Functional MRI Based Brain Mapping in Occipital Gyrus using Face Stimuli

Functional magnetic resonance imaging (fMRI) is one of the most powerful neuroimaging modalities due to its high spatio-temporal resolution characteristics. This known modality is applied on mapping the temporal, occipital, frontal cortices of the brain for localizing the neural activities generated due to any visual, physical or mental task or brain diseases or brain disorders. The occipital cortex is composed of middle, left, right, interior and exterior occipital gyrus and is responsible for visional function of human brain. The occipital gyrus reflects the neural image generated in the brain due to any visual activity. In this research paper, four different visual stimuli images of faces, scrambled, scenes and objects along with gap of blank space, forming a long sequence of stimuli observed by two female subjects, are experimented to examine and localize the most contrasting neural image generated in occipital gyrus of the brain. The visual fMRI brain data received from the two subjects is processed through fMRI-SPM12 toolbox based on Matlab software. In order to demonstrate the results statistically, two regressions such as T-contrast and F-contrast vectors are applied on fMRI images to highlight, and to localize the most active neural stimuli activities generated in the occipital gyrus of brain. In the results, it is demonstrated that maximum neural response can be mapped only for face stimulus in the bilateral occipital gyrus of the brain by applying T-contrast vectors regressions as when compared to other stimuli conditions and F-contrast vectors regressions. Further, it is also investigated that, the response of the face stimulus in F-contrast regressions achieved is somehow dispersed and unclear due to the large variances and interlinked communication of other stimuli or induced neural noises generated in entire volume of the brain.  Further from the given images, it is also investigated that the most reflecting and contrast area for any visual stimuli (such as face stimulus in this case) is either the middle or bilateral part of occipital gyrus of the human brain as identified through application of  T-contrast vectors regressions.

Improving Drought Tolerance in Maize Zea Mays L. by Exogenous Application of Thiourea

Drought stress is one of the most important constraints in crop production, particularly in arid and semi-arid regions of the world. Seed priming and foliar application of growth hormones, osmolytes and nutrients is an important tool to decrease the drastic effects of drought stress. The effects of thiourea in improving drought tolerance in maize were studied from 2010-12. Four green house and one field experiment was carried out at Research Area of Agronomy Department. First experiment was screening trial in which seven maize hybrids (32F10, 32B33, 33H25, 3335, 34N43, 6142, 6525) were sown under three water regimes (80% WHC, 6O% WHC, 40% WHC). Among seven hybrids, 34N43 recorded vigorous germination, maximum growth and improved water relations under stress as well as under well watered conditions and hybrid 32F10 recorded least vigorous germination, growth and water relations. So on the basis of screening trial hybrid 32F10 was selected as sensitive and hybrid 34N43 as tolerant to drought stress for further studies. Three green house experiments with different levels of thiourea application were conducted. In first experiment four levels of thiourea (200mg/l, 400mg/l, 600mg/l, 800mg/l) was applied through seed treatment under two water regimes (80% WHC, 40% WHC). Seed treatment with TU increased growth under normal and drought stress conditions and improved water relations, increased proline contents, decreased MDA content and electrolyte leakage and increased the activities of antioxidant enzymes in both the hybrids, however effect was more pronounced in hybrid 34N43 than 32F10 and 800 mg/l TU proved to be best for seed treatment. In rooting medium again TU increased shoot length, root dry weight, shoot dry weight, leaf area, improved water relations and increased proline contents, decreased electrolyte leakage and MDA content. In third experiment three thiourea levels (500mg/l,1000mg/l,1500mg/l) were applied through foliar application. Foliar application of TU increased plant biomass, increased water potential, turgor potential and relative contents. One field experiment was conducted in which tensiometers were used for measuring soil water potential and irrigation was made on Lthe basis of tensiometer reading. Thiourea levels and its method of application for field experiment were decided on the basis of green house experiments. From seed treatment experiment, 800 mg/l TU was best treatment and from foliar application, 1500mg/l TU was best. These two treatments were used in field experiment along with dry seed sowing and distilled water foliar application using as control. The experiment was laid out in randomized complete block design with split-split arrangement using four replications. Data regarding various agronomic, physiological and biochemical traits of crop were recorded using standard procedures available in the literature. The present study suggests that seed priming with TU and its foliar application not only improved water relations, increased growth, nutrients uptake and yield of maize crop under water stress but also improved performance of maize under normal availability of water.