THE ROLE OF SALIENCE DETECTION AND ERROR MONITORING IN ANOSOGNOSIA: A BEHAVIORAL AND fMRI STUDY

Background Anosognosia, defined as the reduced awareness of one’s own cognitive deficits, is a frequent symptom of Alzheimer’s disease (AD) and is associated with poorer clinical outcomes. Recent evidence suggests that alterations within the Default Mode Network, Salience Network, and Frontoparietal Network may contribute to impaired self-awareness. These large-scale networks collectively support self-referential processing, salience detection, and error-monitoring, processes that have been proposed as key mechanisms underlying anosognosia. Objectives The present study investigated salience detection and error-monitoring in AD using a visual oddball fMRI paradigm, examining behavioral performance and brain activation in patients and controls, and comparing individuals with and without anosognosia. Materials and methods Twenty patients with AD and 40 healthy controls underwent clinical, neuropsychological, and functional MRI assessment. Awareness of cognitive deficits was evaluated using the Anosognosia Questionnaire-Dementia (AQ-D), allowing patients to be classified as aware or unaware. During fMRI acquisition, participants performed a visual oddball task requiring the discrimination of frequent (70%) and infrequent (30%) stimuli. Accuracy and reaction times were analyzed using mixed-model ANOVAs. Functional MRI data were processed using SPM25, and brain activation associated with salience processing was examined through the Infrequent > Frequent contrast. ROI analyses were performed to compare activation patterns between aware and unaware patients. Results Within the patient group, 7 individuals were classified as unaware, while 13 showed preserved awareness (aware). Behavioral results showed a significant main effect of stimulus type, with slower reaction times and lower accuracy for infrequent compared to frequent stimuli across groups. A significant main effect of the group was also observed for accuracy, with patients performing worse than controls. No significant effects of awareness were found on reaction times or accuracy within the patient group. Functional MRI results revealed that controls showed widespread activation of occipital, parietal, temporal, frontal, and subcortical regions, while AD patients showed a more restricted pattern. Direct comparisons between aware and unaware patients showed reduced activation in unaware individuals across salience-related regions, although these differences did not reach statistical significance. Conclusions Our findings support a network-based model of anosognosia in Alzheimer’s disease, suggesting that impaired awareness is related to altered salience detection mechanisms. . This dysfunction may disrupt the updating of internal self-representations, contributing to reduced awareness of cognitive impairment. Future studies integrating fMRI and electrophysiological measures are needed to further clarify the temporal dynamics of these processes.