Commentary – Consciousness and aura: Two controversial concepts on epilepsy
The concept of consciousness remains unclear. The International League Against Epilepsy (ILAE) defined consciousness as a degree of awareness and/or responsiveness of the patient to externally applied stimuli (ILAE, 1981).
ILAE used this concept so far to divide partial seizures into simple partial seizures (without impairment of consciousness) and complex partial seizures (with impairment of consciousness). But the latest Classifications and Terminology of ILAE suppressed this distinction, arguing that it was impossible to accurately define consciousness (Berg et al., 2010).
However, the ILAE continues the use the concept consciousness as a criterion to describe different kinds of partial seizures, as Berg et al. (2010) state a little bit later: “Without impairment of consciousness or awareness: this roughly corresponds to the concept of simple partial seizure. With impairment of consciousness or awareness: this roughly corresponds to the concept of complex partial seizure.”
To overcome this contradiction it would be advisable to seek a more suitable solution to this problem.
Tentative Definition of Consciousness
According to many authors, today it is not possible to provide a complete and scientific explanation of consciousness and it might never be possible (Gloor, 1986). Opposite to this pessimistic approach, we think it is possible to get a valid neuropsychological definition of consciousness, although there may some problems, including:
- Little validity of two elements used by ILAE to define consciousness: the degree of responsiveness and the capacity to recall data of a concrete situation.
- Difficulty in reconciling under a single definition two concepts so different as the self-awareness in a particular moment, and the self-awareness as a unified experience along life.
First, the two elements contained in ILAE's definition of consciousness do not seem essential features to define it. Indeed, lack of responsiveness or recall can be due a range of circumstances such as the impossibility to understand the question because of an auditory aphasia, or the impossibility to answer it because of a motor one (Gloor, 1986).
In addition, these two elements can be modified in many mental states, but that does not necessarily mean an impaired consciousness. A simple example will help us to better understand this point: a man is sitting in a park bench in his little town. He contemplates the scene developing in front of him: people walking, children playing, and so on. Suddenly, he experiences an intense feeling of déjà vu. A little later, when he is returning home, a car hits a boy crossing the street carelessly and the boy falls bloodstained near him.
The intensity of consciousness is always preserved, but the focused field is different in each one of these three contexts. In the first moment, it is diffused on everything around him and, at the same time, it entails a vague awareness of the inner world. On the contrary, in the second situation his consciousness is completely focused on the automatic experience occurring in his mind and the outside world goes almost unperceived during these seconds. Finally, in the third context the consciousness is also focused, but this time on the outside world, with the inside reality going now nearly unperceived. The responsiveness and the recall of facts are different in each case, but we cannot consider that these different degrees of recall and responsiveness are pathologic and, so, we cannot state that consciousness is impaired, but simply modified or changed.
So, ILAE's definition, although of great pragmatic social importance (e.g., for driving), does not seem useful in order to determine a dysfunction of consciousness.
The second problem to get an operational definition of consciousness to neurosciences arises from the impossibility to conciliate two concepts as far apart as a one-time observation of self-awareness and a longitudinal vision of it in a single definition. Indeed, if we want to maintain these two meanings under an operational neuropsychological definition we will have to use a broader definition that implies consciousness as the only and primal reality of our existence, and that nothing exists outside it. From this position, many authors conclude that consciousness is indefinable and it must be interpreted as a simple epiphenomenon of function of the central nervous system (Gloor, 1986).
In order to obtain a tentative definition useful to neurosciences, we must refuse including the concept of the Self as a unified experience along the life, since this concept does not seem necessary in a neuropsychological definition of consciousness. In fact, this meaning of the self is lost in many different clinical situations, for example, in Korsakoff's syndrome and other advanced dementias, and the consciousness remains present and functioning.
As previously explained, we can work out that the definition of consciousness has three essential features: the awareness of the inner experience, the awareness of the external experience, and how the subject perceives these two worlds in a particular moment. In this regard, Gloor opines that identification of one's self-conscious state is only possible in the here and now (Gloor, 1986). So, the particular moment at which consciousness is examined, together with the external and inner experiences, is the third necessary element to define this function, because only by taking into account the” here and now” will we understand the continuous fluidity of this function.
Curiously, this proposal is in line with renowned psychopathologists' definition of consciousness as the whole of psychic life at any given moment (Jaspers, 1977; Ey, 2008).
Thus defined, consciousness is the result of all neuropsychological activities of our central nervous system in a specific moment. So, by definition, consciousness cannot be conceived as a static state but as a dynamic one, in which intensity can be continuous, but focused field is constantly changing, sometimes focusing more on the outside word and sometimes on the inner one.
This conception of consciousness enables us to continue to use taxonomies of impairments of consciousness that have already proved their worth in different neuropsychological fields, for example, the classification that arranges the alterations of consciousness according to intensity (lethargy, obnubilation, stupor, coma, and so on) and according to the focused field (epileptic narrowing of consciousness, hypnotic consciousness, meditative consciousness, and so on)
Epileptic Consciousness in Partial Seizures: The Concept of Aura
The study of consciousness during a partial seizure requires first the analysis of a second controversial concept on epilepsy: aura. ILAE considers that aura is equivalent to a partial seizure involving subjective sensory or psychic phenomena only (Berg et al., 2010). According this definition, there is no possibility of motor, sensitivity, visceral, or autonomic auras.
By contrast, the concept of aura was different for classical authors, neurologists, and psychiatrists alike, who interpreted aura as the psychic experience indicating that a partial seizure had begun and therefore, the usual state of consciousness during wakefulness had been replaced by epileptic consciousness (Wilson, 1928; Ey, 2008). Probably the most forthright author in this regard is the British neurologist Samuel Kinnier Wilson, who described Wilson's disease. He conceives aura as the first conscious indication of the beginning of a process that is about to reveal itself by signs of the physical series, although it belongs to the psychic series (Wilson, 1928). The aura, therefore, is only the psychological experience occurring as a consequence of the triggering of a partial seizure.
And what are the psychological features invariably found in every aura? The above mentioned psychopathologists (Jaspers, 1977; Ey, 2008) agree to conceive aura as a narrowing of consciousness that is accompanied by the next characteristic features:
- Suddenness: epileptic consciousness begins always in a sudden and unexpected way.
- Timeless nature: the events occurring during simple partial seizures seem to take place outside time, so the person affected seems incapable of calculating its duration.
- A passive or automatic nature: the experiences burst into the consciousness with the absolute passiveness of the individual, dominating them beyond their control.
- Great intensity of psychic experience occurring in the mind because consciousness is completely focused on it.
- Strangeness of the experience: the extraordinary clarity and the automatic nature described provide a distinctive strangeness of the experience. The strangeness is frequently perceived from outside as perplexity.
Of course the psychological experience of aura is independent from the contents of each specific discharge. Indeed, regardless of specific behavioral manifestations characteristic of cortical localization of seizure (motor seizures, sensitive seizures, sensorial seizures, autonomic or vegetative seizures, visceral seizures, psychological seizures, and so on), all five of these invariable psychological features that indicate that the usual wakefulness of consciousness has been replaced with epileptic consciousness are always present.
We propose a definition of consciousness in which the concept of self-awareness must be restricted to the present moment. Such definition seems operational and useful to work with in some neurosciences.
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