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Parkinsonian thalamic activity represents pathophysiology underlying progression of motor symptoms
Author(s) -
Narabayashi Yohsuke,
Oshima Tomokazu
Publication year - 2015
Publication title -
neurology and clinical neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.125
0ISSN - 2049-4173
DOI - 10.1111/ncn3.12014
Subject(s) - rigidity (electromagnetism) , muscle rigidity , thalamus , motor symptoms , medicine , parkinson's disease , pathophysiology , subthalamic nucleus , neuroscience , resting tremor , physical medicine and rehabilitation , deep brain stimulation , disease , anesthesia , psychology , physics , quantum mechanics
Background Parkinsonian thalamic 13‐ to 27‐Hz (β‐band) and 3‐ to 7‐Hz (τ‐range) hyperactivity is linked to rigidity and tremor, respectively, but not to bradykinesia. Aim To clarify the contributions of different types of thalamic activity to the progression of parkinsonian symptoms, we modeled a neural converter that translates thalamic activity into symptoms and examined its input‐output relationship. Methods We scored pre‐ and postoperative rigidity, tremor, and bradykinesia as well as case‐representative τ‐range (Vτ) and β‐band (Vβ) activity in 170 patients with Parkinson's disease. Results The relationship between abolished rigidity ( dR ) and Vβ was described by a hysteresis curve, which was simulated by two parabolas relating dR and Vβ to preoperative rigidity (preR) using the calculated time lag corresponding to 1.5 preR grades. The abolished tremor was linearly related to Vτ. The partly abolished bradykinesia was related to Vβ by hysteresis. Hysteresis in the dR ‐to‐Vβ relationship was observed as a result of 11 patients with preR scores of 4. Their brain activity was generally low and similar to that of patients without rigidity. Conclusion In contrast to the direct correlation between Vτ and tremor, Vβ caused rigidity and, in part, bradykinesia via time‐consuming processes, as demonstrated by the delayed parabola model. Patients with the severest rigidity showed a loss of thalamic activity and the spread of pathophysiological abnormalities in the neural circuitry beyond the thalamus with progressive age.