Emotion and attention in visual word processing: an ERP study

Emotional words are preferentially processed during silent reading. Here, we investigate to what extent different components of the visual evoked potential, namely the P1, N1, the early posterior negativity (EPN, around 250 ms after word onset) as well as the late positive complex (LPC, around 500 ms) respond differentially to emotional words and whether this response depends on the availability of attentional resources. Subjects viewed random sequences of pleasant, neutral and unpleasant adjectives and nouns. They were first instructed to simply read the words and then to count either adjectives or nouns. No consistent effects emerged for the P1 and N1. However, during both reading and counting the EPN was enhanced for emotionally arousing words (pleasant and unpleasant), regardless of whether the word belonged to a target or a non-target category. A task effect on the EPN was restricted to adjectives, but the effect did not interact with emotional content. The later centro-parietal LPC (450-650 ms) showed a large enhancement for the attended word class. A small and topographically distinct emotion-LPC effect was found specifically in response to pleasant words, both during silent reading and the active task. Thus, emotional word content is processed effortlessly and automatically and is not subject to interference from a primary grammatical decision task. The results are in line with other reports of early automatic semantic processing as reflected by posterior negativities in the ERP around 250 ms after word onset. Implications for models of emotion-attention interactions in the brain are discussed.     

Modulation of event-related potentials by word repetition: The role of visual selective attention

Event-related potentials (ERPs) were recorded while subjects viewed visually presented words, some of which occurred twice. Each trial consisted of two colored letter strings, the requirement being to attend to and make a word/non word discrimination for one of the strings. Attention was manipulated by color in Experiment 1, and color and a precue were used in Experiment 2. As in previous ERP studies of word repetition, a positive offset to repeated words developed when both first and second presentations were the focus of attention. In Experiment 2, ERPs showed evidence of positive-going repetition effects in all conditions in which at least one of the two presentations of the repeated word was attended. In the visual modality, the positive-going ERP repetition effect occurs only when at least one of the two presentations of a repeated item is the object of attention, which suggests that one or more of the processes reflected by the effect is capacity limited.     

EEG in 1-week, 1-month and 3-month-old infants of depressed and non-depressed mothers

EEGs were examined in data collected from 348 1-week, 1-month and 3-month-old infants of depressed and non-depressed mothers across several studies. Both the percentage of infants exhibiting spectral peaks and the frequency in Hz at which those peaks were exhibited increased with age. Consistent with previous studies, infants of depressed mothers exhibited greater left frontal EEG power, suggesting greater relative right frontal EEG activity than infants of non-depressed mothers. This profile was apparent across a narrow frequency range, which shifted from 3-9 Hz at 1 week of age to 4-9 Hz by 3 months of age.     

Affective picture modulation: valence, arousal, attention allocation and motivational significance

The present study analyses the modulatory effects of affective pictures in the early posterior negativity (EPN), the late positive potential (LPP) and the human startle response on both the peripheral (eye blink EMG) and central neurophysiological levels (Probe P3), during passive affective pictures viewing. The affective pictures categories were balanced in terms of valence (pleasant; unpleasant) and arousal (high; low). The data shows that EPN may be sensitive to specific stimulus characteristics (affective relevant pictures versus neutral pictures) associated with early stages of attentional processing. In later stages, the heightened attentional resource allocation as well as the motivated significance of the affective stimuli was found to elicit enhanced amplitudes of slow wave processes thought to be related to enhanced encoding, namely LPP,. Although pleasant low arousing pictures were effective in engaging the resources involved in the slow wave processes, the highly arousing affective stimuli (pleasant and unpleasant) were found to produce the largest enhancement of the LPP, suggesting that high arousing stimuli may are associated with increased motivational significance. Additionally the response to high arousing stimuli may be suggestive of increased motivational attention, given the heightened attentional allocation, as expressed in the P3 probe, especially for the pleasant pictures. The hedonic valence may then serve as a mediator of the attentional inhibition to the affective priming, potentiating or inhibiting a shift towards defensive activation, as measured by the startle reflex.     

Neural evidence of effects of emotional valence on word recognition.

