Phasic affective signals by themselves do not regulate cognitive control

Cognitive control is a set of mechanisms that help us process conflicting stimuli and maintain goal-relevant behaviour. According to the Affective Signalling Hypothesis, conflicting stimuli are aversive and thus elicit (negative) affect, moreover – to avoid aversive signals – affective and cognitive systems work together by increasing control and thus, drive conflict adaptation. Several studies have found that affective stimuli can indeed modulate conflict adaptation, however, there is currently no evidence that phasic affective states not triggered by conflict also trigger improved cognitive control. To investigate this possibility, we intermixed trials of a conflict task and trials involving the passive viewing of emotional words. We tested whether affective states induced by affective words in a given trial trigger improved cognitive control in a subsequent conflict trial. Applying Bayesian analysis, the results of four experiments supported the lack of adaptation to aversive signals, both in terms of valence and arousal. These results suggest that phasic affective states by themselves are not sufficient to elicit an increase in control

Dynamic Adjustments of Cognitive Control Across Adolescence

Cognitive control refers to our ability to stay on task even in the face of distractions. During task performance, control is dynamically adjusted trial-by-trial, based on changes in task demands (e.g., the occurrence of response conflict). In my thesis, I investigated how the ability to dynamically regulate control levels in response to conflict changes across adolescence when control-related brain areas such as the anterior cingulate cortex are still undergoing maturation. I also examined whether the frequency of lapses in attention during a task (mind-wandering; MW) is related to age and dynamic adjustments of control. Before addressing my central research questions, I first investigated whether dynamic control adjustments are motivated by the aversive nature of response conflict using an affective priming paradigm, but found no robust evidence for this hypothesis (Chapter 2), therefore this avenue was not pursued further. Across two subsequent studies (Chapters 3 & 4) I found no significant age-related differences in the size of the congruency sequence effect (CSE) - an effect hypothesized to reflect dynamic control adjustments - between adolescents and young adults in reaction time on a Simon and a flanker task. However, adolescents did show less flexible and less temporally consistent recruitment of control processes in response to conflict at the neural level as indicated by non-adult-like dynamics in the theta frequency range (4-7 Hz) during the flanker task (Chapter 4). MW frequency was inconsistently related to age (Chapters 3 & 4), however, it did appear to correlate negatively with CSE magnitude. Using a modified flanker task, I examined this association in Chapter 5 but the relationship did not replicate. In sum, this thesis provides some evidence for the protracted maturation of control, however, it also suggests that certain aspects of control, such as the ability to dynamically regulate control levels mature early on

Mate Gyurkovics' Quick Files

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Gyurkovics, Stafford, & Levita: "Cognitive control across adolescence: Dynamic adjustments and mind-wandering"

This page contains the data files belonging to the manuscript Gyurkovics, Stafford, & Levita (in revision) "Cognitive control across adolescence: Dynamic adjustments and mind-wandering", and the R code used to analyse them

Mind-wandering in healthy aging and early stage Alzheimer’s disease

Objective: The frequency of mind-wandering (MW) decreases as a function of age in healthy individuals. One possible explanation is that MW is a resource-dependent process, and cognitive resources decline with age. The present study provides the first investigation of MW in the earliest stages of Alzheimer’s disease (AD) to further examine the resource model and discontinuities between healthy aging and AD. Method: Three large cohorts completed the Sustained Attention to Response Task (SART): a healthy middle-aged group (mean age = 61.79 ± 5.84 years; N = 270), a healthy older adult group (mean age = 76.58 ± 5.27 years; N = 282), and a group with early stage AD (mean age = 76.08 ± 7.17; N = 77), comparable in age to the second group. Results: Self-reports of MW during the SART decreased as a function of age, and there was a further decrease in the AD group. All 3 groups produced faster responses on trials before No-Go errors, suggesting MW occurred in all cohorts. After No-Go errors, healthy older adults slowed disproportionately compared with middle-aged adults. This was not evident in AD individuals who showed posterror slowing comparable with that in the middle-aged group. Conclusions: The decreased self-reported MW in older adults and the further decline in AD are consistent with the cognitive resource account of MW. Behavioral indices suggest that AD is on a continuum with healthy aging, with the exception of posterror slowing that may suggest performance monitoring deficits in early AD individuals (e.g., lack of error awareness)

