Temporal relations of the complex spike activity of Purkinje cell pairs in the vestibulocerebellum of rabbits

Abstract

Parasagittal zones in the vestibulocerebellum contain Purkinje cells whose complex spike (CS) activity is modulated in response to rotational optokinetic stimulation (OKS) about either the vertical axis (VA) or a horizontal axis (HA) that is approximately perpendicular to the ipsilateral anterior canal. In rabbits, there are two VA zones in both the ventral nodulus and flocculus, two HA zones in the flocculus, and one HA zone in the ventral nodulus. We investigated the temporal relationship of the CS activity of Purkinje cell pairs in the same or different zones of the vestibulocerebellum in ketamine-anesthetized pigmented rabbits. A synchronous temporal relationship was defined as the tendency of the CS of each Purkinje cell to fire within, at most, 2 msec of one another. Generally, neurons in the same zone showed a tendency to exhibit CS synchrony. Of 82 pairs consisting of two Purkinje cells in the same zone (e.g., two nodulus HA cells), 33 were synchronous. In contrast, none of 26 pairs consisting of two neurons in functionally different zones (e.g., a VA cell paired with an HA cell), showed CS synchrony. Pairs consisting of neurons in spatially separated VA zones in the ventral nodulus also showed a tendency to be synchronously related (6/16), as did pairs consisting of a nodulus VA cell and a flocculus VA cell (3/14). The CS synchrony was higher during OKS in the preferred direction than during spontaneous activity. This is the first demonstration that CS synchrony in the vestibulocerebellum can be manipulated with a natural sensory stimulus.

Spatial Pattern Coding of Sensory Information by Climbing Fiber-Evoked Calcium Signals in Networks of Neighboring Cerebellar Purkinje Cells

“…Others have emphasized that climbing fibers are activated synchronously in response to unexpected sensory consequences of motor actions (Lou and Bloedel, 1992). In anesthetized rat Crus IIa and rabbit vestibulocerebellum, sensory stimulation has been found to modulate CS synchrony Wylie et al, 1995). These results leave open how sensory stimulation spatiotemporally shapes the prevalent spontaneous synchrony.…”

Topography and Response Timing of Intact Cerebellum Stained With Absorbance Voltage-Sensitive Dye

“…Complex spike synchrony was observed in sagittally oriented groups of PCs but there was almost no cross-correlation of complex spikes of PCs oriented transversely (Sasaki et al 1989). Synchrony of sagittally oriented cells was enhanced during motor behaviors (Welsh et al 1995;Wylie et al 1995), whereas perturbing IO activity disrupted rhythmic tongue movements (Placantonakis et al 2004).…”

Role of Myelination in the Development of a Uniform Olivocerebellar Conduction Time

“…The olivocerebellar system generates synchronous, on a millisecond time scale, CS activity (Lang et al 1999;Llinás and Sasaki 1989;Sasaki et al 1989;Wylie et al 1995). The ability to generate synchronous activity has long been ascribed to the electrotonic coupling of IO neurons by gap junctions (Llinás 1974;Llinás et al 1974).…”

“…In the rat, the distance between the IO and the cortex can vary by almost twofold (Sugihara et al 1993). However, synchronous CS activity does occur (Lang et al 1999;Llinás and Sasaki 1989;Sasaki et al 1989;Wylie et al 1995), even between widely separated regions of the cortex because of mechanisms that allow a uniform conduction time across the cerebellum (De Zeeuw et al 1996).…”