All Publications

  • Multi-band FMRI compromises detection of mesolimbic reward responses. NeuroImage Srirangarajan, T., Mortazavi, L., Bortolini, T., Moll, J., Knutson, B. 2021: 118617


    Recent innovations in Functional Magnetic Resonance Imaging (FMRI) have sped data collection by enabling simultaneous scans of neural activity in multiple brain locations, but have these innovations come at a cost? In a meta-analysis and preregistered direct comparison of original data, we examined whether acquiring FMRI data with multi-band versus single-band scanning protocols might compromise detection of mesolimbic activity during reward processing. Meta-analytic results (N=44 studies; cumulative n=5005 subjects) indicated that relative to single-band scans, multi-band scans showed significantly decreased effect sizes for reward anticipation in the Nucleus Accumbens (NAcc) by more than half. Direct within-subject comparison of single-band versus multi-band scanning data (multi-band factors=4 and 8; n=12 subjects) acquired during repeated administration of the Monetary Incentive Delay task indicated that reductions in temporal signal-to-noise ratio could account for compromised detection of task-related responses in mesolimbic regions (i.e., the NAcc). Together, these findings imply that researchers should opt for single-band over multi-band scanning protocols when probing mesolimbic responses with FMRI. The findings also have implications for inferring mesolimbic activity during related tasks and rest, for summarizing historical results, and for using neuroimaging data to track individual differences in reward-related brain activity.

    View details for DOI 10.1016/j.neuroimage.2021.118617

    View details for PubMedID 34600102

  • Investigating serotonergic contributions to cognitive effort allocation, attention, and impulsive action in female rats JOURNAL OF PSYCHOPHARMACOLOGY Silveira, M. M., Wittekindt, S. N., Mortazavi, L., Hathaway, B. A., Winstanley, C. A. 2020; 34 (4): 452-466


    Individuals must frequently evaluate whether it is worth allocating cognitive effort for desired outcomes. Motivational deficits are a common feature of psychiatric illness such as major depression. Selective serotonin reuptake inhibitors are commonly used to treat this disorder, yet some data suggest these compounds are ineffective at treating amotivation, and may even exacerbate it.Here we used the rodent Cognitive Effort Task (rCET) to assess serotonergic (5-hydroxytryptamine, 5-HT) contributions to decision-making with cognitive effort costs.The rCET is a modified version of the 5-choice serial reaction time task, a well-validated test of visuospatial attention and impulse control. At the start of each rCET trial, rats chose one of two levers, which set the difficulty of an attentional challenge, namely the localization of a visual stimulus illuminated for 0.2 or 1ā€‰s on hard versus easy trials. Successful completion of hard trials was rewarded with double the sugar pellets. Twenty-four female Long-Evans rats were trained on the rCET and systemically administered the 5-HT1A agonist 8-OH-DPAT, the 5-HT2A antagonist M100907, the 5-HT2C agonist Ro-60-0175, as well as the 5-HT2C antagonist SB 242, 084.5-HT2A antagonism dose-dependently reduced premature responding, while 5-HT2C antagonism had the opposite effect. 8-OH-DPAT impaired accuracy of target detection at higher doses, while Ro-60-0175 dose-dependently improved accuracy on difficult trials. However, none of the drugs affected the rats' choice of the harder option.When considered with existing work evaluating decision-making with physical effort costs, it appears that serotonergic signalling plays a minor role in guiding effort allocation.

    View details for DOI 10.1177/0269881119896043

    View details for Web of Science ID 000506981100001

    View details for PubMedID 31913079

  • Stigma, the Media, and Pre-exposure Prophylaxis for HIV Prevention: Observations for Enhancing Knowledge Translation and Resisting Stigma in the Canadian Context AIDS AND BEHAVIOR Card, K. G., Hawkins, B. W., Mortazavi, L., Gregory, A., Ng, K., Lachowsky, N. J. 2019; 23 (7): 1877-1887


    Pre-Exposure Prophylaxis (PrEP) is an effective, though sometimes stigmatized, strategy for HIV prevention. With the goal of examining how PrEP stigma can be addressed, this study examined the media's handling of stigma related to PrEP by searching the Canadian Newsstream and Daily Xtra news databases for key terms related to PrEP. Overall, 101 media articles were thematically coded in triplicate; 36.3% of which included mentions of PrEP stigma. LGBT media sources were more likely than mainstream sources to have included content coded as relating to PrEP stigma (pā€‰=ā€‰0.02). In these articles, uncertainty regarding PrEP, and neo-liberal attitudes towards sexual responsibility were major factors associated with media discussion of PrEP stigma. We discuss the role that heuristics play in shaping lay readers perceptions and interpretation of PrEP media coverage and discuss methods for overcoming stigma using evidence-based communication strategies.

    View details for DOI 10.1007/s10461-018-2332-x

    View details for Web of Science ID 000471709800020

    View details for PubMedID 30390190