Low Exploration Level Research Articles

Role of the cerebellum in exploration behavior

Compared to +/+ mice, Lurcher (+/Lc) mutant mice whose cerebellar cortex is lacking almost all Purkinje cells and granule cells, exhibit a low level of exploration; this deficit is not due to a low level of activity but to both a decreased motivation to explore a novel environment and to spatial deficits. The characteristics of exploration in cerebellectomized +/+ and +/Lc mice suggest that the cerebellum is involved not only in cognitive but also in motivational processes.

THE STRATIGRAPHY AND HYDROCARBON POTENTIAL OF THE RIPHEAN‐VENDIAN (MIDDLE‐LATE PROTEROZOIC) SUCCESSION ON THE RUSSIAN PLATFORM

Recent studies of the Riphean‐ Venetian succession of the Russian Platform have indicated that geological factors favourable for the occurrence of hydrocarbons may be present. These factors include substantial thicknesses of sedimentary rocks; the presence of reservoir rocks and seals, together with source rocks containing sapropelic organic matter; and the occurrence of oil shows, indicating that hydrocarbons have been generated. These factors, coupled with a favourable geographic and economic environment, contrast with the low level of exploration in the area.Following an interval of many years, geological studies in the central parts of the Russian Platform recommenced in the 1990s. A network of seismic lines has been shot, and has provided data on deeply‐buried structures in this area, and also on the nature of the lowermost parts of the sedimentary cover. The latter is represented by Proterozoic (Riphean and Vendian) strata, whose petroleum prospectivity on the Russian Platform may be comparable to that of the Siberian Platform.Both the Riphean succession, which was deposited in extensive fault‐bound grabens, and the unconformably overlying Vendian, include very thick sandstones and clay stones. Individual units can be traced on seismic records over distances of tens or even hundreds of km. There is evidence that these sedimentary rocks, particularly those of Vendian age, are of shallow‐ and deep‐marine origin. The high content of sapropelic organic matter which has been recorded in individual units, together with the presence of oil shows, indicate that hydrocarbons have been generated within the Proterozoic interval. Both previous studies in this region, and the more recently‐obtained data, have encouraged exploration to be continued, and have led to the identification of specific targets.

EXPLORATION POTENTIAL OF THE TIMOR GAP ZONE OF CO-OPERATION

The area covered by the Zone of Co-operation (ZOC) in the eastern Timor Sea represents the last large area of sparsely explored continental shelf around Australia that has obvious potential for significant hydrocarbon accumulations.Extravagant claims about the assumed exploration potential of the area have been widely published in Australia and Indonesia. The low level of exploration within the Zone does not allow confident prediction of potential at this time. Only five wells and less than 20 000 km of seismic are present in the ZOC. A similar level of exploration had been reached in the Ashmore-Cartier area in the western Timor Sea by 1972. With such a small data base, extrapolation of conclusions drawn from exploration of adjacent areas is fundamental to the present evaluation.Many technical comparisons can be made between the ZOC and the heavily explored Ashmore-Cartier area. Evaluation of data within the ZOC and extrapolation of important information from other parts of the Timor Sea indicates that all the prerequisites for hydrocarbon accumulations exist within the area.Jurassic reservoirs sealed by the Cretaceous Bathurst Island Formation provide the primary reservoir objectives in all areas of the ZOC away from the Malita Graben. Oil recovered in wells situated on the Londonderry High has been correlated with mature source rocks of the Jurassic Plover Formation in the Sahul Syncline. This depocentre is concluded to have the capacity of generating both oil and gas for potential accumulations in the southern and western part of the ZOC. The capacity of the Malita Graben to source major volumes of hydrocarbons from potential source rocks of the Flamingo Group is still to be established. Insufficient information is available to reliably predict the distribution of oil and gas in the ZOC.Play types similar to those seen in the Ashmore-Cartier area are present in the ZOC. Fault-controlled horst plays, typified by the Jabiru Field, are prevalent on the Sahul Platform. Upper Cretaceous sandstone plays dominate the southern part of the ZOC where reservoir objectives in the Jurassic Plover Formation and Flamingo Group are considered to be too deep for economic exploration.Application of some of the exploration lessons learnt in the western Timor Sea is essential to future activities in the ZOC in order to minimise possible discovery costs.

The effects of repeated doses of ethanol on exploration and its habituation.

The effects of ethanol (0.8-2.4 g/kg) on exploratory behavior and its habituation were investigated by testing DBA/2 mice in a holeboard apparatus. Mice familiar with the holeboard had lower levels of exploration than animals with no previous experience in the apparatus. If the animals received ethanol during their first exposure to the holeboard they did not show the same degree of habituation. Ethanol (0.8 g/kg) increased the exploration of animals naive to the holeboard, but failed significantly to increase the exploration of animals familiar with the apparatus. An increase in locomotor activity was observed following treatment with ethanol (2.4 g/kg). This was potentiated if animals received a single treatment with ethanol 3 days earlier, but only if they were tested in the apparatus following the initial treatment. These results have important implications for the design of experiments investigating tolerance and sensitization to ethanol's effects on locomotor activity and exploration.

Cholecystokinin accelerates the rate of habituation to a novel environment

Cholecystokinin (CCK 8), an octapeptide present in high concentrations in both gut and brain, has been proposed as a putative satiety signal in a variety of species. Exploratory and social behaviors in particular are inhibited by exogenously administered CCK 8. One hypothesis for the mechanism by which CCK reduces feeding and exploration is that CCK 8 is reducing arousal and attention to environment stimuli. This possibility was tested by analyzing the rate of habituation to the novelty of objects placed in an unfamiliar arena. A video-tracking computer-assisted animal behavior monitor measured four parameters of exploratory behaviors in rats pretreated with intraperitoneal CCK 8. During the first 30 minutes in the novel environment, CCK 8-treated animals showed a reduced latency to cessation of exploration as compared to saline controls. In repeated five minute sessions on consecutive days, CCK 8 treatment accelerated the decline in exploration over daily sessions. Pentobarbital, a known sedative, induced low levels of exploration throughout the repeated daily sessions. These data suggest that CCK 8 is inducing a more rapid rate of habituation to the novelty of environmental stimuli. An accelerated rate of habituation might underlie some of the satiety-related behavioral effects of this peptide.

MOTHER-INFANT RELATIONSHIP AND WEIGHT GAIN IN THE FIRST MONTH OF LIFE

Female rats were repeatedly stressed for 10 periods of 15 min by the presence of a cat, at the 10th (S10) or the 19th (S19) gestational day. The litter from stressed females often contained a majority of males or a majority of females, especially in the S19 group. The death of pups was dramatically high in the S19 group and, compared with controls, growth of the surviving animals was slower. When adult, their long-term memory was altered and they exhibited an aversive behavior relative to wide areas. Moreover, cognitive alterations were revealed by the low level of exploration and the inability to rapidly process the relevant environmental cues. These deficits resemble those of psychiatric patients who had been submitted to pre-natal stress.