Abstract
Historically, the central mesencephalic reticular formation has been regarded as a purely horizontal gaze center based on the fact that electrical stimulation of this region produces horizontal saccades, it provides monosynaptic input to medial rectus motoneurons, and cells recorded in this region often display a peak in firing when horizontal saccades are made. We tested the proposition that the central mesencephalic reticular formation is purely a horizontal gaze center by examining whether this region also supplies terminals to superior rectus and levator palpebrae superioris motoneurons, both of which fire when making vertical eye movements. The experiments were carried out using dual tracer techniques at the light and electron microscopic level in macaque monkeys. Injections of biotinylated dextran amine or Phaseolus vulgaris leukoagglutinin into the central mesencephalic reticular formation produced anterogradely labeled terminals that were in synaptic contact with superior rectus and levator palpebrae superioris motoneurons that had been retrogradely labeled. These results indicate that this region is not purely connected with horizontal gaze motoneurons. In addition, we found that the number of contacts on vertical gaze motoneurons increased with more rostral injections involving the mesencephalic reticular formation adjacent to the interstitial nucleus of Cajal. This suggests that there is a caudal to rostral gradient for horizontal to vertical saccades, respectively, represented within the midbrain reticular formation. Finally, we utilized post-embedding immunohistochemistry to show that a portion of the labeled terminals were GABAergic, indicating they likely originate from downgaze premotor neurons.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Data sharing
The data supporting this study are available for loan upon reasonable request to the authors.
Abbreviations
- At:
-
Axon terminal
- At*:
-
Anterogradely labeled At
- At*+ :
-
GABA-positive At*
- At*−:
-
GABA-negative At*
- Ax:
-
Axon
- BDA:
-
Biotinylated dextran amine
- CC:
-
Caudal central subdivision of III
- cMRF:
-
Central MRF
- Den:
-
Dendrite
- Den*:
-
Retrogradely labeled Den
- EWpg:
-
Preganglionic Edinger–Westphal nucleus
- III:
-
Oculomotor nucleus
- InC:
-
Interstitial nucleus of Cajal
- PAG:
-
Periaqueductal gray
- PhaL:
-
Phaseolus vulgaris Leukoagglutinin
- piMRF:
-
Peri-InC MRF
- MIF:
-
Multiply innervated fiber
- MLF:
-
Medial longitudinal fasciculus
- MRF:
-
Mesencephalic reticular formation
- nD:
-
Nucleus of Darkschewitsch
- Nu:
-
Nucleus
- SIF:
-
Singly innervated fiber
- SOA:
-
Supraoculomotor area
- Soma:
-
Soma
- Soma*:
-
Retrogradely labeled Soma
- Sp:
-
Spine
References
Appell PP, Behan M (1990) Sources of subcortical GABAergic projections to the superior colliculus in the cat. J Comp Neurol 302:143–158. https://doi.org/10.1002/cne.903020111
Barnerssoi M, May PJ (2015) Postembedding immunohistochemistry for inhibitory neurotransmitters in conjunction with neuroanatomical tracers. In: Van Bockstaele EJ (ed) Transmission electron microscopy methods for understanding the brain. Springer, New York, pp 181–203
Becker W, Fuchs AF (1988) Lid-eye coordination during vertical gaze changes in man and monkey. J Neurophysiol 60:1227–1252. https://doi.org/10.1152/jn.1988.60.4.1227
Blumer R, Konakci KZ, Pomikal C, Wieczorek G, Lukas JR, Streicher J (2009) Palisade endings: cholinergic sensory organs or effector organs? Invest Ophthalmol vis Sci 50:1176–1186. https://doi.org/10.1167/iovs.08-274810.1167/iovs.15-18716
Blumer R, Maurer-Gesek B, Gesslbauer B Blumer M, Pechriggl E, Davis-López de Carrizosa MA, Horn AK, May PJ, Streicher J, de la Cruz RR, Pastor AM (2016) Palisade endings are a constant feature in the extraocular muscles of frontal-eyed, but not lateral-eyed, animals. Invest Ophthalmol Vis Sci 57:320–31 https://doi.org/10.1167/iovs.15-18716
