Authored by Dott Giulio Perrotta
Starting from the concept of “executive functions”; we proceeded to
describe the object under examination in a more complete and functional
way; and their possible role in neuropsychology and developmental
psychopathology. The use of statistical methods and clinical observation
have
allowed us to emphasize the understanding of the multi-componential
structure of the processes themselves. Paying particular attention to
the
psychopathological contents listed in the DSM-V psychiatric manual; the
main pathological forms were then analyzed to better contextualize the
present discussion; also from a psychotherapeutic point of view; with
the preferential choice of the strategic approach for the management of
pathological disorders related to the deficit of executive functions.
Definition and clinical context of executive functions
The term “executive functions” (E.F.) refers to a complex
cognitive construct in the form of a system organized in functional
modules of the mind; where a series of processes necessary to
maintain an appropriate; organized and flexible planning mode are
included. resolution (or problem solving); control and coordination;
aimed at a purpose [1-3].
To simplify; the executive functions are those abilities that
answer the question << Who is in charge? >> and concern mental
processes aimed at the elaboration of adaptive cognitive-behavioral
schemes; at the base of planning; decision making; working
memory; corrective response to error feedback; predominant
habits; mental flexibility.
This complex construct thus implies:
a. An ability to inhibit a response or to postpone it at a later
and more appropriate time.
b. A strategic and flexible planning of behavioral sequences.
c. A mental representation of the task that includes both
the relevant information encoded in the memory and the future
objectives to be achieved.
There are several possible definitions; from a theoretical and
organizational point of view [4]:
1) The executive functions represent a system of abilities
that allows to create objectives; to preserve them in memory;
to control the actions; to foresee the obstacles and to reach
objectives (Stuss 1992).
2) Executive functions represent the set of abilities that allow
the person to successfully implement independent; intentional
and useful behaviors (Lezak 1993).
3) Executive functions are higher-order cognitive functions
that make it possible to formulate objectives and plans;
remember these plans over time; choose and start actions that
allow us to reach those goals; monitor the behavior and adjust
it so as to arrive at those goals (Aron 2008).
It therefore appears evident that the executive functions are not
easy to define; since this term does not refer to a single capacity
but rather to a set of different sub-processes necessary to perform a
specific task. They are superior cortical functions responsible for
the control and planning of behavior; they are processes that allow
the person to plan and implement projects aimed at achieving a
goal and are necessary because they guarantee the monitoring and
modification of their behavior in case of need or they adapt it to
new contextual situations.
They consist of six steps:
1) Analyzing the task.
2) Plan how to achieve the task.
3) Organize the steps needed to carry out the task in
question.
4) Develop a timeline to complete the task.
5) Adjust or change steps; if necessary; to complete the task.
6) Complete the task in a timely manner.
They are therefore executive functions surely:
a) The inhibition; or the ability to focus attention on the
relevant data ignoring the distractors and inhibiting inadequate or
impulsive motor and emotional responses with respect to stimuli.
b) Flexibility; or the ability to move from one set of stimuli to
another based on information from the context.
c) Planning; or the ability to formulate a general plan and
organize actions in a hierarchical sequence of goals.
d) The working memory; or the ability to activate and
maintain the plan and the work area at a mental level; to have a
mental reference set on which to work mentally.
e) Attention; or the ability to maintain concentration on a
given element.
f) Fluency; or the ability of divergent thinking and ability to
generate new and different solutions with respect to a problem [5].
Although those most investigated for information on cognitive
functioning are the basic functions of working memory [6] (or
updating; the ability to maintain; update and process information in
mind in time for the resolution of a task); of cognitive flexibility (or
shifting; the ability to pass from one mental operation to another by
controlling the mutual interference between the two actions) and
inhibition (or inhibition; the ability to control automatic responses
that interfere in achieving of a purpose); the executive domain does
not end with the only cognitive processes listed above; but also
involves mechanisms that play a part in the regulation of emotions;
behavior and motivation.
A dichotomous distinction has been formulated in recent years
between “Hot” executive functions and “Cool” executive functions
[Zelazo 2004]:
a) The “Cool” executive functions represent those functions
based on a complex; cognitive; controlled and slower processing;
which are activated when the subject is dealing with abstract
and decontextualized problems. The neurophysiological area
used for these functions is the dorso-lateral prefrontal cortex
[7].
b) The “Hot” executive functions are linked to an automatic
and emotional processing of the stimuli; or a simple and
rapid programming that intervenes in situations of stress;
these functions are required in significant situations and
involved in the regulation of emotion and motivation. The
neurophysiological area used for these functions is the ventromedial
prefrontal cortex [8].
