Reappraisal is a cognitive emotion regulation strategy that induces a reduction in the arousal response elicited by both unpleasant and pleasant stimuli.One form of reappraisal is that of temporal distancing. Temporal distancing is the cognitive tool that allows the individual to perceive the stimuli in a broader temporal perspective.Reappraisal’s impact on the arousal response can be measured by assessing the amplitude of the event-related potential (ERP) component the late positive potential(LPP), a centro-parietal slow-wave ERP beginning around 350 ms post-stimulus and sustaining for up to several seconds. The aim of this study was to test various temporal-related perspectives in order to see their effect on the LPP. The analysis of the data suggests that a decrease in the amplitude of the LPP in response to emotionally unpleasant facial stimuli corresponds to adopting a temporal distancing strategy, regardless of the exact temporal distance chosen.

In addition to low mood, major depressive disorder (MDD) is characterized by persistent cognitive deficits that impair daily functioning and resist improvement with conventional pharmacotherapies. Repetitive transcranial magnetic stimulation (rTMS) holds promise as an efficacious alternative, offering better outcomes than medication for patients with treatment-resistant depression (TRD). Yet, current rTMS protocols that administer sinusoidal biphasic pulses achieve remission in less than the majority. However, monophasic pulses may yield higher success rates based on greater cortical excitation/neuromodulation strength. MDD is associated with altered P300 event-related potentials (ERPs), indexing decreased attentional resource allocation and slower cortical processing speed. Using a cohort of 20 TRD patients who received high-frequency rTMS, this study aimed to assess the impact of monophasic and biphasic stimulation on attention-related P300 measures and their utility as correlates of clinical/cognitive response. Based on baseline and post-treatment change in P300 components, rTMS-induced increases in automatic attention/passive information processing differed by pulse type and predicted greater clinical improvement in depressed individuals. This study represents an important step towards identifying cognitive changes and underlying cortical mechanisms associated with rTMS response and targeted MDD treatment.

Event-related potentials play a significant role in error processing and attentional processes. Specifically, event-related negativity (ERN), feedback-related negativity (FRN), and the P300 are related to performance monitoring. The current study examined these components in relation to subjective probability, or confidence, regarding response accuracy on a complicated learning task. Results indicated that confidence ratings were not associated with any changes in ERN, FRN, or P300 amplitude. P300 amplitude did not vary according to participants’ subjective probabilities. ERN amplitude and FRN amplitude did not change throughout the task as participants learned. Future studies should consider the relationship between ERN and FRN using a learning task that is less difficult than the one employed in this study.

L’objectif central de cette thèse consiste à étudier les effets des couleurs associées au genre, particulièrement bleu et rose, sur la perception du sexe des visages. Les enregistrements électrophysiologiques de surface (potentiels évoqués cérébraux) et les données comportementales issus de mon travail indiquent que la perception du visage, au-delà de sa dimension physiologique, est soumise à l’influence de processus top-down induits par le stéréotype de la couleur bleue pour le genre masculin et de la couleur rose pour le genre féminin. Ces influences s’observent précocement au cours de l'étape d'encodage perceptif des visages. / The present thesis aims at studying the impact of the colors associated to gender, particularly blue and pink, on the perception of face gender. Our electrophysiological and behavioral data indicate that the perception of the face, beyond its physiological dimension, is subject to the influence of top-down processes induced by pink for female and blue for male stereotype. These influences are evident at early perceptual stage of face processing.

Previous work has attempted to fit reward-driven attentional selection as being exogenous (stimulus-driven) or endogenous (goal-driven). However, recent work suggests that reward’s effects on attention depend on the type of stimulus feature that the motivational information is imparted during learning (incentive salience). If true, then reward should not be limited to solely impacting early perceptual or late categorization processes attention. The current study used event-related potentials (ERPs) to test the idea that reward’s effects on attention depend on the process that the reward information is embedded – early perceptual or late categorization. Results demonstrated reward-driven effects on perceptual representation when value information was conveyed by cues in a spatial cuing task, but did not find any value-driven effects when value was introduced later in processing in target-defined features in a target detection task. The current work suggests that reward can be rapidly acquired and sustained throughout a task, recruiting mechanisms of both exogenous and endogenous attention.

