Factor analysis of local cerebral blood flow changes observed in physiological experiments.

Local blood flow values measured by 14C-iodoantipyrine autoradiography in 78 cerebral structures of the rat brain were compiled from 128 physiological experiments concerning neurohumoral influences and anaesthesia. The data were evaluated by common factor analysis in order to reveal correlative relationships between cerebral areas and to determine representative structures for the observed reaction patterns. The calculations showed that 92% of the regional variations could have been represented by 5 independent factors accounting for 37%, 20%, 19%, 10% and 6% of the total variance, respectively. The most closely associated structures and their loadings for the above factors were colliculus inferior (0.92), cingulum (0.89), tractus opticus (-0.86), radix tractus spinalis nervi trigemini (-0.93) and nucleus olivarius superior (0.86). The results suggest that the local blood flow response of a given cerebral area depends, above all, on the fact whether it is part of the carotid or the vertebro-basilar territory.