The memory trace of an intrusive trauma-analog episode.

Intrusive memories are a core symptom of posttraumatic stress disorder. Compared with memories of everyday events, they are characterized by several seemingly contradictory features: intrusive memories contain distinct sensory and emotional details of the traumatic event and can be triggered by various perceptually similar cues, but they are poorly integrated into conceptual memory. Here, we conduct exploratory whole-brain analyses to investigate the neural representations of trauma-analog experiences and how they are reactivated during memory intrusions. We show that trauma-analog movies induce excessive processing and generalized representations in sensory areas but decreased blood-oxygen-level-dependent (BOLD) responses and highly distinct representations in conceptual/semantic areas. Intrusive memories activate generalized representations in sensory areas and reactivate memory traces specific to trauma-analog events in the anterior cingulate cortex. These findings provide the first evidence of how traumatic events could distort memory representations in the human brain, which may form the basis for future confirmatory research on the neural representations of traumatic experiences.

[Influence of blood volume drain on some factors of circulation in rabbit]. / Einfluss eines Blutvolumenentzuges auf einige Kreislauffaktoren beim Kaninchen.

Blood volume were drained from 20 female rabbits, all White New Zealanders, 2.5 kg in average body weight. Several factors of their circulation were determined twice, prior to and after the blood volume withdrawals. Included in the tests were haematocrit, haemoglobin, plasma volume by means of Evans blue dye dilution technique, and blood volume. The amounts of blood volume, BV0, drained ten, 20, 40, 60, and 70 minutes after beginning of the experiment were 4.4, 6.7, 8.9, 11.2, and 13.4 per cent. The ambient temperature was 15 degrees C and the relative humidity 60 per cent. The haematocrit value dropped to 91.2 per cent of the original figure over the whole experimental period and haemoglobin to 87.5 per cent, but decline of the latter was of minor importance along with blood volume loss from 8.9 per cent to 11.2 per cent BV0. Blood volume drain of 8.9 per cent BV0 was accompanied by 102.04 per cent plasma volume, PV0, and 100.4 per cent BV0. Erythrocyte volume and total haemoglobin exhibited similar behaviour in connection with the above amount of blood drain and did not return to their original values. Rabbit response to blood loss (re-absorption of fluid and splenic depletion) is discussed.