Left frontal hypoactivation in depression.

Baseline resting electroencephalogram activity was recorded with 3 different reference montages from 15 clinically depressed and 13 control subjects. Power in all frequency bands was extracted by fast Fourier transformation. There was a significant Group X Hemisphere interaction in the mid-frontal region, for the alpha band power only. Depressed subjects had less left-sided activation (i.e., more alpha activity) than did normal control subjects. This pattern of diminished left-sided frontal activation is interpreted as indicating a deficit in approach mechanisms in depressed subjects.     

Electroencephalographic asymmetries in adolescents with major depression: influence of comorbidity with anxiety disorders

This study examined whether adolescents with major depressive disorder (MDD) display the abnormal electroencephalographic (EEG) alpha asymmetries found in depressed adults. Resting EEG was recorded in 25 right-handed female outpatients (19 with MDD, 11 of whom also had a current anxiety disorder; 6 with anxiety disorders only) and 10 non-ill controls. In contrast to the non-ill controls, adolescents having MDD but no anxiety disorder showed alpha asymmetry indicative of less activation over right than over left posterior sites. Within the MDD patient group, comorbid anxiety disorders reduced the posterior alpha asymmetry, supporting the potential importance of evaluating anxiety in studies of regional brain activation in adolescent MDD. These preliminary findings are similar to those from adult studies that suggest that MDD is associated with right parietotemporal hypoactivation.     

Recall of parental behavior by acute depressives, remitted depressives, and nondepressives

The goal of this study was to determine whether depressives' recall of parental behavior is a stable characteristic that persists even during asymptomatic periods. Recall of parental behavior was measured in a large community sample that was followed for one year. Four groups of subjects were formed according to their depression status: depressed, remitted depressed who had a history of depression but were not depressed during the study, cases who became depressed during the follow-up period, and never-depressed subjects. The results were generally consistent with the hypothesis that recalling one's parents as having been rejecting and unloving is not a stable personality characteristic of depression-prone persons. The currently depressed subjects differed as expected from the nondepressed subjects; however, the remitted depressed, regardless of how many past episodes of depression they had, did not differ from the nondepressed controls in their recall of parental behavior. The comparison of controls and cases resulted in an unexpected and difficult-to-interpret Sex X Group interaction. The implication of these findings for cognitive theories of depression are discussed.     

Topographic electroencephalographic alpha in recovered depressed elderly

Late-middle-aged and elderly normal volunteers with past histories of Major Depression according to the Diagnostic and Statistical Manual of Mental Disorders (third edition-revised) criteria were compared with sex- and age-matched control subjects using topographic electroencephalographic (EEG) indices. Healthy, euthymic recovered depressed subjects showed greater alpha amplitudes than controls. Delta, theta, and beta amplitudes did not reliably distinguish the groups. Considered in the context of previous research indicating that actively depressed subjects exhibit elevated EEG alpha compared to controls, these findings raise questions concerning state and trait conceptualizations of depression and EEG alpha.     

So-called slow posterior activity in the EEG and the sensori-motor reaction time. Results of re-examinations made after 5 years

Six persons showing what is called slow posterior activity (4/s rhythm) in the electroencephalogram were reexamined after a period of five years. Sensorimotor reaction times were recorded in addition to the electroencephalogram which was analyzed for the frequency of LPA and for the degree of stability of time dependence. The frequency and distinctness of LPA were found to be stable after five years (r = 0.09 and 0.82, respectively; p less than 0.001), whereas the alpha rhythmus of the subjects had undergone considerable changes (r = 0.34; p greater than 0.05). The extension of reaction times to be observed under the influence of LPA was also seen to remain constant (r = 0.79; p less than 0.05). Accordingly, LPA proved an extremely stable characteristic which did not show any substantial variations in the course of five years.     

Responses to depressed interpersonal behavior: mixed reactions in a helping role

We placed 144 female subjects in a helping role and randomly assigned them to interact with a confederate in a 3 X 3 X 2 X 2 (Psychopathology X Blaming X Advice Seeking X Sex of Confederate) factorial design. In order to study behaviors that mediate interpersonal responses to depression, male and female confederates enacted depressed, anxious, or normal roles and blamed themselves, others, or no one for their problems. The confederates requested advice in half of the conditions. Results indicated that depressed confederates were rejected more on questionnaire measures; however, depressed confederates received more conversational advice and support from subjects than did the equally disturbed anxious confederates. The self-blaming and advice-seeking manipulations did not interact with depression to produce more negative reactions in subjects. There was no evidence of a negative mood induction in subjects, nor did the sex of the confederate have important interpersonal consequences. Results are discussed in terms of theoretical and methodological issues in studies of interpersonal factors in depression.     

