A presentation of two recent papers:

Topography of emotional valence and arousal within the motor part of the
subthalamic nucleus in Parkinson’s disease, by Serranová T, Sieger T,
Růžička F, Bakštein E, Dušek P, Vostatek P, Novák D, Růžička E,
Urgošík D, Jech R. Sci Rep. 2019 Dec 27;9(1):19924.
https://doi.org/10.1038/s41598-019-56260-x.

Clinical motor and non-motor effects of deep brain stimulation (DBS) of the
subthalamic nucleus (STN) in Parkinson's disease (PD) seem to depend on the
stimulation site within the STN. We analysed the effects of the position of the
stimulation electrode within the motor STN on subjective emotional experience,
expressed as emotional valence and arousal ratings to pictures representing
primary rewards and aversive fearful stimuli in 20 PD patients. Patients’
ratings from both aversive and erotic stimuli matched the mean ratings from a
group of 20 control subjects at similar position within the STN. Patients with
electrodes located more posteriorly reported both valence and arousal ratings
from both the rewarding and aversive pictures as more extreme. Moreover,
posterior electrode positions were associated with a higher occurrence of
depression at a long-term follow-up. This brain–behavior relationship
suggests
a complex emotion topography in the motor part of the STN. Both valence and
arousal representations overlapped and were uniformly arranged
anterior-posteriorly in a gradient-like manner, suggesting a specific spatial
organization needed for the coding of the motivational salience of the stimuli.
This finding is relevant for our understanding of neuropsychiatric side effects
in STN DBS and potentially for optimal electrode placement.

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Prepulse Inhibition of the Blink Reflex Is Abnormal in Functional Movement
Disorders, by Hanzlíková Z, Kofler M, Slovák M, Věchetová G, Fečíková
A,
Kemlink D, Sieger T, Růžička E, Valls-Solé J, Edwards M J, and Serranová
T., Movement Disorders 2019 May 34(7)
https://doi.org/10.1002/mds.27706

Background: Patients with functional movement disorders also typically have
functional somatic symptoms, including pain, fatigue, and sensory disturbance.
A potentially unifying mechanism for such symptoms is a failure in processing
of
sensory inputs. Prepulse inhibition is a neurophysiological method that allows
for the study of preconscious somatosensory processing.
Objective: The objective of this study was to assess prepulse inhibition in
patients with functional movement disorders and healthy control subjects.
Methods: We analyzed the effect of a weak electrical stimulus to the index
finger (prepulse) on the magnitude of the R2 response of the blink reflex
induced by electrical stimuli delivered to the supraorbital nerve in 22
patients with clinically established functional movement disorders and 22
matched controls. Pain, depression, anxiety, and obsessive-compulsive symptoms
were assessed using self-rated questionnaires. In addition, in patients we
assessed motor symptom severity.
Results: Prepulses suppressed the R2 response of the blink reflex in both
groups, by 36.4% (standard deviation: 25.6) in patients and by 67.3% (standard
deviation: 16.4) in controls. This difference was significant (P < 0.001).
There was no significant correlation between motor and non-motor symptom
measures and prepulse inhibition size.
Conclusions: Impaired prepulse inhibition of the blink reflex suggests an
abnormal preconscious processing of somatosensory inputs, which can be
interpreted within predictive coding accounts of both functional movement
disorders and functional somatic syndromes. Our results, along with previous
findings of a reduced prepulse inhibition in fibromyalgia syndrome, support a
possible unified pathophysiology across functional neurological and somatic
syndromes with noteworthy implications for diagnostic classification and
development of novel biomarkers and treatments.