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M H Rowe

Publications and source records attributed to M H Rowe.

At least 37 records · Page 2Linked to original sources
PubMed1982

Retinal W-cell projections to the medial interlaminar nucleus in the cat: implications for ganglion cell classification.

The perikaryal sizes and retinal distribution of ganglion cells labeled after small iontophoretic injections of horseradish peroxidase (HRP) into the medial interlaminar nucleus (MIN) were studied. Injections were also made into the LGNv and the C-laminae of the dorsal lateral geniculate nucleus (LGNd) for comparison. The results are consistent with suggestions that the MIN contains three approximately vertically oriented laminae which, from medial to lateral, receive their input from, respectively, contralateral nasal, ipsilateral temporal, and contralateral temporal retina. Each MIN lamina receives afferents from two distinct groups of retinal ganglion cells (1) cells with large somas (over 25 micron), coarse primary dendrites, large dendritic trees (500-900 micron in diameter), and coarse axons; (2) cells with medium-sized somas (14-20 micron), medium-caliber primary dendrites, large dendritic trees (350-700 micron), and fine axons. The large cells are clearly Y-cells or alpha cells, and they provide approximately 50% of the retinal input to all layers of the MIN. The medium-sized cells, which provide the remaining 50% of the retinal output in the MIN, are, we argue, W-cells, since they do not differ in soma size, dendritic morphology, axon caliber, or receptive field properties from medium-sized W-cells which project to other thalamic or midbrain structures. These results suggest two phylogenetic trends within the W-cell group: (1) the differentiation of thalamic and midbrain components; and (2) the further differentiation of ipsilateral and contralateral projections within the midbrain component. This latter division corresponds to the distinction between W1 and W2 cells described previously (Rowe and Stone, '77, '80).

Animals↗
PubMed1982

Functional morphology of beta cells in the area centralis of the cat's retina: a model for the evolution of central retinal specializations.

The dendritic morphology of beta cells in and around the area centralis of the retinae of normally pigmented and Siamese cats is described. Individual central beta cells in the Siamese cat do not differ morphologically from central beta cells in normally pigmented cats, and in both groups of animals, there is a clear morphological continuity between central and peripheral beta cells. On the basis of systematic patterns of beta cell dendritic orientation, ther area centralis of the normal cat can be divided into a central region, approximately 200 micrometers in diameter, and a pericentral region, approximately 1,400 micrometers in diameter. In the central region, nearly all beta cells have a single large primary dendrite which descends perpendicular to the plane of inner plexiform layer, and gives rise to a dendritic tree which is vertically aligned with the cell's soma. In the pericentral region, the single primary dendrite of most cells descends obliquely through the inner plexiform layer and gives rise to a dendritic tree which is displaced laterally from the position of the soma. For most of the cells the trajectory of the dendrite is systematically related to the location of the cell relative to the area centralis such that the somas are displaced away from its center, presumably in order to minimize the thickness of the ganglion cell layer in the high acuity region. Many beta cells outside the pericentral region also have oriented single primary dendrites, but their orientation seems fairly random with respect to the location of the area centralis. In the Siamese area centralis, this systematic pattern of beta cell dendritic orientation is markedly reduced, suggesting that the pattern is under genetic control. On the basis of these observations, a model for the evolution of the area centralis and fovea is presented which involves selection for systematic for systematic patterns of dendritic orientation in regions of high ganglion cell density.

Animals↗
PubMed1981

The distribution of ganglion cells in the retina of the North American opossum (Didelphis virginiana).

The distribution of ganglion cells in the retina of the opossum was determined from whole-mounted retinae stained with cresyl violet. Isodensity lines were approximately circular with a peak density of 2,000 to 2,700 cells/mm2 in superior temporal retina (area centralis). The total number of retinal ganglion cells was estimated to be 72,000 to 135,000 (mean 101,026) in retinae ranging from 125 to 187 mm2 in total area. Three groups of ganglion cells were distinguished on the basis of soma size and retinal topography. Large cells (24 to 32 micrometer diameter) were fairly evenly distributed across the retina. Medium cells (12 to 23 micrometer diameter) were more numerous in the superior temporal quadrant than in other regions of the retina. Small cells (7 to 11 micrometer diameter) were prominent in all retinal regions, but particularly in nasal and inferior retina. An analysis of topographical differences in soma size distribution suggests that the medium size cells can be further subdivided into small-medium and large-medium groups.

