Pattern of blood circulation in the brain during rest and functional tests by Salyut-4 space crewmen

Changes in the rheoencephalogram (REG) obtained for cosmonauts on the first and second expeditions during their time aboard the orbiting station, Salyut-4, are described. REGs were recorded by a small apparatus, Levkoi-3, with subsequent transmittal of the information to Earth stations. It was established that during flight under conditions of negative pressure on the lower half of the body (NPLHB), there was a decrease, in all cases, in pulse filling of brain blood vessels and an improvement in venous outflow from the cranial cavity. This indicates the efficiency of the compensation-adaptation reaction of the system studied to the state of weightlessness and the positive effect of prophylactic measures taken during flight. REG changes in indices affected by negative pressure were mainly such as were observed in preflight investigations, but there were individual differences. It was discovered that in all cosmonauts during performance of functional tests on a veloergometer, there was a significant increase in indices of pulse filling of brain blood vessels in response to muscle load in comparison with preflight studies. Normalization of basic REG indices took 3-7 min after the work was concluded. Planimetric analysis with REGs registered under conditions of long flight disclosed a variety of reactions of different sections of the vascular channels in the brain. Data obtained indicated the value of the REG method for making observations on crew members of space ships during orbital flights.