There are no clear reports of electrophysiological evidence of the facilitating effect of negative valence on word recognition. However, behavioral psychological studies have suggested that negative words can be recognized more accurately than positive and neutral words. This study aimed to examine whether, and if so how, the valence of words could influence accuracy and event-related potentials (ERPs) in a recognition task. ERPs were recorded from 20 healthy subjects during performance of a word recognition task. We found a behavioral advantage in discriminability between old and new items for negative words. As for ERPs, the positive-going shift was evident for correct responses to targets in late latency at midline and left centro-parietal sites. Additionally, the magnitude of this component was greatest for negative targets, next for positive targets, and least for neutral targets. The findings offer support for the idea that negative content greatly accelerates recognition memory compared to positive and neutral words.     

Beta activity: a carrier for visual attention

The alpha (8-13 Hz), beta (15-25 Hz) and gamma (30-60 Hz) bands of the EEG have been long studied clinically because of their putative functional importance. Old experimental results indicate that repetitive stimulation of the visual pathway evokes synchronous responses at the cortical level with a gain that depends on frequency; oscillations within relevant bands are less damped at subsequent processing levels than others. Our current results show in the cat that cortico-geniculate feedback has a build-in potentiation mechanism that operates at around the beta frequency and activates thalamic cells thus lowering the threshold for visual information transmission. We have also shown that enhanced beta activity is propagated along this feedback pathway solely during attentive visual behavior. This activity consists of 300-1,000 ms bursts that correlate in time with gamma oscillatory events. Beta-bursting activity spreads to all investigated visual centers, including the lateral posterior and pulvinar complex and higher cortical areas. Other supporting data are discussed that are concerned with the enhanced beta activity during attentive-like behavior of various species, including humans. Finally, we put forward a general hypothesis which attributes the appearance of oscillations within the alpha, beta and gamma bands to different activation states of the visual system. According to this hypothesis, alpha activity characterizes idle arousal of the system, while beta bursts shift the system to an attention state that consequently allows for gamma synchronization and perception.     

Affective visual event-related potentials: arousal, valence, and repetition effects for normal and distorted pictures.

Event-related potentials (ERPs) were used to assess arousal (low, high), valence (negative, positive), and stimulus repetition effects for normal and distorted images from the International Affective Pictures System (IAPS). Distorted stimuli were constructed by dividing each image into small squares and rearranging the segments randomly to produce a "scrambled" picture. Event-related potentials (ERPs) were elicited by presenting the normal and scrambled images as target stimuli, with a repeated visual pattern used as the standard stimulus. Participants (N=32) were instructed to press a button to the targets and ignore the standard. Stimulus repetition effects were assessed by presenting each stimulus twice in the normal and scrambled condition. High-arousal stimuli yielded larger late positive components for both the normal and scrambled pictures. No overall valence effects were obtained, but arousal and valence influenced component amplitudes for middle-latency ERPs from the scrambled stimuli. For the normal pictures, stimulus repetition was associated with increased component amplitudes for all potentials and decreased RTs of all affective categories. For the scrambled pictures, no repetition changes were obtained. The findings suggest that stimulus arousal level contributes more than valence to affective ERP measures for normal as well as perceptually distorted pictures. Stimulus repetition engages memory for previous normal picture items but is not influenced by affective category. Theoretical implications are discussed.     

Stability of negative self-structures: a longitudinal comparison of depressed, remitted, and nonpsychiatric controls

To be considered a vulnerability marker for depression, a variable should, in addition to demonstrating sensitivity and specificity, also show evidence of temporal stability (i.e., remain present in the absence of depressive symptomatology). Although many cognitive factors are associated with depression, the majority of them appear to be episode rather than vulnerability markers. This study examined cognitive organization of positive and negative interpersonal and achievement content in clinically depressed, remitted, and nonpsychiatric controls. At initial assessment, a sample of 54 clinically depressed individuals and 37 never-depressed controls completed self-report measures of positive and negative automatic thoughts and two cognitive organizational tasks. They were retested 6 months later when half of the depressed group no longer met diagnostic criteria for major depression. Negative automatic thoughts decreased and positive automatic thoughts increased significantly in individuals who had improved clinically. The organization of negative interpersonal content remained stable despite symptom amelioration, but negative achievement content was less interconnected at follow-up in those patients who had improved. The structure of relational schemas, in particular, appears to be stable and may be an important cognitive vulnerability factor for depression.     

