Retinotopic organization of the posterior suprasylvian area of the feline cerebral cortex

Representation of the visual field was investigated in the feline posterior suprasylvian area (PSA) using electrophysiological mapping techniques. The PSA is one of the extrastriatal visual structures of the cerebral cortex. The PSA retinotopic organization pattern was also studied. Neuronal receptive fields (RF) were mainly located in the upper contralateral quadrant and just a small number in the lower contralateral quadrant of the visual field. Approximately 10% of RF were located in the upper ipsilateral quadrant. The central area of the visual field extending in a radius of 20–30° from the area centralis was mainly represented in the upper section of the PSA (areas 21a and 21b). The RP of neurons located more peripherally to the area centralis are found in the lower portion of the PSA (areas 20a and 20b); these occupy a correspondingly greater area. Experimental finding did not confirm any substantial differences in the retinotopic organization of areas 21a, 21b, 20a, and 20b comprising the PSA. Data obtained would tend to indicate that the PSA consists of two areas, 21a and 21b, which do not appear to be subdivided, with more densely distributed visual neurons in the former than in the latter.Institute of Experimental Biology of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 23, No. 3, pp. 290–296, May–June, 1991.     

“Regular” visual receptive fields of neurons of the cat lateral geniculate body

The spatial organization of receptive fields (RF) of neurons was studied in the lateral geniculate body (LGB) of cats with pretrigeminal transection of the brainstem (without general anesthesia). Using systematic point testing of the entire RF area and adjacent regions, the RF configuration and distribution of the response types for a stable flickering stimulus throughout the RF area were determined. Only 40% (64 units of 160 studied) LGB neurons had simple RF configuration. Such RF of ellipsoid or round shape were called regular receptive fields, RRF. Most RRF (51, or about 80%) demonstrated spatially homogeneous organization with similar-type (on, off, oron-off) responses to stimulation of the entire RF area. The RRF of 13 neurons, i.e., about 20%, included subfields with qualitatively different responses to application of a stable flickering light spot. The position of subfields was asymmetrical in 8 neurons (13%), while a nearly concentric RF arrangement, with the center surrounded by an antagonistic area, was found only in 5 units (7%) with RRF. Nearly all neurons with heterogeneous RRF demonstrated directional selectivity to moving stimuli.Neirofiziologiya/Neurophysiology, Vol. 27, No. 5/6, pp. 413–424, September–December, 1995.     

Organization of afferent inputs of the parietal association (area 7) and Clare-Bishop areas of the cat neocortex

Unit activity was recorded from two parietal areas of the cat neocortex in semichronic experiments. Cell responses to presentation of adequate stimuli of different modalities and to direct electrical stimulation of various cortical zones were studied. About 4% of neurons of the Clare-Bishop area did not respond to visual stimulation. Cells responding to stimuli of different modalities were found in the Clare-Bishop area. A high percentage of cells in this area responded to direct electrical stimulation of area 17. In the association area (area 7) 27% of neurons tested responded to visual stimuli, but only a very small relative number of cells (compared with responding neurons of the Clare-Bishop area) responded to stimulation of the primary sensory areas. Electrical stimulation of area 7 inhibited evoked and spontaneous unit activity in the Clare-Bishop area. The hypothesis that these areas are the association representation of two different sections of the visual system — retino-geniculocortical and retino-tecto-thalamocortical — is discussed.Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 13, No. 6, pp. 612–620, November–December, 1981.     

Divergence between axonal collaterals of thalamic neurons running to the cat visual and association cortex

Projections from thalamic neurons to the visual (area 17) and parietal association cortex (area 7) were investigated in cats by means of retrograde axonal transport of fluorescent dyes. Pulvinar neurons may be divided into three groups on the basis of their connections with these areas: those projecting to area 7 (the largest (the largest group of cells), those projecting to area 17 (the smaller group), and others sending out axons to two cortical areas at the same time (a few isolated units). The two first groups only were found in the posterolateral thalamus. Divergence between axonal collaterals of pulvinar neurons may be responsible for parallel routes of information transmission to the visual and association cortex.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 4, pp. 513–520, July–August, 1990.     

