The effect on the cerebral blood flow (CBF) (27:1-6,1972)

No abstract

Dhyana-Yoga is a Sanskrit word for the ancient discipline of meditation, as a means to Samadhi or enlightenment. Samadhi is a self-absorptive, adaptive state with realization of ones being in harmony with reality. It is unitive, undifferentiated, reality-consciousness, an essential being, which can only be experienced by spontaneous intuition and self-understanding. Modern neuroscience can help us to better understand Dhyana-Yoga. This article discusses topics including brain-mind-reality, consciousness, attention, emotional intelligence, sense of self, meditative mind, and meditative brain. A new hypothesis is proposed for a better understanding of the meditative mind. Meditation is an art of being serene and alert in the present moment, instead of constantly struggling to change or to become. It is an art of efficient management of attentional energy with total engagement (poornata, presence, mindfulness) or disengagement (shunyata, silence, emptiness). In both states, there is an experience of spontaneous unity with no sense of situational interactive self or personal time. It is a simultaneous, participatory consciousness rather than a dualistic, sequential attentiveness. There is a natural sense of well being with self-understanding, spontaneous joy, serenity, freedom, and self-fulfillment. It is where the ultimate pursuit of happiness and the search for meaning of life resolve. One realizes the truth of ones harmonious being in nature and nature in oneself. It is being alive at its fullest, when each conscious moment becomes a dynamic process of discovery and continuous learning of the ever-new unfolding reality.

The effect of intravertebral infusion of propranolol (0.01 mg per kilogram of body weight) was compared to intravenous infusion of identical doses of propranolol so that any specific action of the drug on a possible vasomotor center in the brain stem may be assessed. Significant reductions (-25%) in CBF and CPP followed both intravertebral and intravenous infusion of propranolol. Cerebral metabolic rate for oxygen (CMRO 2 ) decreased significantly ( -18%) and cerebrovascular resistance (CVR) increased significantly ( + 19%) after intravertebral infusion of propranolol while less significant changes ensued following intravenous infusion of propranolol. Cerebral autoregulatory vasoconstriction during increases in CPP was significantly enhanced following both intravertebral and intravenous propranolol. Cerebral autoregulatory vasodilatation during decrease in CPP was not influenced by propranolol. Cerebral vasodilatory responsiveness to CO 2 inhalation was significantly inhibited following intravertebral propranolol while no significant change resulted from intravenous propranolol. Cerebral vasoconstrictive responsiveness to hyperventilation was not influenced by propranolol.These results indicate that the CBF and CMRO 2 are reduced by a pharmacological beta adrenergic blockade with propranolol hydrochloride.

Ten patients with severe dementia due to Alzheimer's disease (AD) or multi-infarct dementia (MID) or both, were treated with the precursor amino acids of the neurotransmitters serotonin and dopamine. The precursor amino acids (PAA) were given orally in a preparation that included tyrosine (4 gm daily) and 5-hydroxy-tryptophan (5-HTP) (800 mg daily), plus carbidopa (100 mg daily) as an aromatic amino-acid decarboxylase inhibitor. Diagnosis was established by an electroencephalogram, brain scan, computerized axial tomographic scan, and in one case by necropsy findings. Serial clinical evaluations and measurements of neuropsychologic function were performed. Levels of homovanillic acid (HVA) and 5-hydroxyindole-acetic acid (5-HIAA) were determined before and after administration of probenecid. Side effects of the PAA therapy were diarrhea, drowsiness, nausea, vomiting and agitation, all of which were controlled by reducing the dosage. One patient with MID and one with AD+MID showed clinical and psychologic improvement, but the others did not improve. Analysis of the cerebrospinal fluid for HVA and 5-HIAA before and after the probenecid test indicated some improvement in the metabolic turnover of these acid metabolites of serotonin and dopamine after administration of their precursor amino acids.