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PubMed1988

Lateral thalamic infarcts.

A patient with occlusion of the proximal posterior cerebral artery (PCA), a lateral thalamic infarct, and hemisensory loss later developed hemianopia and hemiparesis and had extensive PCA territory infarction in the midbrain, the lateral portion of the thalamus, and the occipital lobe noted at necropsy. Two other patients had lateral thalamic infarcts on computed tomography, normal angiographic findings, and presumed thalamogeniculate artery branch occlusion. There are three clinical syndromes associated with lateral thalamic infarction: (1) hemisensory loss, hemiataxia, and involuntary movements; (2) pure sensory stroke; and (3) sensory-motor stroke. Ataxia, adventitious movements, and sensory loss are due to infarction of the lateral, posterolateral, and posteromedial ventral nuclei caused by occlusion of the PCA proximal to the thalamogeniculate artery branches or by occlusion of large thalamogeniculate arteries. Pure sensory and sensory-motor strokes are due to smaller infarcts in the posterolateral-posteromedial ventral complex and adjacent internal capsule caused by occlusion of penetrating artery branches of the thalamogeniculate arteries.

Aged↗
PubMed1999

Adjuvant lateral canthal advancement in the surgical management of exophthalmic eyelid retraction.

The eye is convergent from the orbital axis when in the primary gaze position; greater projection of the lateral sclera results from the posterior location of the lateral orbital rim relative to the medial orbital rim. If the horizontal tarsal ligamentous band cannot lengthen to accommodate an increasingly exophthalmic globe in thyroid ophthalmopathy, a horizontally tight eyelid with increased exposure of the lateral sclera will result; thus, temporal flare is accentuated. Lateral canthal advancement was developed as an adjuvant procedure to reduce temporal flare in the surgical repair of thyroid-related eyelid retraction. Lateral canthal advancement is a theoretically rational and effective adjunct to retractor recession when horizontal tightness of the eyelid is present. In the horizontally tight eyelid, lateral canthal advancement is effective in enhancing the effect of retractor recession and in reducing temporal flare.

Adult↗
PubMed2002

Involutional lateral entropion of the upper eyelids: a new physical finding in asian patients.

OBJECTIVE: To describe a new physical finding called involutional lateral entropion (ILE) of the upper eyelid found in Asian patients. METHODS: A prospective case series study of 53 consecutive patients with ILE of the upper eyelid, from the practice of one of the authors (J.G.C.), was performed. All of the patients in this series were Asian. Clinical findings on ocular examination, symptoms, age, and sex were obtained and tabulated. RESULTS: The mean +/- SD age of patients was 68.9 +/- 10.1 years (range, 41-88 years); 70% were women and 30% were men. All patients presented with in-turning of only the lateral aspect of the upper eyelid bilaterally. The presenting symptoms were foreign-body sensation (85%), tearing (77%), eye redness (34%), eye pain (26%), and itchiness at the lateral canthal area (25%). Clinical findings included lateral dermatochalasis (100%), trichiasis (100%), lateral canthal eyelid laxity (100%), localized lateral conjunctivitis (42%), punctate epithelial keratopathy (11%), blepharitis (11%), and distichiasis (8%). CONCLUSION: We describe ILE of the upper eyelid in Asian patients and explain the anatomic correlates responsible for this condition.

Adult↗
PubMed1996

Lateral extensions of the Müller muscle.

