Vestibular Interactions in the Thalamus

Abstract

It has long been known that the vast majority of all information en route to the cerebral cortex must first pass through the thalamus. The long held view that the thalamus serves as a simple hi fidelity relay station for sensory information to the cortex, however, has over recent years been dispelled. Indeed, multiple projections from the vestibular nuclei to thalamic nuclei (including the ventrobasal nuclei, and the geniculate bodies)- regions typically associated with other modalities- have been described. Further, some thalamic neurons have been shown to respond to stimuli presented from across sensory modalities. For example, neurons in the rat anterodorsal and laterodorsal nuclei of the thalamus respond to visual, vestibular, proprioceptive and somatosensory stimuli and integrate this information to compute heading within the environment. Together, these findings imply that the thalamus serves crucial integrative functions, at least in regard to vestibular processing, beyond that imparted by a "simple" relay. In this mini review we outline the vestibular inputs to the thalamus and provide some clinical context for vestibular interactions in the thalamus. We then focus on how vestibular inputs interact with other sensory systems and discuss the multisensory integration properties of the thalamus.

Keywords: LGN; multisensory integration; thalamus; vestibular; vestibular nuclei.

Figure 1

Schematic representation of some of the major vestibulothalamic projections. Defined projections from the four main vestibular nuclei to their thalamic targets are shown. Note that the vast majority of vestibulothalamic projections originate in the medial vestibular nucleus (MVN; orange) and SuVN (mauve), and terminate in the lateral nuclei of the thalamus (Blue).

Figure 2

An example cell with significant tuning during both the visual (optic flow) and vestibular stimulus conditions. (A) Response PSTHs for each of 26 directions during translation. Red asterisks mark the maximum response directions. The corresponding peak-times are marked by gray bars. (B) The corresponding color contour tuning (at peak time) for each stimulus condition. Figure modified from Meng and Angelaki (2010) with permission from the Journal of Neurophysiology.