Impaired distractor inhibition on a selective attention task in unmedicated, depressed subjects

BACKGROUND: Impaired distractor inhibition may contribute to the selective attention deficits observed in depressed patients, but studies to date have not tested the distractor inhibition theory against the possibility that processes such as transient memory review processes may account for the observed deficits. A negative priming paradigm can dissociate inhibition from such a potentially confounding process called object review. The negative priming task also isolates features of the distractor such as colour and location for independent examination. METHOD: A computerized negative priming task was used in which colour, identification and location features of a stimulus and distractor were systematically manipulated across successive prime and probe trials. Thirty-two unmedicated subjects with DSM-IV diagnoses of non-psychotic unipolar depression were compared with 32 age, sex and IQ matched controls. RESULTS: Depressed subjects had reduced levels of negative priming for conditions where the colour feature of the stimulus was repeated across prime and probe trials but not when identity or location was the repeated feature. When both the colour and location feature were the repeated feature across trials, facilitation in response was apparent. CONCLUSIONS: The pattern of results supports studies that found reduced distractor inhibition in depressed subjects, and suggests that object review is intact in these subjects. Greater impairment in negative priming for colour versus location suggests that subjects may have greater impairment in the visual stream associated with processing colour features.     

Basic emotion profiles in healthy, chronic pain, depressed and PTSD individuals

Objectives: To compare self‐reports of five basic emotions across four samples: healthy, chronic pain, depressed and post‐traumatic stress disorder (PTSD), and to investigate the extent to which basic emotion reports discriminate between individuals in healthy or clinical groups. Methods: In total, 439 participants took part in this study: healthy (n = 131), chronic pain (n = 220), depressed (n = 24) and PTSD (n = 64). The participants completed the trait version of the Basic Emotion Scale. Basic emotion profiles were compared both within each group and between the healthy group and each of the three other groups. Discriminant analysis was used to assess the extent to which basic emotions can be used to classify the participants as belonging to the healthy group or one of the clinical groups. Results: In the healthy group, happiness was experienced more than any other basic emotion. This was not found in the clinical groups. In comparison to the healthy participants, the chronic pain group experienced more fear, anger and sadness, the depressed group reported more sadness and the PTSD group experienced all of the negative emotions more frequently. Discriminant analysis revealed that happiness was the most important variable in determining whether an individual belonged to the healthy group or one of the clinical groups. Anger was found to further discriminate between depressed and chronic pain individuals. Conclusion: The findings demonstrate that basic emotion profile analysis can provide a useful foundation for the exploration of emotional experience both within and between healthy and clinical groups. Copyright © 2011 John Wiley & Sons, Ltd. Key Practitioner Message: ? More frequent experiences of happiness relative to discrete negative emotions most clearly discriminate between individuals in healthy and clinical groups. More frequent anger experiences further discriminate between individuals with chronic pain and those with depression while disgust levels help discriminate between those with post‐traumatic stress disorder (PTSD) and depression. ? More frequent experiences of high arousal negative emotions—fear, anger and disgust—are characteristic of individuals with PTSD. ? Fear is the most frequently experienced negative emotion in both healthy and clinical groups. Higher levels of fear compared with other discrete negative emotions are not necessarily an indicator of psychopathology. Consideration of emotional profiles more generally and the relative frequency with which happiness is experienced relative to negative emotions may be more useful in delineating between healthy individuals and those with chronic pain, depression or PTSD.     

Lateralization of visual hemifield attention across development.

Heilman and Valenstein (Clinical Neuropsychology, 1979, Oxford University Press, New York) have hypothesized a right hemispheric mechanism which mediates attention bilaterally. Shapiro and Hynd ("The development of functional lateralization in visual hemifield attention." Developmental Neuropsychology, Vol. 1, pp 67-80, 1985) examined the developmental validity of this model and their findings did not provide evidence for a lateralized mechanism for visual hemifield attention in 9, 13, and 18 year olds. However, length of foreperiod and gender effects were noted. This study attempted to compare these groups with a group of normal adults (ages 25-35) using the same reaction time paradigm. The study demonstrated support for the length of foreperiod effect found by Shapiro and Hynd. Hand effects were also found. However, these results do not lend support to either the model proposed by Heilman and Valenstein (1979) or Shapiro and Hynd's (1985) notion of developmental differences across age groups with respect to right hemisphere dominance for mediating attention.     

A comparison of phonemic, semantic, and alternating word fluency in Parkinson's disease.

