id_832. CONTRIBUTION OF THE PREFRONTAL CORTEX TO CONTROLLED SEMANTIC RETRIEVAL
Adam Kubinec1, Rastislav Rovný1, Igor Riečanský1,2, Martin Marko1,3
1 Centre of Experimental Medicine, Slovak Academy of Sciences, Department of Behavioural Neuroscience, Sienkiewiczova 1, Bratislava, Slovak Republic
2 Slovak Medical University in Bratislava, Faculty of Medicine, Department of Psychiatry, Limbová 12, Bratislava, Slovak Republic
3 Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Department of Applied Informatics, Mlynská dolina F1, Bratislava, Slovak Republic
INTRODUCTION: Semantic control refers to the cognitive and neural mechanisms that guide goal-directed retrieval of conceptual knowledge, often altered in neurodivergent populations. While neuroimaging consistently implicates the left lateral prefrontal cortex (PFC) in controlled semantic processing, its precise functional role remains unclear.
AIM(S): The study aimed to provide causal evidence for the role of the left lateral PFC in semantic control, particularly in executive inhibition of dominant conceptual associations during controlled retrieval.
METHOD(S): In a double-blind, randomized controlled trial, we applied anodal or sham transcranial direct current stimulation (tDCS) over the left lateral PFC to participants from two experimental groups (anodal: n = 49; sham: n = 50), who performed automatic-associative and controlled-dissociative word retrieval tasks before and during stimulation.
RESULTS: We found that anodal tDCS selectively impaired dissociative retrieval fluency—requiring executive inhibition of dominant associations—while leaving free-associative fluency unaffected. Crucially, prefrontal stimulation also increased the rate of conceptual intrusions during dissociative trials, and this effect substantially mediated the observed decline in retrieval fluency.
CONCLUSIONS: These findings provide causal evidence that the left lateral PFC supports proactive inhibitory control over semantic memory, suppressing context-inappropriate activations and intrusions to enable flexible, goal-relevant retrieval. Disruption of this mechanism impairs executive regulation of semantic retrieval, shedding new light on the neural architecture of semantic control and highlighting the potential of neuromodulatory approaches for addressing disordered conceptual processing.
FINANCIAL SUPPORT: APVV-23-0145, VEGA 2/0052/23, VEGA 2/0067/25, DoktoGrant APP0598