Bohlen MO, Warren S, May PJ (2015) Central mesencephalic reticular formation projections to horizontal gaze motoneurons – A green light or red? Soc Neurosci Abst 41(417):05
Bohlen MO, Warren S, Mustari MJ, May PJ (2016) Examination of feline extraocular motoneuron pools as a function of muscle fiber innervation type and muscle layer. J Comp Neurol 525:919–935. https://doi.org/10.1002/cne.24111
Bohlen MO, Warren S, May PJ (2017) A central mesencephalic reticular formation projection to medial rectus motoneurons supplying singly and multiply innervated extraocular muscle fibers. J Comp Neurol 525:2000–2018. https://doi.org/10.1002/cne.901970103
Büttner-Ennever JA, Akert K (1981) Medial rectus subgroups of the oculomotor nucleus and their abducens internuclear input in the monkey. J Comp Neurol 197:17–27
Büttner-Ennever JA, Horn AK, Scherberger H, D’Ascanio P (2001) Motoneurons of twitch and nontwitch extraocular muscle fibers in the abducens, trochlear, and oculomotor nuclei of monkeys. J Comp Neurol 438:318–335. https://doi.org/10.1002/cne.1318
Carrero-Rojas G, Hernández RG, Blumer R, de la Cruz RR, Pastor AM (2021) MIF versus SIF motoneurons, what are their respective contribution in the oculomotor medial rectus pool? J Neurosci 41:9782–9793. https://doi.org/10.1523/JNEUROSCI.1480-21.2021
Chen B, May PJ (2000) The feedback circuit connecting the superior colliculus and central mesencephalic reticular formation: a direct morphological demonstration. Exp Brain Res 131:10–21. https://doi.org/10.1007/s002219900280
Chen B, May PJ (2002) Premotor circuits controlling eyelid movements in conjunction with vertical saccades in the cat: I. The rostral interstitial nucleus of the medial longitudinal fasciculus. J Comp Neurol 450:183–202. https://doi.org/10.1002/cne.10313
Chen B, May PJ (2007) Premotor circuits controlling eyelid movements in conjunction with vertical saccades in the cat: II. interstitial nucleus of Cajal. J Comp Neurol 500:676–692. https://doi.org/10.1002/cne.2120
Chiarandini DJ, Stefani E (1979) Electrophysiological identification of two types of fibres in rat extraocular muscles. J Physiol 290:453–465
Cohen B, Matsuo V, Fradin J, Raphan T (1985) Horizontal saccades induced by stimulation of the central mesencephalic reticular formation. Exp Brain Res 57:605–616
Cohen B, Waitzman DM, Büttner-Ennever JA, Matsuo V (1986) Horizontal saccades and the central mesencephalic reticular formation. Prog Brain Res 64:243–256. https://doi.org/10.1016/S0079-6123(08)63419-6
Cromer JA, Waitzman DM (2006) Neurones associated with saccade metrics in the monkey central mesencephalic reticular formation. J Physiol 570:507–523. https://doi.org/10.1113/jphysiol.2005.096834
Cromer JA, Waitzman DM (2007) Comparison of saccade-associated neuronal activity in the primate central mesencephalic and paramedian pontine reticular formations. J Neurophysiol 98:835–850. https://doi.org/10.1152/jn.00308.2007
Eberhorn AC, Horn AK, Eberhorn N, Fischer P, Boergen KP, Büttner-Ennever JA (2005A) Palisade endings in extraocular eye muscles revealed by SNAP-25 immunoreactivity. J Anat 206:307–315. https://doi.org/10.1111/j.1469-7580.2005.00378.x
Eberhorn AC, Ardeleanu P, Büttner-Ennever JA, Horn AK (2005B) Histochemical differences between motoneurons supplying multiply and singly innervated extraocular muscle fibers. J Comp Neurol 491:352–366. https://doi.org/10.1002/cne.20715
Eberhorn AC, Büttner-Ennever JA, Horn AK (2006) Identification of motoneurons supplying multiply- or singly-innervated extraocular muscle fibers in the rat. Neuroscience 137:891–903. https://doi.org/10.1016/j.neuroscience.2005.10.038
Erichsen JT, Wright NF, May PJ (2014) Morphology and ultrastructure of medial rectus subgroup motoneurons in the macaque monkey. J Comp Neurol 522:626–641. https://doi.org/10.1002/cne.23437
Evinger C, Manning KA (1993) Pattern of extraocular muscle activation during reflex blinking. Exp Brain Res 92:502–506. https://doi.org/10.1007/BF00229039
