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A total of 2306 serum samples obtained from adult sheep were analysed for Toxoplasma gondii IgG antibodies by modified direct agglutination test and indirect immunofluorescence assay test. Similar results were obtained with both procedures (seroprevalence of 35.27% for modified direct agglutination test and 33.72% for indirect immunofluorescence assay test(More)
  • J M Ramos
  • 1998
Several recent studies have shown a flat retrograde amnesia for spatial information following lesions to the hippocampus in rats and mice. However, the results of the present investigation demonstrate that in rats that presurgically learned a spatial reference memory task based on extramaze cues, a temporally graded retrograde amnesia is evident following(More)
We designed a battery of tactual discrimination tasks to study whether rats with perirhinal cortex (Prh) lesions had any deficit in resolving complex/ambiguous tactual tasks in the dark. Animals had to discriminate among 3 stimuli simultaneously exposed in 3 arms of a 4-arm plus-shaped maze. Rats with Prh lesions showed a profound impairment in a texture(More)
Lesions to the hippocampal system in rats result in a profound impairment of place or locale spatial learning although other learning strategies remain unaltered. The main objective of the present study was to investigate whether the spatial knowledge preserved in the hippocampal animals can be expressed flexibly under conditions different from those of the(More)
Two groups of 32 laying hens and two groups of 32, 23-day-old broiler chickens were given 2.5 and 5 mg kg-1 of aflatoxin in their diet for four, eight, 16 and 32 days; 16 hens and 32 broiler chicks served as control groups. In the laying hens, aflatoxicosis was characterised mainly by an increase in prothrombin time, and decreases in total plasma proteins(More)
Rats and other mammals can orient themselves in their habitat and locate various goals using different learning strategies. When a cartographic or local strategy is used, the animals construct and store in their long-term memories a complex representation of the extramaze space. However, exactly what constitutes the behaviorally key components of the(More)
  • J M Ramos
  • 2000
In animal models of human amnesia, using lesion methods, it has been difficult to establish the role played by the hippocampus in the formation of long-term spatial knowledge. For example, lesions sustained after acquisition have generally produced a flat retrograde amnesia for spatial information. These results have not made it possible to dissociate the(More)
Two groups of 32 laying hens (Hyssex Brown) and two groups of 32 23-day-old (Hybro) broiler chickens were fed 2.5 and 5 parts/10(6) of aflatoxin in their diet for 4, 8, 16 and 32 days; 16 hens and 32 chicks were maintained as control groups (0 parts/10(6)). After the intoxication period, a clearance period was established of 1, 2, 4 and 8 days. Relative(More)
A survey to determine the level of parasite resistance to benzimidazoles (BZ) under field conditions was performed on 107 commercial sheep farms located in the Aragon region of northeast Spain. Resistance was measured using the discriminant dose, a simplified form of the in vitro egg hatch assay (EHA). Taking into account the spatial structure of the data,(More)