Association connections of the cat's parietal cortex

Intercortical connections of primary sensory (visual, auditory, somatosensory) areas with the parietal association cortex were studied in cats by the retrograde axonal transport of horseradish peroxidase and the Fink-Heimer silver impregnation of degenerated fibers techniques. This combined study revealed the shape, size, and intracortical location of cells connecting the primary sensory areas monosynaptically with the parietal cortex and also the distribution of preterminals and terminals of the fibers of these cells in the parietal association cortex. The greatest number of cells forming connections with area 7 of the parietal association cortex was shown to occur in visual area V1, and with area 5 in somatosensory area S1. Besides pyramidal neurons tagged with horseradish peroxidase, which were located mainly in layers II–IV, a few tagged stellate and fusiform cells also were found. The results supplement and confirm data on afferent connections of the parietal association cortex in cats.M. Gor'kii Donetsk Medical Institute. Translated from Neirofiziologiya, Vol. 13, No. 1, pp. 3–6, January, 1981.     

Regional morphological variations within the crayfish eye

Summary The existence of structural asymmetries has been quantitatively demonstrated in the crayfish compound eye. Variations in the size of the rhabdomes and corneal facets, as well as the size and extent of the accessory reflecting pigment cells, have been found. It was determined that the mean rhabdome diameter within a 70° arc in the dorsal quadrant of the retina is 11–19% smaller than the mean rhabdome diameter in the remaining areas of the eye. Also, the extent of the accessory reflecting pigment cells is diminished over an area corresponding generally to the dorsal region of smaller rhabdomes. Corneal facet size and shape vary over the surface of the cornea, with smaller facets occurring in the dorsal region. Both the mean rhabdome diameter and the mean corneal facet area for whole eyes increases linearly in animals ranging in size from 3.9–12 cm. The estimated number of corneal facets, and therefore the number of rhabdomes, increases from an average of 4700 in the 3–6.9 cm size range to about 6000 in 7–12 cm animals. These data indicate that structural asymmetries and various size-related parameters exist in the crayfish eye and should be considered in any quantitative analysis of this structure.Supported by a grant from the National Science Foundation (BNS 80-04587)     

Macrobenthic distribution and community structure in the upper navigation pools of the Upper Mississippi River

The northern section of the Upper Mississippi River supports a diverse macrobenthic assemblage. Distribution of this benthic fauna, benthic community structure, and factors which influences which influence both of these phenomena in these upper pools are reviewed. Dumping of heavy loads of municipal and industrial wastes from the Minneapolis-St. Paul metropolitan area has severely stressed the benthic community. Once abundant, pollution-sensitive mayflies, Hexagenia bilineata and H. limbata, are noticeably absent, replaced by pollution-tolerant oligochaetes and midges (notably Chironomus). Harmful effects of this pollution are not restricted to the area immediately downstream from the Twin Cities. In Lake Pepin, the Hexagenia population has suffered a drastic decline. The benthic community is characterized by low species diversity and a dominant, pollution-tolerant Chironomus plumosus — Oligochaeta — Sphaeriidae — Hirudinea community complex. Farther south, effects of the high organic load which originates approximately 226 km upstream are ameliorated. Inundation of large, diverse land areas contributes to the great ecological diversity in Pools No. 7 and No. 8. In Navigation Pool No. 7, benthic standing crops in the backwater pool areas (biomass range: 2.08–26.96 g m^–2) exceed those in the main channel (biomass range: 0.05–1.02 g m^–2). Greater numbers of burrowing mayflies and mollusks were found in the pool areas. Of 131 taxa collected from 1976–1977 in Lake Onalaska, which occupies most of Pool No. 7, eight dominant groups — Oligochaeta, Hirudinea, Isopoda, Amphipoda, Lepidoptera, Diptera, Gastropoda, and Pelecypoda — accounted for 90–93% of the macroinvertebrates. In Pool No. 8, over half of the 144 benthic taxa collected during the summer of 1975 were insect nymphs and larvae. Oligochaetes were by far the most ubiquitous and dominant macroinvertebrates. Habitat preferences of particular benthic forms reflected distributional relationships between macroinvertebrates and physical-chemical conditions. Benthic production, in terms of total wet weight m^–2 and macroinvertebrate density in each study area, was generally greater in the more eutrophic areas. However, fewer taxa were supported in these areas. These taxa were generally pollution-tolerant organisms, such as oligochaetes and certain chironomids, which were capable of burrowing into depositional-type substrates. More taxa and greater numbers of gill breathers and filter feeders, such as caddisflies, mayflies, stoneflies, and dipterans, were collected from less eutrophic areas.     

