Understanding how the human brain translates sensory impressions into conscious percepts is a key challenge of neuroscience research. Work in this area has overwhelmingly centered on the conscious experience of vision at the exclusion of the other senses—in particular, smell. We hypothesized that the orbitofrontal cortex (OFC) is a central substrate for olfactory conscious experience because of its privileged physiological role in odor processing. Combining functional magnetic resonance imaging, peripheral autonomic recordings, and olfactory psychophysics, we studied a case of complete anosmia (smell loss) in a patient with circumscribed traumatic brain injury to the right OFC. Despite a complete absence of conscious olfaction, the patient exhibited robust “blind smell,” as indexed by reliable odor-evoked neural activity in the left OFC and normal autonomic responses to odor hedonics during presentation of stimuli to the left nostril. These data highlight the right OFC’s critical role in subserving human olfactory consciousness.
Objective
The Color Trails Test (CTT) is a neuropsychological measure tapping into frontal and executive functioning, while at the same time minimizing the cultural and language barriers inherent in similar neurocognitive measures such as the Trail Making Test (TMT). This study generates culturally-appropriate normative data for the CTT in an adult Indian population.
Method
Six-hundred and sixty-nine cognitively healthy, community dwelling Indian individuals between ages 18 and 69 participated in the study. Eligible participants were stratified on the basis of age, gender, and educational attainment. Participant performance on the CTT and TMT were correlated to establish concurrent validity.
Results
Significant correlations were found between TMT-part A and CTT-part 1 (r = .61) and between TMT-part B and CTT-part 2 (r = .66). In addition to generating culturally-appropriate normative data, the current study found that age and educational attainment significantly impacted participant performance on CTT-Part 1 [F(4, 649) = 4.395, p = .002], whereas gender, along with age, and educational attainment significantly impacted performance on CTT-Part 2 [F(4,649) = 2.446, p = .045]. In general, younger participants with more educational attainment performed better on both parts of the CTT. Interestingly, older female participants with lower educational attainment performed better than their younger counterparts on CTT-Part 2, whereas no such findings were noted for male participants.
Conclusions
Age, gender, and educational attainment are important factors to consider when interpreting CTT completion times in the Indian population. Normative data generated from this study has important clinical implications and contributes to the growing body of culturally-appropriate normative data available for the Indian population.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.