Word fluency in 45 medicated non-demented Parkinson's disease (PD) patients and 45 normal control subjects was studied with a Phonemic Word Fluency (PWF) task using the letters F, A, and S, a Semantic Word Fluency (SWF) task using the categories animals, boys' names, and states, and an Alternating Word Fluency (AWF) task requiring the person to alternate between colors and occupations, animals and states, and words beginning with C and P. The number of words generated did not differ for trials with F, A, S, or states, but PD patients generated significantly fewer animal names and boys' names. PD patients also generated significantly fewer words on each of the three AWF trials. The PD patients scored 21% lower than the normal control group on the total AWF score, but only 10% lower for the PWF and SWF scores. The greater impairment on the AWF task which requires the use of internal attentional control to rapidly shift mental set can be considered a type of executive functioning deficit. This is consistent with the growing literature suggesting frontal systems dysfunction in PD and with the view that dopaminergic treatment only incompletely restores functioning in the frontostriatal system.     

Laterality of hippocampal responses to infrequent and unpredictable omissions of visual stimuli

Summary Previous studies have demonstrated that externally measured magnetic field patterns are indicative of activity in the vicinity of the right hippocampal formation during infrequent and unpredictable intrusions or omissions of visual stimuli in an oddball evoked response paradigm. These fields occur coincident with late endogenous evoked potential components that are consistently recorded in similar situations. In the present study, magnetic fields temporally corresponding to the late P300 component of simultaneously recorded evoked potentials were accounted for by sources in the vicinity of the left and right hippocampus in addition to previously reported sources in the vicinity of the primary visual cortex. Projection of these sources onto MRIs suggested that both hippocampal structures are simultaneously active and that there is an amplitude and strength-related dominance of the right hippocampal sources to visual stimulation.This research was supported by NIH grant NS29540 to A.C. Papanicolaou and NIH grant NS20806 to W. Sutherling. Data collection was completed by R.L. Rogers, L.F.H. Basile, W.T. Bourbon and A.C. Papanicolaou at the Magnetoencephalography Laboratory of the Division of Neurosurgery, University of Texas Medical Branch in Galveston, Texas.     

Biological and clinical features of recurrent brief depression: a comparison with major depressed and healthy subjects.

Recurrent brief depression (RBD) has recently been proposed as a new subtype of affective disorder characterized by episodes of major depression which last less than two weeks. The aim of this study was to further evaluate the validity of this putative subtype by means of clinical and biological data. DST, TSH response to TRH and sleep EEG variables were compared in 25 RBD patients sex- and age-matched to 25 major depressed (MD) and 25 healthy subjects. Family history, age at onset, and psychiatric comorbidity did not discriminate RBD from MD. Recurrent unipolar depression was found to be more prevalent in MD. Although less severely depressed during the biological tests, patients with RBD did not significantly differ from those with MDD on basis of DST non-suppression, blunted TSH response and shortening of REM latency. Compared to controls, a greater sleep onset latency was observed both in RBD and MD and a lower total sleep time in MD patients only. These results suggest that RBD could be viewed as a subtype of affective disorder sharing many characteristics with MDD.     

Measurement of dyspnea: word labeled visual analog scale vs. verbal ordinal scale

We previously used a verbal ordinal rating scale to measure dyspnea. That scale was easy for subjects to use and the words provided consistency in ratings. We have recently developed a word labeled visual analog scale (LVAS) with labels placed by the subjects, retaining the advantages of a verbal scale while offering a continuous scale that generates parametric data. In a retrospective meta-analysis of data from 43 subjects, individuals differed little in their placement of words on the 100 mm LVAS (mean+/-S.D. for slight=20+/-2.5 mm, moderate=50+/-5 mm and severe=80+/-6 mm) and ratings were distributed uniformly along the scale. A significant stimulus-response correlation was obtained for both the LVAS (r(2)=0.98) and for the verbal ordinal scale (Spearman r=0.94). The resolution of the two scales differed only slightly. With meaningful verbal anchors, well-defined end-points, and clear instructions about the specific sensation to be rated, both scales provide valid measures of dyspnea.     

The neural basis of visual selective attention: a commentary on Harter and Aine

Harter and Aine (1984) have proposed a 'neural specificity' model of visual selective attention, based primarily on evidence from recordings of event-related brain potentials (ERPs) in human subjects. In this framework, they consider ERP components elicited during visual-spatial attention to reflect selective neural processing in the tectopulvinar-partietal pathway, whereas selection of visual attributes such as pattern, color, and orientation is manifested by ERPs arising from the geniculostriate-inferotemporal projection system. The present article examines the empirical basis for anatomically-specific hypotheses and considers alternative explanations for the observed ERP changes during selective attention.