OBJECTIVES: To define the lateral extension of the Müller muscle and to elucidate its involvement in the development and surgical treatment of Graves (thyroid) eye disease. METHODS: Twelve lateral halves of orbits exenterated from patients with medial or posterior orbital neoplasms were fixed, embedded, and step sectioned at 250-microns intervals to produce histological sections. Gross anatomical dissections of human cadaver heads were also used to corroborate the histological findings. RESULTS: Histological analysis revealed that the Müller muscle extended laterally between the orbital and palpebral lobes of the lacrimal gland in all specimens. The smooth muscle fibers were found to interdigitate with lacrimal ducts passing from the orbital to palpebral lobe and to extend close to the ductal orifices at the conjunctival surface. Gross dissections confirmed that the Müller muscle accompanied the levator aponeurosis lateral extension, which is known to pass between the orbital and palpebral lobes of the lacrimal gland. CONCLUSIONS: Our anatomical findings suggest that the Müller muscle may contribute to the temporal flare frequently seen in eyelid retraction associated with thyroid eye disease. They may also explain the difficulty of treating lateral eyelid retraction in thyroid eye disease and indicate the need for new surgical approaches for severe lateral eyelid retraction.

Eye Enucleation↗
PubMed1997

Lateral arm microvascular flap in head and neck reconstruction.

OBJECTIVES: To report our results of a study of 28 patients who underwent sequential reconstructions of the head and neck using the lateral arm flap. To discuss the situations where we have found the procedure useful, report the complication rates, and delineate the advantages and disadvantages of using this flap. DESIGN: A clinical series of patients was followed up prospectively. The swallowing function of a subgroup that underwent oropharyngeal reconstruction was compared with that of a simultaneous control group that underwent reconstruction with the pectoralis major flap. SETTING: University medical center. PARTICIPANTS: Patients with malignant neoplasms of the head and neck who underwent resections and reconstruction with the lateral arm flap. INTERVENTIONS: Twenty-eight patients underwent head and neck reconstruction using lateral arm flaps. In 17 patients, the lateral arm flaps were used for pharyngeal and posterior oral cavity defects. Thirteen of these patients underwent reinnervation. Nine combined palatal and midfacial defects were reconstructed, and 1 lateral facial defect was reconstructed. Most cases were advanced malignant neoplasms and represented a selected minority of similar resections performed at our institutions. Three maxillary reconstructions were performed secondarily. All other reconstructions were performed at the time of tumor ablation. MAIN OUTCOME MEASURES: Data were collected regarding flap survival, return of sensation in flaps, complication rates, and the ability to feed orally. RESULTS: All flaps survived in their entirety. Of 7.5 tested flaps acquired sensation. Of 14 patients with large oropharyngeal defects, 8 resumed early oral feeding and all survivors eventually obtained nutrition orally. The ability to swallow was superior to the results obtained in a retrospective analysis of a group reconstructed using pectoralis major flaps. CONCLUSIONS: A unique feature of this flap is that it incorporates both thin skin from the proximal forearm and thicker skin from the upper arm. This is ideal for an oropharyngeal defect, where the thin malleable portion can be used in the posterior oral cavity or pharyngeal wall and the thicker portion in the tongue base. Either portion can be used alone as well. The availability of intermediate tissue bulk can also be advantageous for midfacial reconstruction. Sensation can be reliably reconstituted with this flap. We think that the lateral arm flap is versatile and has particularly low donor-site morbidity.

Adult↗
PubMed1997

Glycine immunoreactivity in the lateral nucleus of the trapezoid body of the cat.

The central auditory system contains several predominantly glycine-immunoreactive nuclei, and one of these, the lateral nucleus of the trapezoid body, contains cell bodies exhibiting a spectrum of labeling intensity. By using post-embedding glycine immunocytochemistry on thin sections, and toluidine blue staining of adjacent sections, we established that darkly glycine-immunoreactive neurons constituted a distinct morphological class and form one of three subnuclei of the lateral nucleus of the trapezoid body, called the posteroventral subnucleus. These neurons resemble, in both labeling intensity and cell body morphology, the principal cells of the medial nucleus of the trapezoid body. The other two subnuclei of the lateral nucleus of the trapezoid body, its main and hilus subnuclei, contained predominantly glycine-immunoreactive and glycine-immunonegative neurons, respectively. Glycine immunoreactivity was compared with gamma-aminobutyric acid (GABA) immunoreactivity in order to identify other organizational features of the lateral nucleus of the trapezoid body. Cell bodies that displayed either dark glycine-immunoreactivity or which were glycine-immunonegative were GABA-immunonegative. Cell bodies that displayed GABA immunoreactivity were preferentially located in the main subnucleus. Patterns of distribution of axosomatic innervation in the lateral nucleus of the trapezoid body were revealed in which glycine-immunoreactive puncta were (1) more numerous than GABA-immunoreactive puncta on glycine-immunonegative cell bodies and (2) equal to or less numerous than GABA-immunoreactive puncta on glycine-immunoreactive cell bodies. The characteristics of neural circuitry revealed by glycine and GABA immunoreactivity in the lateral nucleus of the trapezoid body may be generalizable to other populations of neurons of the superior olivary complex and to other regions of the central nervous system containing glycinergic neurons, such as the retina.

