ABSTRACT
OBJECTIVE: The authors investigated the links between depression, cardiac disease, and microcirculatory cerebral blood flow (CBF). METHOD: A magnetic resonance imaging technique based on arterial spin tagging was used to estimate microcirculatory CBF in depressed (N = 5) and comparison (N = 14) elderly subjects with coronary artery disease. Signal intensity ratios corresponding to relative microcirculatory CBF were calculated for four regions on two axial images through the upper and lower halves of the lateral ventricles. RESULTS: On the superior image, estimates of microcirculatory CBF were statistically significantly lower on the left side in the depressed subjects than in the nondepressed group. When the ratios in the superior and inferior images were averaged, the depressed subjects had lower values for both left periventricular regions of interest and the parietal region. CONCLUSIONS: Despite the small study group and indirect estimates of blood flow, these preliminary findings suggest that a relative cerebral hypoperfusion may underlie depression in elderly cardiac patients.
Subject(s)
Brain/blood supply , Coronary Disease/diagnosis , Depressive Disorder/diagnosis , Magnetic Resonance Imaging , Microcirculation/physiopathology , Age Factors , Aged , Comorbidity , Coronary Disease/epidemiology , Coronary Disease/physiopathology , Depressive Disorder/epidemiology , Depressive Disorder/physiopathology , Functional Laterality/physiology , Humans , Middle Aged , Regional Blood FlowABSTRACT
Previous work showed that the activity rates of certain neurons in the anterior dorsal tegmentum (ADT) of the midbrain correlated with the onset of stepping elicited by hypothalamic stimulation. This study determined if reversible inactivation of the ADT would block locomotion elicited by hypothalamic stimulation of anesthetized rats (urethane, 800 mg/kg). GABA (concentrations 0.25-1.0 mg/microl in saline) were injected in 52 sites in 21 rats. GABA at volumes of 0.1 or 0.2 microl blocked hindlimb stepping in 18 cases. Locomotor blocks occurred within 5 min of the injection, and typically recovered within 10-20 min. The effective blocking sites were clustered around the interstitial nucleus of the medial longitudinal fasciculus. Sites more dorsal and more anterior were not as effective as sites in and ventral to this nucleus. The data are consistent with a role for the ADT of the midbrain in locomotor initiation.
