Alpha asymmetry indicative of right parietotemporal hypoactivity, previously reported for depressed adolescents and adults, and heightened anterior-to-posterior gradient of alpha are present in high-risk offspring having parents concordant for MDD.
Biological Psychiatry 03/2005; 57(4):328-35. · 8.28 Impact Factor
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ABSTRACT: This report compares event-related brain potentials (ERPs) of patients having a depressive disorder alone (n = 58), an anxiety disorder alone (n = 22), comorbidity of these disorders (n = 18), and healthy controls (n = 49). ERPs were recorded from 30 electrode sites during auditory oddball tasks using consonant-vowel syllables (phonetic) or complex tones (tonal). Overlapping ERP components were identified and measured using covariance-based principal components analysis. An early P3 subcomponent (P315) was larger in patients having an anxiety disorder alone when compared to depressed patients with or without an anxiety disorder and healthy controls, whereas a late P3 subcomponent (P400) was larger in patients having comorbidity of anxiety and depressive disorders than in the other groups. Also, the N2-P3 complex showed task-dependent hemispheric asymmetries, including larger N2-P3 amplitude over left than right temporoparietal sites during the phonetic oddball task. This hemispheric asymmetry was greatest in patients having a depressive disorder alone and smallest in patients having an anxiety disorder alone. The opposite nature of the alterations of hemispheric asymmetry and early P3 amplitude in depressive and anxiety disorders underscores the importance of taking comorbidity with anxiety into account in studies of cognitive ERPs in depressive disorders.
Clinical EEG (electroencephalography) 08/2002; 33(3):119-24.
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ABSTRACT: A hypothesis of overfocused attention in obsessive-compulsive disorder was investigated by measuring auditory event-related potentials (ERPs) during a selective attention task. Unmedicated patients (n= 18) with this disorder showed significantly larger attention-related processing negativity (PN), with earlier onset and longer duration, than did normal controls (n= 15). In the N200 region (160–250 ms), PN was larger in patients with fewer nonspecific neurological soft signs. This task, however, did not yield any group differences in mismatch negativity (N2a) or classical N200 (N2b). P300 amplitudes for attended targets were smaller for patient than normal groups, but the reverse was true for P300 and positive slow wave amplitudes for unattended nontargets. Collectively, these ERP abnormalities suggest a misallocation of cognitive resources. Because of the importance of the frontal lobe in the control of selective attention, PN enhancement in patients with obsessive-compulsive disorder may reflect hyperactivation of this region. This conceptualization is consistent with recent functional neuroimaging findings.
Psychophysiology 10/1994; 31(6):535 - 543. · 3.29 Impact Factor
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ABSTRACT: Electrophysiologic correlates of perceptual asymmetry for dichotic pitch discrimination were investigated in 20 normal subjects. Brain event-related potentials (ERPs) elicited by dichotic pairs and binaural probe tones in the Complex Tone Test (Sidtis, 1981) were recorded from homologous scalp locations over left and right hemispheres (F3, F4; C3, C4; P3, P4; O1, O2). Baseline-to-peak amplitudes were measured for N100, P200, and a late positive complex consisting of P350, P550, and slow wave. A left ear advantage (LEA) was evident in 70% of the subjects, and hemispheric asymmetries related to this behavioral asymmetry were found for P350 and P550 amplitudes to probe stimuli. Subjects with a strong LEA had greater amplitudes over the right hemisphere than the left, whereas subjects with little or no LEA showed a nonsignificant trend toward the opposite hemispheric asymmetry. Hemispheric asymmetry of these late ERPs at parietal and occipital sites was highly correlated with behavioral asymmetry. These findings suggest the utility of electrophysiological measures in assessing hemispheric asymmetries for processing complex pitch information.
Psychophysiology 12/1992; 30(1):62 - 70. · 3.29 Impact Factor
