bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal evolution of the Ryoke metamorphic belt, southwestern Japan: Tectonic and numerical modeling
Authors: Okudaira Takamoto
Published: April 2006

Abstract The Ryoke metamorphic belt of southwestern Japan is composed of Cretaceous Ryoke granitoids and associated metamorphic rocks of low‐pressure facies series. The Ryoke granitoids are divided into sheet‐like bodies (e.g. Gamano granodiorite) and stock‐like bodies. The Gamano granodiorite intruded concordantly into the high‐grade metamorphic rocks without development of a contact metamorphic aureole, and the intrusion ages of the granodiorite are similar to the ages of thermal peak of the low pressure (low‐P) metamorphism. It is suggested that the low‐P Ryoke metamorphism resulted from the intrusion of the Gamano granodiorite. In this study, a simple 1‐D numerical model of conductive heat transfer was used to evaluate the thermal effects of emplacement of the Gamano granodiorite. Calculated temperature‐time (T‐t) paths are characterized by a rapid increase of metamorphic temperature and a relatively short‐lived period of high temperature. For example, the T‐t path at the 15‐km depth is characterized by a rapid average increase in temperature of 1.4 × 10‐3°C/year and high temperatures for < ca 0.5 Ma. The calculated peak temperature for each depth is nearly equal to the petrologically estimated value for each correlated metamorphic zone. The results suggest that the magma‐intrusion model is one possible thermal model for low‐pressure facies series metamorphism.
Evolution of fault geometry and development of strike‐slip basins: Comparative studies on the transform zones in Turkey and Japan
Authors: Yoshioka Toshikazu
Published: April 2006

Abstract Although the origins of pull‐apart basins and push‐up bulges have been discussed by numerous geologists, no discussion has been held on the development process of the basins based on recent active traces and Quaternary chronology. The author has investigated recent fault‐active traces and fault topography in the Havza‐Ladik, Erbaa‐Niksar, Susehri‐Golova and Erzincan sedimentary basins along the North Anatolian fault in northern Turkey and the Suwa basin along the Itoigawa‐Shizuoka tectonic line (fault system) in central Japan. As a result of this investigation, the locations and sense of deformation of recent active traces seldom coincide with topographic scarps along basin margins in the studied basins. The fault traces have migrated from the basin margins to the center of the basins and become straight. Because of this migration, jogs are extinguished and basins stop subsiding as time passes. Fault topography formed by a strike‐slip fault has a certain life span, and the life span is in proportion to the size of the topography. Fault topography formed by various sizes of jogs of a strike‐slip fault is formed and extinguished in the corresponding time range, and this extinction is repeated in the course of migration of fault traces.
Marine geology of the Medriff Corridor, Mediterranean Ridge
Authors: Fusi Nicoetta , de Larderel Giovanni Aloisi , Borelu Ada , Amelio Ottavio , Castradori Davide , Negri Alessandra , Rimoldi Bianca , Sanvoisin Rossella , Tarbini Paola , Cita Maria B.
Published: April 2006

Abstract Thirty‐one piston and/or gravity cores not exceeding 10 m in length were raised in selected areas of a 300 km‐long transect (Medriff Corridor) crossing the Mediterranean Ridge, an accretionary complex subject to continent/continent collision, containing an important evaporitic body (Messinian evaporites), in order to ground‐truth the geological make‐up. Core location, very accurate with reference to a complex bottom configuration, was preceded by swathe mapping, seismic profiling and side‐scan sonar investigations. Most sediment cores have a pelagic facies, with biogenic marls as dominant lithology, and sapropels and tephras as minor, isochronous lithologies. A combination of isochronous lithologies and calcareous plankton biochronology permits high resolution stratigraphic correlations. Pelagic facies sediments are Middle Pleistocene to Holocene in age. Two cores associated with mounds located along thrusts contain a matrix‐supported mud breccia of deep provenance, Burdigalian‐Langhian in age, similar to that characteristic of the Mediterranean Ridge diapiric belt (Cita et al.1995). Three new brine‐filled anoxic basins (Urania, l'Atalante and Discovery) were discovered. The brines originated from submarine dissolution of Messinian evaporites and are different in the various basins. The sedimentary record strongly differs from basin to basin. These brine lakes are very young (35 000 years or less). A drastic change in sedimentation rate recorded in the Discovery Basin suggests that basin collapse was sudden and followed by progressive development of basin anoxia. Some cores were analyzed with a prototype multisensor for P‐wave velocity, magnetic susceptibility and density. Sapropels show up as abrupt decreases in P‐wave velocity and density, and tephra as sudden increases in magnetic susceptibility. Mud breccia displays P‐wave velocities greater than pelagic marls, with peaks related to lithic clasts. Anoxic sediments have high P‐wave velocities; peaks are associated with gypsum crystals.
Structure and evolution of the backstop in the eastern Nankai Trough area (Japan): Implications for the soon‐to‐come Tokai earthquake
Authors: Le Pichon X , Wmant S. , Tokuyama H. , Thoué F. , Huchon P. , Henry P.
Published: April 2006

