Haily Merritt

Both cortical and subcortical regions can be functionally organized into networks. Regions of the basal ganglia are extensively interconnected with the cortex via reciprocal connections that relay and modulate cortical function. Here we employ an edge-centric approach, which computes co-fluctuations among region pairs in a network to investigate the role and interaction of subcortical regions with cortical systems. By clustering edges into communities, we show that cortical systems and subcortical regions couple via multiple edge communities, with hippocampus and amygdala having a distinct pattern from striatum and thalamus. We show that the edge community structure of cortical networks is highly similar to one obtained from cortical nodes when the subcortex is present in the network. Additionally, we show that the edge community profile of both cortical and subcortical nodes can be estimates solely from cortico-subcortical interactions. Finally, we used a motif analysis focusing on edge community triads where a subcortical region coupled to two cortical regions and found that two community triads where one community couples the subcortex to the cortex were overrepresented. In summary, our results show organized coupling of the subcortex to the cortex that may play a role in cortical organization of primary sensorimotor/attention and heteromodal systems and puts forth the motif analysis of edge community triads as a promising method for investigation of communication patterns in networks.

The social environment has a critical influence on human development, cognition, and health. By using network approaches to map and analyze the connectivity between all pairs of brain regions simultaneously, we can clarify how relationships between brain regions (e.g. connectivity) change as a function of social relationships. Here we apply multilayer modeling and modularity maximization--both established tools in network neuroscience--to jointly cluster patterns of brain-behavior associations for seven social support measures. Our analyses build on both neuroecological findings and network neuroscientific approaches. In particular we find that subcortical and control systems are especially sensitive to different constructs of perceived social support. Network nodes in these systems are highly flexible; their community affiliations, which reflect groups of nodes with similar patterns of brain behavior associations, differ across social support measures. The multilayer approach used ...

Previous exploratory analyses by our lab suggests that social early life stress mediates the effects of economic factors on internalizing symptoms and reward sensitivity. These results prompted us to develop the following analysis plan to learn more about the role of social stress in the context of social early life stress using an independent sample. We collected data from a second cohort to conduct confirmatory analyses to replicate models derived from the original pilot.

Successfully solving a problem should help people solve similar problems, but such generalization is often surprisingly limited. We investigated generalization performance when people explicitly verbalized solutions to open-ended categoryinduction ”Bongard problems”, compared to tacitly indicating that they had found a solution. In a Bongard problem people are presented with an array of items falling into two classes, and have to induce the basis for the classification by working out what (sometimes quite abstract) feature of the items is relevant, from a vast set of possibilities. We measured objective performance by testing people with new items, and observed how explicitly vs. tacitly expressed solutions affected generalization across concretely similar or abstractly similar problems. For the concretely similar problems, explicitness boosted transfer of correct solutions. For the abstractly similar problems, there was no evidence of transfer, though there was a general positive e...

The present study aims to fill the gap at the intersection of the phenomena of language mode (the state of activation of the bilingual’s languages and language processing mechanisms) and the subset problem (issues learners face when the second language has fewer of some kind of feature than the first language). Spanish and English serve as great languages for comparison because Spanish has fewer vowels than English. With these phenomena and languages in mind, we ask the question “Does language mode affect language-specific perception and categorization?” Possible effects could be realized in terms of processing speed, error rate, and interference by the less activated language. To investigate these effects, we ran a pilot test by having native English-speaking, proficient Spanish learners perform an AX task in both English and Spanish, where they identified whether two stimuli (in this case vowels) were the same or different. After measuring response time and accuracy in English mod...

Both cortical and subcortical regions can be functionally organized into networks. Regions of the basal ganglia are extensively interconnected with the cortex via reciprocal connections that relay and modulate cortical function. Here we employ an edge-centric approach, which computes co-fluctuations among region pairs in a network to investigate the role and interaction of subcortical regions with cortical systems. By clustering edges into communities, we show that cortical systems and subcortical regions couple via multiple edge communities, with hippocampus and amygdala having a distinct pattern from striatum and thalamus. We show that the edge community structure of cortical networks is highly similar to one obtained from cortical nodes when the subcortex is present in the network. Additionally, we show that the edge community profile of both cortical and subcortical nodes can be estimates solely from cortico-subcortical interactions. Finally, we used a motif analysis focusing on...

The present study aims to fill a gap at the intersection of the phenomena of language mode—the state of activation of the bilingual’s languages and language processing mechanisms—and the subset problem—issues learners face when the second language has fewer of some kind of contrast than the first language. When the subset problem is present in second language acquisition, learners may struggle to acquire specific contrasts of a language and may map them incorrectly to their first language. By studying advanced learners of Spanish and considering language mode, we are able to investigate whether learners create separate categories for Spanish vowels—as opposed to simply adapting their English categories—and whether the use of such categories depends on the language being perceived. Spanish and English serve as convenient languages for study of these phenomena because Spanish has fewer vowels than English. With this, we ask: “Does language mode influence language-specific categorizati...