Failure to Affect Decision Criteria During Recognition Memory With Continuous Theta Burst Stimulation

Abstract

A decision criterion establishes the minimum amount of memory evidence required for recognition. When a liberal criterion is set, items are recognized based on weak evidence whereas a conservative criterion requires greater memory strength for recognition. The decision criterion is a fundamental aspect of recognition memory but little is known about the underlying neural mechanisms of maintaining a criterion. We used continuous theta burst stimulation (cTBS) with the goal of inhibiting prefrontal cortex excitability while participants performed recognition tests. We hypothesized that inhibiting the right inferior frontal gyrus (rIFG), right middle frontal gyrus (rMFG), and right dorsolateral prefrontal cortex (rDLPFC) would cause participants to establish less conservative decision criteria without affecting recognition memory performance. Participants initially performed recognition memory tests while maintaining conservative decision criteria during fMRI scanning. Peak activity in the successful retrieval effect contrast (Hits > Correct Rejections) provided subject-specific cTBS target sites. During three separate sessions, participants completed the same recognition memory paradigm while maintaining conservative and liberal decision criteria both before and after cTBS. Across two experiments we failed to significantly alter decision criteria placement by applying cTBS to the rIFG, rMFG, and rDLPFC despite efforts to precisely target individualized brain areas. However, we unexpectedly improved discriminability following cTBS to the rDLPFC specifically when participants maintained a liberal criterion. Although this finding may guide future studies investigating the neural mechanisms underlying discriminability in recognition memory, cTBS proved ineffective at altering decision criteria.

Who gives a criterion shift? A uniquely individualistic cognitive trait.

“…Although criterion shifting tendencies are quite stable within people, there are vast individual differences across people (Aminoff et al, 2012, 2015; Frithsen et al, 2018; Kantner et al, 2015; Layher et al, 2018; Miller & Kantner, 2020). Individual differences in strategic criterion shifting do not appear to be a result of an inability for certain people to shift criteria.…”

“…If people are unaware of the advantages for shifting criteria, criterion shifts are generally not observed (Rhodes & Jacoby, 2007; Verde & Rotello, 2007). When people are made aware of the advantages for shifting, the extent of criterion shifting increases on average , but analyses of individual differences reveal that this is not true for everyone (Aminoff et al, 2012, 2015; Frithsen et al, 2018; Kantner et al, 2015; Layher et al, 2018; Miller & Kantner, 2020). Our studies revealed that these individual differences in criterion shifting behavior are remarkably consistent across multiple testing sessions.…”

“…In recognition memory, criterion placement is the threshold of familiarity strength that must be exceeded to recognize items. Criterion placement, like criterion shifting, is quite variable across individuals (Aminoff et al, 2012, 2015; Frithsen et al, 2018; Kantner et al, 2015; Kantner & Lindsay, 2012, 2014; Layher et al, 2018; Miller & Kantner, 2020). Despite large between-subjects variability, Kantner and Lindsay (2012, 2014) propose that the within-subject consistency of criterion placement over time makes it a stable cognitive trait.…”

“…However, if you are on vacation in Tahiti you should establish a conservative criterion by only greeting a potential coworker when your memory is strong because this encounter is much less likely to occur (a strategy to avoid false alarms). Remarkably, in situations where criterion shifting is clearly advantageous, some individuals will readily shift decision criteria while others fail to shift entirely, which can detrimentally impact decisional outcomes (Aminoff et al, 2012(Aminoff et al, , 2015Frithsen, Kantner, Lopez, & Miller, 2018;Kantner, Vettel, & Miller, 2015;Layher, Santander, Volz, & Miller, 2018;Miller & Kantner, 2020). Extreme variability in criterion shifting across participants is well-documented, but currently no studies have systematically characterized the stability of criterion shifting tendencies within individuals over time.…”

Low-Frequency TMS Results in Condition-Related Dynamic Activation Changes of Stimulated and Contralateral Inferior Parietal Lobule

“…Over the past decades, a plethora of studies have investigated behavioral changes after transcranial magnetic stimulation (TMS, for reviews see e.g., Pascual-Leone et al, 2000;Rushworth and Taylor, 2006;Koch and Rothwell, 2009;Rossini et al, 2010;Crivelli and Balconi, 2017;Klaus and Schutter, 2018). Although brain stimulation is a promising approach to study the causal relationship and close the explanatory gap between brain function and behavior, it has its drawbacks as exemplified in interpreting behavioral null results after stimulation (e.g., Rossi et al, 2006;Zanto et al, 2013;Gohil et al, 2016;Bor et al, 2017;Engelen et al, 2018;Layher et al, 2018;Lopez-Alonso et al, 2018;Codol et al, 2020;see also De Graaf and Sack, 2011). There are a number of possible explanations for TMS null results ranging from the stimulated brain region not being causally involved in the tested behavior (Rossi et al, 2006;Gohil et al, 2016) to dynamic brain network changes compensating for the stimulation (Lee et al, 2003;O'Shea et al, 2007;Zanto et al, 2013;Hartwigsen, 2018).…”