Global and regional brain metabolic scaling and its functional consequences

Background: Information processing in the brain requires large amounts of metabolic energy, the spatial distribution of which is highly heterogeneous reflecting complex activity patterns in the mammalian brain. Results: Here, it is found based on empirical data that, despite this heterogeneity, the volume-specific cerebral glucose metabolic rate of many different brain structures scales with brain volume with almost the same exponent around -0.15. The exception is white matter, the metabolism of which seems to scale with a standard specific exponent -1/4. The scaling exponents for the total oxygen and glucose consumptions in the brain in relation to its volume are identical and equal to $0.86\pm 0.03$, which is significantly larger than the exponents 3/4 and 2/3 suggested for whole body basal metabolism on body mass. Conclusions: These findings show explicitly that in mammals (i) volume-specific scaling exponents of the cerebral energy expenditure in different brain parts are approximately constant (except brain stem structures), and (ii) the total cerebral metabolic exponent against brain volume is greater than the much-cited Kleiber's 3/4 exponent. The neurophysiological factors that might account for the regional uniformity of the exponents and for the excessive scaling of the total brain metabolism are discussed, along with the relationship between brain metabolic scaling and computation.Comment: Brain metabolism scales with its mass well above 3/4 exponen

Parkinson's patient runs an ultra marathon: a case report.

International audienceStudies show that physical activity involving prolonged endurance may benefit patients with Parkinson's disease by promoting the secretion and/or availability and use of dopamine. We report the case of a Parkinson's patient who took part in an ultra-marathon to show that extreme physical activity is possible and can facilitate medical treatment with a possible positive effect on brain structures. We report the case of a 48-year-old man in the initial stages of Parkinson's disease who took part in a 100-km run. Preparation included running approximately 90 km a week in six sessions. Evaluation included clinical monitoring and DaTSCAN® follow-up. After taking up running, the patient gradually stopped levodopa without worsening of symptoms as assessed on the UPDRS scale. DaTSCAN® imaging performed 3 days after the 100-km run showed partial correction of abnormalities seen 3 days before the race: improvement in binding at the putamen bilaterally and at the caudate nucleus on the right. Since then, the patient has continued to run regularly, for an average of 40 minutes on 5 days out of every 7. This case shows that demanding physical activity is possible in such circumstances and can help reduce medical treatment, potentially with a positive effect on the plasticity of the brain structures involved