Comparison of spontaneous cortical unit activity in several brain areas of unanesthetized cats

Spontaneous unit activity in association area 5 and some projection areas of the cortex (first somatosensory, first and second auditory areas) were studied in cats immobilized with D-tubocurarine in which the index of specific spontaneous activity, the mean frequency, types of spontaneous activity, and statistical parameters — distribution of interspike intervals and autocorrelation function — were determined. The results showed that spontaneous unit activity in the association area differs from that in the projection areas in both intensity and character. A special feature of the spontaneous activity of the auditory areas was a well-marked volley distribution of activity. In the somatosensory area the level of spontaneous activity as reflected in all indices was the lowest. In the association cortex the largest number of neurons with spontaneous activity lay at a depth of 500–1000 µ corresponding to cortical layers III–IV. In the first auditory area neurons with spontaneous activity were concentrated at a depth of 1400 µ (layer V) and in the somatosensory area at a depth of 1000–1400 µ (alyers IV–V). The possible functional significance of these differences is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 8, No. 1, pp. 13–21, January–February, 1976.     

Growth and age structure of the swan mussel Anodonta cygnea (L.) at different depths in lake Mattsee (Salzburg, Austria)

Unionid clams were collected at 1–2 m, 3–4 m and 6–7 m depth in lake Mattsee, a moderately mesotrophic lake, to investigate the effect of depth on clam growth and age structure. No significant differences in age structure of Anodonta cygnea were found (p=0.65). Three and ten years old clams were present at all depths, but in different percentages. Whereas at 1–2 m 13.3% of the collected clams were <4 years old, this percentage was 4.4% at 6–7 m and 7.1% at 3–4 m. A greater percentage (6.7%) of older mussels (9, 10 years) were collected at 6–7 m than at 1–2 m (2.2%). Growth declined with depth. Total length at a given age of clams at 1–2 m and 3–4 m did not differ (p=0.54), whereas differences were significant between clams at 1–2 m and 6–7 m (p<0.05) as well as between 3–4 m and 6–7 m (p<0.05). The Growth constant k was highest at 1–2 m depth.     

Direct connections between the R7/8 and R1–6 photoreceptor subsystems in the dipteran visual system

Summary Musca and related flies have three main photoreceptor subsystems. The R1–6 group has short axons that terminate in the cartridges of the first optic neuropile, the lamina. The cartridges are bypassed by the longer axons of R7 and R8, which run together to terminate at different levels in the underlying medulla neuropile. The present account describes a shallow, previously unidentified zone in the lamina within which R7/8 make glancing contact with R1–6. At the distal border of the cartridge over no more than 3–4 m depth, the tangentially directed short axon of R6 squeezes between the pair from R7 and R8, forming quite large areas of mutual contact (approximately 7 m²). Less frequently, R1 is contacted. At least some of these sites contain smaller membrane specialisations indistinguishable from the more numerous gap junctions found more proximally that interconnect the terminals of R1–6. The R7/8 junctions with R6 are of comparable size (0.15 m²) and likewise possess symmetrical membrane densities. They provide proposed pathways for direct electrical interaction to account for observed electrical input from R7/8 to the R1–6 subsystem. In two cases R7/8 was possibly postsynaptic to R1–6 at a multiple-contact synapse, but even if functional, these sites were so rare that they are unlikely to have much operational significance.     