Abstract We present data showing that the intra‐oceanic shortening now occurring south of the eastern Nankai Trough that has produced the Zenisu Ridge has also been responsible for the formation of a previous ridge now buried below the continental margin. This ridge, that we refer to as Paleo‐Zenisu, is presently adjacent to the backstop and its location coincides with the outer limit of the seismogenic decollement. The subduction of the paleo‐Zenisu ridge below the wedge has led to its complete reorganization and has given its identity to the Great Tokai earthquake rupture zone. The formation of paleo‐Zenisu and its consequent subduction has induced the tilting of the backstop toward the northwest since ca2 Ma. This model suggests that the backstop and possibly the wedge are dextrally sheared because they are extruded southwestward in relation to the collision of the Izu‐Bonin Ridge with Japan. We use the finite motion from Zenisu to paleo‐Zenisu to derive both the subduction vectors along the Nankai Trough and the shortening vectors within Zenisu‐Izu. The amount of shortening absorbed within Zenisu‐Izu increases toward the northeast. The corresponding subduction vectors of the Zenisu platelet below the wedge decrease accordingly to the northeast from 50 to less than 20 mm/year and the Zenisu body rotates clockwise with a pole near 36° North, 139° East. This might explain the apparent longer repetition time of great earthquakes in the Tokai area. On the other hand, the 25‐35 mm/year obtained for the rate of shortening along the Zenisu thrust indicates a high seismic potential there.
Cretaceous episodic growth of the Japanese Islands
Authors: Kimura G.
Published: April 2006

Abstract
The Japanese Islands formed rapidly in situ along the eastern Asian continental margin in the Cretaceous due to both tectonic and magmatic processes. In the Early Cretaceous, huge oceanic plateaus created by the mid‐Panthalassa super plume accreted with the continental margin. This tectonic interaction of oceanic plateau with continental crust is one of the significant tectonic processes responsible for continental growth in subduction zones. In the Japanese Islands, Late Cretaceous‐Early Paleogene continental growth is much more episodic and drastic. At this time the continental margin uplifted regionally, and intra‐continent collision tectonics took place in the northern part of the Asian continent. The uplifting event appears to have been caused by the subduction of very young oceanic crust (i.e. the Izanagi‐Kula Plate) along the continental margin. Magmatism was also very active, and melting of the young oceanic slab appears to have resulted in ubiquitous plutons in the continental margin. Regional uplift of the continental margin and intra‐continent collision tectonics promoted erosion of the uplifted area, and a large amount of terrigenous sediment was abruptly supplied to the trench. As a result of the rapid supply of terrigenous detritus, the accretionary complexes (the Hidaka Belt in Hokkaido and the Shimanto Belt in Southwest Japan) grew rapidly in the subduction zone. The rapid growth of the accretionary complexes and the subduction of very young, buoyant oceanic crust caused the extrusion of a high‐P/T metamorphic wedge from the deep levels of the subduction zone. Episodic growth of the Late Cretaceous Japanese Islands suggests that subduction of very young oceanic crust and/or ridge subduction are very significant for the formation of new continental crust in subduction zones.
K‐Ar ages of intrusive rocks in the Oban‐Obudu massif and their significance for the tectonic and plutonic history of southeastern Nigeria
Authors: Ekwueme Barth N. , Itaya Tetsumaru , Yabe Hisatomo
Published: April 2006

Abstract
K‐Ar ages have been obtained for mineral separates: plagioclases from two dolerites and biotites from one granite and four granodiorites in the Oban‐Obudu massif of southeastern Nigeria. Dolerites in the Oban area give K‐Ar plagioclase ages of 204.0 ± 9.9 Ma and 219.9 ± 4.7 Ma. The granite of the Obudu area yields a K‐Ar biotite age of 507.6 ± 10.1 Ma whilst the granodiorites in the Oban area yield K‐Ar biotite ages ranging from 474.6 ± 9.4 Ma to 511.8 ± 10.0 Ma. The dolerites are related to the tholeiitic basaltic magmatism at the early opening of the central Atlantic, and are compatible in age with the formation of the Ring Complexes and the rifting of the Benue Trough of Nigeria. The granites and granodiorites belong to the syntectonic Older Granite series in the Pan‐African orogeny. The emplacement timing deduced from the reported Pb‐Pb zircon age of 617 ± 2 Ma and the newly obtained biotite ages suggest that these older granites in southeastern Nigeria had a prolonged cooling history of ∼110 Ma.
The cessation of igneous activity and uplift when an actively spreading ridge is subducted beneath an island arc
Authors: Osozawa Soichi
Published: April 2006

Abstract
Ridge subduction and the resulting formation of a slab window interrupts volcanic arc‐type igneous activity and causes uplift of the arc system. These implied diachronous relationships are examined by comparison of the temporal and spatial positions of ancient migrated trench‐trench‐ridge triple junctions and the distribution of subduction‐related igneous and metamorphic rocks in Japan.
Tectonothermal evolution of the Lesser Himalaya, Nepal: Constraints from 40Ar/39Ar ages from the Kathmandu Nappe
Authors: Arita Kazunori , Dallmeyer R. David , Takasu Akira
Published: April 2006

