Current Psychiatry Reviews, 2007, 3, 243-251 243 1573-4005/07 $50.00+.00 © 2007 Bentham Science Publishers Ltd. Self-Monitoring in Schizophrenia Chlöé Farrer *,a and Nicolas Franck a,b a Centre of Cognitive Neuroscience, CNRS, University Claude-Bernard Lyon I, 67 Bd Pinel 69675, Bron cedex, France b Centre Hospitalier Psychiatrique Le Vinatier, 95 boulevard Pinel 69677, Bron cedex France Abstract: Many patients suffering from schizophrenia feel dispossessed from some of their actions or thoughts. This dis- possession could result from impaired self-monitoring (SM), defined as the ability to monitor self-willed intentions and actions. SM has been widely studied during the past decades with very different paradigms; central error correction, feed- back distortion, sense of effort, and motor imagery. The present article first reviews the methods used and results obtained in investigation of SM. Second, we address what we consider to be the critical questions that must be answered in order to fully understand the role of SM deficit in schizophrenia: 1) Is SM deficit only impaired in patients with specific symp- toms? 2) Is SM deficit associated with other cognitive processes that are also impaired in patients with schizophrenia? 3) Can SM impairment be characterized as a trait or a state marker? Finally, we discuss the consequences of SM investiga- tion on diagnostic evaluation and therapeutic orientations and we propose future research that we think is essential in or- der to clarify the role of SM in schizophrenia. Keywords: Internal model, first-rank schneiderian symptoms, state/trait character. INTRODUCTION During the last two decades the concept of dysfunctional self-monitoring (SM) in schizophrenia has become well- known and very popular. SM is defined as the neurocogni- tive processes that allow an individual to monitor his or her own actions. Without these processes, not only could actions not be executed correctly but actions could also not be rec- ognized as self-generated. Several teams have been working on SM in schizophrenia and substantial experimental data has been collected. In 1992 Christopher Frith published what is now a well regarded book on the topic; Cognitive Neuro- psychology of Schizophrenia [1]. A dysfunction in SM has been used to explain First-Rank symptoms (FRS) that are among the most distressing sensa- tions encountered by patients suffering from schizophrenia. FRS are characterized by patients feeling that actions and personal states are no longer under their own control [2]. The main FRS are auditory hallucinations, thought insertion, thought broadcasting, delusions of influence, and all the feel- ings that another is controlling the patient’s thoughts, actions or emotions (Table 1). Initially, Feinberg [3] proposed that FRS may be ex- plained by a deficit in the internal monitoring of action: pa- tients who suffer from FRS would be unable to correctly monitor their own actions and thoughts. This hypothesis was re-defined by Frith [1], who proposed instead the term of self-monitoring, i.e. the ability to monitor one’s own inten- tions, thoughts, and actions. Action monitoring involves in- ternal forward modeling that allows the central nervous sys- tem to represent the predicted sensory consequences of a movement before its completion [4, 5]. Such a prediction is derived from a copy of the motor command, the so-called *Address correspondence to this author at the Centre of Cognitive Neuro- science, CNRS UMR 5229, 67 Bd Pinel 69675, Bron, France; Tel: +33 (0) 4 37 91 12 26; Fax: +33 (0) 4 37 91 12 10; E-mail: farrer@isc.cnrs.fr Table 1. First Rank Symptoms of Schizophrenia, Initially Described by K. Schneider (1959) Current Names of Symptoms Descriptions Acoustico-verbal hallucinations Voices heard arguing or commenting on patient's actions. Audible thoughts Patient’s own thoughts heard by him/herself. Thought broadcasting Patient’s thought are passively diffused to other people. Thought insertion Other people intrude their thoughts upon the patient. Thought withdrawal Other people actively take pa- tient’s thoughts in his/her mind. Made affect and feelings Experience of influences playing on patient’s sensations. Somatic passivity, delusions of influence, alien control Experience of influences playing on patient’s actions. Delusional perception Patient’s experience of a peculiar, intense, convincing experience not shared by other people. "efference copy" [6], that can be compared with reafferent signals (i.e. sensory signals arising as a consequence of the movement) (Fig. 1). SM deficit in patients with schizophre- nia specifically concerns the predicted sensory conse- quences. Additionally, this deficit is formulated as a lack of awareness of these predicted consequences [7]. Although, accurate representations of predicted states (derived form internal model) are available and used by the motor system, these representations are not available to awareness. Failure to form a representation of the predicted consequences of an action would result in an impaired ability to distinguish be- tween one’s own and another’s actions, resulting in patients