Effect of the abundance of three predominating copepod species on adequate sample volume and sample size in Bransfield Strait (Antarctic Peninsula) and waters north of the Weddell Sea

Summary The effect on adequate sample size and sample volume of the abundances of three predominant copepod species, Metridia gerlachei, Calanus propinquus and Calanoides acutus, were studied in Bransfield Strait (Antarctic Peninsula) in the austral summer of 1988–1989 and waters north of the Weddell Sea in 1989–1990. Copepod abundances were higher in the area north of the Weddell Sea, with the exception of Metridia gerlachei, which was evenly distributed over both areas. Local (intra-station) patchiness was not found, indicating random distribution over small areas. In the assessment of inter-station variability in Bransfield Strait, with standard error of the mean set arbitrarily at 20% of the average abundance and a sampling volume of 150 m³, the theoretical minimum sample size (number of sampling stations) ranged from 6 to 17 for juvenile copepods and from 11 to 25 for adults. The minimum number of stations in the area north of the Weddell Sea reached from 5 to 7, and from 7 to 10 respectively.     

Limnological and morphometrical data of eight karstic systems `cenotes' of the Yucatan Peninsula,Mexico, during the dry season (February–May, 2001)

The karstic nature of the Yucatan Peninsula allows the formation of natural sink-holes from the dissolution of calcareous rock. These systems are almost the only epigean source of fresh water available in this region. In spite of their biological importance, little is known about the morphometric and limnologic characteristics of these karstic systems. We measured limnological variables in eight cenotes in central Quintana Roo during February–May, 2001. Zooplankton biomass and chlorophyll a were also measured in order to determine if the behavior of primary and secondary production was related to environmental parameters. Important short-term changes were observed in nutrients (NO₃ ^–, NO₂ ^–, PO₄ ^3-), biomass, and chlorophyll a. The morphometrically conditioned productivity (MCP), which evaluates the cumulative effect of several morphometric variables on production (area, maximum length, shoreline development, perimeter), showed a negative correlation with respect to zooplankton biomass, as did also both pH and temperature. Conversely, NO₃ ^– and NO₂ ^– had a positive correlation with zooplankton biomass. No correlation was found for chlorophyll a. Significant differences in NO₃ ^– (F = 61.52, p<0.001), NO₂ ^– (F = 7.36, p<0.001), zooplankton biomass (F = 17.57, p<0.001), chlorophyll a (F = 62.19, p<0.001), and conductivity (F = 497.49, p<0.001) were found among the systems. These results indicate the existence of sharp differences between these karstic systems (oligotrophic, with smaller area, deep and less productive) and non-karstic ones, (eutrophic, larger area, shallow and more productive) but are similar to previous data from other karstic systems of Mexico and other parts of the world. However, understanding of these fragile tropical systems is in the initial phase. It is necessary to increase the intensity of these studies in order to allow a full explanation of their limnological behavior.     

Retrosplenial and hippocampal projections of structures of the thalamoparietal associative system in rats

Afferent connections of the nucleus lateralis posterior (NLP) of the thalamus and area 7 of the parietal cortex with the retrosplenial region of the limbic cortex and hippocampus were studied in rats with retrograde axon transport of horseradish peroxidase. It was shown that the NLP receives ipsilateral projections from area 29d neurons, while area 7 receives ipsilateral axons from area 29d and 29c neurons. It was found that associations of the retrosplenial region with associative cortex are far more pronounced than with associative thalamus. Moreover, the afferent connections of area 7 with area 29d are more numerous than with area 29c. We disclosed no projections of areas 29a and 29b to thalamoparietal system structures. In addition to neocortical input from the limbic cortex, area 7 receives afferent fibers from the archicortex; neurons situated in hippocampus area CA1 are the source of these projections.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy Academy of Sciences, Leningrad. Translated from Neirofiziologiya, Vol. 23, No. 6, pp. 647–655, November–December, 1991.     