Abstract
The Himalaya is a fold‐and‐thrust wedge formed along the northern margin of the Indian continent, and consists of three thrust‐bounded lithotectonic units; the Sub‐Himalaya, the Lesser Himalaya, and the Higher Himalaya with the overlying Tethys Himalaya from south to north, respectively. The orogen‐scale, intracrustal thrusts which bound the above lithotectonic units are splays off an underlying subhorizontal dkcollement, and show a southward propagating piggy‐back sequence with an out‐of‐sequence thrust. Among these thrusts, the Main Central Thrust zone (MCT zone) has played a major role in Himalayan tectonics. The MCT zone represents a shear zone which has accommodated southward thrusting of the Higher Himalayan crystalline thrust sheet over the Lesser Himalayan sequence for ∼140 km. The Kathmandu Nappe in central Nepal has been transported over the Lesser Himalayan metasediments along the MCT zone, and is locally separated from the Higher Himalayan thrust sheet in the north by an out‐of‐sequence thrust. 40Ar/39Ar ages have been determined for one whole‐rock phyllite and six muscovite concentrates from metasedimenta‐ry rocks and variably deformed granites in the Kathmandu Nappe. These ages range from 44 Ma to 14 Ma, and suggest a record of both Eo‐Himalayan (Eocene) and Neo‐Himalayan (Miocene) tectonothermal events in the Tertiary Himalayan orogeny. The Miocene event was associated with translation along the MCT zone. No tectonothermal event of the Late Miocene to Early Pliocene ages have been reported near the MCT zone in southern Lesser Himalayan crystalline nappe or klippe, although such events have been documented within and around the MCT zone in the northern root zone of the Higher Himalaya. This suggests that out‐of‐sequence thrusting may have occurred between 14 Ma and 5 Ma, probably during the period 10‐7.5 Ma. Since then the frontal MCT zone below the Kathmandu Nappe has been inactive, but the MCT zone in the northern root zone has remained active. The rapid increase in denudation rates of the Higher Himalaya since the Late Miocene may have been caused by ramping along the out‐of‐sequence thrust at depth.
Origin of a magnetic lineation on Kyushu Island, Japan
Authors: Okubo Yasukuni , Kanaya Hiroshi , Shibuya Akitsura , Okumura Kimio
Published: April 2006

Abstract
Several linear magnetic anomalies over continental crust have been identified in and around the Japanese Islands. The anomalies are probably related to island arc tectonic structures, but identifying specific sources has been difficult. Several deep holes were drilled in and around Aso caldera, where a linear anomaly occurs along an active fault. One drillhole located on the linear anomaly encountered a zone of highly magnetized and altered basement rocks at least 100 m thick at a depth of ∼1000 m. The other hole was located away from the anomaly and did not encounter any high‐magnetic zones. Rocks from the zone have exceptionally strong remanent magnetization (several tens of A/m) sub‐parallel to the present field. AF demagnetization experiments indicated that the magnetization is hard and stable. Magnetic modeling indicates that the linear anomaly is caused mainly by this layer. Microscopic examination of core samples shows that the highly magnetized zone includes secondary magnetic minerals and abundant hydrothermal alterations. Temperatures determined by fluid inclusions and down‐hole temperatures show that the temperature of the highly magnetized zone was elevated in the past relative to surrounding rocks. The high temperature could destroy primary magnetic minerals and replace them with secondary magnetic minerals. Thus, the past hydrothermal system may have enhanced thermo‐chemical remanent magnetization. The results can produce a model indicating that there was a past hydrothermal system related to the tectonic structure.
Structure and development of the lower crust and upper mantle of Southwestern Japan: Evidence from petrology of deep‐seated xenoliths
Authors: Nozaka Toshio
Published: April 2006

Abstract
Basic and ultrabasic xenoliths included in Cenozoic alkali basalts from the Kibi and Sera plateaus, Southwest Japan, can be classified into five groups on the basis of mineral association and texture. Their equilibration P‐T conditions estimated from paragenesis and mineral chemistry indicate that the dominant rock type from the lower crust to upper mantle changes with increasing depth as follows: (i) pyroxene granulite (Group V) and meta‐sediments; (ii) garnet gabbro (Group 111) and corundum anorthosite (Group IV); (iii) spinel pyroxenite (Group 11); and (iv) spinel peridotite and pyroxenite (Group I). Groups I1 and I11 show a lower degree of recrystallization than Groups I and V, and have similarities in composition and mineral chemistry to host basalts. Based on these facts along with the P‐T conditions of equilibration, Groups I1 and I11 are interpreted as formed from basaltic magma that intruded beneath the crust‐mantle boundary at an early stage of the magmatism of the alkali basalts, where the lower crust and uppermost mantle had consisted of Group V and metasediments, and Group I, respectively. It follows that the crust has grown downward due to underplating of basaltic magma beneath the bottom of pre‐existing crust. Group IV has commonly the same mineral assemblage, corundum + calcic plagioclase + aluminous spinel, and shows locally, nearby kyanite crystals, almost the same texture as fine‐grained aggregates in a quartzite xenolith. The aggregates appear to have been formed by reaction between kyanite and host basalt, and accordingly Group IV is interpreted as formed by reaction between metasediments and basaltic magma at the time of the underplating. The Kibi, Sera and Tsuyama areas are distinguished from the areas nearby the Sea of Japan by the occurrence of the garnet gabbro and corundum anorthosite xenoliths, by the absence of the association of olivine + plagioclase in basic and ultrabasic xenoliths, and by the lower temperature of equilibration of basic xenoliths. From these facts it is stressed that in general the crust becomes thinner and geothermal gradient becomes higher towards the back‐arc side. Such a regional variation in crustal structure must reflect the tectonic situation of Southwest Japan at the time of the magmatism of the alkali basalts, namely rifting and shallow‐level magmatism at the back‐arc side.
What controls the lateral variation of large earthquake occurrence along the Japan Trench?
Authors: Tanioka Yuichiro , Ruff Larry , Satake Kenji
Published: April 2006

