David G. Gadian

Bio: David G. Gadian is an academic researcher from University College London. The author has contributed to research in topics: Cerebral blood flow & Voxel-based morphometry. The author has an hindex of 62, co-authored 142 publications receiving 19971 citations. Previous affiliations of David G. Gadian include Royal College of Surgeons of England & Great Ormond Street Hospital.

Navigation-related structural change in the hippocampi of taxi drivers

Abstract: Structural MRIs of the brains of humans with extensive navigation experience, licensed London taxi drivers, were analyzed and compared with those of control subjects who did not drive taxis. The posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects. A more anterior hippocampal region was larger in control subjects than in taxi drivers. Hippocampal volume correlated with the amount of time spent as a taxi driver (positively in the posterior and negatively in the anterior hippocampus). These data are in accordance with the idea that the posterior hippocampus stores a spatial representation of the environment and can expand regionally to accommodate elaboration of this representation in people with a high dependence on navigational skills. It seems that there is a capacity for local plastic change in the structure of the healthy adult human brain in response to environmental demands.

Differential effects of early hippocampal pathology on episodic and semantic memory.

Abstract: Global anterograde amnesia is described in three patients with brain injuries that occurred in one case at birth, in another by age 4, and in the third at age 9. Magnetic resonance techniques revealed bilateral hippocampal pathology in all three cases. Remarkably, despite their pronounced amnesia for the episodes of everyday life, all three patients attended mainstream schools and attained levels of speech and language competence, literacy, and factual knowledge that are within the low average to average range. The findings provide support for the view that the episodic and semantic components of cognitive memory are partly dissociable, with only the episodic component being fully dependent on the hippocampus.

Proton nuclear magnetic resonance spectroscopy unambiguously identifies different neural cell types

Abstract: Proton nuclear magnetic resonance (1H NMR) spectroscopy is a noninvasive technique that can provide information on a wide range of metabolites. Marked abnormalities of 1H NMR brain spectra have been reported in patients with neurological disorders, but their neurochemical implications may be difficult to appreciate because NMR data are obtained from heterogeneous tissue regions composed of several cell populations. The purpose of this study was to examine the 1H NMR profile of major neural cell types. This information may be helpful in understanding the metabolic abnormalities detected by 1H NMR spectroscopy. Extracts of cultured cerebellar granule neurons, cortical astrocytes, oligodendrocyte-type 2 astrocyte (O-2A) progenitor cells, oligodendrocytes, and meningeal cells were analyzed. The purity of the cultured cells was > 95% with all the cell lineages, except for neurons (approximately 90%). Although several constituents (creatine, choline-containing compounds, lactate, acetate, succinate, alanine, glutamate) were ubiquitously detectable with 1H NMR, each cell type had distinctive qualitative and/or quantitative features. Our most unexpected finding was a large amount of N-acetyl-aspartate (NAA) in O-2A progenitors. This compound, consistently detected by 1H NMR in vivo, was previously thought to ne present only in neurons. The finding that meningeal cells have an alanine:creatine ratio three to four times higher than astrocytes, neurons, or oligodendrocytes is in agreement with observations that meningiomas express a higher alanine:creatine ratio than gliomas. The data suggest that each individual cell type has a characteristic metabolic pattern that can be discriminated by 1H NMR, even by looking at only a few metabolites (e.g., NAA, glycine, beta-hydroxybutyrate).(ABSTRACT TRUNCATED AT 250 WORDS)

Bioenergetics of intact human muscle. A 31P nuclear magnetic resonance study.

Abstract: The metabolic state of human muscle in various functional states has been investigated by the non-invasive technique of 31P nuclear magnetic resonance. The concentrations of phosphocreatine, ATP and inorganic phosphate as well as intracellular pH in the flexor digitorum superficialis have been measured during rest, dynamic exercise and recovery from exercise. The observed relationship between phosphocreatine utilization and decrease in intracellular pH during aerobic exercise indicates that lactate production only becomes significant after more than 60% of the phosphocreatine is used up. Surprisingly intracellular pH may reach as low a value as 5.9 to 6.1, indicating that phosphofructokinase is still partially active at pH 6.0. There is no metabolic recovery if the muscle is made ischaemic following exercise, implying that glycolysis is switched off as soon as exercise is stopped. Lactic acidosis is not the cause of this and presumably Ca2+ is needed to maintain the activation of phosphorylase kinase. The time-course of phosphocreatine recovery after exercise reflects the rate of oxidative metabolism, while pH recovery probably represents H+ ion export from the muscle cell. The dynamics of metabolic changes can now be observed with a time resolution of 10 to 60 seconds and thus disturbances in energy metabolism can be readily detected in several pathological states.

Breastfeeding and the Use of Human Milk

Abstract: Considerable advances have occurred in recent years in the scientific knowledge of the benefits of breastfeeding, the mechanisms underlying these benefits, and in the clinical management of breastfeeding. This policy statement on breastfeeding replaces the 1997 policy statement of the American Academy of Pediatrics and reflects this newer knowledge and the supporting publications. The benefits of breastfeeding for the infant, the mother, and the community are summarized, and recommendations to guide the pediatrician and other health care professionals in assisting mothers in the initiation and maintenance of breastfeeding for healthy term infants and high-risk infants are presented. The policy statement delineates various ways in which pediatricians can promote, protect, and support breastfeeding not only in their individual practices but also in the hospital, medical school, community, and nation.

From Neurons to Neighborhoods: The Science of Early Childhood Development

Abstract: How we raise young children is one of today's most highly personalized and sharply politicized issues, in part because each of us can claim some level of "expertise." The debate has intensified as discoveries about our development-in the womb and in the first months and years-have reached the popular media. How can we use our burgeoning knowledge to assure the well-being of all young children, for their own sake as well as for the sake of our nation? Drawing from new findings, this book presents important conclusions about nature-versus-nurture, the impact of being born into a working family, the effect of politics on programs for children, the costs and benefits of intervention, and other issues. The committee issues a series of challenges to decision makers regarding the quality of child care, issues of racial and ethnic diversity, the integration of children's cognitive and emotional development, and more. Authoritative yet accessible, From Neurons to Neighborhoods presents the evidence about "brain wiring" and how kids learn to speak, think, and regulate their behavior. It examines the effect of the climate-family, child care, community-within which the child grows.