Animals↗
PubMed1998

Results of termino-lateral neurorrhaphy to original and adjacent nerves.

In this comprehensive investigation, we studied three different neurorrhaphy models in an attempt to elucidate the potential of termino-lateral nerve repair to original and adjacent nerves. In experimental group 1, the peroneal nerve was sectioned and then attached to the posterior tibial nerve in a termino-lateral fashion. In experiment group 2, the motor nerves to the gastrocnemius muscle were sectioned and then attached to the posterior tibial nerve in a termino-lateral fashion. In experimental group 3, the obturator nerve (L2-4) was sectioned and attached to the sciatic nerve (L4-6) in a termino-lateral fashion. For the control in each group, the same type of nerve used in each respective group was transected without repair. Experimental groups 1 and 2 showed viable axons in the peroneal nerve distal to the neurorrhaphy site. Experimental group 3 showed no viable axons at these sites. No regeneration was observed in the transected nerve without repair in all three control groups. This study suggests that termino-lateral neurorrhaphy is a viable means of repairing damaged nerves if the distal segment of the sectioned nerve is reattached to its original trunk distal to its original branch point. However, the results from experimental group 3 demonstrate that termino-lateral neurorrhaphy cannot be used to repair nerves when the donor and recipient nerves originate from different spinal cord levels.

Anastomosis, Surgical↗
PubMed2002

Clinical characteristics of adolescents later hospitalized for schizophrenia.

Intellectual and behavioral abnormalities, non-psychotic psychiatric disorders, and drug abuse are sometimes present in adolescents who later develop schizophrenia. We followed a population-based cohort of adolescents with baseline assessments of intellectual and behavioral functioning, non-psychotic psychiatric disorders and drug abuse, and ascertained future hospitalization for schizophrenia. Results of the medical and mental health assessments on 16- to 17-year-old male adolescents screened by the Israeli Draft Board, were cross-linked with the National Psychiatric Hospitalization Case Registry, which contains data on all psychiatric hospitalizations in the country. Male adolescents who were later hospitalized for schizophrenia had significantly poorer test scores on all measures in comparison with adolescents not reported to the Psychiatric Registry, the magnitude of the differences was 0.3-0.5 standard deviation (SD). Adolescents (1.03%) of assigned a non-psychotic psychiatric diagnosis, compared to of the adolescents without any psychiatric diagnosis (0.23%), were later hospitalized for schizophrenia. Patients with schizophrenia (26.8%), compared to only 7.4% in the general population of adolescents, had been assigned a non-psychotic psychiatric diagnosis in adolescence (overall OR = 4.5, 95% CI = 3.6-5.6), ranging from OR = 21.5, (<2 >95% CI = 12.6-36.6) for schizophrenia-spectrum personality disorders to OR = 3.6 (<2 >95% CI = 2.1-6.2) for neurosis. The prevalence of self-reported drug abuse was higher in adolescents later hospitalized for schizophrenia (12.4%), compared to the prevalence of drug abuse in adolescents not later hospitalized (5.9%); adjusted RR = 2.033, 95% CI = 1.322-3.126. These results reflect the relatively common finding of impaired intellectual and behavioral functioning, the presence of non-psychotic psychiatric disorders, and drug abuse, in adolescents later hospitalized for schizophrenia, together with the relatively low power of these disorders in predicting schizophrenia.

