Individual Differences In Activation Research Articles

Recalled through this day but forgotten next week?—retrieval activity predicts durability of partly consolidated memories

Abstract Even partly consolidated memories can be forgotten given sufficient time, but the brain activity associated with durability of episodic memory at different time scales remains unclear. Here, we aimed to identify brain activity associated with retrieval of partly consolidated episodic memories that continued to be remembered in the future. Forty-nine younger (20 to 38 years; 25 females) and 43 older adults (60 to 80 years, 25 females) were scanned with functional magnetic resonance imaging during associative memory retrieval 12 h post-encoding. Twelve hours is sufficient to allow short-term synaptic consolidation as well as early post-encoding replay to initiate memory consolidation. Successful memory trials were classified into durable and transient source memories based on responses from a memory test ~6 d post-encoding. Results demonstrated that successful retrieval of future durable vs. transient memories was supported by increased activity in a medial prefrontal and ventral parietal area. Individual differences in activation as well as the subjective vividness of memories during encoding were positively related to individual differences in memory performance after 6 d. The results point to a unique and novel aspect of brain activity supporting long-term memory, in that activity during retrieval of memories even after 12 h of consolidation contains information about potential for long-term durability.

Physical distance to sensory-motor landmarks predicts language function.

Auditory language comprehension recruits cortical regions that are both close to sensory-motor landmarks (supporting auditory and motor features) and far from these landmarks (supporting word meaning). We investigated whether the responsiveness of these regions in task-based functional MRI is related to individual differences in their physical distance to primary sensorimotor landmarks. Parcels in the auditory network, that were equally responsive across story and math tasks, showed stronger activation in individuals who had less distance between these parcels and transverse temporal sulcus, in line with the predictions of the "tethering hypothesis," which suggests that greater proximity to input regions might increase the fidelity of sensory processing. Conversely, language and default mode parcels, which were more active for the story task, showed positive correlations between individual differences in activation and sensory-motor distance from primary sensory-motor landmarks, consistent with the view that physical separation from sensory-motor inputs supports aspects of cognition that draw on semantic memory. These results demonstrate that distance from sensorimotor regions provides an organizing principle of functional differentiation within the cortex. The relationship between activation and geodesic distance to sensory-motor landmarks is in opposite directions for cortical regions that are proximal to the heteromodal (DMN and language network) and unimodal ends of the principal gradient of intrinsic connectivity.

Effects of anxiety sensitivity, disgust, and intolerance of uncertainty on the COVID stress syndrome: a longitudinal assessment of transdiagnostic constructs and the behavioural immune system

ABSTRACT Excessive fear and worry in response to the COVID-19 pandemic (e.g., COVID stress syndrome) is prevalent and associated with various adverse outcomes. Research from the current and past pandemics supports the association between transdiagnostic constructs—anxiety sensitivity (AS), disgust, and intolerance of uncertainty (IU)—and pandemic-related distress. Recent research suggests a moderating effect of disgust on the relationship of AS-physical concerns and COVID-19-related distress, suggesting that transdiagnostic constructs underlie individual differences in activation of the behavioral immune system (BIS). No previous study has examined the independent and conjoint effects of pre-COVID-19 AS-physical concerns, disgust propensity (DP), disgust sensitivity (DS), and IU in this context; thus, we did so using longitudinal survey data (N = 3,062 Canadian and American adults) with simple and moderated moderations controlling for gender, mental health diagnosis, and COVID-19 diagnosis. Greater AS-physical concerns, DP, and DS predicted more severe COVID stress syndrome assessed one month later. Either DP or DS further amplified the effect of AS-physical concerns on COVID stress syndrome, except danger and contamination fears. IU did not interact with AS-physical concerns and DS or DP. Theoretical and clinical implications pertaining to delivery of cognitive behavioural therapy for pandemic-related distress are discussed.

