An early study employed a sleep deprivation model to investigate the effect of Brahmi on the learning process in rats. When deprived of sleep, the levels of the stress hormone, serotonin, increased in rats. There was also an increase in glutamate levels, while GABA (gamma aminobutyric acid), a chemical involved in the transmission of nerve impulses, showed marked reduction. Discrimination learning was significantly reduced following sleep deprivation stress. Brahmi significantly reduced the levels of stress hormones following sleep deprivation and improved discrimination learning in the animals. The authors concluded that Brahmi helps to regulate the altered levels of biogenic amines following stress, thereby improving learning.
An important feature of memory formation in various animal species is its progression from a short-lived labile form to a long-lasting stable form, probably by consolidation through a multiphasic pathway. During this period of consolidation, memory can be disrupted by administering agents that induce amnesia. Electroconvulsive shock, hypothermia, and hypoxia are conditions that induce retrograde amnesia non-invasively. Other chemical agents (e.g. diethyldithiocarbamate) could induce temporary amnesia. Earlier studies on the processing of memory have revealed that memory consolidation involves both serial and parallel processing of information.
A recent study tested the ability of rats to remember skills learned before amnesia was induced in order to confirm the mode of action of the bacosides on the memory process. Retrograde amnesia was induced in rats by immobilization stress administered for 18 hours or by administering electroconvulsive shock (0.5 mA, 50 Hz, 0.5 sec). Both treatments were administered immediately after the completion of training. The training schedule involved a brightness discrimination reaction. The animals were divided into two groups; one group served as the untreated controls. Bacosides were administered to the second group at an oral dose level of 20 mg/kg for three days before the induction of amnesia. The amnesic treatments led to a significant disruption of consolidation in control groups compared to the groups pretreated with bacosides.
(a) Learning skills: ease of acquisition
Effect of bacosides (20 mg/kg oral dose for 3 days) on immobilization-induced amnesia