Origin of the mind (4)

Maybe some of those who have read the fragments I presented from my new book “Origin of the mind; From viruses to beliefs” asked themselves why I choose this title? In this last part I will answer to this hypothetical question.

 

 

The human body has two immune systems: innate and adaptive (or acquired). Innate immunity refers to an unspecific defense mechanism which is mobilized immediately or several hours after exposure to microbes. Humans are born with this type of immunity. It is the initial response of the organism, targeting microbe elimination and prevention of infections. Within the adaptive immune sustem, there are only some lymphocite B and T that recognize each form of microbe. These cells need to multiply rapidly in order to produce enough cells to generate an efficient immune response against a certain microbe. This process involves several days. In the meanwhile, the microbe may produce considerable harm, and as a consequence, the innate immune system plays a fundamental role. The adaptive immune system is activated by the older, non-specific innate immune system, which represents the main protection system against pathogens in all being. Subsequently, adaptive immunity is elicited when a pathogen surpasses the innate immune system and generates a certain threshold level of antigens. The adaptive immune system has the ability to memorize and recognize specific pathogens (to generate immunity), and to launch attacks each time that specific pathogen is encountered. This is called adaptive immunity because the organism’s immune system prepares for subsequent challenges, as opposed to the innate system.

The adaptive immune system appeared in the first vertebrates with jaws (jaw-fish), 450 million years ago, and evolved in a time interval spreading over a little less than 20 million years. Genetic analyses have shown that the occurrence of the adaptive immune system was preceded by the double duplication of the genome, which is responsible for the genes of the adaptive immune system. Gene duplication plays an important evolutionary role considering that one of the new copies may have a new function. Genetic studies indicated that the majority of genes in the adaptive immune system resulted from the primitive nervous system found in vertebrates, and by virtue of their duplication, they gained a new function. Genome duplication and gene diversification, which occurred 550 million years ago, before the development of the adaptive immune system, is regarded as a possible mechanism underlying the evolution of the vertebrate brain. There is an abundance of evidence demonstrating that the adaptive immune system resulted from the action of retroviruses (a retrovirus is a virus which succeded in inserting into the DNA of the host and in this way is transmitted from parrents to offspings).

The immune and nervous systems are traditionally believed to serve different functions. Nonetheless, the differentiating line between the two becomes more and more flimsy. According to genetic data, it seems that the brain evolved from molecules derived from retroviruses that have lost their initial function, and were instead co-opted to create genetic diversity and aid genome expansion – a process known as exaptation. L1 retrotransposons (retrotransposons are mobile elements from the genome which are actually fragments of ancient viruses) are considered to be the most creative force participating in the construction of genomes throughout evolution. L1 elements are to a greater extent cognate to the elements from the introns in mitochondria and eubacteria. L1-produced retrotranscription is extremely old, and that is why its generating elements may be regarded as relicts of the first systems associated with life self-replication, presumably reaching back to the “RNA world” assumed to have preceded the current “DNA world”. It seems that L1 helped the development of a brain capable to process information about rapid environmental modifications, thus facilitating increased adaptability to climate changes and any other sort of changes.

Humans and their ancestors have been permanently under the attack of viral parasites and other forms of invaders that expanded the human genome using “jumping DNA”. Their organisms were not capable to completely eliminate these invaders. Instead, they had to adapt, and in order to coexist, they silenced these invaders by means of various intelligent mechanisms, which determines their mutations in order to deactivate them. Recent studies found that L1 elements are 100 times more numerous in the adult human brain, compared to the heart, skin or liver. Most of them were found in the hippocampus and frontal cortex, thus reflecting the great contribution of newborn neurons that develop from stem cells, in these areas of the brain. L1 elements produce a specific  enzyme that “writes memories”, and not just genetic memory, but immune memory and memories in the brain as well. So it seems that our memories are written by the same mechanisms that control the immune system and these mechanisms have viral origins. And many experimental data support this hypothesis showing the string connections between the nervous and immune system and also the similarities in their functioning.

Various experimental studies discovered that perception of danger threatening our social connections seems to be processed by the same neuronal network that responds to physical threat. And these structures are  associated with a more general stress/anxiety system activated by any type of negative events, thus generating inflammatory responses. The neuronal mechanisms responsible for generating defensive reactions such as anger or anxiety are coupled with the immune system, which is traditionally regarded as a defender of the organism against non-Self agents or antigens. Considering these origins, the nervous and immune systems hold functional similarities. One of them refers to the process of generating novel neurons and synapses, which are maintained consequently to exposure to information during a sensitive or critical period, similarly to the process underlying T and B lymphocytes in the adaptive immune system.

