Branching cortical neurons in cat which project to the colliculi and to the pons: a retrograde fluorescent double-labeling study (original) (raw)

Summary

The fluorescent double-labeling technique has been used to determine whether the corticopontine and the corticotectal fibers in the cat are derived from two different sets of neurons or whether they are derived from branching neurons which distribute collaterals to the pontine grey and the colliculi. After unilateral DY.2HCl injections in the pontine grey and FB injections in the ipsilateral colliculi, large numbers of FB-DY.2HCl double-labeled neurons were present in the cortex of the ipsilateral hemisphere. However, the labeled neurons in its rostral part may have represented pyramidal tract neurons which were labeled retrogradely because their fibers descended through the DY.2HCl injection area. Therefore, also DY.2HCl injections were made in the pyramid (i.e. caudal to the pons) and the cortical pyramidal tract area, containing the retrograde DY.2HCl-labeled neurons, was delineated. In the rest of the experiments only the DY.2HCl-labeled neurons in the caudal two thirds of the hemisphere (outside the pyramidal tract area) were taken into account because only these neurons could, with confidence, be regarded as corticopontine neurons. In some anterograde HRP transport experiments the trajectories of the corticotectal and the corticopontine fibers were visualized. On the basis of the findings the DY.2HCl injections in the pontine grey were placed such that they could not involve any of the corticotectal fibers passing from the cerebral peduncle to the colliculi. Thus artifactual doublelabeling of cortical neurons was avoided. However, also under these circumstances many double-labeled neurons were present in the caudal two thirds of the hemisphere. This led to the conclusion that in the cat a large proportion of the corticopontine neurons in the caudal two thirds of the hemisphere represent branching neurons which also distribute collaterals to the colliculi. The parietal (anterior part of the lateral gyrus, middle and posterior suprasylvian gyri) and the cingulate areas together contained three quarters of all labeled corticopontine neurons outside the pyramidal tract area. In the parietal areas roughly 25% of them were double-labeled and in the cingulate area 14%. However, in the visual areas 18 and 19 a much larger percentage (30–60%) was doublelabeled. In a recent study from our laboratory it was found that in the cat the pyramidal tract fibers distribute an abundance of collaterals to the pontine grey. Therefore, a large proportion of all corticopontine connections in this species appear to be established by branching neurons which also distribute fibers to other cell groups in the brain stem and the spinal cord.

Access this article

Log in via an institution

Subscribe and save

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

Abbreviations

A.E.:

anterior ectosylvian sulcus

a.e.s.:

anterior ectosylvian sulcus

BC:

brachium conjunctivum

BCI:

brachium colliculus inferior

BP:

brachium pontis

cor. sulc.:

coronal sulcus

CP:

cerebral peduncle

CR.:

cruciate sulcus

CUN:

cuneiform nucleus

DBC:

decussation brachium conjunctivum

DLP:

dorsolateral pontine nucleus

IC:

inferior colliculus

inf. coll.:

inferior colliculus

INS.:

insula cortex

IO:

inferior olive

IP:

interpeduncular nucleus

LAT.:

lateral sulcus

l.s.:

lateral sulcus

MG:

medial geniculate body

LL:

lateral lemniscus

ML:

medial lemniscus

MLF:

medial longitudinal fascicle

NdG:

dorsal nucleus of Gudden

NLL:

nucleus lateral lemniscus

NRTP:

reticular tegmental pontine nucleus

ORB.:

orbital sulcus

P:

pyramid

PAG:

periaqueductal grey

P.E.:

posterior ectosylvian sulcus

RF:

reticular formation

PG:

pontine grey

RB:

restiform body

RN:

red nucleus

S.:

sylvian sulcus

SC:

superior colliculus

SN:

substantia nigra

SO:

superior olive

SPV:

spinal trigeminal complex

S.S.:

suprasylvian sulcus

s.syl.s.:

suprasylvian sulcus

S.SPL.:

suprasplenial sulcus

SPL.:

splenial sulcus

spl.s.:

splenial sulcus

sup. coll.:

superior colliculus

syl.s.:

sylvian sulcus

TB:

trapezoid body

VC:

vestibular complex

Vm:

trigeminal motor nucleus

Vs:

trigeminal principle nucleus

III:

oculomotor nucleus

IV:

trochlear nucleus

VI:

abducens nucleus

VII:

facial nerve

VIII:

vestibulo-trochlear nerve

References

Download references

Author information

Authors and Affiliations

  1. Department of Anatomy II, Erasmus University Medical School, P.O. Box 1738, NL-3000, DR Rotterdam, The Netherlands
    K. Keizer & H. K. Ronday
  2. Department of Anatomy, Cambridge University, Cambridge, UK
    H. G. J. M. Kuypers

Authors

  1. K. Keizer
    You can also search for this author inPubMed Google Scholar
  2. H. G. J. M. Kuypers
    You can also search for this author inPubMed Google Scholar
  3. H. K. Ronday
    You can also search for this author inPubMed Google Scholar

Additional information

Supported in part by grant 13-46-91 of FUNGO/ZWO (Dutch Organization for Fundamental Research in Medicine)

Rights and permissions

About this article

Cite this article

Keizer, K., Kuypers, H.G.J.M. & Ronday, H.K. Branching cortical neurons in cat which project to the colliculi and to the pons: a retrograde fluorescent double-labeling study.Exp Brain Res 67, 1–15 (1987). https://doi.org/10.1007/BF00269447

Download citation

Key words