Abstract The lateral (along trench axis) variation in the mode of large earthquake occurrence near the northern Japan Trench is explained by the variation in surface roughness of the subducting plate. The surface roughness of the ocean bottom near the trench is well correlated with the large‐earthquake occurrence. The region where the ocean bottom is smooth is correlated with‘typical’large underthrust earthquakes (e.g. the 1968 Tokachioki event) in the deeper part of the seismogenic plate interface, and there are no earthquakes in the shallow part (aseismic zone). The region where the ocean bottom is rough (well‐developed horst and graben structure) is correlated with large normal faulting earthquakes (e.g. the 1933 Sanriku event) in the outer‐rise region, and large tsunami earthquakes (e.g. the 1896 Sanriku event) in the shallow region of the plate interface zone. In the smooth surface region, the coherent metamorphosed sediments form a homogeneous, large and strong contact zone between the plates. The rupture of this large strong contact causes great under‐thrust earthquakes. In the rough surface region, large outer‐rise earthquakes enhance the well‐developed horst and grabens. As these structure are subducted with sediments in the graben part, the horsts create enough contact with the overriding block to cause an earthquake in the shallow part of the interface zone, and this earthquake is likely to be a tsunami earthquake. When the horst and graben structure is further subducted, many small strong contacts between the plates are formed, and they can cause only small underthrust earthquakes.
Some features of the arc‐continent collision zone in the Ryukyu subduction system, Taiwan Junction area
Authors: Karp Boris Ya. , Kulinich Ruslan , Shyu Chuen‐Tien , Wang Chengsung
Published: April 2006

Abstract To the northeast of Taiwan, northwestward subduction of the Philippine Sea plate is occurring beneath the Eurasian plate along the Ryukyu Trench. The Ryukyu Trench, which is well defined along the northeastern part of the Ryukyu arc, cannot be easily defined west of 123° east. This is an area where the Gagua Ridge (whose origin is controversial) enters the trench from the south. On the basis of the marine geophysical survey data the following results have been obtained. The structural elements associated with the Ryukyu subduction system deform and partially disappear west of 123° east. Among other things the Ryukyu Trench terminates close to the western slope of the Gagua Ridge. The Gagua Ridge is the result of tectonic heaping and is likely to be an uplifted sliver of oceanic crust. The interaction between the Ryukyu subduction system and the Taiwan collision zone encompasses a wide region from Taiwan to the longitude 124.5° east. The Gagua Ridge is a boundary between the active deformation zone related to the collision in Taiwan and the West Philippine Basin. It is proposed that there is a tectonic zone that can be traced from the Okinawa Trough on the north to the southern termination of the Gagua Ridge on the south.
High‐dose mizoribine treatment for adolescents with systemic lupus erythematosus
Authors: NOZU KANDAI , IIJIMA KAZUMOTO , KAMIOKA ICHIRO , FUJITA TERUO , YOSHIYA KUNIHIKO , TANAKA RYOJIRO , NAKANISHI KOICHI , YOSHIKAWA NORISHIGE , MATSUO MASAFUMI
Published: April 2006

Background: In treating pediatric patients with systemic lupus erythematosus (SLE), it is necessary to quickly attain remission to avoid sequelae in various organs and to maintain it over a long period. However, to maintain remission, the prolonged use of immunosuppressants which have various adverse effects, is often necessary in addition to steroids, and complications due to such immunosuppressants pose very important problems. A regimen of mizoribin (MZR) at 150 mg/day divided into two or three doses has been recommended, but while this regimen has been safe, its efficacy has not been satisfactory. However, MZR produces effects dose‐dependently, and the dose recommended to date may have been insufficient for the treatment of children with SLE.

Methods: The authors administered oral MZR at 300 mg/day in two divided doses, which is twice the conventional dose for adults, to five adolescents with SLE. Three of these five were markedly steroid‐dependent patients and two had previously been treated with steroids only. Thereafter, the authors evaluated the safety and efficacy of the regimen by following the patients for at least 7 months after the beginning of treatment.

Results: Patients 1 and 2 had been treated with prednisolone (PSL) and cyclosporine (CyA), but as the duration of CyA administration became long, it was replaced with 300 mg MZR. This transition could be accomplished smoothly. Patient 3 showed repeated recurrence during the treatment with PSL and CyA or CPM, but the symptoms could be controlled by the addition of 300 mg MZR. In patients 4 and 5, the control of symptoms with PSL alone was judged to be difficult, and concomitant administration of MZR at 300 mg was started. This resulted in a decrease in the dose of PSL. The Cmax (C2) of MZR was 1.33 μg/mL or higher in all five patients, and the efficacy of the treatment was satisfactory. Concerning side‐effects, hyperuricemia was noted in two patients, but it was resolved in one of them by reducing the dose of MZR and in the other spontaneously while the treatment was continued. Temporary exacerbation of hair loss was observed in two patients, but it disappeared in both of them after a few months.