The “Hot” executive functions and the “Cool” executive functions;
according to this theoretical construct; work synchronously in
order to guarantee an ideal functioning; but neuropsychological
studies suggest a double dissociation between the two types of
functions; documenting injuries on load Hot in the absence of
problems against the Cool and the Cool in the absence of Hot.
The advances in the methodological field and in particular
the conception of experimental tests with motor; linguistic and
memory requirements; compatible with the level of competence
of the child in early childhood; have allowed us to observe how
the development of executive functions begins earlier; compared
to what was previously assumed; this applies to both the Cool and
the Hot ones. As far as the Cool is concerned; we have already seen
how at 12 weeks the child is able to preserve the memory of the
objective structure of an event in which he was the protagonist to
reuse it in similar situations; from seven to eight months the first
signs of working memory and inhibitory control begin to appear;
regarding the Hot; some observations seem to suggest difficulties
in the control of this executive domain in the first two years of
life; although the processes of cortical development seem to affect
these regions before those involved in the Cool: the child would
indeed have difficulty in regulating the emotions and in postponing
rewards/gratifications and presenting a way of relating to the
self-centered world. Between the ages of three and five; the child
succeeds in tasks that require maintaining information in the mind
and at the same time the capacity for inhibition; between three
and four years the ability to generate concepts develops; between
four and five years the attentional control matures and there is an
improvement in cognitive flexibility and in the ability to formulate
strategies; at five years there is an increase in working memory
and therefore in the ability to temporarily preserve and manipulate
information online.
With preadolescence some executive skills reach maturity.
Between seven and eight years and between nine and twelve years
there is an increase in sensitivity to feedback in problem-solving;
in the formulation of concepts and in the control of impulsiveness.
At the age of seven; considerable progress has been reported in the
speed of execution; in the ability to use the strategies; in the ability
to maintain information in the mind and to work with it. Between
the ages of eight and ten adult levels are reached in cognitive
flexibility and at ten years the ability to maintain the set; the
verification of hypotheses and impulse control is manifested; there is
an improvement in the inhibitory control; in the vigilance and in
the attention sustained between the eight and eleven years; period
in which besides is assisted to an improvement in the performances
tests that conjugate inhibitory competences and working memory;
this last one suffers further efficiency improvements between nine
and twelve years.
An improvement in the ability to understand emotions;
intentions; beliefs and desires is noted in this period. Between
thirteen and fifteen years there is an increase in memory strategies;
in its efficiency; in time planning; in problem-solving and in the
search for hypotheses. Furthermore; verbal fluency and the ability
to plan complex motor sequences mature at the age of twelve. The
changes of this period; both on the cognitive and the executive side;
allow the person to cope with the new and growing demands that
the physical and social environment put on him; experiencing a
sense of independence; responsibility; and social awareness.
At fifteen years there is an improvement as regards attentional
control and processing speed as well as maturation in inhibitory
control. Between the ages of sixteen and nineteen; progress is
made in working memory; problem-solving and strategic planning.
From an executive point of view; Hot improves the ability to make
decisions in the presence of rewards and losses. Between the ages
of twenty and thirty; working memory; planning; problem-solving
and the ability to implement targeted behaviors reach higher levels
of functioning.
As regards the Hot Executive functions; the achievement of
mature decision-making levels is achieved. With aging there is
a gradual deterioration in some cognitive areas including the
Executive Functions; although some changes are not evident before
eighty years even though the brain degenerative process begins in
the third decade of life. Between the ages of thirty and forty-nine;
there is a decrease in information storage and temporal sequencing
skills; the ability to formulate concepts; organization; planning and
attentional shifting worsen between the fifty-three and sixty-four
years. Starting from the age of sixty-five; memory difficulties are
reported [9-11].
It is good to underline however that even today we think of
the executive system and the attention system as separate entities:
attention would act on sensory information and on internal
representations while the executive system on behavior. If the
attentional aspects allow the executive functions to mature; the
executive system is seen as a form of attention directed towards
oneself. Therefore, the development of E.F. involves a consolidation
of intellectual cognitive abilities; learning and memories.
If neuroscience has been trying for decades to associate
specific brain functions with specific brain areas; with the relative
recent advent of functional neuroimaging and brain mapping; this
commitment seems to have become dominant; however; the debate
on the selective localization of complex faculties remains open;
despite their historical location; identified in the so-called frontal
lobe syndrome; even preceded the formulation of the construct
(Galati; Tosoni; 2010); in fact; traditionally; they were classified
as executive disorders those following damage in the prefrontal
cortex.