Evinger C, Manning KA, Sibony PA (1991) Eyelid movements. Mechanisms and normal data. Invest Ophthalmol vis Sci 32:387–400
Evinger C (1988) Extraocular motor nuclei: location, morphology and afferents. In Büttner-Ennever JA (ed) Neuroanatomy of the Oculomotor System, Reviews of Oculomotor Research Vol. 2, Elsevier, Amsterdam
Fuchs AF, Becker W, Ling L, Langer TP, Kaneko CR (1992) Discharge patterns of levator palpebrae superioris motoneurons during vertical lid and eye movements in the monkey. J Neurophysiol 68:233–243. https://doi.org/10.1152/jn.1992.68.1.233
Fukushima K (1987) The interstitial nucleus of Cajal and its role in the control of movements of head and eyes. Prog Neurobiol 29:107–192. https://doi.org/10.1016/0301-0082(87)90016-5
Fukushima K, Ohashi T, Fukushima J, Kaneko CR (1995) Discharge characteristics of vestibular and saccade neurons in the rostral midbrain of alert cats. J Neurophysiol 73:2129–2143. https://doi.org/10.1152/jn.1995.73.6.2129
Guitton D, Simard R, Codère F (1991) Upper eyelid movements measured with a search coil during blinks and vertical saccades. Invest Ophthalmol vis Sci 32:3298–3305
Handel A, Glimcher PW (1997) Response properties of saccade-related burst neurons in the central mesencephalic reticular formation. J Neurophysiol 78:2164–2175. https://doi.org/10.1152/jn.1997.78.4.2164
Hernández RG, Calvo PM, Blumer R, de la Cruz RR, Pastor AM (2019) Functional diversity of motoneurons in the oculomotor system. Proc Natl Acad Sci USA 116:3837–3846. https://doi.org/10.1073/pnas.1818524116
Hess A, Pilar G (1963) Slow fibers in the extraocular muscles of the cat. J Physiol 169:780–798. https://doi.org/10.1113/jphysiol.1963.sp007296
Horn AK, Büttner-Ennever JA (1998) Premotor neurons for vertical eye movements in the rostral mesencephalon of monkey and human: histologic identification by parvalbumin immunostaining. J Comp Neurol 392:413–427. https://doi.org/10.1002/(SICI)1096-9861(19980323)392:4%3c413::AID-CNE1%3e3.0.CO;2-3
Horn AKE, Straka H (2021) Functional organization of extraocular motoneurons and eye muscles. Annu Rev vis Sci 7:793–825. https://doi.org/10.1146/annurev-vision-100119-125043
Horn AK, Büttner-Ennever JA, Gayde M, Messoudi A (2000) Neuroanatomical identification of mesencephalic premotor neurons coordinating eyelid with upgaze in the monkey and man. J Comp Neurol 420:19–34. https://doi.org/10.1002/(sici)1096-9861(20000424)420:1%3c19::aid-cne2%3e3.0.co;2-d
Horn AK, Helmchen C, Wahle P (2003) GABAergic neurons in the rostral mesencePhaLon of the macaque monkey that control vertical eye movements. Ann N Y Acad Sci 1004:19–28. https://doi.org/10.1196/annals.1303.003
Horn AKE, Horng A, Buresch N, Messoudi A, Härtig W (2018) Identification of functional cell groups in the abducens nucleus of monkey and human by perineuronal nets and choline acetyltransferase immunolabeling. Front Neuroanat 12:45. https://doi.org/10.3389/fnana.2018.00045
Kokkoroyannis T, Scudder CA, Balaban CD, Highstein SM, Moschovakis AK (1996) Anatomy and physiology of the primate interstitial nucleus of Cajal I. efferent projections. J Neurophysiol 75:725–739. https://doi.org/10.1152/jn.1996.75.2.725
Konakci KZ, Streicher J, Hoetzenecker W, Haberl I, Blumer MJ, Wieczorek G, Meingassner JG, Paal SL, Holzinger D, Lukas JR, Blumer R (2005) Palisade endings in extraocular muscles of the monkey are immunoreactive for choline acetyltransferase and vesicular acetylcholine transporter. Invest Ophthalmol vis Sci 46:4548–4554. https://doi.org/10.1167/iovs.05-0726
Leigh RJ, Zee DS (2015) The Neurology of Eye Movements. Oxford University Press, Oxford, pp 529–530
May PJ, Vidal PP, Baker H, Baker R (2012) Physiological and anatomical evidence for an inhibitory trigemino-oculomotor pathway in the cat. J Comp Neurol 520:2218–2240. https://doi.org/10.1002/cne.23039
