Direct synaptic connections of axons from superior colliculus with identified thalamo-amygdaloid projection neurons in the rat: Possible substrates of a subcortical visual pathway to the amygdala
Article first published online: 30 DEC 1998
Copyright © 1999 Wiley-Liss, Inc.
Journal of Comparative Neurology
Volume 403, Issue 2, pages 158–170, 11 January 1999
How to Cite
Linke, R., De Lima, A.D., Schwegler, H. and Pape, H.-C. (1999), Direct synaptic connections of axons from superior colliculus with identified thalamo-amygdaloid projection neurons in the rat: Possible substrates of a subcortical visual pathway to the amygdala. J. Comp. Neurol., 403: 158–170. doi: 10.1002/(SICI)1096-9861(19990111)403:2<158::AID-CNE2>3.0.CO;2-6
- Issue published online: 30 DEC 1998
- Article first published online: 30 DEC 1998
- Manuscript Accepted: 28 JUL 1998
- Manuscript Revised: 22 JUL 1998
- Manuscript Received: 13 MAR 1998
- Deutsche Forschungsgemeinschaft. Grant Number: SFB 426 (B4/B5)
- visual system;
- electron microscopy
The aim of the present study was to identify synaptic contacts from axons originating in the superior colliculus with thalamic neurons projecting to the lateral nucleus of the amygdala. Axons from the superior colliculus were traced with the anterograde tracers Phaseolus vulgaris leucoagglutinin or the biotinylated and fluorescent dextran amine “Miniruby.” Thalamo-amygdaloid projection neurons were identified with the retrograde tracer Fluoro-Gold. Injections of Fluoro-Gold into the lateral nucleus of the amygdala labeled neurons in nuclei of the posterior thalamus which surround the medial geniculate body, viz. the suprageniculate nucleus, the medial division of the medial geniculate body, the posterior intralaminar nucleus, and the peripeduncular nucleus. Anterogradely labeled axons from the superior colliculus terminated in the same regions of the thalamus. Tecto-thalamic axons originating from superficial collicular layers were found predominantly in the suprageniculate nucleus, whereas axons from deep collicular layers were detected in equal density in all thalamic nuclei surrounding the medial geniculate body. Double-labeling experiments revealed an overlap of projection areas in the above-mentioned thalamic nuclei. Electron microscopy of areas of overlap confirmed synaptic contacts of anterogradely labeled presynaptic profiles originating in the superficial layers of the superior colliculus with retrogradely labeled postsynaptic profiles of thalamo-amygdaloid projection neurons. These connections may represent a subcortical pathway for visual information transfer to the amygdala. J. Comp. Neurol. 403:158–170, 1999. © 1999 Wiley-Liss, Inc.