title: Connectivity between the superior colliculus and the amygdala in humans and macaque monkeys: virtual dissection with probabilistic DTI tractography.
abstract: It has been suggested that some cortically blind patients can process the emotional valence of visual stimuli via a fast, subcortical pathway from the superior colliculus (SC) that reaches the amygdala via the pulvinar. We provide in vivo evidence for connectivity between the SC and the amygdala via the pulvinar in both humans and rhesus macaques. Probabilistic diffusion tensor imaging tractography revealed a streamlined path that passes dorsolaterally through the pulvinar before arcing rostrally to traverse above the temporal horn of the lateral ventricle and connect to the lateral amygdala. To obviate artifactual connectivity with crossing fibers of the stria terminalis, the stria was also dissected. The putative streamline between the SC and amygdala traverses above the temporal horn dorsal to the stria terminalis and is positioned medial to it in humans and lateral to it in monkeys. The topography of the streamline was examined in relation to lesion anatomy in five patients who had previously participated in behavioral experiments studying the processing of emotionally valenced visual stimuli. The pulvinar lesion interrupted the streamline in two patients who had exhibited contralesional processing deficits and spared the streamline in three patients who had no deficit. Although not definitive, this evidence supports the existence of a subcortical pathway linking the SC with the amygdala in primates. It also provides a necessary bridge between behavioral data obtained in future studies of neurological patients, and any forthcoming evidence from more invasive techniques, such as anatomical tracing studies and electrophysiological investigations only possible in nonhuman species.
authors.affiliation: Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Bangor, Gwynedd, United Kingdom; r.rafal@bangor.ac.uk.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Rafal
authors.affiliation: Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Bangor, Gwynedd, United Kingdom;
authors.forename: Kristin
authors.initials: K
authors.lastname: Koller
authors.affiliation: Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Bangor, Gwynedd, United Kingdom; Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom;
authors.forename: Janet H
authors.initials: JH
authors.lastname: Bultitude
authors.affiliation: Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Bangor, Gwynedd, United Kingdom;
authors.forename: Paul
authors.initials: P
authors.lastname: Mullins
authors.affiliation: Wolfson Centre for Clinical and Cognitive Neuroscience, School of Psychology, Bangor University, Bangor, Gwynedd, United Kingdom;
authors.forename: Robert
authors.initials: R
authors.lastname: Ward
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom; and.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Mitchell
authors.affiliation: Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom; and MRC Cognition and Brain Sciences Unit, Cambridge, United Kingdom.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Bell
mesh_terms: D000679:Amygdala / Q000502:physiology* / Q000503:physiopathology; D000818:Animals; D019575:Blindness, Cortical / Q000503:physiopathology*; D016022:Case-Control Studies; D063132:Connectome; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D020649:Pulvinar / Q000502:physiology / Q000503:physiopathology; D013477:Superior Colliculi / Q000502:physiology* / Q000503:physiopathology; D014796:Visual Perception; D055815:Young Adult
keywords: DTI tractography; amygdala; pulvinar; superior colliculus; threat