Figure 4. Network abnormalities underlying pathologic tearfulness in autoimmune limbic encephalitis (aLE).

Illustration of the network abnormalities that may underlie pathologic tearfulness following aLE, based on our findings and on the model of “pathological laughing and crying” proposed by Parvizi et al. (2001). The locations mentioned in the figure are only those identified as abnormal in this study, and other regions are likely to be involved as well. Blue box = telencephalic sites that are assumed to process “emotionally competent” stimuli along with relevant context information that may include the middle frontal gyrus (MFG), the posterior ventral posteromedial cortex (PMC), the inferior parietal lobule (IPL), and the fusiform gyrus (FG); these act on the induction sites (green box) (e.g., ventromedial prefrontal cortex, anterior cingulate, amygdala, ventral striatum), which may also include the anterior hippocampus (HPC); these sites detect the stimuli and context, and act on the effector sites (yellow box) (e.g., motor cortex, hypothalamus, periaqueductal gray, cranial nerve nuclei), which trigger the emotional response. Red arrows = cerebro-ponto-cerebellar pathways, through which telencephalic areas convey to the cerebellum information on the emotionally competent stimuli along with context-related information; blue arrows = the cerebellum modulates the profile, intensity, and duration of the emotional responses in accordance with the context of the triggering stimulus by providing input to the induction and effector sites; structural and functional abnormalities in these sites may trigger emotional responses (pathologic tearfulness) that are contextually inappropriate.