It seems that the nervous system, akin to the immune system, underlies a selection in terms of identity and neuronal connectivity occurring both throughout development and during processes associated learning. Once the neurons are “marked” with a certain category of information that particular neurons become dependent upon that information. Any kind of information, from parents to culture. Subsequently, they will attempt to update and defend that information every time they get the chance, thus preventing its “dislocation” by other pieces of information (or cognitive immunity). This mechanism is similar to the one responsible with creating addiction modules, which were initially genetic. Addiction modules reflect the impact drugs have upon our brain, so is a chemical addiction. But more advanced organisms added what we call, learning. Learning mark the genes from our neurons and implement the “addiction modules” in these neurons. Life experiences are reflected in the brain in the form of the “Self”, similarly to the immune Self, while the nervous system defends this construction in the same way the immune system defends the organism against microbes or viruses.   This is why we tend to search for our favorite things in life and to protect our beliefs in face of challenges – like incongruent information. So we are addicted to our beliefs and our habits because information we learn takes control over the genes of our neurons and become resistant to displacement in the same way a virus protect himself.

Given that almost half of the human genes are produced by retroviruses and the learning machine that generates values and beliefs has its origin in ancient viruses we can conclude that humans, among other beings, are the constructions of viruses and the information infects us like a virus infects a species.

 

Origin of the mind (part 3)

In this post I continue to present some topics from my book “Origin of the mind; From viruses to beliefs”. In this part I focus on the things that change our brain by changing the way of how genes express themselves inside the neurons.

 

 

 

Regardless of whether we are talking about people, drugs, activities or the things that we like, end up modifying the architecture of our brains by reinforcing the already existing synapses and creating novel synapses and new neurons. Contrary to the beliefs shaped a few decades ago, the development of the brain as an organ does not cease when reaching adolescence. It modifies its circuits in the course of a lifetime by adding novel neurons and creating new synapses and losing others. These long-lasting alterations represent the basis underlying the mental content that defines us as individuals, or what psychologists term “Self”. Furthermore, these alterations are responsible with the formation of novel memories. These changes occur by virtue of what are called epigenetic mechanisms that alter the DNA inside the neurons exposed to external information.

Epigenetic mechanisms are used to create and store cellular information in response to environmental signals – food, temperature, oxygen level. This informational storage is analogous to memory storage in the nervous system. More and more research has demonstrated the existence of a complex epigenetic mechanism responsible with regulating gene activity turning them on and off without altering the genetic code. So these epigenetic mechanisms act like a switcher. In the center of epigenetic processes lays the idea that genes have a “memory”. The lives of our grandparents – the air they breathed, food they ate or even the things they have seen – may influence us decades later, although we did not live those experiences directly. Subsequently, our experiences may affect the lives of our grandchildren. Therefore, the “memory” of an event can be passed from one generation to the other. A simple stimulus from our environment may turn on or off certain genes. One example relates to stress, which shuts down the genes involved in synaptic plasticity. Hence, chronic stress affects large areas of the brain. Essentially, it affects the connectivity between brain hubs, and thus informational exchange between distal areas. Moreover, it exerts a negative effect on non-emotional learning mechanisms, which are responsible with exploring and learning pieces of information ascertained as novel, more complex or different, compared to the already acquired ones. We might even say that what we call chronic depression is a degenerative disorder affecting the capacity to adapt to novelty. In addition, stress affects DNA, while memory consolidation processes are influenced by genes which encode the enzymes involved in DNA repair.

A fundamental thing is that epigenetic alterations may be transmitted to our children, what on long-term affect the genes of our species. This is how environment shapes the evolution. From the food we eat and the antibiotics we take to the technology we created, all these have the potential to change our species. And all these changes will remain recorded in our genes like in a data base.

Origin of the mind (part 2)

As you probably know if you read my previous post, recently I have published a neuroscience book called Origin of the mind; From viruses to beliefs whose objective is to uncover the actual basis of behavior and what we traditionally call “mental activity”. In this post I continue to present some topics covered in the book.