Conclusion: MZR could be administered at a high dose effectively and safely. However, monitoring of the serum uric acid level was necessary. High‐dose MZR therapy showed an efficacy and safety that would warrant its application to steroid‐dependent pediatric patients with SLE.
Oral hypertonic glucose solution in the treatment of infantile colic
Authors: AKÇAM MUSTAFA , YILMAZ AYGEN
Published: April 2006

Background: Safe and effective treatment of infantile colic (IC) has not yet been determined. In this study, the authors aimed to investigate the efficiency of 30% glucose solution in the treatment of IC.

Methods: A total of 25 infants diagnosed as typical IC were given 1 mL of 30% glucose solution or sterile water for 4 days consecutively, in a randomized, double blind crossover trial. The effect was measured by parents’ scoring.

Results: Parents reported varying degrees of improvement in 16 infants (64%) given glucose solution, and in 12 infants (48%) given placebo. Comparison of treatment modalities were statistically significant (P = 0.031). There was no side‐effect during treatments.

Conclusion: The present study revealed that 30% glucose was effective in the treatment of IC. Since oral glucose solution is natural, safe, cheap and easily achievable, it might be considered as an alternative therapy.
Characteristics of fatigue crack propagation behaviour as identified by hysteresis loop at the crack tip
Authors: XIONG Y. , KATSUTA J. , KAWANO K. , SAKIYAMA T.
Published: April 2006

Fatigue crack propagation tests have been carried out under various load conditions. Hysteresis loops denoting the relationship between load and strain at the crack tip are obtained by using local compliance measurement. Crack growth acceleration, delayed retardation and non‐propagation phenomena are investigated by considering the variation of hysteresis loop expansion and hysteresis loop tail. Based on the physical meaning of hysteresis loops, two types of crack closure are ascertained and the effect of crack closure on fatigue crack propagation is studied. Results show that change of the effective amplitude of the stress intensity factor at the crack tip is the reason that crack propagation rates vary.
Horizontal Cells in the Monkey Retina: Immunocytochemical staining with antibodies against calcium binding proteins
Authors: Röhrenbeck Jürgen , Wässle Heinz , Boycott Brian B.
Published: April 2006

Immunocytochemistry with antibodies against the calcium binding proteins parvalbumin (PV) and calbindin (CaBP‐28kD) was used to study horizontal cells in the macaque monkey retina. Both morphological types (H1 and H2) are stained by PV immunocytochemistry. Horizontal cells in the centre of the fovea are described for the first time. From a minimum of 250/mm2 at the foveal centre, total horizontal cell density rapidly increases to a peak of 23,000/mm2 in an annulus of 0.6 mm radius around the fovea. Horizontal cell density then drops continuously to approximately 800–1000 cells/mm2 in peripheral retina. The density ratio of cones to horizontal cells is 1.5 in central and 4 in peripheral retina.

The cones were stained with antibodies against CaBP‐28kD. Thus the spatial correlation between the cone inner segments and the cone pedicles could be measured to show that they are in perfect register. There is no reorganization of the spatial array of cone outer segments to produce chromatically specific connections between cone pedicles and horizontal cells.
Horizontal Cells in the Monkey Retina: Cone connections and dendritic network
Authors: Wässle H. , Boycott B. B. , Röhrenbeck J.
Published: April 2006

Horizontal cells of the macaque monkey retina were quantified and the number of cones converging onto an individual horizontal cell as well as the number of horizontal cells contacting a single cone were determined. This was done by combining data from individual horizontal cells stained by the Golgi method with the results of immunocytochemical staining described in the preceding paper (Röhrenbeck et al., 1989).

The observation (Boycott et al., 1987) that all horizontal cells contact all cones in their dendritic field irrespective of cone type was confirmed. The particular cones contacted by the terminal aggregates of each horizontal cell were found. The dendritic fields of H1 and H2 cells increase with increasing eccentricity; close to the fovea H1 cells are smaller than H2 cells, at 6 mm eccentricity they are about the same size and in peripheral retina H1 cells are much larger than H2 cells. The density gradients of the two cell types balance their denritic field changes so that throughout the retina each and every cone synapses with 3–5 horizontal cells of each type. Horizontal cells of both cat (Wässle et al., 1978) and monkey retina follow the general rule that all cones in the dendritic fields are contacted, their perikarya form a regular mosaic and the boundaries of their dendritic fields are marked by the perikarya of their homologous neighbours.
Membrane Characteristics and Synaptic Responsiveness of Superficial Dorsal Horn Neurons in a Slice Preparation of Adult Rat Spinal Cord
Authors: Thomson Alex M. , West David C. , Headley P. Max
Published: April 2006

