The course and termination of the striae of Monakow and held in the cat

Abstract

The course and termination of the stria of Monakow and stria of Held were studied with Nauta-Gygax technique following a localized lesion of the dorsal cochlear nucleus i n the cat. A dense preterminal degeneration within all homolateral primary cochlear nuclei and a tract of degenerated fibers crossing the restiform body dorsally were found. This tract divides i n two branches forming the stria of Held and stria of Monakow.The stria of Held followed the course described by classical anatomists. In the homolateral side, the stria gave terminals to the medial and lateral preolivary nuclei, lateral superior olive nucleus and retro-olivary groups. In the contralateral side, preterminal degeneration was found in the medial preolivary nucleus and medial retro-olivary group.The stria of Monakow is essentially crossed pathway given numerous terminals to the contralateral dorsal retro-olivary group, rostra1 part of the lateral preolivary nucleus, the ventral and dorsal nuclei of the lateral lemniscus, and nucleus of the inferior colliculus.The primary cochlear nuclei as described by Lorente de N6 ('33) in Golgi preparations was divided in 13 regions of specific cellular structure. The regions were grouped in six nuclei : tuberculum acousticum ( 4 regions), nucleus centralis ( a specialized region of the tuberculum acousticum), nucleus interstitialis, nucleus posterioris ( 3 regions), nucleus lateralis (a specialized region of the nucleus posterioris), and ganglion ventrale (3 regions). In Nissl's preparations the borderline between one region and another cannot be clearly differentiated. For this reason and for convenience in the analysis of functional data, the classification of Lorente de N6 has been simplified into four major groups (Ross, Galambos and Hughes, '59; Kiang, Pfeiffer, Warr and Backus, '65). The terminology is as follows : The tuberculum acousticum and nucleus centralis is called the dorsal cochlear nucleus; the nucleus posterioris and nucleus lateralis are grouped as the posteroventral nucleus or posterior ventral cochlear nucleus; the ganglion ventrale is called the anteroventral or anterior ventral cochlear nucleus; and the nucleus interstitialis. The latter is here called the interstitial cochlear nucleus in order to clearly differentiate it from the interstitial nucleus of the vestibular nerve and the interstitial nucleus of the medial longitudinal fasciculus.3. COMP. NEUR., 131: 371-386.As described by classical anatomists (von Monakow, 1891; Held, 1893; van Gehuchten, '02; Ram6n y Cajal, '09; Lorente de N6, '33; and others), the auditory second order neurons formed three bundles, the stria of Monakow or dorsal acoustic stria, the stria of Held or intermediate stria, and the trapezoid body. There are excellent anatomical accounts of these ascending auditory pathways. Yet the opinions regarding the details about origin, course and termination of the three striae are controversial. For instance, according

Organization of ventrolateral periolivary cells of the cat superior olive as revealed by PEP-19 immunocytochemistry and Nissl stain

“…Therefore, it is likely that a substantial fraction of PEP-19-IR in the LNTB originates from bushy cells, although a contribution from VCN stellate cells cannot be ruled out. Cartwheel cells of the dorsal cochlear nucleus (DCN) are densely immunolabeled and pyramidal cells are faintly stained by the PEP-19 antiserum (Berrebi and Spirou, 19941, but the superficial layers of the cat DCN do not contain neurons that project into the ventrolateral periolivary region (Fernandez and Karapas, 1967;. We observed scattered, well-labeled, deep DCN neurons, but these few cells cannot account for the bulk of immunolabeling in the SOC.…”

Contralateral Effects and Binaural Interactions in Dorsal Cochlear Nucleus

“…Needles were coupled to a 1-ml syringe to allow reliable injections of microliter amounts of lidocaine solution. The needles were either placed at the medial border of the contralateral DCN, where the fibers of the DAS and IAS intermingle, or moved medial toward the midline of the floor of the fourth ventricle to isolate the DAS (Fernandez and Karapas 1967;Davis 2002). Placement of the needle was guided by searching for noise-evoked background activity where the output tracts were expected to be found.…”

Encoding the Timing of Inhibitory Inputs

“…The cells of the inferior colliculus (IC) receive direct excitatory projections from the pyramidal cells of the DCN (Coleman and Clerici 1987;Ryugo and Willard 1985). The DCN also projects to the GABAergic cells of the dorsal nucleus of the lateral lemniscus (Adams 1979;Adams and Warr 1976;Fernandez and Karapas 1967), which in turn project to the IC. The DNLL, as well as local inhibitory interneurons of the IC, can be sources of feedforward inhibition to cells that receive direct DCN input (Oliver and Huerta 1992).…”