Global and regional brain metabolic scaling and its functional consequences

Table 1 Specific scaling exponents of the regional cerebral glucose utilization rate CMRglc against brain volume

Brain structure	Scaling exponent	95% confidence intervals	Correlation R²	p-value	Species (n)
Cerebral cortex	-0.15 ± 0.03	-0.22 to -0.08	0.870	0.0022	7
Visual	-0.12 ± 0.03	-0.17 to -0.08	0.932	0.0018	6
Prefrontal	-0.17 ± 0.03	-0.23 to -0.10	0.953	0.0044	5
Frontal	-0.14 ± 0.02	-0.17 to -0.12	0.997	0.0015	4
Sensorimotor	-0.15 ± 0.02	-0.19 to -0.11	0.945	0.0002	7
Parietal	-0.15 ± 0.03	-0.20 to -0.11	0.954	0.0008	6
Temporal	-0.15 ± 0.05	-0.27 to -0.03	0.680	0.0224	7
Cingulate	-0.16 ± 0.03	-0.23 to -0.09	0.912	0.0030	6
Occipital	-0.20 ± 0.12	-0.53 to 0.12	0.563	0.1439	5
Thalamus	-0.15 ± 0.03	-0.22 to -0.08	0.858	0.0027	7
Hypothalamus	-0.10 ± 0.04	-0.20 to -0.01	0.692	0.0402	6
Mammillary body	-0.15 ± 0.07	-0.30 to -0.00	0.773	0.0495	5
Cerebellum	-0.15 ± 0.04	-0.24 to -0.06	0.840	0.0102	6
Basal ganglia
Caudate	-0.15 ± 0.03	-0.22 to -0.08	0.905	0.0035	6
Substantia nigra	-0.14 ± 0.02	-0.18 to -0.10	0.956	0.0007	6
Globus pallidus	-0.16 ± 0.04	-0.24 to -0.08	0.926	0.0088	5
Limbic system
Hippocampus	-0.14 ± 0.03	-0.19 to -0.09	0.919	0.0007	7
Amygdala	-0.12 ± 0.03	-0.17 to -0.07	0.919	0.0025	6
Septum	-0.16 ± 0.03	-0.23 to -0.09	0.944	0.0057	5
Brain stem
Superior colliculus	-0.06 ± 0.05	-0.19 to 0.06	0.448	0.2168	5
Inferior colliculus	0.05 ± 0.09	-0.14 to 0.23	0.174	0.4843	5
White matter
Corpus callosum	-0.23 ± 0.09	-0.40 to -0.06	0.947	0.0271	4
Internal capsule	-0.24 ± 0.12	-0.48 to 0.00	0.902	0.0504	4

The t-test showed that population mean of the exponents in the second column was significantly greater than the exponent -0.25 (p = 9 × 10^-9, degrees of freedom (df) = 21 if white matter included; p = 2 × 10^-9, df = 19 if white matter excluded).

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