The brain has become wiser from a good electrical contact
Understanding the principles of the brain and building a comprehensive model of it is one of the biggest challenges facing modern science. A new study has shed light on the evolution of higher nervous activity and how we managed to become so smart. Or at least some of us…
To advance the study of this issue, British neuroscientists have long and painstakingly studied unicellular, flies, mice and, of course, volunteers of the species Homo sapiens. Their labors were not in vain: now we can safely say that the emergence of intelligence was influenced not so much by the amount of gray matter as by the quality of the data transmission system between neurons.
The exchange of impulses (that is, the management of all the activities of living organisms) is carried out through synapses – biochemical complexes responsible mainly for the contact between the axon and the dendrite.
Scientists believe that it was the complication of these contacts that contributed to the emergence of more advanced behaviors in mammals, and subsequently in humans.
The simplified mechanism of signal transmission looks like this: a neurotransmitter is released from the synaptic vesicles of the axon, which exits into the synaptic cleft and, after a certain reaction, connects to the molecular receptors of the dendrite. As a result of induction, a nerve impulse arises. At least two conducting mechanisms are known in the synapse: directly through the synaptic cleft by means of membrane polarization and transmission at a high content of calcium ions. The second mechanism is presumably faster than the first.
Another interesting result of studying synapses is the establishment of a relationship between the intensity of impulse transmission and memory. The synapse has so-called long-term potentiation (LTP) when long-term contact is maintained, and long-term depression (LTD) when it is blocked. Most neurophysiology theorists believe that these two mechanisms underlie the cellular mechanisms of memory and learning.
British scientists have found significant differences in the number and complexity of proteins that determine the nature of pulse transmission. About 600 different types of proteins were found in mammalian synapses, and about 300 in invertebrates.
But that's not all. About 150 types of proteins have been recorded in yeast bacteria – and they don't have a brain at all. But synaptic connections help unicellular cells interpret external signals – temperature changes, for example.
According to Professor Grant, the contacts found in microorganisms are descendants of the ancient "protosynapse", which provided the formation of the first behavioral models. That is, it was in this way that the ability to react to the surrounding reality and develop an appropriate strategy first appeared.
In the future, the number of possible combinations of responses grew – first in invertebrates, and then in vertebrates. The crown of creation in this case, of course, is man. It is possible that the development of synaptic connections eventually led to the emergence of logic.
Already during the first stage of the study, scientists were able to isolate neural proteins from the brain of flies for the first time, which made it possible to evaluate the mechanism of data transmission in invertebrates and compare it with known data on animals.
Further study of behavioral models and the corresponding hereditary mutations in animals confirmed the initial estimates: the evolution of "transfer" proteins is associated with the complication of consciousness models – up to the emergence of higher nervous activity.
For example, one of the localized genes – SAP102 – "allowed" experimental mice to navigate correctly in the maze. The fact is that when it is blocked, the proteins necessary for the passage of nerve impulses (and only certain types) cease to be produced, and in this case the mice simply cannot find their way. Mutations of this gene in humans, we note, lead to mental disability.
Thus, it was possible to link several previously isolated genes with the cognitive abilities of animals and humans – this is a truly serious achievement.
It is possible that it is the complication of proteins that is the key to understanding thinking abilities. The authors of the work believe that such an "upgrade" was the reason for the allocation of specialized departments in the brain, which, in turn, formed the prerequisites for the emergence of higher nervous activity.
"Soon we will be able to build a simple model of the emergence of consciousness and behavior, common to all existing species," says Dr. Grant. In his opinion, we are "one step away" from answering a truly philosophical question: what is thought and what is human logic.
And another participant of the project, Dr. Richard Emes from Keele University, believes that, at least, the evolutionary path of consciousness has begun to emerge: "It's amazing how nature, by trial and error, connected the corresponding proteins into a primitive sensory system first in the simplest, and then we got to more complex synaptic connections in mammals, which allow not only to react to the surrounding world, but also to analyze it."
In general, at this stage, the scheme of consciousness development is presented as follows: the increase in the complexity of molecular complexes – the appearance of "large" synapses – an increase in brain volume. At least, if we rely on the results of a new study.
By the way, the authors of the work compare the evolution of the synapse with an increase in the computing power of processors. I wonder if a person is the ceiling of productivity growth that has already been reached, or are more perfect creatures possible?
Have we reached our quantum ceiling?
Portal "Eternal youth" www.vechnayamolodost.ru20.06.2008