Effects of olfactory bulbectomy on social behavior of male guinea pigs (Cavia procellus)

Effects of olfactory bulbectomy on social behavior in male guinea pigs were studied. Both brief-exposure pairing techniques and a group-living observation period were employed to test for disruption. During short-term testing sessions bulbectomized animals courted females less than but mounted them as frequently as control subjects. While the groups did not differ in fighting behavior during short-term tests, control subjects scent-marked more frequently. Subsequently, animals were observed as same-treatment pairs living continuously with females, and behavior was sampled over a 3-wk period. Under these conditions bulbectomized males, unlike controls, failed to form dominance orders, exhibited virtually no intermale aggressive activity, had markedly depressed sexual activity, and scent-marked rarely. It is concluded that olfactory bulbectomy profoundly alters the behavior of male domestic guinea pigs and that hose alterations are most evident when experimental subjects are observed in a species-typical group-living environment.     

Hemispheric Asymmetry and Regional Differences in Electroencephalographic Alpha Activity at the Wake-Sleep Transition

Electroencephalographic (EEG) alpha activity at the wake-sleep transition was studied in six right-handed adults in terms of hemispheric asymmetry and regional differences. Twelve-channel EEGs with linked mastoid references were recorded together with horizontal and vertical electro-oculograms (EOGs). Two types of alpha coefficient were obtained every 5.12 s by computing the relative proportion of right vs. left alpha band power and of anterior vs. posterior alpha band power. Four stages were scored using EEG sleep patterns (theta waves, vertex sharp waves, spindles, and K complex) and slow eye movement (SEM): stage W had neither EEG sleep patterns nor SEM; stage D1 had SEM and no EEG sleep patterns; stage D2 had theta waves or vertex sharp waves and SEM; stage S had spindles or K complex without SEM. It was found that the two types of alpha coefficient changed as a function of EEG-EOG stage and were correlated. Right-decreased and anterior-shifted alpha activities were manifest at stages D2 and S. Drowsiness was considered to be a heterogeneous state, exhibiting different spatial changes in alpha activity between stages D1 and D2.     

Differential Male and Female Responses to Inadmissible Sexual History Information Regarding a Rape Victim

Two experiments were conducted to assess the effects of exposure to sexual activity information regarding a rape victim. The results of the first experiment indicated that men had a greater tendency to attribute a female target person's sexual activity to dispositional causes than did women. In the second experiment, subjects read an acquaintance rape scenario suggesting that the victim had a promiscuous sexual past. They were instructed either to ignore this sexual history information when making judgments (inadmissible condition) or to use whatever information that they felt was appropriate (admissible condition). Control subjects were given no information regarding the victim's sexual past. Thus, the design was a 2 (Sex of Subject) x 3 (Information Admissibility: Admissible, Inadmissible, or Control) factorial. The results indicated: (a) When compared to those in the inadmissible condition, victim perceptions from subjects in the admissible condition were less favorable, (b) victim perceptions from male subjects were less favorable than those from female subjects, and (c) male subjects in the inadmissible condition attributed more responsibility to the victim than did the controls whereas female subjects in the inadmissible condition attributed less responsibility to the victim than did controls. Possible bases of these findings are discussed.     

Effects of various hippocampal lesions on monkey plasma cortisol levels in two experimental conditions

The plasma cortisol levels of Rhesus monkeys with anterior, posterior, or near-total hippocampal lesions were compared to controls during two separate stressful conditions. In the first condition, each monkey was placed for the first time in a primate restraint chair for 72 h. In the second condition each monkey performed a complex behavioral task (titrating shock avoidance) to control the intensity of frequent footshock for a 24-h period. Control subjects had either no surgical operation or else surgical exposure of the hippocampus with no hippocampal lesion. They manifested lower plasma cortisol levels during shock avoidance compared with during the chair condition. Subjects with posterior hippocampal lesions manifested the same pattern but near-totally hippocampectomized subjects showed an opposite pattern with cortisol levels higher in the shock avoidance condition compared with the chair condition. Subjects with anterior hippocampal lesions had similar cortisol levels in both conditions. Thus hippocampal modulation of corticosteroid levels may depend on the specific condition under which such levels are measured, and may be relatively more subserved by anterior compared with posterior hippocampus in the monkey.     