Repetitive firing in motor nerve endings: Divalent cation,rhythmic activity,and cholinergic agent modulation

Repetitive firing (RF) as two or more end plate currents (EPC) induced by a single stimulus of the motor nerve was studied in sartorius frog muscle under voltage clamp conditions. In the presence of 4-aminopyridine (1.10^–4 M), RF as two EPC with 3–8 msec intervals was found in half of the cells (n=35). When calcium ion concentration was increased from 1.8 to 5.4 mM, magnesium to 5–9 mM, and rhythmic activity beginning with 0.05 Hz and above, RF stopped, but when strontium or barium was substituted for calcium, RF intensified. In the presence of barium, the repeated EPC quantity reached six-eight per one nerve impulse. Slow currents arose in some of the cells when disruption of the EPC series was stimulated. Proserine, an anticholinesterase agent, enhanced RF, whereas -bungarotoxin, a cholinoreceptor blocker, had no effect. The role that calcium and calcium-activated potassium currents play in generating and terminating mechanisms of RF, is discussed.S. V. Kurashov Medical Institute, Russian Federation Ministry of Public Health, Kazan. Translated from Neirofiziologiya, Vol. 24, No. 4, pp. 387–395, July–August, 1992.     

Projections from areas 5 and 7 to subdivisions of the cat sensorimotor cortex

Projections from the parietal cortex (areas 5 and 7) to subdivisions of the sensori-motor cortical region were investigated in cats using axonal degeneration techniques. Differences between the density of distribution of association fibers proceeding from these areas were found within the parietal and sensorimotor cortex. Area 5 projects mainly to the posterolateral portion of the cruciate sulcus (areas 4fu and 4) and to fields 4y, 4sfu, 6iffu, 6aa, and 6ab to a lesser extent. Area 7 is connected mainly to the medial portion of the lower lip of the cruciate sulcus (areas 6iffu, 6aa, and 6ab). Somewhat fewer fibers proceed to areas 4fu and 4. Fewer projections proceed from the parietal cortex to the somatosensory than to the motor region. Only a few single fibers connect the primary somatosensory region (fields 2, 3a, and 3b) with area 5, while area 7 does not project into this area. Neither field 5 nor 7 projects to the secondary somatosensory cortical area.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 20, No. 3, pp. 319–326, May–June, 1988.     

Impact of Preexisting Interstitial Lung Disease on Acute,Extensive Radiation Pneumonitis: Retrospective Analysis of Patients with Lung Cancer

IntroductionThis study investigated the clinical characteristics and predictive factors for developing acute extended radiation pneumonitis with a focus on the presence and radiological characteristics of preexisting interstitial lung disease.MethodsOf 1429 irradiations for lung cancer from May 2006 to August 2013, we reviewed 651 irradiations involving the lung field. The presence, compatibility with usual interstitial pneumonia, and occupying area of preexisting interstitial lung disease were retrospectively evaluated by pretreatment computed tomography. Cases of non-infectious, non-cardiogenic, acute respiratory failure with an extended bilateral shadow developing within 30 days after the last irradiation were defined as acute extended radiation pneumonitis.ResultsNine (1.4%) patients developed acute extended radiation pneumonitis a mean of 6.7 days after the last irradiation. Although preexisting interstitial lung disease was found in 13% of patients (84 patients), 78% of patients (7 patients) with acute extended radiation pneumonitis cases had preexisting interstitial lung disease, which resulted in incidences of acute extended radiation pneumonitis of 0.35 and 8.3% in patients without and with preexisting interstitial lung disease, respectively. Multivariate logistic analysis indicated that the presence of preexisting interstitial lung disease (odds ratio = 22.6; 95% confidence interval = 5.29–155; p < 0.001) and performance status (≥2; odds ratio = 4.22; 95% confidence interval = 1.06–20.8; p = 0.049) were significant predictive factors. Further analysis of the 84 patients with preexisting interstitial lung disease revealed that involvement of more than 10% of the lung field was the only independent predictive factor associated with the risk of acute extended radiation pneumonitis (odds ratio = 6.14; 95% confidence interval = 1.0–37.4); p = 0.038).ConclusionsPretreatment computed tomography evaluations of the presence of and area size occupied by preexisting interstitial lung disease should be assessed for safer irradiation of areas involving the lung field.     

