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Temporal information processing controls many aspects of human mental activity and may be assessed by examining perception of temporal order in the tens of milliseconds time range. Although existing studies suggest an age-related decline in mental abilities, the data on the deterioration of temporal order perception seems inconsistent. Moreover, any evidence on subjects aged over 70 years is lacking. The present experiment aimed to extend the existing data to extremely old people. Temporal order judgment (TOJ) for auditory stimuli was tested across the life span of approx. 80 years, i.e. in young (mean age 22 years), elderly (66 years) and very old (101 years) subjects. Age-related deterioration of performance was observed, with slight changes in elderly subjects and significant deterioration in centenarians which was more distinct in women than in men. The results confirm age-related decrease in temporal resolution which may be explained by slowing of information processing or of a hypothetical internal-timing mechanism. These effects may be influenced by different strategies used in particular age groups.
The efficiency of pre-sowing conditioning/priming methods used to apply melatonin into seeds was verified: osmopriming in the case of dicot Cucumis sativus and hydropriming of monocot Zea mays seeds. Both priming techniques were selected experimentally as optimal for the studied plant species. Four different seed variants were compared: control non-treated ones, and seeds conditioned with water or with 50 or 500 lM melatonin water solutions. The HPLC–MS quantitative and qualitative analyses were used to determine the content of melatonin and of its potential metabolites in the seeds during 1 year following the conditioning. The control seeds and those conditioned with water contained small amount of endogenous melatonin in both species. However, the level of this indoleamine increased markedly in cucumber and corn seeds primed with exogenous melatonin and it was always correlated with the concentration of melatonin applied. It was noted that melatonin was metabolized during seed storage by its gradual oxidation, thus it protects dry seeds against oxidative stress, prevents potential injuries and significantly increases seeds quality. Interestingly, in the control and water-primed seeds, seasonal fluctuations of endogenous melatonin concentration were noted and significant increase in this indoleamine in the winter month was observed. This suggests that in seeds endogenous melatonin could play a crucial role in seasonal rhythms independently of environmental conditions.
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