Factors, affecting the BOLD-response characteristics in patients after stroke

The aim of the study The exploration of the factors affecting the characteristics of BOLD- response (amplitude, latency), and the rate of change of these characteristics in patients after stroke. Materials and methods Registration of fMRI brain activation to the presentation of perceptual event paradigm using Russian language phonemes /ba/ and /pa/ in 10 healthy volunteers and 22 patients after ischemic stroke in the carotid (left medium brain artery) (18 patients) and vertebral - basilar basin (4 persons) was used. Creating fMRI-maps showed activation in superior temporal gyri bilaterally. We evaluated the amplitude and latency of BOLD- response in each participant. Main results The increase of BOLD- response amplitude in the right hemisphere in patients after stroke in carotid basin was found. Also there was found significantly delayed peak of BOLD- response only in group with an episode in the carotid basin in both left and right hemisphere compared to control. The investigation of factors influencing the parameters of BOLD- response in healthy subjects revealed gender and age influence on the hemodynamic response function. In patients with stroke in the carotid basin no similar factors have been identified, but the BOLD-response correlated with the level of blood triglycerides and beta-cholesterol as well as the index of atherogenicity. Main conclusions The subacute or chronic stroke in the carotid effects not only on a volume, but also on an amplitude and latency of the BOLD- response peak. In patients with ischemic stroke in the left cerebral artery the amplitude of the fMRI response increased in the right hemisphere, with the peak latency prolonged bilaterally. Moreover, the parameters of BOLD-response correlated with blood atherosclerotic indices. These factors should be considered when interpreting the fMRI results in patients after stroke.