Recent studies of neuroimage (Galati; Tosoni; 2010); carried
out on healthy people through classical neuropsychological tests
for the examination of E.F. reveal; however; also the activation of
the posterior parietal cortex and of various subcortical centers;
in addition to the areas of prefrontal cortex; whose functional
subdivisions; however; still remain difficult to identify; due to its
anatomy and its heterogeneous functionalities. In particular; the
studies show that the frontal lobes are functionally connected with:
the posterior parietal cortex; which appears to be involved in the
reconfiguration of the responses and in the behavioral modifications
(Sohn et al; 2000; Barber and Carter; 2005); the basal ganglia; the
anterior cingulate; which seems particularly involved in situations
of control of cognitive conflicts between environmental stimuli
or behaviors and in the selection of agent responses in case of
uncertainty (Carter and Van Veen; 2007; Rushworth and Beherens;
2008).
The scholars of the Executive Functions; therefore; remain
cautious about their specific localization; preferring to believe
that they are implemented in multiple distributed circuits; each
of which includes connections with some portion of the prefrontal
cortex (Galati; Tosoni; 2010; p. 36.). The same Luria (1962) who;
on the basis of numerous clinical observations; first theorized
the existence of a central control system for some higher order
functions; such as planning; monitoring; self-regulation; involved
more involvement interconnected cortical and subcortical areas:
prefrontal cortex; cerebellum; some subcortical nuclei.
Therefore; the study on the functions performed by the
prefrontal cortex remains open. It is believed that the executive
functions are anatomically related to different areas of the
prefrontal cortex; and to the associated cortico-subcortical circuits:
a) The dorso-lateral prefrontal area would be particularly
involved in the abstraction and planning of actions.
b) The orbital-frontal area would be involved in the
regulation of emotions and decision-making processes.
c) The anterior cingulate area (especially in the dorsal part)
would be involved in the control of motivation and interfering
stimuli.
The empirical evidences derived from the neuropsychological
approach and from the neuroimaging show however that the
executive functions connected to the orbito-frontal cortex mature
early with respect to the executive functions connected to the
dorso-lateral pre-frontal cortex [13]. An interesting review of 2006
takes in detail; albeit dated; the cognitive; affective and behavioral
correlates of brain maturation that occurs during adolescence.
This maturation; due to phenomena of myelination and synaptic
pruning; is particularly accentuated in the prefrontal cortex; the main
site of decision-making processes. If the executive functions
and the decision-making processes are based on the functioning of
prefrontal areas; which change considerably during adolescence;
it can be hypothesized that the decision-making abilities of
adolescents are still immature, and this may explain their risky
behavior. This hypothesis is discussed; also, in relation to the onset
of psychopathological disorders in this age group [14].
Following an injury or dysfunction in the frontal lobes; due for
example to a head injury; a degenerative pathology or a neoplasm;
the patient can show the symptoms of what is called “frontal
syndrome”. Frontal syndrome is a clinical picture characterized
by cognitive deficits and / or behavioral; emotional and motor
disorders.
Studies on adult patients with lesions in different areas
of the prefrontal cortex show; in fact; partially different
neuropsychological pictures:
1) Lesions in the anterior orbital part; in general; cause
personality modifications and disinhibition.
2) The lesions in the orbito-frontal part; also because it
is closer to the amygdala; to the hippocampus and to the
hypothalamus; areas that mediate between internal states
and environmental stimuli; generally present inattentive;
impulsive behaviors; difficulty in problem solving and in taking
of decisions; serious antisocial conduct.
3) Lesions in the medial part; including the anterior cingulate
gyrus; cause poor motor control and difficulty in maintaining
focused attention.
4) The laterals of the prefrontal cortex present action
planning disorders; especially related to the management of
mental representations useful for achieving a purpose and
the difficulties related to written and spoken language are
understood.
The lesions of the frontal cortex; caused by expansive processes
of tumor; vascular or hypoxic origin; or cranial traumas or
degenerative processes of the nervous system; therefore, lead to
deficits in executive functions; in particular problems:
a) In planning and problem solving: the person has difficulty
planning and executing a sequence of actions to reach a goal;
but also in the planning of sequences of movements.
b) In cognitive flexibility: it has a rigid; non-flexible
behavior and puts into effect perseverances; always giving the
same answer or using the same strategy even when it proves
inadequate.
c) In the working memory: the memory disorders that can
be classified in the frontal amnesic syndrome are characterized
by the inability to retain new information; greater distractibility
and confabulations; difficulty in using memorization strategies;
inability to know how to use the new acquired data; incapacity
to memorize voluntarily.
