Confabulation And The Neurobiology Of Emotion Systems

Adults who have no history of psychiatric disorder show a range of features closely resembling those of psychosis when highly specific brain regions are damaged (e.g., Burgess and McNeil, 1999; Conway and Tacchi, 1996; Solms, 1997, 1998; Villiers et al., 1996). These patients are typically described as showing confabulation. Localization is not well-established (see Benson et al., 1996), but the patients typically have lesions to the ventral and/or medial frontal lobes and associated subcortical structures. The breakdown of reality monitoring becomes a typical symptom (Feinberg, 1997; Solms, 1997, 1998). That is, thoughts are interpreted as real perceptions, relatives are thought to be impostors (Capgras delusion, see Hirstein and Ramachandran, 1997), and dreams are mistaken for real experiences. This remarkable phenomenon (and localization of its associated lesion site) has been described in isolated neuropsy-chological reports for a number of years (Tallard, 1961; Whitty and Lewin, 1957; see Berrios, 1998, for historical review). Recent investigations suggest that simple "executive system" accounts may not fully explain the nature of the disorder (e.g., Burgess and McNeil, 1999) and that motivation/emotion systems may shape the nature of the false belief in such patients (e.g., Conway and Tacchi, 1996; Fotopoulou et al., under review; Villiers et al., 1996). The importance of this brain region in false beliefs is also consistent with the effect of anticholinergics, such as scopalomine, which can produce hallucinatory states (Perry and Perry, 1995), and the paranoid delusions that are part of a dopamine-modifying stimulant psychosis (Mendelson and Mello, 1996).

Recent studies have investigated a small group of these patients in psychoanalytic psychotherapy (Kaplan-Solms and Solms, 2000; Solms, 1998) and has produced a range of evidence favoring a emotion-based explanation of confabulation. In the language of cognitive neuroscience, the false beliefs in these patients were caused by the excessive influence of emotion and motivational systems over cognitive processes (see Fotopoulou et al., under review; Turnbull et al., in press). However, the account has also been cast in psychoanalytic terms, as the excessive influence of the system unconscious (Kaplan-Solms and Solms, 2000).

Freud outlined four principal properties of the system unconscious in his study "The Unconscious." These are: the replacement of external by psychical reality, exemption from mutual contradiction, mobility of cathexis (or primary process thinking), and timelessness (Freud, 1915, p. 187). Several of these principles (timelessness and exemption from mutual contradiction) are self-evident. Mobility of cathexis is best understood using the transference concept by which the attitudes and feelings associated with one person can be directed toward another. The replacement of external by psychical reality can reasonably be understood as arguing that these patients accept views of external reality that are congruent with affective states. In the basic scenario, they are likely to accept versions of reality that lead to positive affective consequences and reject views of external reality that lead to negative affective consequences. The clinical series of Kaplan-Solms and Solms (2000) appeared to present with false beliefs that met all the criteria described by Freud (1915), and these are briefly discussed below.

Anxiety and Depression 101

Anxiety and Depression 101

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