Intracellular recordings have been made from neurons of the superficial dorsal horn in slices of the lumbar and thoracic spinal cord of young adult rats. Three broad categories of neurons could be distinguished on the basis of their firing patterns to intracellular current pulses and their afterhyperpolarizations (AHP); there was no detectable difference in the regional distribution of the three types. Category 1 cells were characterized by maintained firing to intracellular depolarizing current pulses, brief action potential durations and polyphasic AHPs. Category 2 cells showed spike adaptation, without spike attenuation, during intracellular current pulses, and had monophasic AHPs. Category 3 cells fired only 1 or 2 spikes to maintained depolarizing pulses and had smaller monophasic AHPs than category 2 neurons. Spontaneous excitatory and inhibitory postsynaptic potential (epsp and ipsp) activity was seen with psp durations varying widely. Low intensity electrical stimulation of afferent fibres, or of superficial white matter, resulted in polyphasic epsps and/or ipsps. The spike discharge in response to such afferent inputs correlated with the membrane properties of the cells, such that the synaptic responses of category 1 neurons were usually bursts of spikes, whereas category 2 and 3 neurons either failed to fire or fired only a single spike. These results in adult rat spinal cord suggest that the discharge pattern within synaptic sensory responses of superficial dorsal horn neurons is determined by postsynaptic membrane properties as well as by the pattern of the afferent input.
The Functional Organization of the Olivo‐Cerebellar System as Examined by Multiple Purkinje Cell Recordings
Authors: Llinás R. , Sasaki K.
Published: April 2006

Multiple recordings from Purkinje cells in the rat cerebellum allowed the mechanism responsible for the activation of rows of synchronous complex spikes to be investigated. By determining the spatial distribution of the climbing fibre reflex that follows electrical microstimulation of the cerebellar cortex, it was shown that the mechanism for the simultaneity of firing was the electrotonic interactions between neurons in the inferior olive (IO). The spatial organization of the complex spike activity was shown to be regulated by GABAergic inhibitory input into the IO, probably arising from the cerebellar nuclear neurons. The rostro‐caudal organizion of the complex spike activity following physiological stimulation (tactile stimulation of the upper and lower lip) demonstrated the same spatial distribution of synchronous activity in the cerebellar cortex as did the spontaneous activity and this was also disrupted by GABA blockers. Finally, complex spike responses to physiological stimulation indicate that the IO is capable of gating sensory inputs in accordance with its intrinsic autorhythmicity and that strong peripheral stimuli reset the oscillatory properties of the IO. The functional implications of the synchronicity and of the temporo‐spatial organizion of complex spikes in the cerebellar cortex are discussed in the context of motor coordination and timing.
17‐β Oestradiol Pretreatment of Mouse Striatal Neurons in Culture Enhances the Responses of Adenylate Cyclase Sensitive to Biogenic Amines
Authors: Maus M. , Cordier J. , Glowinski J. , Premont J.
Published: April 2006

Embryonic striatal neurons from the mouse grown in primary culture (6 day old culture) were used in order to investigate the effects of 17‐β oestradiol (17‐β E2) on biogenic amine‐sensitive adenylate cyclases. Pretreatment (28 h) of intact cells with 17‐β E2 (10−9 M) enhanced cyclic AMP production induced by either dopamine, isoproterenol, serotonin, or 2‐chloro‐adenosine (maximal effective concentrations). These effects of 17‐β E2 on biogenic amine‐sensitive adenylate cyclases occurred after several hours (8 h at least) and were seen in most cases with a concentration as low as 10−11 M (EC50: 10−10 M). They were additive with those induced by phenol red (5.6 μg/l) and chemically specific since 17α‐oestradiol, 2(OH) 17‐β E2, progesterone, and dexamethasone were without effect. In addition, they were not seen in cells which had been pretreated (30 h) with cycloheximide or α‐amanitin, suggesting an involvement of de novo protein synthesis. Since 17‐β E2 did not influence cyclic AMP production induced by either forskolin or manganese ions, the stimulatory effects of 17‐β E2 pretreatment on biogenic amine‐sensitive adenylate cyclases were not linked to an increase in the amount of enzyme catalytic units. 17‐β E2 pretreatment enhanced twofold the number of β‐adrenergic receptors (as estimated by the specific binding of (125l)iodocyanopindolol) but did not, in contrast, affect either the number or the affinity of dopaminergic receptors (as estimated by (125l)SCH 23982 binding). Therefore, the enhancing effects of 17‐β E2 pretreatment on biogenic amine‐sensitive adenylate cyclases could be related either to an increased number of coupled receptors or to modifications of the adenylate cyclase transducing system (occurring probably at the G‐protein level) or to a combination of the two.
Host Corticostriatal Fibres Establish Synaptic Connections with Grafted Striatal Neurons in the Ibotenic Acid Lesioned Striatum
Authors: Wictorin K. , Clarke D. J. , Bolam J. P. , Björklund A.
Published: April 2006

The connections between host corticostriatal afferents and neurons in intrastriatal grafts of foetal striatal tissue have been studied with electron microscopic immunocytochemistry using Phaseolus vulgaris leucoagglutinin (PHA‐L) as a label of the host corticostriatal fibres. Adult rats with unilateral ibotenic acid lesions of the head of the caudate putamen received foetal cell suspension grafts from E14–15 rat embryos into the lesioned striatal area. Ten months after transplantation, multiple iontophoretic injections of PHA‐L were made into the host frontal cortex. These injections labelled large numbers of corticostriatal fibres which extended across the graft ‐ host border to form a rich axonal network mainly in the peripheral portions of the grafts. At the ultrastructural level a total of 134 PHA‐L‐labelled terminals were identified to form asymmetric synaptic contacts with neurons within the grafts. Of these contacts, 83% were in contact with dendritic spines, 12% with dendritic shafts, and 5% with small shafts or spines. The synaptic contacts were similar to those identified in intact regions of the host striatum that were spared by the lesion. However, the synapses in the host striatum were almost exclusively in contact with spines (98%). These results demonstrate that the corticostriatal projection, which constitutes a major source of afferent control in the normal striatum, not only extends axons into the intrastriatal striatal grafts, but also establishes synaptic connections with the implanted neuronal elements.
Intracellular Calcium and Control of Burst Generation in Neurons of Guinea‐Pig Neocortex in Vitro
Authors: Friedman A. , Gutnick M. J.
Published: April 2006

