Brain responses to verbal stimuli among multiple sclerosis patients with pseudobulbar affect.
OBJECTIVE
To characterize the brain activity and associated cortical structures involved in pseudobulbar affect (PBA), a condition characterized by uncontrollable episodes of emotional lability in patients with multiple sclerosis (MS).


METHODS
Behavioral responses and event related potentials (ERP) in response to subjectively significant and neutral verbal stimuli were recorded from 33 subjects in 3 groups: 1) MS patients with PBA (MS+PBA); 2) MS patients without PBA (MS); 3) Healthy control subjects (HC). Statistical non-parametric mapping comparisons of ERP source current density distributions between groups were conducted separately for subjectively significant and for neutral stimuli.


RESULTS
Behavioral responses showed more impulsive performance in patients with PBA. As expected, almost all ERP waveform comparisons between the MS groups and controls were significant. Source analysis indicated significantly distinct activation in MS+PBA in the vicinity of the somatosensory and motor areas in response to neutral stimuli, and at pre-motor and supplementary motor areas in response to subjectively significant stimuli. Both subjectively significant and neutral stimuli evoked higher current density in MS+PBA compared to both other groups.


CONCLUSIONS
PBA of MS patients involves cortical structures related to sensory-motor and emotional processing, in addition to overactive involvement of motor cortical areas in response to neutral stimuli.


CONCLUSIONS
These results may suggest that a 'disinhibition' of a "gate control"-type mechanism for emotional expression may lead to the lower emotional expression threshold of pseudobulbar affect.
Haiman
Guy
G
Multiple Sclerosis & Brain Research Czenter, Department of Neurology, Carmel Medical Center, Haifa, Israel. guyhaiman@gmail.com
Pratt
Hillel
H
Miller
Ariel
A
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D004569:Electroencephalography / Q000379:methods; D004644:Emotions; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000473:pathology*; D020828:Pseudobulbar Palsy / Q000150:complications / Q000473:pathology*; D011930:Reaction Time / Q000502:physiology