Neuroscience
Manàsseina’s most distinguished contribution in the field of neuroscience was her research on sleep deprivation. She was one of the first scientists to state that while we sleep the brain is active.
To conduct this investigation, she worked alongside professor Ivan Romanovich Tarkhanov, who was also interested in sleep disorders. They put ten puppies (two to four months old) under a state of permanent insomnia by keeping them constantly active. These puppies had previously been fed and well taken care of. The sleep deprivation was fatal after four to five days, leading to the death of all the puppies. As a control measure, they deprived other puppies of food. Even though they had been starving for 20–25 days, they could be rescued and returned to a healthy condition. These results clearly showed the importance of sleeping for life to be maintained and that sleep deprivation leads to a faster death than the deprivation of nutrients. Further research showed that the effects of sleep deprivation in the puppies included a body temperature decrease of four to six degrees[clarification needed], a reduction of the number of red blood cells, local brain hemorrhages, cerebral ganglion impairment, etc.
As a consequence of this research, Manàsseina concluded that sleeping is as necessary as nutrition for the regeneration of the brain cells. She also emphasized the idea that, during sleep, there is a particular activity[clarification needed] in the brain. This assertion challenged the prevailing belief at that time that sleeping was merely a passive state of the organism. She also stressed that only the brain structures involved in maintaining consciousness are inactive during sleep–thus, sleeping means resting the consciousness. This intuition is remarkable considering that the electroencephalogram didn't yet exist.
Her work had a great impact on the scientific community and many scientists replicated her model:
In 1896, the American psychologists George T.W. Patrick and J. Allen Gilbert conducted the first sleep deprivation experiment on humans.[1] In 1898, Italian investigators Lamberto Daddi and Giulio Tarozzi and, separately, Cesare Agostini, expanded Manàsseina’s findings by conducting detailed histopathologic and anatomic analyses of the puppies' brains.
Biochemistry
Though Manàsseina worked in Saint Petersburg the majority of her life, she spent several months at the Polytechnic Institute of Viena working alongside Jullius Wiesner. There, she made a noteworthy finding concerning the fermentation process, which was an important contribution to the field of biochemistry. Against the prevailing belief at that time, Manàsseina was the first to claim that the fermentation process is due to the action of enzymes that can be isolated from the yeast cells. Therefore, she concluded that yeast fermentation is a cell-independent process.
A few years later, Eduard Buchner replicated the results of this research and published them. Despite his being aware of Manàsseina’s work, he did not cite her nor give her any credit. Despite her efforts to obtain recognition for this discovery, it was Buchner who received a Nobel Prize in 1907.