Orbitofrontal cortex and dynamic filtering of emotional stimuli

Event-related potentials (ERPs) were recorded in response to mildly aversive somatosensory and auditory stimuli. Patients with orbitofrontal lesions exhibited enhanced ERPs (i.e., P3 amplitudes), as compared with control subjects. Moreover, these patients did not habituate to somatosensory stimuli across blocks of trials. The results were specific to orbitofrontal damage, since patients with damage to the dorsolateral prefrontal cortex did not exhibit enhanced P3 amplitudes. These findings suggest that damage to the orbitofrontal cortex impairs the ability to modulate or inhibit neural responses to aversive stimuli. The findings are couched in terms of dynamic filtering theory, which suggests that the orbitofrontal cortex is involved in the selection and active inhibition of neural circuits associated with emotional responses.