Depression and processing information about others

We investigated differences between mildly depressed subjects and normal controls in their memory for, and judgments of, another person. All subjects read a story (containing either predominately positive or predominately negative items) under instructions to form an impression of the story target. Subjects later made several judgments about the target and attempted to recall the story. For both the positive and the negative story, depressed subjects produced significantly more negative intrusions (i.e., recalled nonpresented negative items) than did the normal subjects, but they did not recall more negative items correctly than did the normal subjects. Depressed subjects also perceived themselves as more similar to the negative story target than did the normal controls and indicated greater liking for the negative story target than did the normal controls.     

Narrative comprehension in adults with right and left hemisphere brain-damage: theme organization.

The effects of delayed presentation of a central theme on the comprehension and interpretation of narratives were investigated in adults with right and left hemisphere brain-damage and normal individuals. The performance of subgroups of the subjects with right and left hemisphere brain-damage also was examined. Right hemisphere brain-damaged groups with anterior and posterior lesions were significantly less accurate and identified significantly fewer central themes when central theme presentation was delayed until the end of a narrative than when the theme was presented at the beginning. Subjects with anterior right hemisphere brain-damage produced significantly more embellishments and confabulations than subjects with posterior damage and non-brain-damaged controls, regardless of theme condition. The performance of non-brain-damaged subjects and subjects with fluent and nonfluent aphasia was unaffected by the organization of the central theme in the narratives.     

Investigating models of affect: relationships among EEG alpha asymmetry, depression, and anxiety

The approach-withdrawal and valence-arousal models both predict that depressive and anxious profiles will be associated with relatively reduced left frontal and increased right frontal activity respectively, while the valence-arousal model also proposes a dissociation by lower and higher right parietotemporal activity, respectively. Recent work further suggests that subtypes of anxiety disorders may be characterized by distinctive patterns of activity depending on their type of arousal (anxious arousal/apprehension). The aim of this study was to investigate the relationships among nonclinical depression/anxiety and lateralized frontal/parietotemporal activity by categorizing participants (N=428) on the basis of both negative mood and alpha EEG. Key findings include: (i) greater right frontal lateralization in anxious participants, symmetrical frontal activity in depressed/comorbid, and left frontal lateralization in healthy controls; (ii) right frontal lateralization in anxious arousal participants, left frontal and right parietotemporal lateralization in anxious apprehension; (iii) bilateral increase in frontal and increased right parietotemporal activity in depressed/comorbid participants. Findings support predictions for frontal but not posterior regions. Grouping on the basis of EEG may not be reciprocally predictive of negative mood groupings, suggesting involvement of additional factors.     

Regional brain electrical activity in posttraumatic stress disorder after motor vehicle accident

This study examined whether patients with posttraumatic stress disorder (PTSD) related to motor vehicle accidents (MVAs) would show an abnormal pattern of electroencephalographic (EEG) alpha asymmetries, which has been proposed for particular types of anxiety. Patients with PTSD (n = 22) or subsyndromal PTSD (n = 21), traumatized controls without PTSD (non-PTSD with MVA; n = 21), and healthy controls without MVA (n = 23) underwent measurement of EEG activity during baseline and exposure to a neutral, a positive, a negative, and an accident-related picture. Differences in brain asymmetry between groups were observed only during exposure to trauma-related material. PTSD and subsyndromal PTSD patients showed a pattern of enhanced right anterior and posterior activation, whereas non-PTSD with MVA participants showed the opposite pattern. Furthermore, posterior asymmetry in nontraumatized healthy controls varied with gender, with female participants showing a pattern of higher right posterior activation. The results support the hypothesis that symptomatic MVA survivors are characterized by a pattern of right hemisphere activation that is associated with anxious arousal and symptoms of PTSD during processing of trauma-specific information.     

Frontal EEG alpha band asymmetry as a predictor of reasoning deficiency in depressed people

Cognitive deficits in depression are mostly apparent in executive functions, especially when integration of information and reasoning is required. In parallel, there are also numerous studies pointing to the frontal alpha band asymmetry as a psychophysiological marker of depression. In this study, we explored the role of frontal alpha asymmetry as a potential factor explaining the cognitive problems accompanying depression. Twenty-six depressed and 26 control participants completed a reasoning task and underwent 5 minutes of electroencephalography recording. In line with the previous studies, depressed people showed difficulties with reasoning but we did not observe the relationship between frontal asymmetry in the alpha band and depression. However, we found that in the depressed group the frontal alpha asymmetry index was characterised by larger variance than in the control group, and it was also a strong predictor of cognitive functioning exclusively in the depressed group. Our results point to the disruption of a psychophysiological balance, reflected in changed frontal alpha asymmetry (into more left-sided frontal asymmetry in the alpha band, reflecting more right-sided cortical activity) as a possible brain correlate of cognitive disturbances present in depressive disorders.     

