C-fos Expression in the Optokinetic Nuclei of the Rat Following Different Visual Stimulus Conditions
In the present study we characterised by means of the c-Fos method the neuronal populations of the optokinetic nuclei system of the rat activated by different directions of external visual world motion as well as by saccadic exploration of a patterned stationary scene. A major difference was found between the nucleus of the optic tract (NOT) and the nuclei of the accessory optic system (AOS): dorsal terminal (DTN), lateral terminal (LTN) and medial terminal (MTN). c-Fos-positive cells are expressed in the AOS nuclei only after optokinetic stimulation (OKS) according to the direction for which each nucleus is strictly committed: in the DTN after horizontal OKS, in the LTN and MTN after vertical OKS. No segregation of direction-selective cells was observed in the MTN for opposite directions of motion. In the NOT, c-Fos cells became immunoreactive after OKS of any direction, with the greatest expression induced by horizontal OKS in the nucleus contralateral to the eye stimulated nasalward, and even following the presentation of a non-rotating drum. However, the spatial location of the activated neurones is distributed along the nucleus for horizontal OKS and strongly restricted to its rostral region for other stimuli. Given these findings, a larger spectrum of competencies than previously supposed should be attributed to the NOT.
KeywordsOptic Tract Optokinetic Stimulation Rostral Region Pretectal Nucleus Accessory Optic System
Unable to display preview. Download preview PDF.
- Giolli RA, Torigoe Y, Clarke RJ, Blanks RHI, Fallon JH (1992) GABAergic and non-GABAergic projections of the accessry optic nuclei, including the visual tegmental relay zone, to the nucleus of the optic tract and dorsal terminal accessory optic nucleus in rat. J Comp Neurol 319:349–358PubMedCrossRefGoogle Scholar
- Paxinos G, Watson C (1986) The rat brain in stereotaxic coordinates. Academic Press, SidneyGoogle Scholar
- Simpson JI, Giolli RA, Blanks RHI (1988) The pretectal nuclear complex and the accessory optic system. In: Büttner-Ennever JA (ed) Neuroanatomy of the Oculomotor System. Elsevier, Amsterdam: pp 335–364Google Scholar
- Soodak RE, Simpson JI (1988) The accessory optic system of the rabbit. I. Basic visual response properties J Neurophysiol 60: 2037–2054Google Scholar
- Van der Togt C, Van der Want J, Schmidt M (1993) Segregation of direction selective neurons and synaptic organization of inhibitory intranuclear connections in the medial terminal nucleus of the rat: an electrophysiological and immunoelectron microscopical study. J Comp Neurol 338: 175–192PubMedCrossRefGoogle Scholar
- Van der Want JJL, Nunes Cardoso JJ, Van der Togt C (1992) GABÀergic neurons and circuits in the pretectal nuclei and the accessory optic system of mammals. In: Mize RR, Marc R, Sillito A (eds) Progress in Brain Research, vol 90, Elsevier, Amsterdam, pp 283–305Google Scholar