Experiment 2: Lack of Thoughts

Older adults report less mind-wandering (MW) during tasks of sustained attention than younger adults. The control failure × current concerns account argues that this is due to age differences in how contexts cue personally relevant task-unrelated thoughts. For older adults, the university laboratory contains few reminders of their current concerns and unfinished goals. For younger adults, however, the university laboratory is more directly tied to their current concerns. Therefore, if the context for triggering current concerns is the critical difference between younger and older adults’ reported MW frequencies, then testing the two groups in contexts that equate the salience of self-relevant cues (i.e., their homes) should result in an increase in older but not younger adults’ MW rates. The present study directly compared rates of MW and involuntary autobiographical memories (IAMs) in the home versus in the lab for younger and older adults using a within-subjects manipulation of context. Inconsistent with the control failure × current concerns account, no significant reduction in the age-gap in MW was found. Suggesting a lack of cues rather than an abundance of cues elicits MW, participants in both age groups reported more MW in the lab than at home. The number of IAMs recalled did not differ across contexts but was lower in older than younger adults. These findings suggest that a cognitive rather than an environmental mechanism may be behind the reduction in spontaneous cognition in aging

Stimulus-induced changes in 1/f-like background activity in EEG

Research into the nature of 1/f-like, nonoscillatory electrophysiological activity has grown exponentially in recent years in cognitive neuroscience. The shape of this activity has been linked to the balance between excitatory and inhibitory neural circuits, which is thought to be important for information processing. However, to date, it is not known whether the presentation of a stimulus induces changes in the parameters of 1/f activity in scalp recordings, separable from event-related potentials (ERPs). Here, we analyzed event-related broadband changes in human EEG both before and after removing ERPs to demonstrate their confounding effect, and to establish whether there are genuine stimulus-induced changes in 1/f. Using data from a passive and an active auditory task (n = 23, 61% female), we found that the shape of the post-event spectra between 2 and 25 Hz differed significantly from the pre-event spectra even after removing the frequency-content of ERPs. Further, a significant portion of this difference could be accounted for by a rotational shift in 1/f activity, manifesting as an increase in low and a decrease in high frequencies. Importantly, the magnitude of this rotational shift was related to the attentional demands of the task. This change in 1/f is consistent with increased inhibition following stimulus onset, and likely reflects a disruption of ongoing excitatory activity proportional to processing demands. Finally, these findings contradict the central assumption of baseline normalization strategies in time-frequency analyses, namely, that background EEG activity is stationary across time. As such, they have far-reaching consequences relevant for several subfields of neuroscience

Stimulus-induced changes in 1/f-like background activity in EEG

Research into the nature of 1/f-like, non-oscillatory electrophysiological activity has grown exponentially in recent years in cognitive neuroscience. The shape of this activity has been linked to the balance between excitatory and inhibitory neural circuits, which is thought to be important for information processing. However, to date, it is not known whether the presentation of a stimulus induces changes in the parameters of 1/f activity, which are separable from the emergence of event-related potentials (ERPs). Here, we analyze event-related broadband changes in scalp-recorded EEG both before and after removing ERPs to demonstrate their confounding effect, and to establish whether there are genuine stimulus-induced changes in 1/f. Using data from a passive and an active auditory task (n=23), we found that the shape of the post-event spectra differed significantly from the pre-event spectra even after removing the frequency-content of ERPs. Further, a significant portion of this difference could be accounted for by a rotational shift in 1/f activity, manifesting as an increase in low and a decrease in high frequencies. Importantly, the magnitude of this rotational shift was related to the attentional demands of the task. This change in 1/f is consistent with increased inhibition following the onset of a stimulus, and likely reflects a disruption of ongoing excitatory activity proportional to processing demands. Finally, these findings contradict the central assumption of baseline normalization strategies in time-frequency analyses, namely that background EEG activity is stationary across time. As such, they have far-reaching consequences that cut across several subfields of neuroscience