Objective: Sleep deprivation has been proposed as a potential correlate of obesity, particularly influencing energy intake. Therefore, the purpose of this study was to compare neural indices of attention related to food motivation and energy intake in normal-weight and obese women under two separate sleep conditions: 1) sleep-restricted (<5 hours) and 2) recommended sleep (~8 hours). This study used a combined cross-over and ex post facto design with condition order counter-balanced. Methods: Twenty-two normal-weight (age=30.9±9.5y, BMI=22.0±1.6 kg/m2) and 18 obese (age=29.7±10.7 y, BMI=36.4±5.3 kg/m2) women completed both sleep conditions. To confirm sleep levels, participants recorded sleep quality and quantity via sleep logs and wore a wrist actigraph. Following each condition, participants reported to the laboratory under the same fed state (energy shake ~10% of total daily needs) to verify they followed the sleep protocol. Subsequently, motivation for food was tested using electroencephalogram (EEG); participants completed a computerized passive-viewing task of food and flowers, while event-related brain potentials (ERPs) were recorded. After EEG testing, participants continued their normal routine but recorded all energy intake using weighed food scales. There were no instructions or limitations on dietary intake. Analyses included P300 and LPP amplitudes in response to picture type, total next day energy intake, and energy intake by several periods of the day. Results: Participants averaged 4.7±0.4 hours of sleep during the sleep-restricted condition and 7.7±0.3 hours during the recommended sleep condition (F=1057.02; P<0.0001). There was no group*condition interaction for next day food motivation (P300: F<2.896, P>0.09; LPP: F<2.967, P>0.093). Next day total energy intake also did not differ by group*condition (F=1.81; P=0.187). When participants were pooled, there was no difference in energy intake by sleep condition (F=0.00; P=0.953). However, when participants’ energy intake was analyzed during the lunch period (following testing to 1:30pm) there was a significant group*condition interaction (F=6.12; P=0.018). The obese women ate significantly more (~300 kcal) during the sleep-deprived condition compared to the recommended condition, whereas the normal-weight women did not. Conclusion: Compared to suggested levels of sleep, sleep restriction and obesity do not influence next day food motivation or total next day energy intake. However, sleep restriction and obesity may influence feeding during certain portions of the day.

Words that deviate in their physical characteristics from their surrounding lead to enhanced recall memory, a pattern known as the Von Restorff effect. Furthermore, common (high frequency; HF) words are more likely to be recalled than uncommon (low frequency; LF) words when they occur in pure lists, while this pattern is reversed in mixed lists of both HF and LF words. This study investigated whether the Von Restorff effect and the reversal of word frequency effects in mixed lists, which may both be explained by enhanced perceived distinctiveness, are associated with common underlying brain processes. Event-related potentials (ERPs) were recorded while participants studied and subsequently recalled 70 word lists using rote memorization strategies. The three list types included (1) 14 regular-sized and one larger word, (2) 14 HF words and one LF word, or (3) 14 LF words and one HF word. The behavioral data showed a typical Von Restorff effect, a word frequency effect, as well as a reversal of the word frequency effect for LF words isolated in HF word lists ("LF isolates"). Larger words and LF isolates elicited a P300, an ERP component associated with subjective distinctiveness, whose amplitude was correlated with subsequent recall for both word types. This indicates that LF isolates were perceived as distinctive, and that this perceived distinctiveness aided subsequent recall in a similar way as for physically deviant words. Both larger words and LF isolates also elicited a left-lateralized slow wave which was larger for subsequently recalled than for not recalled words. This ERP component supposedly reflects item-to-item elaborative processes, indicating that such elaborative processes are enhanced when LF words occur in HF word list. HF words isolated in lists of LF words did not elicit comparable ERP subsequent memory effects. Rather, for these "HF isolates", the N400 was negatively correlated with subsequent recall, an ERP component that reflects semantic integration processes. We conclude that the reversal of the word frequency effect in mixed lists can be explained by a combination of enhanced subjective distinctiveness and enhanced inter-item elaborative processes for LF words that occur in lists of HF words.