Sex differences in network controllability as a predictor of executive function in youth

Executive function is a quintessential human capacity that emerges late in development and displays different developmental trends in males and females. Sex differences in executive function in youth have been linked to vulnerability to psychopathology as well as to behaviors that impinge on health, wellbeing, and longevity. Yet, the neurobiological basis of these differences is not well understood, in part due to the spatiotemporal complexity inherent in patterns of brain network maturation supporting executive function. Here we test the hypothesis that sex differences in impulsivity in youth stem from sex differences in the controllability of structural brain networks as they rewire over development. Combining methods from network neuroscience and network control theory, we characterize the network control properties of structural brain networks estimated from diffusion imaging data acquired in males and females in a sample of 879 youth aged 8–22 years. We summarize the control properties of these networks by estimating average and modal controllability, two statistics that probe the ease with which brain areas can drive the network towards easy versus difficult-to-reach states. We find that females have higher modal controllability in frontal, parietal, and subcortical regions while males have higher average controllability in frontal and subcortical regions. Furthermore, controllability profiles in males are negatively related to the false positive rate on a continuous performance task, a common measure of impulsivity. Finally, we find associations between average controllability and individual differences in activation during an n-back working memory task. Taken together, our findings support the notion that sex differences in the controllability of structural brain networks can partially explain sex differences in executive function. Controllability of structural brain networks also predicts features of task-relevant activation, suggesting the potential for controllability to represent context-specific constraints on network state more generally.

Individual Differences in Activation of the Parental Care Motivational System: An Empirical Distinction Between Protection and Nurturance

Previous research reveals that individual differences in parental caregiving motives have implications (among both parents and nonparents) for a wide range of psychological outcomes. Here we report reanalyses of existing data sets to examine the extent to which these outcomes are uniquely predicted by two conceptually distinct factors underlying the parental caregiving motive: protection and nurturance. In doing so, we also psychometrically validate a brief self-report measure designed to efficiently assess individual differences in protection and nurturance. Results reveal that individual differences in parental protection uniquely predict a specific subset of attitudes and judgments (e.g., endorsement of restrictive parenting practices, harsher moral judgments of adults who violate social norms), whereas individual differences in parental nurturance uniquely predict a different subset of attitudes and judgments (e.g., nonparents desire to have children, preferences for committed romantic partners, more lenient moral judgments of children who violate social norms).

Moral judgment modulation by disgust priming via altered fronto-temporal functional connectivity

Moral judgments are not just the product of conscious reasoning, but also involve the integration of social and emotional information. Irrelevant disgust stimuli modulate moral judgments, with individual sensitivity determining the direction and size of effects across both hypothetical and incentive-compatible experimental designs. We investigated the neural circuitry underlying this modulation using fMRI in 19 individuals performing a moral judgment task with subliminal priming of disgust facial expressions. Our results indicate that individual changes in moral acceptability due to priming covaried with individual differences in activation within the dorsomedial prefrontal cortex (dmPFC). Further, whole-brain analyses identified changes in functional connectivity between the dmPFC and the temporal-parietal junction (TPJ). High sensitivity individuals showed enhanced functional connectivity between the TPJ and dmPFC, corresponding with deactivation in the dmPFC, and rating the moral dilemmas as more acceptable. Low sensitivity individuals showed the opposite pattern of results. Post-hoc, these findings replicated in the dorsal anterior cingulate cortex (daMCC), an adjacent region implicated in converting between objective and subjective valuation. This suggests a specific computational mechanism – that disgust stimuli modulate moral judgments by altering the integration of social information to determine the subjective valuation of the considered moral actions.

Prereader to beginning reader: changes induced by reading acquisition in print and speech brain networks.

