(17/05/2022)

Where does the processing of the information we use to express ourselves through language take place?

Why is the activity of cooking positive and beneficial to our brain?

What is cognitive rehabilitation?

Rita Levi-Montalcini said, “The brain: if you cultivate it, it works. If you let it go and retire it, it weakens. Its plasticity is formidable. That's why you have to keep thinking”.

To better address this broad topic, we need to list and photograph the neuroanatomical implications of our cognitive processes.

In this article we will therefore see what our higher cortical functions are by distinguishing them by type and try to briefly describe their anatomical substrates. All this will help us understand how these functions can be assessed clinically and measurably, to address (in a future article) the basics of cognitive rehabilitation.

The brain, as is well known, coordinates all of the body's functioning, physical and cognitive functions. To begin with a rather general definition, we can say that “cognitive functions” are abilities organized by the brain that regulate our relationship with the external environment. They are abilities that are acquired from birth and whose use must be constantly stimulated; they can also be "strengthened," "improved," "enhanced" over time (in the sense of "trained" and always within certain reasonable limits) and, in the case of problems resulting from inactivity, advanced age or trauma or disease of various kinds, even rehabilitated.

Our mind ages like the body and, just like the body, needs to be kept in training. As the years pass and age progresses, we need to "train" (and "keep in training") our brains, in a personalized and variable way; therefore, in general, it is important to find strategies that allow our cognitive functions to stay active and continue to operate at their best.

Scientific progress, thanks in part to a multi-disciplinary approach consisting of the search for solutions by several professionals in full synergy with each other (the Physician, the Rehabilitation Engineer or Neuroengineer, the Psychologist, the Physiotherapist, the Speech Therapist, the Occupational Therapist, the Neuropsychomotricist, etc.), has made and is making great strides to identify the most functional tools for the rehabilitation of the mind, or rather of brain and cognitive abilities. In addition to those cases in which it is intended to cope as satisfactorily as possible with the physiological effects of the normal passage of time, well-known pathologies such as Alzheimer's or other types of dementia come to mind when discussing this topic; in reality this type of intervention is also very effective and necessary in post-traumatic situations or following cerebrovascular accidents, such as stroke.

Cognitive rehabilitation is that type of therapy that encompasses a wide range of treatments aimed precisely at improving certain cognitive functions, or rather higher cortical functions in individuals who have suffered brain injuries or are mentally impaired: the ultimate goal of this type of therapeutic intervention is in fact to restore as much as possible the normal functioning of certain abilities or compensate for deficits related to certain, precisely, cognitive processes.

Let us take a small step back and better define the "functions" that cognitive rehabilitation aims to restore.

When we talk about higher cortical functions we are referring to complex skills inherent in attention, memory, language, orientation, the ability to reason, plan, and solve a problem, as well as perception and action itself, visuospatial skills, praxic skills, and executive functions.

In fact, very often (not to say almost always) we find that "exercises" proposed as cognitive stimulation/therapy are divided into categories that correspond to precisely these functions; here they are listed a bit more precisely.

• Language - communication through language is an activity that characterizes human beings and is the ability to use words or signs, combining them into sentences, to understand and be understood by other individuals. Communication can be verbal or nonverbal; the nonverbal one is of course body language, mimicry. Note that the ability to use body language is also a very important and complex skill, as well as functional for many purposes.
• Calculation - the ability to mentally perform mathematical operations, but also to keep in mind the increase or decrease of certain quantities over time and to visualize numbers without writing or reading them.
• Memory - the ability to retain information, i.e., the function aimed at assimilation, retention and recall in the form of "recollection," of information learned during experience or by sensory means. A distinction is made between short-term storage (tens of seconds or minutes) and long-term storage. Then there are other types of memory, such as memory related to automatic behaviors or explicit/implicit memory; due to the vastness of the topic, we cannot delve into it fully in this article.
• Orientation - is the ability to be able to decide on a route based on information, to retrace a path in the opposite direction to a given destination, and also to remember the right direction some time later. See also below under "visuospatial skills.".
• Attenzione - the ability to focus on the most important of the available information and ignore less important information. It can, in turn, be distinguished into selective (the ability to "cut out background noise"), divided (allows one to pay attention to several things at once) and sustained (the "alertness" characteristic of a situation in which attention is maintained for a prolonged time).
• Recognition - the ability to distinguish certain items based on recollection, association but also intuition or abstraction ability. In “The Man Who Mistook His Wife For a Hat” Dr. Oliver Sacks describes a man, "Dr. P." (for whom Sacks titled his entire essay), who suffered from Prosopagnosia, a condition that impaired precisely this seemingly so mundane ability. He was unable to give meaning to what he saw, to the point of confusing objects (and especially people) belonging to his daily life with each other. During an experiment, Dr. Sacks handed him a glove, which he was perfectly able to describe as “a continuous surface with five hollow appendages, probably a coin purse” but not to associate with its actual use until he was forced to wear it (thus bringing his sense of touch into play).
• Praxic skill - is the ability to perform complex voluntary movements, with or without meaning. Imagine holding a rake: the "how" to use it depends on praxic skills, just as in the case of a brush or performing the gesture to "say it's late" (with implications related to language and mimicry).
• Visual-spatial skills - allow us to assess visual space and look for what interests us, relate to the space and objects around us. Every day each of us uses these skills for a variety of common activities such as orienting ourselves, moving around a room, playing with a ball, drawing.
• Executive functions - are cognitive processes that interact with each other to initiate thoughts and organize functional actions to achieve a goal (Shallice, 1994; Benso, 2010), providing the subject with the skills needed to manage his or her own behavior. Executive functions allow one to plan and carry out purpose-oriented behaviors (e.g., brushing one's teeth), gather some information and accomplish something. They are "control functions" that work on information they receive from other functions such as memory, language and perception. Executive functions include: planning, organizing, sequencing and abstract reasoning.