Response properties of neurons in brain slices of guinea pig parietal neocortex were examined following intracellular injection of the Ca2+ chelators, EGTA and BAPTA. Although chelator injection did not cause any consistent change in passive membrane properties, it did induce 81% of neurons encountered at all sub‐pial depths to become ‘bursters’, in that just‐threshold depolarizing current pulses triggered all‐or‐none bursts of 2–5 fast action potentials. Transition to ‘burstiness’ was associated with disappearance of an AHP and appearance of a DAP. Although chelator caused a slight increase in steady‐state firing rate, marked accommodation persisted. Extracellular Co2+ or Mn2+ had an effect on steady‐state firing rate similar to that of the intracellular chelators; however, exposure to these Ca2+ channel blockers also caused steady state depolarization, increased resting input resistance and time constant, and profound spike broadening. This treatment never induced transition to ‘burstiness’. Chelator‐injected neurons ceased to generate bursts when Ca2+ was replaced by Mn2+ in the Ringer's solution. During exposure to 10−6 M TTX and 20 mM TEA, 50–200 msec Ca2+ spikes followed brief depolarizing pulses. As chelator was injected into the cell, there was progressive prolongation of the Ca2+ plateaus, which was associated with slowing of the rate at which membrane resistance gradually recovered following the initial increase in conductance.

These findings indicate that under normal conditions, activity‐related increases in intracellular Ca2+ activate processes which prevent most neocortical neurons from being bursters. These processes probably include Ca2+ ‐dependent K+ currents, and Ca2+ ‐dependent Ca2+ channel inactivation.
The role of the medial caudate nucleus, but not the hippocampus, in a matching‐to sample task for a motor response
Authors: Kesner Raymond P. , Gilbert Paul E.
Published: April 2006

A delayed‐match‐to‐sample task was used to assess memory for motor responses in rats with control, hippocampus, or medial caudate nucleus (MCN) lesions. All testing was conducted on a cheeseboard maze in complete darkness using an infrared camera. A start box was positioned in the centre of the maze facing a randomly determined direction on each trial. On the sample phase, a phosphorescent object was randomly positioned to cover a baited food well in one of five equally spaced positions around the circumference of the maze forming a 180‐degree arc 60 cm from the box. The rat had to displace the object to receive food and return to the start box. The box was then rotated to face a different direction. An identical baited phosphorescent object was placed in the same position relative to the start box. A second identical object was positioned to cover a different unbaited well. On the choice phase, the rat must remember the motor response made on the sample phase and make the same motor response on the choice phase to receive a reward. Hippocampus lesioned and control rats improved as a function of increased angle separation used to separate the correct object from the foil (45, 90, 135, and 180 degrees) and matched the performance of controls. However, rats with MCN lesions were impaired across all separations. Results suggest that the MCN, but not the hippocampus, supports working memory and/or a process aimed at reducing interference for motor response selection based on vector angle information.
The essential haematopoietic transcription factor Scl is also critical for neuronal development
Authors: Bradley Cara K. , Takano Elena A. , Hall Mark A. , Göthert Joachim R. , Harvey Alan R. , Begley C. Glenn , van Eekelen J. Anke M.
Published: April 2006

The basic helix‐loop‐helix (bHLH) transcription factor Scl displays tissue‐restricted expression and is critical for the establishment of the haematopoietic system; loss of Scl results in embryonic death due to absolute anaemia. Scl is also expressed in neurons of the mouse diencephalon, mesencephalon and metencephalon; however, its requirement in those sites remains to be determined. Here we report conditional deletion of Scl in neuronal precursor cells using the Cre/LoxP system. Neuronal‐Scl deleted mice died prematurely, were growth retarded and exhibited an altered motor phenotype characterized by hyperactivity and circling. Moreover, ablation of Scl in the nervous system affected brain morphology with abnormal neuronal development in brain regions known to express Scl under normal circumstances; there was an almost complete absence of Scl‐null neurons in the hindbrain and partial loss of Scl‐null neurons in the thalamus and midbrain from early neurogenesis onwards. Our results demonstrate a crucial role for Scl in the development of Scl‐expressing neurons, including γ‐aminobutyric acid (GABA)ergic interneurons. Our study represents one of the first demonstrations of functional overlap of a single bHLH protein that regulates neural and haematopoietic cell development. This finding underlines Scl's critical function in cell fate determination of mesodermal as well as neuroectodermal tissues.
Tight covariation of BOLD signal changes and slow ERPs in the parietal cortex in a parametric spatial imagery task with haptic acquisition
Authors: Schicke Tobias , Muckli Lars , Beer Anton L. , Wibral Michael , Singer Wolf , Goebel Rainer , Rösler Frank , Röder Brigitte
Published: April 2006