Literacy acquisition is a demanding process that induces significant changes in the brain, especially in the spoken and written language networks. Nevertheless, large-scale paediatric fMRI studies are still limited. We analyzed fMRI data to show how individual differences in reading performance correlate with brain activation for speech and print in 111 children attending kindergarten or first grade and examined group differences between a matched subset of emergent-readers and prereaders. Across the entire cohort, individual differences analysis revealed that reading skill was positively correlated with the magnitude of activation difference between words and symbol strings in left superior temporal, inferior frontal and fusiform gyri. Group comparisons of the matched subset of pre- and emergent-readers showed higher activity for emergent-readers in left inferior frontal, precentral, and postcentral gyri. Individual differences in activation for natural versus vocoded speech were also positively correlated with reading skill, primarily in the left temporal cortex. However, in contrast to studies on adult illiterates, group comparisons revealed higher activity in prereaders compared to readers in the frontal lobes. Print-speech coactivation was observed only in readers and individual differences analyses revealed a positive correlation between convergence and reading skill in the left superior temporal sulcus. These results emphasise that a child's brain undergoes several modifications to both visual and oral language systems in the process of learning to read. They also suggest that print-speech convergence is a hallmark of acquiring literacy.

The relation between craving and binge eating: Integrating neuroimaging and ecological momentary assessment

The role of craving in binge eating characteristic of bulimia nervosa (BN) is inconclusive. A network of regions associated with cue reactivity to food and substances has been identified, comprised of the amygdala, orbitofrontal cortex, insula, and striatum. The goal of this study was to examine individual differences in BOLD response in this appetitive network as moderators of the relationship between craving and binging in the natural environment in women with BN. Women with BN (N = 16) completed a baseline measure of craving and a fMRI scan, where they viewed neutral cues and food cues. After each run, craving for food was assessed. Participants then completed an ecological momentary assessment six times a day via smart phone and recorded binge eating and craving. Participants exhibited significantly increased BOLD response in the left amygdala in response to food cues compared to neutral cues. However, individual differences in BOLD response were not correlated with self-report craving throughout the scan. The relationship between craving and binging in everyday life was moderated by individual differences in activation in the caudate, insula, and amygdala. Women with greater activation in these regions demonstrated significant increases in craving prior to binge eating. Those who did not exhibit increases in activation did not exhibit increases in craving prior to binge eating in the natural environment. Craving may not underlie binge eating for all individuals with BN. However, these results indicate that neural response to food cues may affect individual differences in the daily experience of craving and binge eating.

Neural Correlates of Susceptibility to Group Opinions in Online Word-of-Mouth Recommendations

The present study examines the relationship between social influence and recommendation decisions among adolescents in the new media environment. Participants completed the App Recommendation Task—a task that captures neural processes associated with making recommendations to others, with and without information about peer recommendations of the type commonly available online. The results demonstrate that increased activity in the striatum and orbitofrontal cortex in response to peer recommendations is significantly correlated with participants changing their recommendations to be consistent with this feedback within subjects. Furthermore, individual differences in activation of the temporoparietal junction during feedback that peer recommendations varied from those of the participant correlated with individual differences in susceptibility to influence on recommendation decisions between subjects. These brain regions have previously been implicated in social influence and the concept of being a “successful idea salesperson,” respectively. Together, they highlight a potential combination of internal preference shifts and consideration of the mental states of others in recommendation environments that include peer opinions.

Individual differences in activation of the parental care motivational system: assessment, prediction, and implications.

We report on the development, validation, and utility of a measure assessing individual differences in activation of the parental care motivational system: The Parental Care and Tenderness (PCAT) questionnaire. Results from 1,608 adults (including parents and nonparents) show that the 25-item PCAT measure has high internal consistency, high test-retest reliability, high construct validity, and unique predictive utility. Among parents, it predicted self-child identity overlap and caring child-rearing attitudes; among nonparents, it predicted desire to have children. PCAT scores predicted the intensity of tender emotions aroused by infants, and also predicted the amount of time individuals chose look at infant (but not adult) faces. PCAT scores uniquely predicted additional outcomes in the realm of social perception, including mate preferences, moral judgments, and trait inferences about baby-faced adults. Practical and conceptual implications are discussed.

