There are many questions about the brain that continue to intrigue neuroscientists today. How does this organ develop? Are there stages of brain development? Are there critical periods when certain events must occur for the brain to develop normally? And, perhaps most importantly, how does the brain process information?

Throughout this article we will try to understand the latter: how our brain processes the information it receives from the outside , and how it stores and retrieves that information; but first, we will address some basic concepts that will help us better understand the functioning of this wonderful and complex organ.

Some basic concepts

In order to understand how our brain is able to process the information it receives from the environment, we must first know how it works inside. Nerve cells or neurons are the ones that receive information from other nerve cells or sense organs. These neurons are equipped with a cell body, a kind of metabolic heart, and a huge tree-shaped structure called the dendritic field, which is the input side of the neuron.

The information comes into the cell from projections called axons . Most of the excitatory information reaches the cell from the dendritic field, often through small dendritic projections called spines. The junctions through which information passes from one neuron to another are called synapses, which can be either excitatory or inhibitory in nature.

Synaptic connections are added to the brain in several ways; one of them is through the overproduction of synapses and subsequent selective loss. Overproduction and loss of synapses is a fundamental mechanism that the brain uses to incorporate information from experience, and tends to occur during the early periods of development.

For example, in the visual cortex, the area of the brain’s cerebral cortex that controls sight, a person has many more synapses at 6 months of age than in adulthood. This is because more and more synapses form in the first few months of life, and then disappear, sometimes in large numbers. The time required for this phenomenon to take its course varies in different parts of the brain, from 2 to 3 years in the human visual cortex to 8 to 10 years in some parts of the frontal cortex.

The nervous system establishes a large number of connections ; the experience is reproduced in this network, selecting the appropriate connections and eliminating the inappropriate ones. What remains is a refined final form that forms the sensory and perhaps cognitive foundations for later phases of development. The second method of synapse formation is by adding new synapses.

Unlike overproduction and loss of synapses, this process of synapse addition operates throughout human life and is especially important in later life. This process is not only sensitive to experience, but is actually driven by it. Synapse addition probably lies at the base of some, or even most, forms of memory . But before storing and processing information, the brain needs to encode and filter it. Let’s see how.

How does the brain process information?

Information processing begins with the input of the sense organs , which transform physical stimuli such as touch, heat, sound waves or light photons into electrochemical signals. Sensory information is repeatedly transformed by the brain’s algorithms in both upstream and downstream processing.

For example, when you look at an image of a black box on a white background, upstream processing gathers very simple information such as color, orientation, and where the edges of the object are, where the color changes significantly in a short space (to decide that you’re looking at a box). Top-down processing uses the decisions made in some steps of the bottom-up process to speed up the recognition of the object.

Once the information is processed to some extent, an attention filter decides how important the signal is and what cognitive processes should be available. For example, although the brain processes every blade of grass when you look at your shoes, a specific attention filter prevents you from noticing them individually . Instead, your brain is able to perceive and hear your name, even when you are in a noisy room.

There are many processing steps, and the results of processing are modulated by attention repeatedly. However, for the brain to process information, it must first be stored. Let’s see how it does that.

The storage of information

For the brain to process the information, it must first be stored. There are multiple types of memory, including sensory and short-term memory, working memory, and long-term memory. Information must first be encoded, and there are different types of encoding specific to different types of sensory stimuli.

For example, verbal input can be coded structurally, referring to how the printed word looks; phonologically, referring to how the word sounds; or semantically, referring to what the word means. Once the information is stored, it must be maintained. Some animal studies suggest that working memory, which stores information for approximately 20 seconds, is maintained by an electrical signal that travels through a particular series of neurons for a short period of time.

With regard to long-term memory, it has been suggested that the information that manages to be consolidated in this warehouse is maintained in the structure of certain types of proteins. However, there are numerous models of how knowledge is organised in the brain , some based on the way human subjects retrieve memories, others based on computer science and computation, and others based on neurophysiology.

The semantic network model, for example, establishes that there are nodes that represent concepts and that these nodes are linked according to their relationship. For example, in a semantic network, the word “chair” could be linked to “table”, which can be linked to “wood”, and so on. Another model is the connectionist, which states that a piece of knowledge is represented simply by a pattern of neuronal activation rather than by a meaning.

There is not yet a universally accepted model of knowledge organization , because each one has its strengths and weaknesses, so in this sense more research is needed.

Information retrieval

Once stored, memories must eventually be retrieved from memory storage. Remembering past events is not like watching a video recording. In fact, it has more to do with a process of reconstructing what might have happened based on the details that the brain chose to store and was able to remember.

Information retrieval is triggered by a signal, an environmental stimulus that prompts the brain to retrieve the memory in question. Evidence shows that the better the signal for recovery, the greater the chances of remembering something. It is important to note that the recall signal can also cause a person to incorrectly reconstruct a memory.

Distortions in memories can occur in a number of ways, including varying the wording of a question. For example, simply asking someone if a black car had left the scene of a crime may cause the person to remember seeing a black car during a subsequent interrogation. This has been consistently observed in studies with witnesses in court cases, where it has been shown how easy it is to manipulate and implant false memories.

Studies in this field also indicate that the mind is not just a passive event recorder , but that it works actively to both store and retrieve information. Research shows that when a series of events occur in a random sequence, people reorder them into sequences that make sense when they try to remember them.

Recovering memory, therefore, requires revisiting the nerve pathways in the brain formed when a memory is encoded, and the strength of those pathways determines how quickly it can be recovered. Such retrieval effectively returns a memory located in the long-term store to short-term or working memory , where it can be accessed again, in a kind of mirror image of the encoding process.

After all, the memory is stored again in the long-term memory, which consolidates and strengthens it again. In short, our memory system is as complex as it is efficient, although there is still a lot of research to be done.

Bibliographic references:

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