Adolescent↗
PubMed1994

Selective vulnerability in Huntington's disease: preferential loss of cannabinoid receptors in lateral globus pallidus.

Selective neuronal vulnerability is a key feature of the neuropathology of Huntington's disease. We used [3H]CP-55,940, a synthetic cannabinoid, to label cannabinoid receptors in tissue sections from individuals dying with Huntington's disease and from normal control subjects. The density of cannabinoid receptors in striatum and pallidum was measured using quantitative autoradiography. There was a greater loss of cannabinoid receptors on striatal nerve terminals in the lateral pallidum compared to the medial pallidum, in Huntington's disease of all neuropathological grades. The disparity in binding density between the lateral and medial pallidum increased with higher grades of disease. There was also a greater loss of receptors in the lateral pallidum than in the putamen. The disproportionate loss of receptors in the lateral pallidum compared to the putamen increased in magnitude with severity of neuropathological grade. These data support the relative preferential loss or dysfunction of striatal neurons projecting to the lateral pallidum compared to neurons projecting to the medial pallidum. Terminals in the lateral pallidum containing cannabinoid receptors may be affected earlier or more severely than terminals in the medial pallidum, and both pallidal segments may be affected before or more severely than cell bodies or dendrites in the striatum. Terminal loss of markers may represent a response to perikaryal injury or dysfunction, or less likely, may indicate the primary site of neuronal damage in Huntington's disease.

Adult↗
PubMed2003

Organization of somatosensory cortex in the laboratory rat (Rattus norvegicus): Evidence for two lateral areas joined at the representation of the teeth.

Lateral somatosensory areas have not been explored in detail in rats, and theories on the organization of this region are based largely on anatomical tracing experiments. We investigated the topography of this region by using microelectrode recordings, which were related to flattened cortical sections processed for cytochrome oxidase (CO). Two lateral somatosensory areas were identified, each containing a complete representation of the body. A larger, more medial representation formed a mirror image of S1 along the rostrocaudal axis of the head region corresponding to the previously identified secondary somatosensory area (S2). A smaller, more lateral representation formed a mirror image of S2 along the rostrocaudal axis of the forelimb and hindlimb regions and likely corresponds to the parietal ventral area (PV) identified in other mammals. We also investigated the representation of the dentition and identified regions of cortex responsive to tooth stimulation. The lower incisor representation was rostral to the lower lip region of S1, and the upper incisor representation was lateral to the buccal pad region of S1. The upper and lower incisors flanked the tongue representation. An additional large region of far lateral cortex responded to both incisors. Finally, five CO-dense modules were consistently identified rostral and lateral to the S1 face representation, which we refer to as OM1, OM2, OM3, FM, and HM. These modules closely correspond to the physiologically identified areas representing the lower incisor (OM1) and tongue (OM2) regions of S1 and the mixed tooth (OM3), forelimb (FM1), and hindlimb (HM) representations of S2 and PV.

Animals↗
PubMed2004

Expression of Dbx1, Neurogenin 2, Semaphorin 5A, Cadherin 8, and Emx1 distinguish ventral and lateral pallial histogenetic divisions in the developing mouse claustroamygdaloid complex.