Peculiarities of Visually Sensitive Neurons of the Extrastriate Associative Area 21b of the Cat Brain Cortex

On cats with pretrigeminal brainstem transection, we studied the properties of visually sensitive neurons of the extrastriate associative cortical area 21b. The dimensions and spatial distribution of the receptive fields (RF) of the neurons within the vision field were determined. It was found that large-sized RF prevailed within the area 21b (10 to 200 deg², 61%; greater than 200 deg², 22%), whereas small-sized RF (1 to 10 deg²) constituted 17% of all the studied RF. Stationary visual stimuli evoked on–off, off, and on responses in 43, 30, and 27% neurons of the area 21b, respectively. In the cases where moving stimuli were presented, 35% of the neurons demonstrated directional sensitivity; the rest of the neurons (65%) were directionally insensitive. We also found a group of neurons that were capable of differentiating not only the direction of the stimulus movement along the RF but also the dimension, shape, and orientation of a complicated moving stimulus. Taking into account the data obtained, we discuss the functional role of the neurons, which demonstrated a specific (specialized with respect to a set of the parameters of visual stimulus, and not to a single parameter) response in central processing of the sensory information.     

Spatial variation in polyphenolic content of Ascophyllum nodosum (Fucales,Phaeophyta)

Spatial variation in polyphenolic content in annual shoots of the brown alga Ascophyllum nodosum was quantified using a hierarchical sampling design. Three sampling levels, covering distances of 10⁰–10⁶ m, were used. Comparisons were made between two areas, Tjärnö on the Swedish west-coast and the Isle of Man in the Irish Sea, with very different types of environmental conditions. No significant differences in mean polyphenolic levels were found between the two study areas (6.6% of dry mass at Tjärnö and 9.2% at the Isle of Man), whereas significant and substantial differences were found among sites within areas (range 5.7%–11.4%) and among quadrats within sites (range 3.7%–13.1 %). The extensive variation at the smaller spatial scales points out the importance of using thorough sampling procedures at all levels in large-scale studies on algal polyphenolics, e.g. biogeographical comparisons, which have been neglected in several previous studies. Moreover, the results imply that experiments on causal factors of polyphenolic variation should be designed to explain the spatial scales on which the factors are impportant. This study also investigated the relationship between polyphenolic concentration and both plant size and mean area of annual shoots. The mean area was used as an estimate of the mean growth rate of the annual shoots within an individual. No significant relationships were found between shoot growth rate, or plant size, and polyphenolic levels in annual shoots at any of the three spatial scales that were investigated.     

Morphological characteristics of the neuronal population in the feline auditory cortex projecting into the medial geniculate body

The location and morphological profile of auditory cortex neurons projecting to the medial geniculate body were investigated in adult cats using horseradish peroxidase retrograde axonal transport techniques. Sources of descending projections to the medial geniculate body from auditory cortex areas I and II were found to be neurons belonging to deep-lying layers (layer VI and layer V to a lesser extent). By far the majority of corticogeniculate neurons in the auditory cortex were pyramidal cells. In layer VI of the primary auditory area (A1), the number of corticogeniculate neurons reaches 60% of all cells belonging to that layer. The average area (M±m) of the profile of perikarya of corticogeniculate neurons in layer VI, area Al equaled 139.3±2.5 µm² and 219.5±7.0 µm² in layer V neurons; average size of long diameter: 15.0±0.19 and 18.3±0.4 µm respectively. The lower regions of layers III and IV in area Al were found to be the termination point of the greater mass of anterogradely-labeled geniculocortical fibers (terminals of relay neuron axons belonging to the medial geniculate body).A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 4, July–August, pp. 513–521, 1989.