Functional dissociations between four basic arithmetic operations in the human posterior parietal cortex: A cytoarchitectonic mapping study

Although lesion studies over the past several decades have focused on functional dissociations in posterior parietal cortex (PPC) during arithmetic, no consistent view has emerged of its differential involvement in addition, subtraction, multiplication, and division. To circumvent problems with poor anatomical localization, we examined functional overlap and dissociations in cytoarchitectonically defined subdivisions of the intraparietal sulcus (IPS), superior parietal lobule (SPL) and angular gyrus (AG), across these four operations. Compared to a number identification control task, all operations except addition, showed a consistent profile of left posterior IPS activation and deactivation in the right posterior AG. Multiplication and subtraction differed significantly in right, but not left, IPS and AG activity, challenging the view that the left AG differentially subserves retrieval during multiplication. Although addition and multiplication both rely on retrieval, multiplication evoked significantly greater activation in right posterior IPS, as well as the prefrontal cortex, lingual and fusiform gyri, demonstrating that addition and multiplication engage different brain processes. Comparison of PPC responses to the two pairs of inverse operations: division versus multiplication and subtraction versus addition revealed greater activation of left lateral SPL during division, suggesting that processing inverse relations is operation specific. Our findings demonstrate that individual IPS, SPL and AG subdivisions are differentially modulated by the four arithmetic operations and they point to significant functional heterogeneity and individual differences in activation and deactivation within the PPC. Critically, these effects are related to retrieval, calculation and inversion, the three key cognitive processes that are differentially engaged by arithmetic operations. Our findings point to distribute representation of these processes in the human PPC and also help explain why lesion and previous imaging studies have yielded inconsistent findings.

Relationship between limb and trunk muscle hypertrophy following high‐intensity resistance training and blood flow–restricted low‐intensity resistance training

We examined the relationship between training-induced limb and trunk muscle hypertrophy in high-intensity resistance training (HIT) or blood flow-restricted low-intensity resistance training (LI-BFR) programmes. Thirty young men were divided into three groups: HIT (n = 10), LI-BFR (n = 10) and non-training control (CON, n = 10). The HIT and LI-BFR groups performed 75% and 30%, respectively, of one-repetition maximal (1-RM) bench press exercise, 3 days per week for 6 weeks. During the training sessions, the LI-BFR group wore elastic cuffs around the most proximal region of both arms. Muscle cross-sectional area (CSA) and 1-RM bench press strength were measured before and 3 days after the final training session. Total training volumes (lifting weight × number of repetitions) for all of the sessions were similar between the two training groups. The training led to a significant increase (P < 0·05) in bench press 1-RM in the two training groups, but not in the CON group. Triceps brachii and pectoralis major muscle CSA increased 8·8% and 15·8% (P < 0·01), respectively, in the HIT group and 4·9% (P < 0·05) and 8·3% (P < 0·01), respectively, in the LI-BFR group, but not in the CON group (-1·1% and 0·0%, respectively). There was significant correlation (r = 0·70, P < 0·05) between increases in triceps brachii and pectoralis major muscle CSA in the HIT group; however, the correlation was lower and non-significant in the LI-BFR group (r = 0·54). Our results suggest that limb and trunk muscle hypertrophy occurs simultaneously during HIT but not during LI-BFR, possibly owing to individual differences in activation of the arm and chest muscles during the training sessions.

Dual-task processing in younger and older adults: Similarities and differences revealed by fMRI

fMRI was used to explore age differences in the neural substrate of dual-task processing. Brain activations when there was a 100ms SOA between tasks, and task overlap was high, were contrasted with activations when there was a 1000ms SOA, and first task processing was largely complete before the second task began. Younger adults (M=21yrs) showed activation in dorsolateral prefrontal cortex and in parietal areas as well as in ventral medial frontal cortex and sub-lobar areas. Activations in older adults (M=71yrs) did not differ significantly from younger adults except for higher activations in occipital and polar prefrontal cortex. The results were well fit by a model with two networks managing dual-task interference, a medial prefrontal network that detects changes in the stimulus situation and maps them to associated changes in the valence of response mappings and a lateral frontal–parietal network that initiates and carries out the shift from one task to the other. The additional activations in older adults as a group and the correlations of individual differences in activation with performance were consistent with recruitment within each of these networks. Alternative explanations such as hemispheric asymmetry reduction and reactive rather than proactive processing in older adults were not supported.

