Showing 1 - 3 of 3 Items

Date: 2018-02-01

Creator: Erika Nyhus

Access: Open access

Evidence from fMRI has consistently located a widespread network of frontal, parietal, and temporal lobe regions during episodic retrieval. However, the temporal limitations of the fMRI methodology have made it difficult to assess the transient network dynamics by which these distributed regions coordinate activity. Recent evidence suggests that beta oscillations (17-20 Hz) are important for top-down control for memory suppression. However, the spatial limitations of the EEG methodology make it difficult to assess the relationship between these oscillatory signals and the distributed networks identified with fMRI. This study used simultaneous EEG/fMRI to identify networks related to beta oscillations during episodic retrieval. Participants studied adjectives and either imagined a scene (Place Task) or judged its pleasantness (Pleasant Task). During the recognition test, participants decided which task was performed with each word (“Old Place Task” or “Old Pleasant Task”) or “New.” EEG results revealed that posterior beta power was greater for new than old words. fMRI results revealed activity in a frontal, parietal network that was greater for old than new words, consistent with prior studies. Although overall beta power increases correlated with decreased activity within a predominantly parietal network, within the right dorsolateral and ventrolateral pFC, beta power correlated with BOLD activity more under conditions requiring more cognitive control and EEG/fMRI effects in the right frontal cortex correlated with BOLD activity in a frontoparietal network. Therefore, using simultaneous EEG and fMRI, the present results suggest that beta oscillations are related to postretrieval control operations in the right frontal cortex and act within a broader postretrieval control network. © 2017 Massachusetts Institute of Technology.

Date: 2013-10-01

Creator: Brendan Eliot Depue, Nick Ketz, Matthew V. Mollison, Erika Nyhus, Marie T. Banich, Tim Curran

Access: Open access

Although investigations of memory and the dynamics of ERP components and neural oscillations as assessed through EEG have been well utilized, little research into the volitional nature of suppression over memory retrieval have used these methods. Oscillation analyses conducted on the Think/No-Think (TNT) task and volitional suppression of retrieval are of interest to broaden our knowledge of neural oscillations associated not only during successful memory retrieval but also when retrieval is unwanted or suppressed. In the current study, we measured EEG during a TNT task and performed ERP and EEG spectral power band analyses. ERP results replicated other researchers' observations of increases in 500-800 msec parietal effects for items where retrieval was instructed to be elaborated compared with being suppressed. Furthermore, EEG analyses indicated increased alpha (8-12 Hz) and theta (3-8 Hz) oscillations across parietal electrodes for items that were instructed to be suppressed versus those to be elaborated. Additionally, during the second half of the experiment (after repeated attempts at control), increases in theta oscillations were found across both frontal and parietal electrodes for items that were instructed to be suppressed and that were ultimately forgotten versus those ultimately remembered. Increased alpha power for items that were instructed to be suppressed versus elaborated may indicate reductions of retrieval attempts or lack of retrieval success. Increased theta power for items that were instructed to be suppressed versus elaborated may indicate increased or prolonged cognitive control to monitor retrieval events. © 2013 Massachusetts Institute of Technology.

Date: 2017-05-01

Creator: Meghan Elizabeth Bellerose

Access: Open access

This thesis argues that international development programs focused on adolescent girls reproduce problematic and contradictory depictions of girls in the global South. Using Girl Effect marketing materials and interviews with INGO staff, I demonstrate that present-day international aid programs center on the neoliberal notion that an empowered adolescent girl holds the unique potential to end global poverty. Through empowerment programs, girls are encouraged to recognize their agency and take personal responsibility for improving the wellbeing of their communities. However, I argue that even as development leaders claim that an empowered adolescent girl is a source of indefatigable strength who can transform her community, they carry a deep conviction that such a feat is not possible without significant Western aid. Despite the empowerment rhetoric that The Girl Effect and related international initiatives espouse, their programs depict adolescent girls in the developing world as vulnerable and oppressed by poverty, local men, and their cultures. Thus, Western donors are called upon to save “Third World” adolescent girls. I argue that these contradictions in the language of international development contribute to the perception of girls in the global South as weak, inferior, and homogenous and lead to the establishment of programs that strengthen inequitable structures and sideline girls’ sexual rights.