A direct projection from superior colliculus to substantia nigra for detecting salient visual events.
Midbrain dopaminergic neurons respond to unexpected and biologically salient events, but little is known about the sensory systems underlying this response. Here we describe, in the rat, a direct projection from a primary visual structure, the midbrain superior colliculus (SC), to the substantia nigra pars compacta (SNc) where direct synaptic contacts are made with both dopaminergic and non-dopaminergic neurons. Complementary electrophysiological data reveal that short-latency visual responses in the SNc are abolished by ipsilateral lesions of the SC and increased by local collicular stimulation. These results show that the tectonigral projection is ideally located to relay short-latency visual information to dopamine-containing regions of the ventral midbrain. We conclude that it is within this afferent sensory circuitry that the critical perceptual discriminations that identify stimuli as both unpredicted and biologically salient are made.
Comoli
Eliane
E
Department of Psychology, University of Sheffield, Sheffield S10 2TP, UK.
Coizet
Véronique
V
Boyes
Justin
J
Bolam
J Paul
JP
Canteras
Newton S
NS
Quirk
Rachel H
RH
Overton
Paul G
PG
Redgrave
Peter
P
D000818:Animals; D005260:Female; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D013477:Superior Colliculi / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D013569:Synapses / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D014796:Visual Perception / Q000187:drug effects / Q000502:physiology*