Modeling of smooth pursuit-related neuronal responses in the DLPN and NRTP of the rhesus macaque.
The dorsolateral pontine nucleus (DLPN) and nucleus reticularis tegmenti pontis (NRTP) comprise obligatory links in the cortico-ponto-cerebellar system supporting smooth pursuit eye movements. We examined the response properties of DLPN and rNRTP neurons during step-ramp smooth pursuit of a small target moving across a dark background. Our neurophysiological studies were conducted in awake, behaving juvenile macaques (Macaca mulatta). We used multiple linear-regression modeling to estimate the relative sensitivities of neurons to eye parameters (position, velocity, and acceleration) and retinal-error parameters (position, velocity, and acceleration). We found that a large proportion of pursuit-related DLPN neurons primarily code eye-velocity information, whereas a large proportion of rNRTP neurons primarily code eye-acceleration information. We calculated the relative decrease in variance found when using a six-component model that included both eye- and retinal-error parameters compared with three-component models that include either eye or retinal error. These comparisons show that a majority of DLPN (14/20) and rNRTP (17/19) neurons have larger contributions from eye compared with retinal-error parameters (P < 0.001, paired t-test). Even though eye-motion parameters provide the strongest contributions in a given model, a significant contribution from retinal error was often present (i.e., >20% reduction in variance in 6-component model compared with 3-component models). Thus our results indicate that the DLPN plays a larger role in maintaining steady-state smooth pursuit eye velocity, whereas rNRTP contributes to both the initiation and maintenance of smooth pursuit.
Ono
Seiji
S
Yerkes National Primate Research Center, Division of Visual Science, Emory University, 954 Gatewood Road N.E., Atlanta GA 30322, USA.
Das
Vallabh E
VE
Economides
John R
JR
Mustari
Michael J
MJ
D000054:Acceleration; D000200:Action Potentials / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D008253:Macaca mulatta; D008954:Models, Biological; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011149:Pons / Q000166:cytology* / Q000502:physiology; D011698:Pursuit, Smooth / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*