AEPおよび脳波へのinsulin低血糖の影響

The effects of insulin-induced hypoglycemia on the central nervous system were studied by auditory evoked potential (AEP), with 8 schizophrenic patients (31~47 y.o.), during the 'kleine Insulinbehandlung'. In the three experimental session on different days, human regular insulin was injected subcutaneously to each patient, whose consciousness level was lowered to the stage of somnolence and recovered by intake of a glucose solution (100 g). EEG containig AEPs evoked by click simuli was derived from the two derivations (3rd ch : Cz→A1+2, 6th ch : Cz→T5). In the experimental session, EEG containing AEPs was recorded before and 20, 40, 60, 80, 100 and 120 min after the injection of insulin, and 20 min after intake of glucose. Consecutive changes of group mean AEP were studied. Individual AEPs were subjected to the component analysis, and to the statistical assessment together with EEG power %. As a result, the middle latency components of AEP significantly reduced in latency and significantly increased in amplitude in the early stage after the injection of insulin, but significantly prolonged in latency in the latter stage. On the other hand, the long latency components of AEP significantly prolonged in latency and significantly decreased in amplitude throughout hypoglycemia. EEG power % significantly decreased in δ power% in the early stage, but significantly increased in δ and θ power % and significantly decreased in α and β power % in the latter stage. These results were attributed to the inhibitory effects of insulin-induced hypoglycemia on the cerebral cortex, and to the activation of the noradrenergic neurons responding to the hypoglycemia in the early stage. The results also indicate that the activated noradrenergic neurons are gradually declined during prolonged hypoglycemia

The differences in VEP (Visual Evoked Potentials) between epileptics and normal subjects

The differences between epileptics and healthy subjects on the visual evoked potential (VEP) were studied. VEPs were recorded through the two derivations (2 ch : O 1→A 1+2, 5 ch : O 1→Cz). The differences in the latencies and interpeak amplitudes were compared and tested statistically, respectively for each sex, with special reference to the drugs been administered. 1. The latencies of VEP components in epileptics were longer than those in healthy subjects, in both sexes. 2. Interpeak amplitudes of VEP components in epileptics were smaller than those in healthy subjects, especially in late components, in both sexes. 3. These tendencies were more marked in males than in females. 4. In epileptics, between the subjects being administered each drug (CBZ, PB, VPA or PHT) or not, significant differences in latencies and intrerpeak amplitudes were not confirmed, with the components in which significant differences in latencies and amplitudes between epileptics and healthy subjects were found. We verified the significant differences in VEPs between epileptics and healthy subjects, which suggested the dysfunction in epileptics in its brain stem and lateral geniculate body, even not considering the seizure types nor epileptic focus sites

The effects of insulin-induced hypoglycemia on the human VEP (Visual Evoked Potential) and EEG

The effects of insulin-induced hypoglycemia on central nervous system were studied by visual flash evoked potential (VEP), with 8 schizophrenic patients (31~47 y.o.), during the 'Kleine Insulinbehandlung'. In the three experimental sessions on different days, human regular insulin were injected subcutaneously to each patient, whose consciousness level were lowered to the stage of somnolence and recovered after intake of a solution of glucose (100 g). EEG containing VEPs evoked by flash stimuli once every 5 seconds were derived from the two derivations (2 nd ch : O1→A1+2, 5 th ch : O1→Cz). In the experimental session, EEG containing VEPs were recorded before and 20, 40, 60, 80, 100 and 120 min after the injection of insulin, and 20 min after intake of glucose. Consecutive changes of group mean VEP were studied. Individual VEPs were subjected to the component analysis, and to the statistical assessment together with EEG power%. The following results were obtained. 1. The long latency components of VEP significantly increased in latency and significantly deceased in peak-to-peak amplitude in the early stage after the injection of insulin. These findings indicate the inhibitory effects of insulin-induced hypoglycemia on the cerebral cortex in the early stage. 2. The short latency components of VEP significantly increased in the latency of N2 and significantly decreased in the peak-to-peak amplitude of P2-N2 in the latter stage. In EEG, the power% of δ and θ frequency bands significantly increased and that of α 1~β 2 significantly decreased in the latter stage. These findings indicate the inhibitory effects on the lateral geniculate body due to the decline of the brainstem activity, in the latter stage of insulin-induced hypoglycemia