Faculty Bibliography

BACKGROUND:The ventroanterior insula is implicated in the experience, expression, and recognition of disgust; however, whether this brain region is required for recognizing disgust or regulating disgusting behaviors remains unknown. METHODS:We examined the brain correlates of the presence of disgusting behavior and impaired recognition of disgust using voxel-based morphometry in a sample of 305 patients with heterogeneous patterns of neurodegeneration. Permutation-based analyses were used to determine regions of decreased gray matter volume at a significance level p <= .05 corrected for family-wise error across the whole brain and within the insula. RESULTS:Patients with behavioral variant frontotemporal dementia and semantic variant primary progressive aphasia were most likely to exhibit disgusting behaviors and were, on average, the most impaired at recognizing disgust in others. Imaging analysis revealed that patients who exhibited disgusting behaviors had significantly less gray matter volume bilaterally in the ventral anterior insula. A region of interest analysis restricted to behavioral variant frontotemporal dementia and semantic variant primary progressive aphasia patients alone confirmed this result. Moreover, impaired recognition of disgust was associated with decreased gray matter volume in the bilateral ventroanterior and ventral middle regions of the insula. There was an area of overlap in the bilateral anterior insula where decreased gray matter volume was associated with both the presence of disgusting behavior and impairments in recognizing disgust. CONCLUSIONS:These findings suggest that regulating disgusting behaviors and recognizing disgust in others involve two partially overlapping neural systems within the insula. Moreover, the ventral anterior insula is required for both processes.

INTRODUCTION/BACKGROUND:The Behavioral Inhibition System (BIS) and the Behavioral Activation System (BAS) have been theorized as neural systems that regulate approach/withdrawal behaviors. Behavioral activation/inhibition balance may change in neurodegenerative disease based on underlying alterations in systems supporting motivation and approach/withdrawal behaviors, which may in turn be reflected in neuropsychiatric symptoms. METHOD/METHODS:A total of 187 participants (31 patients diagnosed with behavioral variant of FTD [bvFTD], 13 semantic variant of primary progressive aphasia [svPPA], 14 right temporal variant FTD [rtFTD], 54 Alzheimer's disease [AD], and 75 older healthy controls [NCs]) were included in this study. Changes in behavioral inhibition/activation were measured using the BIS/BAS scale. We analyzed the correlation between regional atrophy pattern and BIS/BAS score, using voxel-based morphometry (VBM). RESULTS:ADs had significantly higher BIS scores than bvFTDs and NCs. bvFTDs activation-reward response (BAS-RR) was significantly lower than ADs and NCs, though their activation-drive (BAS-D) was significantly higher than in ADs. Both AD and rtFTD patients had abnormally low activation fun-seeking (BAS-FS) scores. BIS score correlated positively with right anterior cingulate and middle frontal gyrus volume, as well as volume in the right precentral gyrus and left insula/operculum. CONCLUSIONS:AD, bvFTD, and rtFTD patients show divergent patterns of change in approach/withdrawal reactivity. High BIS scores correlated with preservation of right-predominant structures involved in task control and self-protective avoidance of potentially negative reinforcers. Damage to these regions in bvFTD may create a punishment insensitivity that underlies patients' lack of self-consciousness in social contexts.

This multidisciplinary article compares the pattern of memory loss described in Gabriel García Márquez's One Hundred Years of Solitude to that exhibited by patients with semantic dementia (SD). In his renowned novel, García Márquez depicts the plight of Macondo, a town struck by the dreaded insomnia plague. The most devastating symptom of the plague is not the impossibility of sleep, but rather the loss of 'the name and notion of things'. In an effort to combat this insidious loss of knowledge, the protagonist, José Arcadio Buendía, 'marked everything with its name: table, chair, clock, door, wall, bed, pan'. 'Studying the infinite possibilities of a loss of memory, he realized that the day might come when things would be recognized by their inscriptions but that no one would remember their use'. The cognitive impairments experienced by Macondo's inhabitants are remarkably similar to those observed in SD, a clinical syndrome characterized by a progressive breakdown of conceptual knowledge (semantic memory) in the context of relatively preserved day-to-day (episodic) memory. First recognized in 1975, it is now considered one of the main variants of frontotemporal lobar degeneration. Writing within the realm of magical realism and investigating the power of language as a form of communication, García Márquez provides beautiful descriptions of the loss of 'the name and notion of things' typical of the syndrome. He further speculates on ways to cope with this dissolution of meaning, ranging from 'the spell of an imaginary reality' to José Arcadio's 'memory machine', strategies that resonate with attempts by semantic dementia patients to cope with their disease. Remarkably, García Márquez created a striking literary depiction of collective semantic dementia before the syndrome was recognized in neurology. The novel also provides an inspiring and human account of one town's fight against 'the quicksand of forgetfulness'.