 

 

Traditionally, both in psychology and common sense, decision making is considered as separate from action planning. However, recent neurophysiological studies suggest that potential action plans aimed at multiple targets, are simultaneously represented in multiple areas of the cortex responsible for motion control. Selecting one target – or “the decision” – involves the same cerebral mechanism as the one involved in action planning, the two of them functioning in an integrated manner. While making decision about actions, the signal related to the value of an action is encoded in cerebral regions involved in movement generation, thus suggesting that decision-making and action generation share a common level of neural organization. Therefore, voluntary actions are a form of decision-making. So we don’t speak here about a “superior” cognitive faculty but of the same basic function that control our movements. And the decision making style has a lot in common with our motor abilities like sports.

Other studies have extended these findings, indicating that decisions which dictate upon our actions are built in the neural circuits used by the brain for learning the value of actions. Any learning system needs to look up information in advance, and the better this task is performed, the more learning speed and accuracy increases. As a result, the brain developed mechanisms that process information even when this information is irrelevant for the ongoing behavior - the act of successful prediction involves an intrinsic motivational/rewarding role. The same neuronal system that reinforces behavior through reward or punishment, that aids the search of water or food supplies, also participates in decisions making processes underlying risky situations. In addition, this system teaches the brain to seek information in advance, thus selectively reinforcing the actions leading up to the information that unveil future rewards. These neuronal networks called “instrumental learning networks” underlie all the mental activities related to our actions, from planning and decision making, to attention/action monitoring and feedback processing. All these mental abilities analyzed as separate entities in psychology books, either as cognitive abilities or personality traits, are actually different aspects of the same generator in the brain, being manifestations of the learning process. As a consequence, inter-individual differences in terms of planning, decision making, action monitoring or feedback-related processing, should be investigated within the activity of these instrumental learning networks. And if you want to improve your decision making abilities you have only one chance to proceed: not to study books about decisions but to do things. Taking actions in various situations and involving various people train your decision making ability.

As I said above, we tend to see decision making as a separate, independent entity. But is not the case. And obviously is not the case when it comes to inter-individual differences in the decision making style. One example is impulsivity. Although impulsivity is presented in psychology as a unified concept, functionally speaking, it implies several different mechanisms. We can therefore argue that people can present several forms of impulsivity. Particularly, impulsivity can be divided into components that are related to: 1) “reflection impulsivity”, meaning behaviors inadequate to sensory stimuli; 2) “impulsive action”, namely, motor inhibition deficits; 3) “impulsive choice” or the tendency to accept small and immediate rewards in the detriment of large but uncertain rewards; 4) “sensation seeking”, entailing risky behaviors such as drug consumption or bungee jumping; 5) “compulsions”, meaning situation-inadequate actions that persist, are unrelated to set objectives and often attract negative consequences.

            All these forms of impulsivity have distinct neuronal pathways in the brain, and distinct causes for their manifestation. And if we want to help somebody not to be impulsive first we have to identify what form/forms of “impulsivity” he’/she has and act upon it. For instance in the case of impulsive actions we have to learn how to control the initiation of a behavior (so a self-control over action) while in the case of impulsive choice we have to learn how to imagine/simulate alternative options and focused on them.

Origin of the mind

Traditionally, we explain human behavior in terms of “mental activity”. We believe that our actions are the result of emotions, attitudes, conscious thinking and personality. Subsequently, the brain has been regarded as a “Swiss penknife”, each anatomical part being a specialized tool for a certain faculty, the same faculties we found in the psychology textbooks. But what is the nature of this taxonomy, how was it established and how sure of its validity are we?

This theoretical scheme is known to be grounded in the philosophical heritage of Ancient Greece. Now, 2000 years after Plato and Aristotle, various authors argue that the use of concepts extracted from traditional psychology hinders the understanding of brain functions and instead of trying to match the brain activity with psychology textbooks we should rather try to understand the actual function of different brain networks, the representations they entail and the processes they employ.

Recently I have published a neuroscience book called Origin of the mind; From viruses to beliefs whose objective is to uncover the actual basis of behavior and what we traditionally call “mental activity”, the way in which they develop whilst interacting with the environment and how they have evolved. Here are briefly presented some topics coved in my book.

Data from neuroscience have shown that what we call “beliefs” or conscious thoughts regarding a certain situation or activity are not generated by an independent Self, as philosophers and psychologists claim, but instead, within the brain circuits involved in dealing with actions. The conscious Self with its belief system seems to be a construction of the brain networks responsible with perception of environment and with learning movements.

