Anatomical Evidence for Interconnections Between the Central Mesencephalic Reticular Formation and Cervical Spinal Cord in the Cat and Macaque
Open Access
- 22 January 2008
- journal article
- research article
- Published by Wiley in The Anatomical Record
- Vol. 291 (2), 141-160
- https://doi.org/10.1002/ar.20644
Abstract
A gaze‐related region in the caudal midbrain tegementum, termed the central mesencephalic reticular formation (cMRF), has been designated on electrophysiological grounds in monkeys. In macaques, the cMRF correlates with an area in which reticulotectal neurons overlap with tectoreticular terminals. We examined whether a region with the same anatomical characteristics exists in cats by injecting biotinylated dextran amine into their superior colliculi. These injections showed that a cat cMRF is present. Not only do labeled tectoreticular axons overlap the distribution of labeled reticulotectal neurons, these elements also show numerous close boutonal associations, suggestive of synaptic contact. Thus, the presence of a cMRF that supplies gaze‐related feedback to the superior colliculus may be a common vertebrate feature. We then investigated whether cMRF connections indicate a role in the head movement component of gaze changes. Cervical spinal cord injections in both the cat and monkey retrogradely labeled neurons in the ipsilateral, medial cMRF. In addition, they provided evidence for a spinoreticular projection that terminates in this same portion of the cMRF, and in some cases contributes boutons that are closely associated with reticulospinal neurons. Injection of the physiologically defined, macaque cMRF demonstrated that this spinoreticular projection originates in the cervical ventral horn, indicating it may provide the cMRF with an efference copy signal. Thus, the cat and monkey cMRFs have a subregion that is reciprocally connected with the ipsilateral spinal cord. This pattern suggests the medial cMRF may play a role in modulating the activity of antagonist neck muscles during horizontal gaze changes. Anat Rec, 291:141–160, 2008.Keywords
This publication has 66 references indexed in Scilit:
- Projections of somatosensory cortex and frontal eye fields onto incertotectal neurons in the catThe Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology, 2006
- On the actions that one nerve cell can have on another: Distinguishing “drivers” from “modulators”Proceedings of the National Academy of Sciences, 1998
- Coordination of gaze shifts in primates: Brainstem inputs to neck and extraocular motoneuron poolsJournal of Comparative Neurology, 1994
- An uncrossed tectopontine pathway mediates ipsiversive circlingBehavioural Brain Research, 1993
- The laminar distribution of macaque tectobulbar and tectospinal neuronsVisual Neuroscience, 1992
- Sources of subcortical GABAergic projections to the superior colliculus in the catJournal of Comparative Neurology, 1990
- Descending pathways to the spinal cord: A comparative study of 22 mammalsJournal of Comparative Neurology, 1988
- The interstitial nucleus of Cajal and its role in the control of movements of head and eyesProgress in Neurobiology, 1987
- Axonal patterns and sites of termination of cat superior colliculus neurons projecting in the tecto-bulbo-spinal tractExperimental Brain Research, 1982
- Spinal projections from the midbrain in monkeyJournal of Comparative Neurology, 1978