Brain networks for working memory and factors of intelligence assessed in males and females with fMRI and DTI

Neuro-imaging studies of intelligence implicate the importance of a parietal–frontal network. One unresolved issue is whether this network underlies a general factor of intelligence ( g) or other specific cognitive factors. A second unresolved issue is whether males and females use different parts of this network. Here we obtained intelligence factors (general, speed of reasoning, spatial, memory, and numerical) from a large set of tests completed by 6929 young adults, 40 of whom (21 males, 19 females) also completed DTI and fMRI during a working memory n-back task. Within brain areas activated during this task, correlations were computed between percent activation and scores on the intelligence factors. The main findings were: (1) individual differences in activation during the n-back task were correlated to the general intelligence factor ( g), as well as to distilled estimates (removing g) of speed of reasoning, numerical ability, and spatial ability, but not to memory, (2) the correlations were mainly bilateral for females and unilateral for males, and (3) differences in the integrity of the axonal connections were also related to the functional findings showing that integrity of interhemispheric connections was positively correlated to some intelligence factors in females but negatively correlated in males. This study illustrates the potential for identifying aspects of the neural basis of intelligence using a combination of structural and functional imaging.

Structure-function relationships in the context of reinforcement-related learning: a combined diffusion tensor imaging–functional magnetic resonance imaging study

In the context of probabilistic learning, previous functional magnetic resonance imaging studies have shown decreasing uncertainty accompanying decreasing neuronal activation in task-relevant networks. Moreover, initial evidence points to a relationship between white matter structure and cognitive performance. Little is known, however, about the structural correlates underlying individual differences in activation and performance in the context of probabilistic learning. This combined functional magnetic resonance imaging–diffusion tensor imaging study aimed at investigating the individual ability to reduce processing resources with decreasing uncertainty in direct relation to individual characteristics in white matter brain structure. Results showed that more successful learners, as compared with less successful learners, exhibited stronger activation decreases with decreasing uncertainty. An increased mean and axial diffusivity in, among others, the inferior and superior longitudinal fasciculus, the posterior part of the cingulum bundle, and the corpus callosum were detectable in less successful learners compared with more successful learners. Most importantly, there was a negative correlation between uncertainty-related activation and diffusivity in a fronto-parieto-striatal network in less successful learners only, indicating a direct relation between diffusivity and the ability to reduce processing resources with decreasing uncertainty. These findings indicate that interindividual variations in white matter characteristics within the normal population might be linked to neuronal activation and critically influence individual learning performance.

Space and time in perceptual causality.

Inferring causality is a fundamental feature of human cognition that allows us to theorize about and predict future states of the world. Michotte suggested that humans automatically perceive causality based on certain perceptual features of events. However, individual differences in judgments of perceptual causality cast doubt on Michotte's view. To gain insights in the neural basis of individual difference in the perception of causality, our participants judged causal relationships in animations of a blue ball colliding with a red ball (a launching event) while fMRI-data were acquired. Spatial continuity and temporal contiguity were varied parametrically in these stimuli. We did not find consistent brain activation differences between trials judged as caused and those judged as non-caused, making it unlikely that humans have universal instantiation of perceptual causality in the brain. However, participants were slower to respond to and showed greater neural activity for violations of causality, suggesting that humans are biased to expect causal relationships when moving objects appear to interact. Our participants demonstrated considerable individual differences in their sensitivity to spatial and temporal characteristics in perceiving causality. These qualitative differences in sensitivity to time or space in perceiving causality were instantiated in individual differences in activation of the left basal ganglia or right parietal lobe, respectively. Thus, the perception that the movement of one object causes the movement of another is triggered by elemental spatial and temporal sensitivities, which themselves are instantiated in specific distinct neural networks.