• Pawan Kumar

      Articles written in Journal of Biosciences

    • Differential neural activation for camouflage detection task in Field-independent and Field-Dependent individuals: Evidence from fMRI

      Janani Rajagopalan Shilpi Modi Pawan Kumar Subash Khushu Manas K Mandal

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      It is not clearly known as to why some people identify camouflaged objects with ease compared with others. The literature suggests that Field-Independent individuals detect camouflaged object better than their Field-Dependent counterparts, without having evidence at the neural activation level. A paradigm was designed to obtain neural correlates of camouflage detection, with real-life photographs, using functional magnetic resonance imaging. Twenty-three healthy human subjects were stratified as Field-Independent (Fl) and Field-Dependent (FD), with Witkins Embedded Figure Test. FIs performed better than FDs (marginal significance; 𝑝=0.054) during camouflage detection task. fMRI revealed differential activation pattern between Fl and FD subjects for this task. One sample T-test showed greater activation in terms of cluster size in FDs, whereas FIs showed additional areas for the same task. On direct comparison of the two groups, Fl subjects showed additional activation in parts of primary visual cortex, thalamus, cerebellum, inferior and middle frontal gyrus. Conversely, FDs showed greater activation in inferior frontal gyms, precentral gyms, putamen, caudate nucleus and superior parietal lobule as compared to FIs. The results give preliminary evidence to the differential neural activation underlying the variances in cognitive styles of the two groups.

    • Trait anxiety and neural efficiency of abstract reasoning: An fMRI investigation


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      Worries preoccupy the working memory capacity in anxious individuals, thereby affecting their performance during tasksthat require efficient attention regulation. According to the attentional control theory (ACT), trait anxiety affects theprocessing efficiency, i.e. the effort required for task performance, more than the accuracy of task performance. Weinvestigated the relation between trait anxiety and neural response for a reasoning task in healthy subjects. Functionalmagnetic resonance imaging (fMRI) was carried out on 22 healthy participants and blood oxygenation level dependent(BOLD) contrast estimates were extracted from a priori regions of interest (ROIs) that were earlier implicated in reasoning(i.e., bilaterally caudate head, globus pallidus, thalamus, prefrontal cortex [rostral, dorsal and ventral regions], inferiorparietal lobule and middle occipital gyrus). Controlling for the effects of age, gender, state anxiety and depressivesymptoms, for equivalent levels of task performance, trait anxiety of the participants was found to be associated with anincrease in task related BOLD activation in right globus pallidus, left thalamus and left middle occipital gyrus. Our resultssuggest a reduced processing efficiency for reasoning in high trait anxiety subjects and provides important brain–behaviourrelationships with respect to sub-clinical anxiety.

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