Direct evidence for a prefrontal contribution to the control of proactive interference in verbal working memory

Abstract

Controlling the effects of proactive interference (PI), the deleterious effect of prior mental activity on current memory representations, is believed to be a key function of the prefrontal cortex. This view is supported by neuroimaging evidence for a correlation between the longer reaction times caused by high PI conditions of a working memory task and increased activity in left inferior frontal gyrus (IFG) of the prefrontal cortex. An alternative that has never been ruled out, however, is that this left IFG effect may merely reflect sensitivity to such nonspecific factors as difficulty and/or time on task. To resolve this confound, we applied the interference methodology of repetitive transcranial magnetic stimulation (rTMS) to the left IFG and two control regions while subjects performed delayed letter recognition. rTMS was guided with high-resolution magnetic resonance images and was timelocked to the onset of the memory probe. The effect of rTMS, a disruption of accuracy restricted to high-PI probes, was specific to the left IFG. These results demonstrate that unpredictable, phasic disruption of the left IFG selectively disrupts control of responses to high-conflict verbal working memory probes, and they conclusively reject nonspecific alternative accounts.cognitive control ͉ inferior frontal gyrus ͉ transcranial magnetic stimulation T he left inferior frontal gyrus (IFG) of the prefrontal cortex is central to many theoretical accounts of cognitive control, including retrieval of semantic knowledge (1), selection among competing alternatives (2), reactive control (3), and the control of the effects of proactive interference (PI) in working memory (4). PI, the deleterious effect of previously remembered information on current memory representations, is widely seen as a critical factor in forgetting, and therefore capacity, in working memory (5-7). Thus, understanding the control of PI in working memory has implications for understanding the cognitive and neural bases of a remarkable breadth of cognitive functions and ''real-world'' outcome measures, from general fluid intelligence, to reading ability, to standardized test performance, to income and socioeconomic status, to personality traits, that are predicted by working memory capacity (8-10).One influential experimental paradigm for the investigation of PI is the ''recent probes'' variant of the classic item-recognition task (Fig. 1), which controls the level of PI by varying whether or not an invalid memory probe matches an item from the preceding trial. The PI produced by such ''recent negative'' (RN) probes manifests as costs in reaction time (RT), and, less reliably, in accuracy. This PI derives from the presumed conflict of processing the probe's high level of familiarity vs. its absence from the current trial's memory set. The neuroimaging correlate of these effects is an increase of signal in the left IFG that is time-locked to the onset of the memory probe. It has been interpreted as evidence for prefrontal cortex-based control of PI (reviewed in ...

Neural Substrates for Reversing Stimulus–Outcome and Stimulus–Response Associations

“…The posterior IFC and adjacent precentral gyrus are strongly connected with the superior parietal lobule (Petrides, 2005). The pIFC has been implicated in several processes associated with cognitive control, including semantic selection (Thompson-Schill et al, 1997;, response selection (Bunge et al, 2002;Dux et al, 2006), proactive interference resolution Feredoes et al, 2006), and conflict resolution (Derrfuss et al, 2004(Derrfuss et al, , 2005. Our study extended these studies by suggesting that this network might play a domain-general role in resolving both stimulus-outcome and stimulus-response interference.…”

Efficiency of Go/No-Go Task Performance Implemented in the Left Hemisphere

“…Statistical significance is indicated using the color scale at the bottom, and the transverse section level is indicated by the Z coordinates of Talairach space (Talairach and Tournoux, 1988). Feredoes et al, 2006;Hodgson et al, 2007;Eagle et al, 2008;Verbruggen et al, 2010;Severens et al, 2012).…”

The Cognitive Neuroscience of Working Memory: Relevance to CNTRICS and Schizophrenia

“…Further, individuals who are better at preventing proactive interference show greater activity in left ventrolateral prefrontal cortex [70]. In addition, lesions to left ventrolateral prefrontal cortex make individuals more susceptible to proactive interference in working memory [71], as does TMS over left ventrolateral prefrontal cortex [72].…”