Animals↗
PubMed1981

Conduction of velocity groups in the optic nerve of the North American opossum (Didelphis virginiana): retinal origins and central projections.

The axonal conduction velocity groups in the optic nerve of the North American opossum were analyzed electrophysiologically and related to soma size groups of ganglion cells in terms of their retinal origin and laterality of projection. On the basis of analysis of field potentials and single unit responses recorded at the optic disc, three velocity groups were identified (d1, d2, and d3) and estimated to have average conduction velocities of 12, 8, and 5 meters/second. From recordings of the field potential around the perimeter of the optic disc, it was found that the d1 group was equally represented at all points around the disc, whereas the d2 group was largest in amplitude in superior temporal regions. Electrical stimulation of the optic tracts indicated that axons in the d1 group project either ipsilaterally or contralaterally, whereas the d2 group projects predominantly ipsilaterally, and the d3 group projects predominantly contralaterally. In order to relate these physiological data directly to soma size groups, horseradish peroxidase (HRP) was injected into one optic tract, and subsequently the retinae were processed for peroxidase reaction product in the ganglion cells. Labeled cells were seen in contralateral nasal, contralateral temporal, and ipsilateral temporal retina. Cells in all size classes were labeled in contralateral nasal retina. In contralateral temporal retina, labeled cells were either 10-17 micrometers diameter (small and medium) or 23-27 micrometer diameter (large), whereas in ipsilateral temporal retina, most labeled cells (94%) were 15-30 micrometer diameter (medium and large). The correspondence between these conduction velocity groups and the soma size groups described in the preceding paper (Rapaport et al., "81) is discussed.

Afferent Pathways↗
PubMed1980

Different regional specializations of neurons in the ganglion cell layer and inner plexiform layer of the California horned shark, Heterodontus francisci.

We have described a population of neurons in the retinal of a shark, Heterodontus francisci, which is precisely aligned within the inner plexiform layer (IPL) and which differs from neurons in the ganglion cell layer (GCL) in soma size and topographical distribution. GCL neurons are relatively small and form a horizontally oriented visual streak; IPL neurons are significantly larger and form a circular specialization in the far temporal retina. Thus, it appears that there are two distinct retinal specializations in Heterodontus: one subserving frontal vision and one which provides a panoramic view of the lateral visual field.

Animals↗
PubMed1980

Parametric and feature extraction analyses of the receptive fields of visual neurones. Two streams of thought in the study of a sensory pathway.

Two major conceptual approaches to the study of visual receptive field physiology can be identified; one, here termed the 'parametric' approach, which considers all the properties of a cell to be potentially related to that cell's functional role, and a second, here termed the 'feature extraction' approach, which regards a particular receptive field property as defining a cell's role in the visual system. The parametric approach seems most compatible with network theories of visual information processing, while the feature extraction approach suggests a localized single-cell form of visual representation. In this paper we trace the growth and development of these two approaches, from 1938 to the present, by dividing this period into four segments: 1938--1953, during which the foundations of both approaches were laid; 1953--1966, the major period of growth for feature-extraction analyses; 1966--1975, the major period of growth for parametric analyses; and 1975 to the present, during which the parametric approach has been expanded by the incorporation of principles of systematics and population biology to enable groups of neurones to be studied from a biological perspective.

Animals↗
PubMed1980

The interpretation of variation in the classification of nerve cells.