May PJ, Warren S, Bohlen MO, Barnerssoi M, Horn AK (2016) A central mesencephalic reticular formation projection to the Edinger-Westphal nuclei. Brain Struct Funct 221:4073–4089. https://doi.org/10.1007/s00429-015-1147-z
May PJ, Billig I, Gamlin PD, Quinet J (2019) Central mesencephalic reticular formation control of the near response: lens accommodation circuits. J Neurophysiol 121:1692–1703. https://doi.org/10.1152/jn.00846.2018
Mayadali ÜS, Fleuriet J, Mustari M, Straka H, Horn AKE (2021) Transmitter and ion channel profiles of neurons in the primate abducens and trochlear nuclei. Brain Struct Funct 226:2125–2151. https://doi.org/10.1007/s00429-021-02315-7
Mayr R, Gottschall J, Gruber H, Neuhuber W (1975) Internal structure of cat extraocular muscle. Anat Embryol (berl) 148:25–34. https://doi.org/10.1007/BF00315560
Mays LE, Porter JD, Gamlin PD, Tello CA (1986) Neural control of vergence eye movements: neurons encoding vergence velocity. J Neurophysiol 56:1007–1021. https://doi.org/10.1152/jn.1986.56.4.1007
Moschovakis AK, Karabelas AB, Highstein SM (1988) Structure-function relationships in the primate superior colliculus. II. Morphological identity of presaccadic neurons. J Neurophysiol 60:263–302. https://doi.org/10.1152/jn.1988.60.1.263
Moschovakis AK, Scudder CA, Highstein SM (1991) Structure of the primate oculomotor burst generator. I. Medium-lead burst neurons with upward on-directions. J Neurophysiol 65:203–217. https://doi.org/10.1152/jn.1991.65.2.203
Murphy EH, Garone M, Tashayyod D, Baker RB (1986) Innervation of extraocular muscles in the rabbit. J Comp Neurol 254:78–90. https://doi.org/10.1002/cne.902540107
Nelson JS, Goldberg SJ, McClung JR (1986) Motoneuron electrophysiological and muscle contractile properties of superior oblique motor units in cat. J Neurophysiol 55:715–726. https://doi.org/10.1152/jn.1986.55.4.715
Perkins E, May PJ, Warren S (2014) Feed-forward and feedback projections of midbrain reticular formation neurons in the cat. Front Neuroanat 7:55. https://doi.org/10.3389/fnana.2013.00055
Porter JD, Guthrie BL, Sparks DL (1983) Innervation of monkey extraocular muscles: localization of sensory and motor neurons by retrograde transport of horseradish peroxidase. J Comp Neurol 218:208–219. https://doi.org/10.1002/cne.902180208
Porter JD, Burns LA, May PJ (1989) Morphological substrate for eyelid movements: innervation and structure of primate levator palpebrae superioris and orbicularis oculi muscles. J Comp Neurol 287:64–81. https://doi.org/10.1002/cne.902870106
Quinet J, Schultz K, May PJ, Gamlin PD (2020) Neural control of rapid binocular eye movements: Saccade-vergence burst neurons. Proc Natl Acad Sci USA 117:29123–29132. https://doi.org/10.1073/pnas.201531811
Schultz KP, Williams CR, Busettini C (2010) Macaque pontine omnipause neurons play no direct role in the generation of eye blinks. J Neurophysiol 103:2255–2274. https://doi.org/10.1152/jn.01150.2009
Spencer RF, Porter JD (1981) Innervation and structure of extraocular muscles in the monkey in comparison to those of the cat. J Comp Neurol 198:649–665. https://doi.org/10.1002/cne.901980407
Spencer RF, Porter JD (2006) Biological organization of the extraocular muscles. Prog Brain Res 151:43–80. https://doi.org/10.1016/S0079-6123(05)51002-1
Szabo J, Cowan WM (1984) A stereotaxic atlas of the brain of the cynomolgus monkey (Macaca fascicularis). J Comp Neurol 222:265–300. https://doi.org/10.1002/cne.902220208
Tang X, Büttner-Ennever JA, Mustari MJ, Horn AK (2015) Internal organization of medial rectus and inferior rectus muscle neurons in the C group of the oculomotor nucleus in monkey. J Comp Neurol 523:1809–1823. https://doi.org/10.1002/cne.23760
Ugolini G, Klam F, Doldan Dans M, Dubayle D, Brandi AM, Büttner-Ennever J, Graf W (2006) Horizontal eye movement networks in primates as revealed by retrograde transneuronal transfer of rabies virus: differences in monosynaptic input to “slow” and “fast” abducens motoneurons. J Comp Neurol 498:762–785. https://doi.org/10.1002/cne.21092
