Neural correlates of negative and disease-specific emotional stimuli in panic disorder: a functional magnetic resonance imaging study.

OBJECTIVE: Decades of research have highlighted the involvement of the prefrontal cortex, anterior cingulated cortex, and limbic areas (amygdala) in panic disorder (PD). However, little attention has been given specifically to the inferior frontal gyrus. The current study aimed to investigate the neural substrates, including the inferior frontal gyrus, of both panic-related and negative conditions among individuals with PD and healthy controls. METHODS: We examined 13 medication-free PD patients and 14 healthy controls with functional magnetic resonance imaging (fMRI) during exposure to negative and neutral pictures and a set of specific panic-related pictures. RESULTS: Subtraction between the conditions indicated activation of the left amygdala region and the right inferior frontal gyrus in PD patients during the specific panic-related condition, whereas the left amygdalar region and left inferior frontal gyrus were activated during the negative condition in controls. CONCLUSION: These results suggest that in patients with PD, a prominent bottom-up process is involved in specific panic-related conditions, which might be associated with weak modulation of the left frontal area. These data add to our current understanding of the neural correlates of PD and can contribute to future clinical interventions targeting the functional reestablishment of these regions.

Early and late inhibitions elicited by a peripheral visual cue on manual response to a visual target: Are they based on Cartesian coordinates?

A non-informative cue (C) elicits an inhibition of manual reaction time(MRT) to a visual target (T). We report an experiment to examine if thespatial distribution of this inhibitory effect follows Polar or Cartesiancoordinate systems. C appeared at one out of 8 isoeccentric (7o) positions,the C-T angular distances (in polar coordinates) were 0º or multiples of 45ºand ISI were 100 or 800ms. Our main findings were: (a) MRT was maximalwhen C- T distance was 0o and minimal when C-T distance was 180o and (b)besides an angular distance effect, there is a meridian effect. When C and Toccurred in the same quadrant, MRT was longer than when T and C occurredat the same distance (45o) but on different sides of vertical or horizontalmeridians. The latter finding indicates that the spatial distribution of the cueinhibitory effects is based on a Cartesian coordinate system