Activity of Ventroposterior Thalamus Neurons During Rotation and Translation in the Horizontal Plane in the Alert Squirrel Monkey

• Published in: Journal of neurophysiology 2008-05, Vol.99 (5), p.2533-2545
• Main Authors: Marlinski, Vladimir, McCrea, Robert A
• Format: Article
• Language: English
• Subjects: Acceleration; Animals; Darkness; Data Interpretation, Statistical; Light; Microelectrodes; Midline Thalamic Nuclei - cytology; Midline Thalamic Nuclei - physiology; Neurons - physiology; Orientation - physiology; Physical Stimulation; Rotation; Saimiri; Vestibule, Labyrinth - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00761.2007

Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, Illinois Submitted 6 July 2007; accepted in final form 12 March 2008 The firing behavior of 107 vestibular-sensitive neurons in the ventroposterior thalamus was studied in two alert squirrel monkeys during whole body rotation and translation in the horizontal plane. Vestibular-sensitive neurons were distributed primarily along the anterior and posterior borders of ventroposterior nuclei; three clusters of these neurons could be distinguished based on their location and inputs. Eighty-four neurons responded to rotation; 66 (78%) of them responded to rotation only and 18 (22%) to both rotation and translation. Forty-one neurons were sensitive to linear translation; 23 (56%) of them responded to translation only. The population rotational response to 0.5-Hz sinusoids with a peak velocity of 40°/s showed a gain of 0.23 ± 0.15 spike·s –1 ·deg –1 ·s –1 and phase lagging behind the angular velocity by –9.3 ± 34.1°. Although rotational response amplitude increased with the stimulus velocity across the range 4–100°/s, the rotational sensitivity decreased with and was inversely proportional to the stimulus velocity. The rotational response amplitude and sensitivity increased with the stimulus frequency across the range 0.2–4.0 Hz. The population response to sinusoidal translation at 0.5 Hz and 0.1 g amplitude had a gain of 111.3 ± 53.7 spikes·s –1 · g –1 and lagged behind stimulus acceleration by –71.9 ± 42.6°. Translational sensitivity decreased as acceleration increased and this was inversely proportional to the square root of the acceleration. Results of this study imply that changes in the discharge rate of vestibular-sensitive thalamic neurons can be approximated using power functions of the angular and linear velocity of spatial motion. Address for reprint requests and other correspondence: V. Marlinski, University of Chicago, Department of Neurobiology, Pharmacology and Physiology, 947 E. 58th Street, MC0926, Chicago, IL 60637 (E-mail: vmarlinsk{at}gmail.com )