Waitzman DM, Silakov VL, Cohen B (1996) Central mesencephalic reticular formation (cMRF) neurons discharging before and during eye movements. J Neurophysiol 75:1546–1572. https://doi.org/10.1152/jn.1996.75.4.1546
Waitzman DM, Silakov VL, DePalma-Bowles S, Ayers AS (2000A) Effects of reversible inactivation of the primate mesencephalic reticular formation. I. Hypermetric goal-directed saccades. J Neurophysiol 83:2260–2284. https://doi.org/10.1152/jn.2000.83.4.2260
Waitzman DM, Silakov VL, DePalma-Bowles S, Ayers AS (2000B) Effects of reversible inactivation of the primate mesencephalic reticular formation. II Hypometric vertical saccades. J Neurophysiol 83:2285–2299. https://doi.org/10.1152/jn.2000.83.4.2285
Waitzman DM, Van Horn MR, Cullen KE (2008) Neuronal evidence for individual eye control in the primate cMRF. Prog Brain Res 171:143–150. https://doi.org/10.1016/S0079-6123(08)00619-
Wang N, Warren S, May PJ (2010) The macaque midbrain reticular formation sends side-specific feedback to the superior colliculus. Exp Brain Res 201:701–717. https://doi.org/10.1007/s00221-009-2090-0
Wang N, Perkins E, Zhou L, Warren S, May PJ (2013) Anatomical evidence that the superior colliculus controls saccades through central mesencephalic reticular formation gating of omnipause neuron activity. J Neurosci 33:16285–16296. https://doi.org/10.1523/JNEUROSCI.2726-11.2013
Wang N, Perkins E, Zhou L, Warren S, May PJ (2017) Reticular formation connections underlying horizontal gaze: The central mesencephalic reticular formation (cMRF) as a conduit for the collicular saccade signal. Front Neuroanat 11:36. https://doi.org/10.3389/fnana.2017.00036
Warren S, May PJ (2021) Macaque monkey trigeminal blink reflex circuits targeting levator palpebrae superioris motoneurons. J Comp Neurol 529:3389–3409. https://doi.org/10.1002/cne.25198
Wasicky R, Horn AKE, Büttner-Ennever JA (2004) Twitch and nontwitch motoneuron subgroups in the oculomotor nucleus of monkeys receive different afferent projections. J Comp Neurol 479:117–129. https://doi.org/10.1002/cne.20296
Zhou L, Warren S, May PJ (2008) The feedback circuit connecting the central mesencephalic reticular formation and the superior colliculus in the macaque monkey: tectal connections. Exp Brain Res 189:485–496. https://doi.org/10.1007/s00221-008-1444-3
Acknowledgements
We would like to thank the Jinrong Wei who assisted us in surgeries, undertook the histological processing and helped with illustrations. We are also beholden to Glen Hoskins for his preparation of the EM samples.
Funding
Grant support: This work was supported by Nation Eye Institute grant EY014263 to Paul J. May & Susan Warren.
Author information
Authors and Affiliations
Contributions
The experiments were designed by PJM and were carried out by MOB, with the assistance of SW and PJM. The data were analyzed by MOB & PJM. Figures were prepared by MOB & PJM, with assistance from SW. The manuscript was initially drafted by PJM and edited by all three authors.
Corresponding author
Ethics declarations
Conflict of interest
The authors declare no competing interests. None of the authors has any conflicts of interest, financial or otherwise, with respect to the work described in this manuscript.
Ethical use of animal statement
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution at which the studies were conducted. Specifically, they were undertaken under protocols approved by the Institutional Animal Care and Use Committee of the University of Mississippi Medical Center (USDA Animal Welfare Assurance # D16-00174).
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Bohlen, M.O., Warren, S. & May, P.J. Is the central mesencephalic reticular formation a purely horizontal gaze center?. Brain Struct Funct 227, 2367–2393 (2022). https://doi.org/10.1007/s00429-022-02532-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00429-022-02532-8