Publications by authors named "Shawn Nielsen"

The locus coeruleus (LC) regulates attention via the release of norepinephrine (NE), with levels of tonic LC activity constraining the intensity of phasic LC responses. In the current fMRI study, we used isometric handgrip to modulate tonic LC-NE activity in older women and in young women with different hormone statuses during the time period immediately after the handgrip. During this post-handgrip time, an oddball detection task was used to probe how changes in tonic arousal influenced functional coordination between the LC and a right frontoparietal network that supports attentional selectivity.

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The stress response differs between women using hormonal contraception and naturally cycling women. Yet, despite ample evidence showing that the stress response differs across the menstrual cycle in naturally cycling women, limited work has investigated whether the stress response differs across the hormonal contraceptive cycle, during which synthetic hormones are taken most of the month but not all of it. To induce a stress response, women using hormonal contraception completed the cold pressor test during either the active phase, when hormones are present, or during the inactive phase, when hormones are not present.

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Recent findings indicate that emotional arousal can enhance memory consolidation of goal-relevant stimuli while impairing it for irrelevant stimuli. According to one recent model, these goal-dependent memory tradeoffs are driven by arousal-induced release of norepinephrine (NE), which amplifies neural gain in target sensory and memory processing brain regions. Past work also shows that ovarian hormones modulate activity in the same regions thought to support NE's effects on memory, such as the amygdala, suggesting that men and women may be differentially susceptible to arousal's dual effects on episodic memory.

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Studies with animals of both sexes show that the adrenal glands release progesterone in addition to cortisol in response to stress. However, little is known about the progesterone response to stress in naturally cycling women. We investigated the effect of stress on estradiol, progesterone, and cortisol levels in women during the follicular phase of the menstrual cycle.

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Arousal's selective effects on cognition go beyond the simple enhancement of emotional stimuli, sometimes enhancing and other times impairing processing of proximal neutral information. Past work shows that arousal impairs encoding of subsequent neutral stimuli regardless of their top-down priority via the engagement of β-adrenoreceptors. In contrast, retrograde amnesia induced by emotional arousal can flip to enhancement when preceding neutral items are prioritized in top-down attention.

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Emotionally arousing events are typically better attended to and remembered than neutral ones. Current theories propose that arousal-induced increases in norepinephrine during encoding bias attention and memory in favor of affectively salient stimuli. Here, we tested this hypothesis by manipulating levels of physiological arousal prior to encoding and examining how it influenced memory for emotionally salient images, particularly those that are negative rather than positive in valence.

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Isometric handgrip is commonly used in stress research because the task reliably increases sympathetic arousal. Various handgrip protocols have been used; they vary in handgrip strength, duration of grip, and the number of cycles of handgrip and rest. However, most protocols require the calibration of a maximum voluntary contraction (MVC) prior to the handgrip task, which is not always convenient (i.

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Sex hormones are increasingly implicated in memory formation. Recent literature has documented a relationship between hormones and emotional memory and sex differences, which are likely related to hormones, have long been demonstrated in a variety of mnemonic domains, including false memories. Hormonal contraception (HC), which alters sex hormones, has been associated with a bias towards gist memory and away from detailed memory in women who use it during an emotional memory task.

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Sex differences in emotional memory have received increasing interest over the past decade. However, to date, no work has explored how a postlearning stressor might modulate the influence of sex hormone status on memory for gist and peripheral detail in an emotional versus neutral context. Here, we tested 3 predictions.

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Sex influences on emotional memory have received increasing interest over the past decade. However, only a subset of this previous work explored the influence of sex on memory for central information (gist) and peripheral detail in emotional versus neutral contexts. Here we examined the influence of sex and menstrual cycle phase at encoding on memory for either an emotional or neutral story, specifically with respect to the retention of gist and peripheral detail.

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Emotionally arousing material is typically better remembered than neutral material. Since norepinephrine and cortisol interact to modulate emotional memory, sex-related influences on stress responses may be related to sex differences in emotional memory. Two groups of healthy women - one naturally cycling (NC women, n=42) and one using hormonal contraceptives (HC women, n=36) - viewed emotionally arousing and neutral images.

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Substantial evidence now documents sex-related influences on the neurobiology of emotional memory. Robust sex influences exist, for example, on the amygdala's role in emotional memory formation, as well as on retention of central information (gist) and detail for an emotional event. Evidence also suggests that the well-documented effects of stress hormones on memory depend upon sex hormone levels.

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