Traditionally, decision making is regarded as being separate from action planning. However, recent neurophysiological studies suggest that potential action plans aimed at multiple targets, are simultaneously represented in multiple motor areas of the cortex. Selecting one target – or “the decision” – involves the same cerebral mechanism as the one involved in action planning, the two of them functioning in an integrated manner. While making decision about actions, the signal related to the value of an action is encoded in cerebral regions involved in movement generation, thus suggesting that decision-making and action generation share a common level of neural organization.

There is sufficient proof to demonstrate that the ability to mentally represent our future works hand in hand with the ability to represent our past. Thus, episodic memory can be regarded as the capacity to picture ourselves in time, both in the past and in the future. Evidence from clinical psychology, developmental psychology and neuropsychology congruently points toward this hypothesis. Representing future episodes requires a system that can flexibly recombine details of past events. Recalling implies that pieces of stored information are recombined and not that past events are sequentially unfolded in the same form as they have been lived before. Subsequently, episodic memory builds future events by extracting and recombining stored information, thus simulating a new event. Novel memories cannot be constructed in the absence of recalling past memories, whereby the information associated with the present perception gains significance and organization. Memory updating only occurs when the brain enters a labile state. The new information will subsequently become apparent based on this substrate. Studies have shown that re-exposure to the initial context is absolutely necessary for the purpose of rewriting an old memory according to the coordinates of the novel information. As a result, one needs to know and understand the actual functional organization of the brain in order to explain and facilitates its performance, such as that associated with learning or relearning (i.e., “extinction”, in the case of phobia or addiction). 

Related with the above statement, experimental data has revealed that the ability to recall information is not independent from what we traditionally call “perception”, “imagination” or “attention” but rather shares an intimate relation with them. The “perceptual-mnemonic” theory of the brain implies that it may not be constructive to make a distinction between “perception” and “memory” as mental functions, as they may seem to be from introspection. Instead, they should be regarded as different manifestations of a common neural substrate.

Various experimental data suggests a strong neuronal connection between romantic love and the drug-generated euphoric state. As a result, numerous authors have distinctly formulated a strong connection between attachment and addiction. Furthermore, regardless of whether we are talking about people, drugs, activities or the things that we like, end up modifying the architecture of our brains by reinforcing the already existing synapses and creating novel synapses, synaptic buttons and newborn neurons. Contrary to the beliefs shaped a few decades ago, the development of the brain as an organ does not cease when reaching adolescence. It modifies its circuits in the course of a lifetime by adding novel neurons and creating new synapses and losing others. These long-lasting alterations represent the basis underlying the mental content that defines us as individuals, or what psychologists term “Self”. Hence, what psychologists call “Self” is in fact, a sum of connectivity networks – or hubs – that are formed in the brain as a consequence of exposure to experiences. Furthermore, these alterations are responsible with the formation of novel memories. These changes occur by virtue of epigenetic mechanisms that alter chromatin and DNA in neurons exposed to external information. Subsequently, our experiences may affect the lives of our grandchildren. Therefore, the “memory” of an event can be passed from one generation to the other. A simple stimulus from our environment may turn on or shut down certain genes. Subsequently, this change may be transmitted to offspring, thus affecting the genes of the species.

According to genetic data, it seems that the brain evolved from molecules derived from endogenous viruses that have lost their initial function, and were instead co-opted to create genetic diversity and aid genome expansion – a process known as exaptation. Considering these origins, the nervous and immune systems hold functional similarities. One of them refers to the process of generating novel neurons and synapses, which are maintained consequently to exposure to information during a sensitive or critical period, similarly to the process underlying T and B lymphocytes in the adaptive immune system. It seems that the nervous system, akin to the immune system, underlies a selection in terms of identity and neuronal connectivity occurring both throughout development and during processes associated learning and with brain regeneration. Therefore, it can be assumed that the nervous system, similarly to the immune system, evolves in situ as a consequence of experience. Once they are “marked” with a certain category of information, cells in these systems undergo epigenetic modifications by virtue of which they become dependent upon that information. Subsequently, they will attempt to update and defend that information every time they get the chance, thus preventing its “dislocation” by other pieces of information (or cognitive immunity). This mechanism is similar to the one responsible with creating addiction modules, which were initially genetic. In more advanced organisms, they subsequently added the epigenetic dimension, thus determining what we call, learning. Life experiences are reflected in the brain in the form of the “Self”, similarly to the immune Self, while the nervous system defends this construction in the same way the immune system defends the organism against antigens.