As is clear, a person's activities can be so varied and complex that his or her higher cortical functions cannot always be divided into "watertight compartments," but can also alternate, or even better "partially overlap" and in an almost nuanced manner. Consider, for example, the activity of cooking: during the preparation of a dish, for its success (and our and our guests' well-being!) it is important to maintain a good level of attention, concentration but also memory (related to a recipe, to the ingredients we have on hand or to the moments when we performed an action, e.g., "when we baked this ingredient while this other one is browning"). In some cases we may need some abstraction skills, such as deciding to combine some ingredients based on our "intuition." We will also need to do some calculations (the amount of water, grams of flour, etc.), plan our actions, and manage a set of different operations that strain the brain areas responsible for programming and coordinating complex movements. It is no coincidence that Cooking Therapy is proposed in certain circles as a form of rehabilitative training that stimulates neural plasticity phenomena within our brains. In fact, says neuroscientist Antonio Cerasa, "Today Cooking Therapy is often used for the rehabilitation of patients with cognitive deficits, mental disabilities or psychiatric disorders".

Representation of neurogenesis, a form of neural plasticity involving the formation of new nerve cells

In any case, as "fuzzy" as some of the processes referring to the "overlap" of certain cortical functions or different brain areas in charge of them may be, the categorization made above is as fundamental as it is useful in being able to distinguish and set up various types of cognitive stimuli.

Without going too much into the specifics of the anatomy of higher cortical functions, which, moreover, is not yet fully known, we can say what we know and summarize the basic concepts: everything about these abilities takes place in the largest functional portion of the entire Central Nervous System. This portion is called the cerebral cortex, and it is the layer of gray matter that lines the outer surface of the hemispheres of our brain (of which it accounts for 42 percent of the entire mass). We can recall it visually by recalling its obvious grooves (furrows or scissures), which alternate with raised areas (circumvolutions or laps).

A brain. The furrows and circumvolutions of the cerebral cortex are noted.

Given its pivotal role in the control of the most important cognitive abilities and in the management of sensory functions and voluntary movements, the cerebral cortex is the main center of nerve information processing and integration in the Central Nervous System.

From a strictly functional point of view, the cerebral cortex is ideally divided into 3 sections, which in turn consist of areas:

• sensory cortex (sensory areas involved in hearing, smell, sight, touch and taste)
• motor cortex (motor areas related to voluntary movements, and all those activities - precisely, motor - that occur behind the command of a precise will such as walking, running, gesturing with the hands, etc.)
• associative cortex (unimodal or polymodal associative areas - so distinguished on the basis of the number of sensory modalities, i.e., sensations given by touch, hearing, sight, smell and taste, from which they integrate information - implicated in the higher cortical functions described above such as memory, learning, language comprehension, attention and even in thinking and consciousness)

To summarize: at the moment when (having to perform a task, an action subordinate to a cognitive process) we perceive a certain piece of information, the information signal is intercepted in our brain by the primary sensory areas; subsequently, through a stepwise process in which the unimodal associative areas project to the polymodal associative areas, it is finally transmitted to the motor areas.

Thus precisely the polymodal associative areas are believed to be the anatomical substrate of higher cortical functions-and it is no accident that they are particularly developed in primates and humans. In this regard, three polymodal associative areas are particularly important:

• posterior associative area (occipito-temporo-parietal): integrates information from different modalities and is involved in attention, language, spatial orientation, recognition of self and environment, and participates in the organization of complex movements;
• anterior associative area (prefrontal cortex): is associated with the executive functions of behavior, such as problem solving, planning a strategy of action leading to the set goal, monitoring performance, the ability to change strategy when circumstances require it, evaluating the consequences of one's own and others' actions, abstract thinking, and working memory;
• limbic associative area: located along the medial faces of the cerebral hemispheres, it is involved in the formation of declarative long-term memory and emotional behavior.

As pointed out earlier, the most complex higher cortical functions are likely to emerge from the coordination of the activities of different associative areas.

In particular, it appears that the associations between the parietal and prefrontal cortices are primarily responsible for the higher functions closest to what we call intelligence.

In summary, the sensory information that is “processed” by the, precisely, sensory areas is used by the higher cortical functions to formulate complex concepts that can be communicated, remembered (in the short or long term), used to create new ideas, associations, and purposes, and that can also be developed into an action.

Perception and action itself can also be considered “higher functions” since the task of recognizing a stimulus or implementing the appropriate motor plan to achieve a certain purpose is particularly complex. For example: the ability to hear and distinguish between a series of sounds when we listen to someone speak depends on our basic auditory functions; instead, it is thanks to a higher cortical function that we have the ability to recognize words and phrases of full meaning in the sequence of these sounds, and to connect them to concepts already known in our minds - and then formulate a new idea that we can communicate to our interlocutor and later remember and combine with other ideas on the basis of which to act.

In a future article, we will consider a little more "practical" aspect and see what the cognitive implications of brain damage may be; we will do this by reporting some experimental evidence of the role played by the different associative areas of our brain. This will also help us to better understand the very anatomy of some higher cortical functions.