The present study investigated the relation of brain activity patterns measured with functional magnetic resonance imaging (fMRI) and slow event‐related potentials (ERPs) associated with a complex cognitive task. A second goal was to examine the neural correlates of spatial imagery of haptically – instead of visually – acquired representations. Using a mental image scanning task, spatial imagery requirements were systematically manipulated by parametrically varying the distance between haptically acquired landmarks. Results showed a close relation between slow ERPs and the blood oxygenation level dependent (BOLD) signal in human parietal lobe. Reaction times of mental scanning correlated with the distances between landmarks on the learned display. In parallel, duration and amplitude of slow ERPs and duration of the haemodynamic response systematically varied as a function of mental scanning distance. Source analysis confirmed that the ERP imagery effect likely originated from the same cortical substrate as the corresponding BOLD effect. This covariation of the BOLD signal with slow ERPs is in line with recent findings in animals demonstrating a tight link between local field potentials and the BOLD signal. The parietal location of the imagery effect is consistent with the idea that externally triggered (perceptual) and mentally driven (imagery) spatial processes are both mediated by the same supramodal brain areas.
On Models, Behaviorism and the Neural Basis of Learning
Authors: Staddon J.E.R. , Bueno J.L.O.
Published: April 2006

The history of psychology is full of disputes among various “-isms”: behaviorism, cognitivism, functionalism, and many others. Nevertheless, all are unanimous in their opposition to one other -ism: reductionism. From Skinner to Simon, there is tacit agreement that behavior (or mind) is a subject matter in its own right that need not, perhaps cannot, be “reduced to” neurophysiology. This consensus has begun to crack in recent decades, with advances in neurobiology and the growth of understanding of the properties of brainlike theoretical systems. What, then, is the status of the study of behavior in its own right? This paper proposes a framework in which realtime theoretical models provide the link between behavioral research and the structure and function of the nervous system. We argue that such models arise most naturally from studies at the behavioral level, especially when the behavior under study depends on context and remote past history, as in learning and memory. We conclude that Skinner was probably right to argue that behavior must be understood in its own right before we can expect to understand brain—behavior relations. But he was wrong in limiting behavioral science to descriptive laws and catalogs of input-output relationships.
Stimulus Generalization and Representation in Adaptive Network Models of Category Learning
Authors: Gluck Mark A.
Published: April 2006

An exponential-decay relationship between the probability of generalization and psychological distance has received considerable support from studies of stimulus generalization ( Shepard, 1958 ) and categorization ( Nosofsky, 1984 ). It is shown here how an approximate exponential generalization gradient emerges from stimulus representation assumptions isomorphic to a special case of Shepard's (1987) theory of stimulus generalization in a “configuralcue” network model of human learning that represents stimulus patterns in terms of elementary features and pairwise conjunctions of features ( Gluck & Bower, 1988b ; Gluck, Bower, & Hee, 1989 ). The network model can be viewed as a combination of Shepard's theory and an associative learning rule derived from Rescorla and Wagner's (1972) theory of classical conditioning.
Double-Blind Tests of Subliminal Self-Help Audiotapes
Authors: Greenwald Anthony G. , Spangenberg Eric R. , Pratkanis Anthony R. , Eskenazi Jay
Published: April 2006

Three replications of a double-blind experiment tested subliminal audiotape products that were claimed to improve memory or to increase self-esteem. Conditions of use adhered to manufacturers' recommendations, and subjects (N = 237) were limited to persons who desired the effects offered by the tapes. Actual content and labeled content of tapes were independently varied, so that some subjects who believed they were using memory tapes were actually using self-esteem tapes, and vice versa. After a month of use, neither the memory nor the self-esteem tapes produced their claimed effects. Nevertheless, a general improvement for all subjects in both memory and self-esteem (a nonspecific placebo effect) was observed, and more than a third of the subjects had the illusion of improvement specific to the domain named on the tape's label.
A Review from a High Place: The Field of Judgment and Decision Making as Revealed in Its Current Textbooks
Authors: Hastie Reid
Published: April 2006

Decisions, decisions…. PS takes a broad look at a currently active field that provides a model for the fruitful combination of theory, research, and application
On the Psychology of Ampliative Inference
Authors: Myers Tracy S. , Osherson Daniel N.
Published: April 2006

It is sometimes necessary to guess which probability distribution governs random sampling over a given event space. When the correct guess cannot be deduced from information available about the space, the problem is said to require ampliative inference. The most familiar form of ampliative inference is represented in the principle of maximum entropy. We examine this principle from a descriptive, psychological point of view.
Intact Artificial Grammar Learning in Amnesia: Dissociation of Classification Learning and Explicit Memory for Specific Instances
Authors: Knowlton Barbara J. , Ramus Seth J. , Squire Larry R.
Published: April 2006

The present study investigates whether the ability to classify on the basis of rules can be learned independently of memory for the specific instances used to leach the rules. Thirteen amnesic patients and 14 control subjects studied letter strings generated by an artificial grammar. Subjects were then shown new letter strings and were instructed to classify them as grammatical or nongrammatical. Amnesic patients performed as well as normal subjects. However, amnesic patients performed more poorly than control subjects on a recognition test of the exemplars that had been presented. Amnesic patients also performed more poorly than control subjects when the instructions were to base the classification on explicit comparison with the original exemplars. The results show that classification learning based on exemplars of an artificial grammar can develop normally despite impaired memory for the exemplars themselves. Whereas exemplar memory depends on interactions between neocortex and the limbic system, classification learning may depend on interaction between neocortex and the neostriatum.