Sylvian fissure and parietal anatomy in children with autism spectrum disorder

Autism spectrum disorder (ASD) is characterized by deficits in social functioning and language and communication, with restricted interests or stereotyped behaviors. Anatomical differences have been found in the parietal cortex in children with ASD, but parietal subregions and associations between Sylvian fissure (SF) and parietal anatomy have not been explored. In this study, SF length and anterior and posterior parietal volumes were measured on MRI in 30 right-handed boys with ASD and 30 right-handed typically developing boys (7-14 years), matched on age and non-verbal IQ. There was leftward SF and anterior parietal asymmetry, and rightward posterior parietal asymmetry, across groups. There were associations between SF and parietal asymmetries, with slight group differences. Typical SF asymmetry was associated with typical anterior and posterior parietal asymmetry, in both groups. In the atypical SF asymmetry group, controls had atypical parietal asymmetry, whereas in ASD there were more equal numbers of individuals with typical as atypical anterior parietal asymmetry. We did not find significant anatomical-behavioral associations. Our findings of more individuals in the ASD group having a dissociation between cortical asymmetries warrants further investigation of these subgroups and emphasizes the importance of investigating anatomical relationships in addition to group differences in individual regions.     

Decreased responsiveness to reward in depression

We have interpreted the literature showing left anterior hypoactivation in depression as reflecting a decrease in approach-related motivation and behaviour among depressed subjects. In support of this model, we have previously demonstrated a decreased responsiveness to reward in subclinically depressed dysphoric subjects. The current study was designed to replicate and extend those findings. Clinically depressed subjects who met DSM-IV criteria for major depression were compared to a group of nondepressed control subjects on a verbal memory task under three monetary payoff conditions: neutral, reward, and punishment. Although control subjects changed their pattern of responding in both the reward and punishment conditions, relative to the neutral condition, so as to maximise their earnings, depressed subjects did not do so during reward. The two groups did not differ during the punishment condition. These findings provide additional evidence of a decreased responsiveness to reward in depressed individuals, and are consistent with the hypothesis that the left prefrontal hypoactivation observed in depression reflects a deficit in approach-related behaviour.     

Eye movements during REM sleep: the influence of personality and presleep conditions.

Male subjects scoring high (n=17) or low (n=14) on the Maudsley Neuroticism scale were randomly assigned to a positive (n=17) or negative (ego threat) (n=14) presleep condition and then slept a single night in the laboratory. The negative condition elicited significantly more rapid eye movement activity (REM density) than did the positive condition (pless than.03). There was a significant interaction for Groups X Conditions (pless than.007) indicating that low neuroticism subjects had greater REM density in the negative condition, and less REM density in the positive condition, compared to high neuroticism subjects under either condition. The low neuroticism subjects in the negative condition showed a discrepancy between greater REM density but less admission of stress on a presleep mood questionnaire compared to high neuroticism subjects. These results support the hypothesis that REM density is a correlate of stress-induced arousal that is subject to the modifying effects of individual differences.     

Efficiency and automaticity of self-schema processing in clinical depressives

In this study, female clinical depressives and nondepressed control subjects made a series of self-referent personality judgments concerning depressed and nondepressed content personal adjectives. Employing rating times (RTs) for the personality decisions as a dependent measure, it was found that both clinical depressives and nondepressed psychiatric controls processed self-schema congruent content more efficiently (with quicker RTs), than incongruent content. To further test for the automaticity of self-schema processing, half the depressed and nondepressed adjectives were rated while subjects held six digits in memory (a concurrent memory load). Here it was found that the independent variable of memory load (zero vs. six digits) did not interact significantly with the remaining independent variables of groups (clinical depressives, psychiatric nondepressives, normal nondepressives), decision type (yes, no), and adjective content (depressed, nondepressed). The lack of any interactions involving the memory load factor provides initial evidence for self-schema processing as an automatic process, rather than as a process that demands attentional capacity.This research was supported, in part, by a Social Sciences and Humanities Research Council Doctoral Fellowship to Michael R. MacDonald.