Within any biological population there is considerable variation in the physical characteristics of individual members, and the understanding and classification of such populations always depends on the interpretation of this variation. A major point of this paper is that groups of neurones can also be regarded as biological populations, and that at least three distinct types of variation can be found within any neural population:role-indicating variation, which enables different cells or groups of cells to perform different functions; systematic variation, which allows different cells (or sometimes the same cell) to perform a particular function under varying conditions; and residual variation, which is principally related to mechanisms of evolution and provides the population with its biological adaptability. Examples of these three types of variation are suggested for a number of properties of retinal ganglion cell populations. A second major point is that any functional classification of nerve cells should contain multiple taxonomic levels, corresponding to different levels of complexity and interaction within the nervous system. Thus, individual cells can belong to more than one group, each at a different taxonomic level, and these groups of cells can be viewed as interacting with each other rather than as operating in isolation. A multiple-level classification of cat retinal ganglion cells is presented with two broad groups, each subdivided into two lower-level groups, and an attempt is made to identify the categories of visual function to which these groups are related.

Animals↗
PubMed1979

The importance of knowing our own presuppositions.

This essay is in two parts. In the first part, consideration is given to specific issues raised in the preceding article, stressing two considerations. First, although Dr. Hughes disclaims an essentialist position, he in fact argues consistently for a classification of nerve cells based on key, essential features; except where, briefly, he argues for a numerical taxonomic approach. He apparently has not understood the hypothetico-deductive approach proposed by us. Second, he has not given consideration to important biological aspects of the problem of cell classification, in particular to the significance of variation of properties both within groups of cells and between corresponding groups. In the second part we argue that underlying the exchange of specific criticisms are differences in scientific methodology. We attempt to identify these differences, and to relate them to the present discussion. We hope that this will help focus subsequent discussion on the central issues involved and we argue for increased awareness on the part of neurobiologists of our own presuppositions about how science works.

Animals↗
PubMed1978

Retinal abnormalities in the Siamese cat.

Ganglion cell density maps of the retinas of Siamese cats show the same major features of ganglion cell distribution as are found in normally pigmented cats, in particular the area centralis and visual streak. In the retinas of the seven Siamese cats investigated, however, the areas centralis was "underdeveloped" when compared with the normally pigmented cat. The peak ganglion cell density was lower and the ganglion cells usually larger than at the area centralis of the normally pigmented cat, and the characteristic blood vessel pattern around the area centralis was less developed. One animal showed a marked blood vessel abnormality, a vessel crossing the area centralis in each retina. In another animal, the distribution of ganglion cells appeared abnormal throughout the retina. Medium-sized, possibly X-type ganglion cells were lacking from all retinal areas, overall cell numbers were low and the distribution of ganglion cells showed a prominent visual streak.

Animals↗
PubMed1977

Naming of neurones. Classification and naming of cat retinal ganglion cells.

Many schemes of ganglion cell classification seek to classify the cells by some particular characteristic, such as the time course of the cells' physiological responses or their dendritic morphology. It is here argued that such schemes are based on the Aristotelian concept of "essences" and raise the same difficulties as have arisen with the essentialist approach to animal taxonomy. A better approach to the classification of neurones, it is proposed, is to base the classification on as many features of the cells as possible, and to regard the classification as an hypothesis, subject to testing and modification by experience, about the "functional niches" occupied by the cell types distinguished.

Animals↗
PubMed1976

Effects of early retinal lesions on conduction velocity relationships in the dorsal lateral geniculate nucleus of the cat.

Bilateral retinal lesions have been made in and around the area centralis in 5 kittens 23-28 days of age. Twelve to 14 months later, microelectrode recordings were made in the LGN of these animals. Penetrations through the medial, deafferented portion of the nucleus encountered retinally innervated cells at the same rate as penetrations through the intact lateral half of the nucleus or through the LGN of normal adult cats. The correlation between orthodromic anc antidromic latency for LGN relay cells in experimental animals was reduced when compared to normal animals, and the percentage of cells receiving dual fast and slow retinal input was increased in experimental animals. These observations are interpreted as evidence that the medial portion of the LGN was reinnervated following the neonatal retinal lesions, and that the specificities that normally exist between relay cells and their retinal afferents in terms of axonal conduction velocity were not maintained during the course of this reinnervation.