d) In the inhibition of automatic behaviors not congruent
with the situation: it is the case of the “environmental
syndrome” or “dependence of use”: placed for example in front
of objects that it is used to use; the person uses them without
any invitation and without any reason (for example; a patient
who in front of a bottle of water placed on the examiner’s desk;
takes it and drinks it).
e) In decision-making: the difficulty of deciding in an
advantageous way for oneself and of respecting social norms
is understood (Bechara et al. 2000; Rolls; 2000). Patients with
this disorder are more likely to make risky choices and develop;
for example; a gambling addiction.
f) In the regulation of emotions and behavior: we can
have a patient who shows a picture of disinhibited type
symptoms characterized by euphoria; restlessness; sexual
disinhibition; inappropriate social behavior; poor interest in
others; uninhibited behavior; with little impulse control; easy
irritability and aggressiveness; euphoria; emotional lability; or
an apathetic type symptomatology with a “pseudo-depressed”
personality; therefore with modifications characterized by
indifference; apathy; decreased spontaneity; reduced sexual
interest; reduced expression of emotions; decreased verbal
productivity (including mutism); decreased motor behavior.
g) Low self-criticism and judgment: the person have a
deficit in judging reality; especially when the situation is new
or complex and a lack of critical attitude towards the actions
carried out. It also shows difficulty in correcting its errors and
inability to modify or schedule new behaviors.
In some syndromes then there are deficits in executive
functions; such as in autism and dyslexia; Executive deficits have
been detected in attention deficit / hyperactivity disorder (ADHD);
schizophrenia and conduct disorder. It is thought that many mental
disorders are associated with this type of deficit; although in every
disorder it is likely to change the degree to which each component
of executive functions is involved. Deficits related to executive
functions can be manifested in behavioral symptoms such as:
environmental dependence syndrome; with use behavior; that is;
as soon as the subject notices an object that he is used to using in a
certain way; he uses it; even if the context would require a inhibition
of this behavior (eg the subject goes to the doctor and as soon as
he notices the window opens it; without a precise reason); and
imitation behaviors; that is; the subject spontaneously imitates the
gestures of the person in front of him; hypoactivity; such as apathy
or anhedonia (in which the person does not perform behaviors
that would also give him gratification (such as activities related
to food or affective activities); hyperactivity; ie distractibility;
impulsiveness; disinhibition. In general; the behavior may appear
disorganized [16].
Compared to the diagnosis; however; one must rely on a series of
neuropsychological tests; including the Trail making test (versions
A and B). The other tests that are most used for the evaluation of
the executive functions are: the Tower of London that proves the
ability of planning; problem solving and inhibition; the dimentional
change card sort test; which is a task that evaluates flexibility; the
matching familiar figure test that evaluates the use of visual search
strategies; control of the impulse response and interference [17].
The E.F. they represent an important field of research
and clinical work in the field of cognitive developmental
neuropsychology. There are numerous attempts to summarize the
common characteristics of the skills related to E.F.: the ability to
inhibit overbearing responses and to organize behavior based on
arbitrary rules [18]; the ability of the “central executive” to select
the appropriate schemes of action from a repertoire activated by
specific inputs [19].
The hypothesis of the multidimensionality of FEs [20-22] is
increasingly accepted and several studies are highlighting the
evolutionary trajectories of the different subdomains in the typical
development; starting to outline a staged process with a complex
hierarchical organization. In the clinical field the impairments
of the E.F. they are related to numerous cognitive and behavioral
difficulties: limited sustained attention; perseverative responses;
impaired initiation of actions; poor use of feedback; difficulties in
planning and organization; problems related to the storage and
manipulation of mental representations. Furthermore; studies on
the impairment of E.F. in neurodevelopmental disorders.
These include autism and DGS; in which the E.F. they appear
to be pervasive in different domains; severe and pre-existing over
time. Other developmental disorders seem to show a more specific
profile; with the impairment of some subdomains: the A.H.D.; with
the deficit in inhibition; represents one of the most studied cases.
For other disorders the research results are more controversial. The
differences in the profiles of the E.F. in these disorders they support
the hypothesis of a fraction ability of E.F. in subdomains; at least
partially independent. It should also be specified that the various
subdomains have not been fully studied in all the disorders. Despite
these limitations; at least partially specific “executive profiles” of
various disorders are emerging [23].
A greater knowledge of these profiles and their evolutionary
trajectories; combined with an attention to “ecological validity”;
can allow us a greater understanding of the mental functioning
of children with typical and atypical development; with potential
relapses in the diagnostic and therapeutic-rehabilitative field [24-
26].
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