We studied the lateral and ventral pallial divisions of the claustroamygdaloid complex by means of analysis of expression patterns of the developmental regulatory genes Tbr1, Dbx1, Neurogenin 2, Emx1, Cadherin 8, and Semaphorin 5A in mouse developing telencephalon, from embryonic day 12.5 until birth. Our results indicate that these genes help to distinguish distinct lateral and ventral pallial histogenetic divisions in the embryonic telencephalon. Tbr1 is broadly expressed in both lateral and ventral pallial histogenetic divisions (the lateroventral migratory stream plus the mantle) during early and intermediate embryonic development; its signal becomes weak in parts of the mantle during late embryonic development. Dbx1 is strongly and specifically expressed in progenitor cells (ventricular zone) of the ventral pallium during early embryonic development, but there is no signal of this gene in the rest of the pallium nor the subpallium. Neurogenin 2 and Semaphorin 5A are both expressed in a ventral subdivision of the lateroventral migratory stream (called by us the ventral migratory stream). Further, specific nuclei of the claustral complex and pallial amygdala show strong expression of Neurogenin 2 and/or Semaphorin 5A, including the ventromedial claustrum and endopiriform nuclei, the lateral and basomedial amygdalar nuclei, the anterior and posteromedial cortical amygdalar areas, plus the amygdalo-hippocampal area. We interpret these nuclei or areas of the claustroamygdaloid complex as possible derivatives of the ventral pallium. In contrast, during embryonic development the dorsolateral claustrum, the basolateral amygdalar nucleus, and the posterolateral cortical amygdalar area do not express or show weak expression of Neurogenin 2 or Semaphorin 5A, but express selectively and strongly Cadherin 8 plus Emx1, and may be derivatives of the lateral pallium. The lateral pallial and ventral pallial divisions of the claustroamygdaloid complex appear to have some different sets of connections, although this requires further investigation.

Amygdala↗
PubMed1975

Observations on the lateral olfactory tract of the rat.

The number and size of the axons in the later olfactory tract of the rat have been measured at several rostro-caudal levels, from material prepared for electron microscopy. Immediately caudal to the olfactory peduncle, an average of 42,000 +/- 3,000 axons were counted in the tract, while near the caudal limit of the tract an average of 32,000 +/- 2,800 axons were counted. The average internal cross-sectional area of axons measured at two levels of the tract was 1.6 +/- 1.3 mum2 and 1.1 +/- 0,9 mum2, corresponding to average internal diameters 1.4 +/- 1.3 mum and 1.2 +/- 1.1 mum, respectively. The axons in the lateral part of the tract were found to be significantly larger than those in the medial part of the tract; for one level the average cross-sectional area of axons in the lateral part of the tract was 1.6 +/- 1.0 mum2 (equivalent diameter 1.4 +/- 1,1 mum) while only 0.7 +/- 0.6 mum2 (equivalent diameter 0.9 +/- 0.9 mum) in the medial part of the tract. The thickness of the myelin sheath of the axons is generally related to axon diameter, increasing from 0.1-0.2 mum for axons 0.4 to 0.8 mum in diameter to 0.3-0.4 mum for axons greater than 2.0 mum in diameter. The ratio of the inside diameter to the outside diameter of the fiber (ratio "g") is between 0.7 and 0.8 for most axons in the lateral olfactory tract. The axons which leave the tract laterally and medially are substantially smaller than the axons within the tract (average cross-sectional area 0.55 +/- 0.35 mum2 on the lateral side) and probably are collaterals of the axons within the tract. Unmyelinated nerve processes, probably axons, were also found in the tract. Qualitative observations from light and electron microscopical material agree well with the quantitative data, and further suggest that mixing of axons from different parts of the olfactory bulb occurs in the rostral part of the tract. This is supported by experiments with injections of 3H-amino acids into localized portions of the olfactory bulb. These indicate that there is some degree of point-to-point organization in the most rostral part of the tract, but that this is lost in the caudal part of the olfactory peduncle.

Animals↗
PubMed1980

[14C]Deoxyglucose mapping of first-order projections activated by stimulation of lateral hypothalamic sites eliciting gnawing, eating, and drinking in rats.

