We previously measured regional cerebral blood flow (rCBF) with oxygen-15 water and positron emission tomography in normal subjects during tasks involving working memory and found that most activate a cortical network including dorsolateral prefrontal cortex, superior parietal cortex (particularly the inferior parietal lobule), and inferior temporal cortex. During more complex tasks the hippocampus is also activated. We also previously showed that the acquisition, but not the retrieval of spatial data involves the frontal cortex, particularly on the right. We have now shown that word generation during semantic versus phonologic cues activated several similar brain regions including anterior cingulate, left frontal cortex, thalamus and cerebellum. Phonological fluency activated Brodmann areas 40 and 44 relatively more than semantic fluency, while semantic fluency was associated with relatively more blood flow in left temporal cortex than phonological fluency Studies of normal monozygotic twins aimed at determining the degree of heritability of cognitively-related regional brain function had suggested that while there are more similarities between twins than between age and sex-matched unrelated individuals, the degree of genetic influence may not be large. A new comparison with normal dizygotic twins has allowed the relative contributions of heritability and common environmental effects on cognitively-related rCBF to be calculated. The results to date indicate that the contributions of both environmental and hereditary factors to rCBF pattern are greater than to rCBF level. Very recently we have also found that several different pathophysiological mechanisms underly cognitive changes that occur in normal aging. In regions where physiological activity is normally suppressed when young subjects perform the tasks older subjects activate more, and, moreover, the more they activate (or fail to suppress), the worse they perform on the tasks. In other areas, where physiological activity is normally increased in young people performing the tasks, older subjects activate less; and the less they activate these regions, the more impaired their performance.
| Eisenberg, Daniel P; Kohn, Philip D; Hegarty, Catherine E et al. (2016) Common Variation in the DOPA Decarboxylase (DDC) Gene and Human Striatal DDC Activity In Vivo. Neuropsychopharmacology 41:2303-8 |
| Jabbi, Mbemba; Kohn, Philip D; Nash, Tiffany et al. (2015) Convergent BOLD and Beta-Band Activity in Superior Temporal Sulcus and Frontolimbic Circuitry Underpins Human Emotion Cognition. Cereb Cortex 25:1878-88 |
| Eisenberg, Daniel P; Kohn, Philip D; Baller, Erica B et al. (2010) Seasonal effects on human striatal presynaptic dopamine synthesis. J Neurosci 30:14691-4 |
| Dreher, Jean-Claude; Kohn, Philip; Kolachana, Bhaskar et al. (2009) Variation in dopamine genes influences responsivity of the human reward system. Proc Natl Acad Sci U S A 106:617-22 |
| Dreher, Jean-Claude; Schmidt, Peter J; Kohn, Philip et al. (2007) Menstrual cycle phase modulates reward-related neural function in women. Proc Natl Acad Sci U S A 104:2465-70 |
| Volkow, Nora D; Wang, Gene-Jack; Franceschi, Dinko et al. (2006) Low doses of alcohol substantially decrease glucose metabolism in the human brain. Neuroimage 29:295-301 |
| Dreher, Jean-Claude; Kohn, Philip; Berman, Karen Faith (2006) Neural coding of distinct statistical properties of reward information in humans. Cereb Cortex 16:561-73 |
| Meyer-Lindenberg, Andreas; Kohn, Philip D; Kolachana, Bhaskar et al. (2005) Midbrain dopamine and prefrontal function in humans: interaction and modulation by COMT genotype. Nat Neurosci 8:594-6 |
| Schulz, G M; Varga, M; Jeffires, K et al. (2005) Functional neuroanatomy of human vocalization: an H215O PET study. Cereb Cortex 15:1835-47 |
| Buchsbaum, Bradley R; Greer, Stephanie; Chang, Wei-Li et al. (2005) Meta-analysis of neuroimaging studies of the Wisconsin card-sorting task and component processes. Hum Brain Mapp 25:35-45 |
Showing the most recent 10 out of 17 publications
