Impulsivity Markers in Parkinsonian Subthalamic Single‐Unit Activity

Abstract

Background: Impulsive-compulsive behaviors are common in Parkinson's disease (PD) patients. However, the basal ganglia dysfunctions associated with high impulsivity have not been fully characterized. The objective of this study was to identify the features associated with impulsive-compulsive behaviors in single neurons of the subthalamic nucleus (STN). Methods: We compared temporal and spectral features of 412 subthalamic neurons from 12 PD patients with impulsive-compulsive behaviors and 330 neurons from 12 PD patients without. Single-unit activities were extracted from exploratory microrecordings performed during deep brain stimulation (DBS) implant surgery in an OFF medication state. Results: Patients with impulsive-compulsive behaviors displayed decreased firing frequency during bursts and a larger fraction of tonic neurons combined with weaker beta coherence. Information carried by these features led to the identification of patients with impulsive-compulsive behaviors with an accuracy greater than 80%.

Impulsivity is associated with firing regularity in parkinsonian ventral subthalamic nucleus

“…The difference is relevant to the extent that it supports a significant discrimination of the two conditions patient‐wise. We previously found that firing regularity was among the markers of ICB+ condition 13 . The novel analysis presented in this manuscript shows that the difference between conditions is localized in the ventral part.…”

“…Microelectrode recording (MER) studies on STN single neuron activity showed a relationship with decision‐making and ICB 12 but did not investigate how this relationship varied within the STN. Recently, we observed in PD ICB subjects in drugs OFF condition a significant reduction in standard PD markers in STN single unit activity such as beta oscillations and burstiness 13 . Here, we investigate whether this ICB‐specific feature can be associated to a specific location within STN.…”

“…We retrospectively considered 32 consecutively acquired patients, 16 of whom were diagnosed with at least one current ICB. From this set, we selected the recordings in which the number of neurons identified in MER was sufficient to perform a depth‐wise analysis (see below) 13 . The final dataset included 24 patients, 12 of whom with ICB.…”

“…First, every recording in which more than 50% of the total duration of the signal was visually identified as noisy was discarded. Then, for each insertion, the recordings performed within STN were identified as those exceeding the 80th percentile of activity, 14 as in previous works 13 . In total, we selected 548 STN recordings which were used for the analysis.…”

“…Recently, we observed in PD ICB subjects in drugs OFF condition a significant reduction in standard PD markers in STN single unit activity such as beta oscillations and burstiness. 13 Here, we investigate whether this ICB-specific feature can be associated to a specific location within STN.…”