Rats having hypothalamic electrodes that elicited gnawing, eating, and drinking in free-moving tests received intermittent electrical stimulation for 45 min following i.v. injection of [14C] deoxyglucose. Autoradiographs of regional brain glucose utilization were made by the method of Sokoloff et al. ('77). To maximize the detectability of first-order neuronal effects and minimize potentially complex transsynaptic effects, baseline metabolism and synaptic transmission were reduced by light barbiturate anesthesia. Laterally asymmetrical increases in glucose utilization indicative of elicited activity were largely coterminous with the known projections of the lateral hypothalamus and some projections of adjoining areas, indicating that most first-order efferents were above threshold for deoxyglucose visualization, while most transsynaptic effects were subthreshold. Although the majority of hypothalamic projections were similarly affected in control rats that received hypothalamic stimulation that elicited other responses, a number were activated significantly less than in the rats whose electrodes induced gnawing, eating, and drinking. Chief among these areas was a continuous descending pathway from the ventral tegmental area through the lateral tegmentum to the cuneiform and parabrachial nuclei. Smaller and/or less reliable increases above controls were found in the dorsomedial caudate-putamen, the posterolateral zona incerta, the anterior lateral central gray, the caudal linear nucleus, the laterodorsal tegmental nucleus, the pontine tegmental nucleus, and a previously undescribed pathway lying medially between the pontine medial lemniscus and cerebral peduncle. These areas, especially the lateral tegmental and parabrachial zone, are the most likely candidates for the pathways and/or destinations of the directly excited efferents or fibers of passage that constitute the first link in the elicitation of gnawing, eating, and drinking by lateral hypothalamic stimulation. Since self-stimulation and exploratory activity were elicited by control as well as experimental electrodes, they are probably dependent on other projections among those affected similarly in both groups.

Animals↗
PubMed1982

Ascending lateral line pathways to the midbrain of the clearnose skate, Raja eglanteria.

Efferent projections of the electroreceptive dorsal and the mechanoreceptive intermediate octavolateralis nuclei were revealed, in the brain of the clearnose skate Raja eglanteria, by means of silver degeneration and autoradiographic methods. Efferents from each nucleus give rise to ipsilateral and contralateral lemnisci and commissural components. Commissural fibers terminate within their respective nuclei of the opposite side. The lemnisci from each nucleus parallel each other as they course from medullary to mesencephalic levels; those from the dorsal nucleus assume a lateral position and terminate within the lateral part of the nucleus of the lateral line lemniscus and the lateral nucleus of the midbrain; those within the medial part of the lateral line lemniscal nucleus and the dorsomedial mesencephalic nucleus. A substantial number of fibers of each class course through the mesencephalic nuclei and terminate bilaterally within the central tectal zone. The segregation of electroreceptive and mechanoreceptive information is maintained from medullary to mesencephalic levels although there probably is convergence within the central tectal zone and the magnocellular nucleus, the only octaval center to receive terminals from secondary lateral line fibers.

Animals↗
PubMed1983

Posterior lateral line afferent and efferent pathways within the central nervous system of the goldfish with special reference to the Mauthner cell.

The goldfish posterior lateral line nerve consists of a dorsal and a ventral branch, each of which is associated with a ramus of the sensory branch of the VIIth nerve (ramus recurrens facialis). The afferent and efferent pathways of these nerves within the central nervous system were studied by using horseradish peroxidase (HRP) histochemistry. The afferent fibers of the ramus recurrens facialis travel in the ventral portion of the VIIth nerve as it enters the brain and project predominantly to the ipsilateral half of the facial lobe. The afferent fibers of either the dorsal or ventral branch of the posterior lateral line nerve split into two bundles as they enter the brain. The caudally projecting fascicle terminates predominantly in the nucleus medialis. The fibers of the rostrally projecting bundle terminate predominantly in nucleus medialis and nucleus magnocellularis and in the eminentia granularis. The posterior lateral line efferent somata were located in the diencephalon as well as in the medulla oblongata. The medullary efferent neurons formed two distinct groups, a rostral and a caudal nucleus. The cell bodies of the latter were more numerous and larger than those of the former. The axons of the efferent neurons exit from the brain by one of two routes. The first is at the level of the rostral efferent nucleus and the second at the level of the Mauthner cell. Previous reports have described input of posterior lateral line afferent fibers to the Mauthner cell soma and proximal lateral dendrite of the goldfish. This electrophysiological input was bilateral and was interpreted as monosynaptic. The afferent input described in this study was ipsilateral and ended in the vicinity of the distal lateral dendrite. These differences are discussed in the context of the neuronal circuitry that may be present.