Age Factors↗
PubMed1976

Properties of ganglion cells in the visual streak of the cat's retina.

The properties of ganglion cells in the visual streak of the cat's retina have been investigated. Evidence is presented that the streak is formed principally, but not entirely, by a concentration of small-bodied ganglion cells with the receptive field properties and slow-conducting axons typical of W-cells.

Action Potentials↗
PubMed1976

Properties of relay cells in cat's lateral geniculate nucleus: a comparison of W-cells with X- and Y-cells.

1. Observations are presented on the physiological properties of W-, X-, and Y-type relay cells in the cat's lateral geniculate nucleus (LGN). Emphasis is placed on the most recently recognized type, W-cells; data are presented on X- and Y-cells by way of comparison. 2. Seventy-seven W-cells were recognized on 70 microelectrode penetrations through the LGN. They resembled W-type retinal ganglion cells in their responses to visual stimuli. Tonic (on-center and off-center) W-cells, phasic (on-, off- and on-off center) W-cells, suppressed-by-contrast, and color-coded cells were recognized. 3. W-type relay cells also resembled retinal W-cells in their maintained activity and receptive field-center diameters. 4. W-type relay cells comprised 11.5% X-cells 48.4%, and Y-cells 22.3% of all LGN cells encountered on a reference sample of 62 electrode tracks. W-cells were found in laminae C, C1, and C2, comprising 36.5% of the sample in these laminae, but were not encountered in laminae A or A1. X- and Y-cells were found in laminae A, A1, and C. Within lamina C there was a tendency for X- and Y-cells to be located dorsal to W-cells. There was thus a substantial dorsoventral segregation of W-cells from X- and Y-cells. W-cells being found in the ventral parvocellular component of the dorsal LGN. 5. Cells considered to be W-type relay cells were shown to respond to electrical stimulation of the optic nerve and chiasm at latencies which were longer than those of X- and Y-cells, and were consistent with their receiving monosynaptic input from retinal W-cells. Geniculate W-cells of all subtypes were activated antidromically from the visual cortex. Their antidromic latencies were, on the average, longer than for Y- or X-cells, indicating that W-type relay cells had slower axons as well as slower retinal afferents, than X- or Y-cells. 6. The visual cortex thus appears to receive input from all three major types of retinal ganlion cells (W-, X-, and Y-cells) relayed separately, in parallel, by different groups of relay cells.

Action Potentials↗
PubMedDate not supplied

The surgical treatment of infective endocarditis.

We have reviewed 108 cases of bacterial endocarditis treated surgically since 1968. The mean age of the patients was 47.7 +/- 15.6 years (+/- SD) (range, 14-79 yr). Seventy-seven percent were male. The most common causative organisms were staphylococci (46%), streptococci viridans group (5%), and other streptococci (20%). Forty-five percent, 25%, and 13% of patients had native aortic valve, native mitral valve, or native double valve (AV/MV) involvement, respectively. Eighteen patients had prosthetic valve endocarditis. No patient underwent surgery for tricuspid valve endocarditis. Seventy-three patients were considered to have active endocarditis (AE) (positive blood or tissue cultures and/or annular abscess). The 35 remaining patients had healed endocarditis (HE). Preoperative complications in patients with either AE or HE were stroke (11%, 11%), renal failure (33%, 3%; p less than 0.001), pulmonary edema (83%, 34%; p less than 0.001), anemia (36%, 8%; p less than 0.01), and inotrope dependence (22%, 6%; p less than 0.05). Hospital mortality for native valve AE was 19.5% (11/56), and for healed endocarditis, 5.7% (2/35). Independent predictors of hospital mortality were inotrope dependence (p less than 0.001), annular abscess (p less than 0.01), pulmonary edema (p less than 0.01), and staphylococcal infection (p less than 0.05). The 5-year actuarial survival for operative survivors was 68.4 +/- 7.5% (AE) and 78.3 +/- 9.2% (HE). We conclude that the operative mortality for patients with continuing sepsis is high and that surgery should be undertaken early in staphylococcal endocarditis. If surgery is successful, then the long-term prognosis is good.