In the study of covert visual attention, two event-related potential (ERP) components have been identified by earlier research. The N2 posterior contralateral (N2pc) component has been suggested to index the enhancement of attention to a specific lateralized target item. The distractor positivity (PD) component has been suggested to index the suppression of distractors appearing in the same search array. Earlier studies have reported different latencies for the PD component depending on the task and experiment. Furthermore, the N2pc and the PD component are not always elicited in the same experiment. Relative target-to-difficult-distractor placement have been shown to affect the mean amplitude of the N2pc. Less is known about how different relative placements affect the PD component. The aim of the present study was to try and elicit both an N2pc and a PD component in the same visual search paradigm. The PD was recorded later time-window which previous studies have suggested to indicate the ending of attention to a previously attended target. Three relative placements were analysed, horizontally opposite, vertically opposite and diagonally opposite. When combining all three relative placements an N2pc component was elicited contralateral to the target. No PD component was found when combining all relative placements. A larger mean amplitude N2pc was measured for the vertically opposite condition. The results are not in line with previous research, that have found the N2pc to be smaller in conditions where both target and distractor are on the same side of the visual field. However, when comparing upper and lower visual field targets the N2pc was found to be larger for lower visual field stimuli, which is in line with previous research. A larger mean amplitude for the PD was found in the diagonally opposite condition. Earlier research has suggested that when difficult distractor and target are located on separate sides of the visual field, this leads to successful inhibition, indexed by the PD component. In contrast to earlier research a larger PD component was not found for upper visual field stimuli. The present study differs from previous studies in the way the target and difficult distractor were placed and analysed. By separating what has previously been called “opposite side” condition into two separate conditions diagonally opposite and horizontally opposite the results from the present study seem to suggest that these two conditions are not synonymous. However, the results should be regarded with caution due to the small sample size. Furthermore, the horizontally opposite side condition also differs from previous studies with regards to relative target and distractor distances, which could have had an effect on the results.

Speech perception typically takes place within the auditory cortex as evidenced by data collected using quantitative electroencephalography (qEEG). The purpose of this study was to determine if motor responses influence speech perception. We examined P300 event-related potentials during oddball stimulus recognition tasks that either required or did not require a motor response. Based on a review of the literature, it was hypothesized that similar areas of the brain would be activated in both the motor response task and the same task without a motor response immediately following the button-push condition. Two syllables, /ba/ and /ga/, were presented to 20 native English speakers (10 females and 10 males) between the ages of 19 and 30 years. An oddball paradigm consisting of standard and deviant stimuli was presented in three trials: passive listening, mental counting, and button-push. Participants were randomly assigned an order to the trials for passive listening and mental count; however, the button-push response was completed second each time. Data from event-related potentials were recorded for each participant using qEEG and combined across participants to create grand averaged waveforms. Cortical regions of activation were identified and compared across conditions. Results showed that different cortical areas were activated when the mental counting and passive listening conditions were done before and after the motor response condition. Requiring a more complicated response than is typically used to discriminate phonemes, such as with the button push response, may alter speech perception based on the cortical regions activated as measured through source localization. Further research on latencies and amplitudes of the even-related potential (ERP) waveforms is needed to determine how speech perception changes.

The late positive potential (LPP) is increasingly used as an indicator of emotional salience, which can be reduced by effective emotion regulation (ER), thus making LPP differences a practical marker of ER effects. One commonly used ER strategy is that of explicit distraction, a form of distraction that is consciously monitored and directed. Studies have shown that distraction modulates the LPP, and there are theoretical as well as empirical reasons to suspect that distraction occurs at an early stage in the timecourse of the LPP. However, the consistency of these findings have not yet been systematically assessed. This systematic review was conducted to address this gap in the literature. Following a literature search across three databases, nine empirical studies were systematically reviewed to assess the consistency of the effect of distraction on LPP latency and amplitudes. Mean LPP amplitude measurements from 270 healthy young adults, engaging in distraction and passive viewing during exposure to emotional stimuli, were gathered and reviewed. Mean differences were compared to assess the consistency of the LPP during distraction. Results showed consistent early LPP activation at centro-parietal sites, but not at frontal sites. These findings support the predictions of the process model of ER and its conceptualization of distraction as an antecedent strategy. The review was limited by the small number of studies, low mean ages of participants, and lack of diversity in stimuli, among other factors. As additional research is needed to further the scientific understanding of ER and its mechanisms, future directions are suggested.