Mediodorsal thalamic nucleus receives a direct retinal input in marmoset monkey (Callithrix jacchus): a subunit B cholera toxin study.
The mediodorsal thalamic nucleus is a prominent nucleus in the thalamus, positioned lateral to the midline nuclei and medial to the intralaminar thalamic complex in the dorsal thalamus. Several studies identify the mediodorsal thalamic nucleus as a key structure in learning and memory, as well as in emotional mechanisms and alertness due to reciprocal connections with the limbic system and prefrontal cortex. Fibers from the retina to the mediodorsal thalamic nucleus have recently been described for the first time in a crepuscular rodent, suggesting a possible regulation of the mediodorsal thalamic nucleus by visual activity. The present study shows retinal afferents in the mediodorsal thalamic nucleus of a new world primate, the marmoset (Callithrix jacchus), using B subunit of cholera toxin (CTb) as an anterograde tracer. A small population of labeled retinofugal axonal arborizations is consistently labeled in small domains of the medial and lateral periphery of the caudal half of the mediodorsal nucleus. Retinal projections in the mediodorsal thalamic nucleus are exclusively contralateral and the morphology of the afferent endings was examined. Although the functional significance of this projection remains unknown, this retina-mediodorsal thalamic nucleus pathway may be involved in a wide possibility of functional implications.
Department of Morphology/Laboratory of Neuroanatomy, Biosciences Center, Federal University of Rio Grande do Norte, RN, Brazil. expeditojr@cb.ufrn.br
Twyla Barros
TB
de Sousa
Melquisedec Abiaré Dantas
MA
de Santana
Alane de Medeiros
Ade M
Silva
Fausto Pierdoná
FP
Guzen
Francisco Gilberto
FG
Oliveira
Judney Cley
JC
Cavalcante
Jeferson de Souza
Jde S
Cavalcante
Miriam Stela Maris Oliveira
MS
Costa
Expedito Silva do
ES
Nascimento
D000818:Animals; D001369:Axons / Q000502:physiology; D002144:Callithrix; D002772:Cholera Toxin; D007150:Immunohistochemistry; D008297:Male; D020645:Mediodorsal Thalamic Nucleus / Q000033:anatomy & histology* / Q000502:physiology*; D008867:Microtomy; D012160:Retina / Q000033:anatomy & histology* / Q000502:physiology*; D014795:Visual Pathways / Q000033:anatomy & histology* / Q000502:physiology*
D002772:Cholera Toxin