Adolescent↗
PubMedDate not supplied

Spatial receptive-field structure of cat retinal W cells.

We have used frequency-domain methods to characterize the spatial receptive-field structure of cat retinal W cells. For most ON- and OFF-center tonic and phasic W cells, measurements of responsivity to drifting gratings at various spatial frequencies could be adequately described by a difference-of-Gaussians (DOG) function, consistent with the presence of center and surround mechanisms that are approximately Gaussian in shape and whose signals are combined additively. Estimates of the responsivity of the center mechanisms of tonic and phasic W cells were similar, but both were significantly lower than the corresponding values for X or Y cells. The width of the center mechanisms of tonic W cells, phasic W cells, and Y cells did not differ significantly from each other, but all were significantly larger than the width of X-cell centers. Surround parameters did not vary significantly among the four groups of ganglion cells. Measurements of contrast gain in both tonic and phasic W cells gave values that were significantly lower than in X or Y cells. Virtually all of the phasic W cells in our sample displayed evidence of spatial non-linearities in their receptive fields, in the form of either d.c. responses to drifting sine-wave gratings or second harmonic responses to counterphased gratings. The spatial resolution of the mechanism underlying these nonlinearities was typically higher than that of the center mechanism of these cells. Most tonic W cells exhibited linear spatial summation, although a subset gave strong second harmonic responses to counterphased gratings. Spatial-responsivity measurements for most ON-OFF and directionally selective W cells were not adequately described by DOG functions. These cells did, however, show evidence of spatial nonlinearities similar to those seen in phasic W cells. Suppressed-by-contrast cells gave both modulated and unmodulated responses to drifting gratings which both appeared to involved rectification, but which differed from each other in both spatial resolution and contrast gain. These data confirm earlier reports that the receptive fields of tonic and most ON- or OFF-center phasic W cells appear to include classical center and surround mechanisms. However, the receptive fields of some phasic cells, as well as ON-OFF and directionally selective W cells may have quite different structures. Our results also suggest that phasic, ON-OFF, directionally selective, suppressed-by-contrast, and a subset of tonic W cells may all receive nonlinear inputs with characteristics similar to those described in the receptive fields of retinal Y cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Spatio-temporal receptive-field structure of phasic W cells in the cat retina.

The spatio-temporal receptive-field structure of 54 phasic W cells in cat retinas has been examined using the reverse-correlation method of Jones and Palmer (1987). Within this sample, 12 cells had on-center, 16 off-center, and 26 on-off receptive fields. Three of the on-center and seven of the on-off cells were directionally selective. Forty percent of the cells in this sample had local receptive fields consisting of two or more distinct subregions. However, no correlation was observed between the number of subregions in the local receptive field and other response properties such as center sign or direction selectivity. In all cases, individual subregions, including those in on-off cells, appear to be produced by a half-wave rectification of the input signal. For 76% of the cells, these local receptive fields were contained within large suppressive fields which could be seen to extend for at least 10 deg in all directions with no apparent spatial structure. The mechanism producing the suppressive field also appears to involve a rectification of the input signal, and has a relatively high spatial resolution. Furthermore, the suppressive field itself is only responsive to moving or flickering stimuli; large, stationary gratings have no effect on the output of the local receptive-field mechanism. Thus, the overall receptive-field organization of these cells is particularly well suited for detecting local motion. The remaining 24% of cells in the sample lacked suppressive fields, and consequently responded well to large moving stimuli, but these cells were otherwise similar in their receptive-field properties to cells with suppressive fields. The significance of these properties is discussed in the context of the projections of phasic W cells to the superior colliculus and accessory optic system.

Animals↗