Animals↗
PubMed1983

Differential olivocochlear projections from lateral versus medial zones of the superior olivary complex.

An anterograde tracer (35S-methionine) was injected unilaterally in the superior olivary complex (SOC) at regions previously demonstrated by retrograde labeling to contain olivocochlear (OC) cell bodies. Quantitative analysis of cochlear autoradiographs from these cats demonstrates that there are two OC systems. The lateral OC system has cell bodies lateral to the medial superior olivary nucleus (MSO) and projects to the inner hair cell (IHC) region bilaterally (mostly ipsilaterally). The medial OC system has cell bodies medial, ventral, and anterior to the MSO and projects to the outer hair cell (OHC) region bilaterally (mostly contralaterally). A single medial OC neuron innervates many small patches of OHCs with substantial gaps between the patches. Medial OC neurons also appear to project to the IHC region to a small extent. A review of the literature with the medial-lateral division of OC efferents in mind reveals many differences between these two systems. In particular, lateral OC axons are unmyelinated and innervate the dendrites of radial afferent fibers under IHCs, whereas medial OC axons are myelinated and directly innervate OHCs. Although both systems appear to be cholinergic, the lateral OC system also shows met-enkephalin-like immunoreactivity. The synapses of the medial OC system are formed in development before those of the lateral OC system and they degenerate more slowly after the OC axons are cut. The many differences between these two OC systems suggest that they are functionally separate systems.

Animals↗
PubMed1984

Topographic organization of the olivocochlear projections from the lateral and medial zones of the superior olivary complex.

By anterograde tracing using autoradiography, we have found topographic organizations in the projections of both medial and lateral olivocochlear (OC) systems in the cat. Lateral-zone injections show an ipsilateral cochleotopic projection pattern with more medial injections projecting more basally in the cochlea. In the contralateral cochlea, in contrast, the projections from all of the lateral-zone injections were predominantly to the apex. However, detailed analysis suggests the possibility that the contralateral lateral-zone projections may have the same cochleotopic organization as the ipsilateral projections but with a heavy bias toward the apex. Medial-zone injections show a pattern in which more dorsal regions project more basally in both cochleas. The ipsilateral projections of lateral OC neurons appear to connect regions with similar best frequencies but the projections of medial OC neurons do not. Summation of data from all of the injections in each zone indicates that lateral OC projections are relatively evenly distributed throughout the ipsilateral cochlea but are predominantly to the apex in the contralateral cochlea. Medial OC projections are predominantly to the middle and basal parts of the cochlea on both sides with contralateral projections somewhat more basal than ipsilateral projections.

Animals↗
PubMed1984

Genesis of neurons in the dorsal lateral geniculate nucleus of the cat.

Neurons that will ultimately form the dorsal and ventral lateral geniculate nuclei, the medial interlaminar nucleus, the perigeniculate nucleus, and the nucleus reticularis of the cat undergo their final cell division beginning on, or slightly before, embryonic day 22 (E22) and ending on, or before, E32. Early in this period, neurogenesis proceeds for all of these geniculate nuclei, whereas only in the dorsal lateral geniculate nucleus does cell birth continue until E32. Distinct spatiotemporal gradients of cell birth are not obvious within any of the individual geniculate nuclei. For the dorsal lateral geniculate nucleus in particular, and for the other geniculate nuclei in general, neurons born early in this period exhibit a full range of adult soma sizes, including large and small neurons. Neurons born late in this period exhibit only small adult somas. The location and size of a neuron within the dorsal lateral geniculate nucleus provide clues to that cell's functional properties. On the basis of presently available information regarding the relationship between structure and function of neurons in the cat's dorsal lateral geniculate nucleus, the findings described here suggest that all functional classes of neurons in the dorsal lateral geniculate nucleus are born at the same time throughout most of this period.

Animals↗