I will first turn to philosophical concepts of the minimal or momentary self as supposed by William James and Galen Strawson, which are very similar to the concept of self which Jun Tani referred to in the morning and which he employs in his work with robotics. Specifically, I will depict the so called immunity principle which characterizes a basic implication of the use of the first-person pronoun, and I will illustrate the distinction between the sense of self-agency and the sense of self-ownership. Subsequently, I will attempt to apply the model of the distinction between self-agency and self-ownership to the disruption of self-referential information processing observed in schizophrenic patients. Secondly, I will focus on similarities and differences between concepts of the extended or narrative self and their theoretical implications, in particular with regard to the debate on fictional and non-fictional aspects of the extended self. The interrelations between the narrative self and episodic autobiographical memory will be illustrated. Assumptions on the neural underpinnings of episodic autobiographical memory and taking a self-perspective will be introduced on the basis of recent functional neuroimaging data. Eventually, interrelations between the narrative self and the minimal self will be discussed with respect to future perspectives of interdisciplinary research on the characteristics of the self. 

The minimal self is unextended in time, that is, it is a momentary self which is limited to what is accessible to immediate self-consciousness. The minimal self must not be aware of having self-experiences, however, it involves the sense of self-ownership and the sense of self-agency in the context of both motor action and cognition. I will describe this distinction in detail, but prior to this, I want to outline a further element which is essential to the definition of the minimal self: it concerns an implication of the use of the first-person pronoun in self-reference. The use of the first-person pronoun in self-reference is immune to error through misidentification. For example, when I say "I think it is raining outside" I certainly can be wrong about the rain but not about the I. That is, I cannot misidentify myself when I state that it is me who is thinking. This is referred to as the immunity principle. Thus, access to myself in first-person experience is immediate and non-observational. It is the immediate self that is referred to here, and this immediate self is the pre-reflective point for origin of action, experience, and thought. Now, there are two closely related aspects of minimal self-awareness: these are the sense of self-agency and the sense of self-ownership. According to Gallagher (2000), the sense of self-agency is characterized by the sense that I am generating or causing an action, that I am the initiator or the source of the action. For example, the sense that I am the one who is causing something to move, or the sense that I am the one who is generating a certain thought in my stream of consciousness represent the sense of self-agency. In contrast, the sense of self-ownership is characterized by the sense that I am the one who is undergoing an experience. This would be the case when I sense that my body is moving regardless of whether the movement is voluntary or involuntary. In a review of philosophical conceptions of the self, Shaun Gallagher (2000) proposed a neurocognitive model of immediate self-awareness based on the distinction between the senses of self-agency and self-ownership. Referring to this model, he attempts to comprehend disruptions of self-referential information processing observed in schizophrenia. In patients with schizophrenia, symptoms like thought insertion, delusions of control, and auditory hallucinations are assumed to be based on a dysfunction of self-monitoring processes (Feinberg, 1978; Frith, 1992). Gallagher (2000) supposes the senses of self-ownership and self-agency to coincide and to be indistinguishable in normal voluntary or willed action and thus specifies the dysfunction of self-monitoring processes seen in schizophrenia as a disruption of the sense of self-agency with normal functioning of the sense of self-ownership. In cases of delusions of control or thought insertion, a schizophrenic patient would have the sense that it is his body that is moving or that a certain thought occurs in his stream of consciousness, that is, he obviously has a sense of self-ownership. However, the movement or the thought would not seem to him to be self-generated, but rather would appear to be alien and out of the subject's control. This might be referred to as a disruption of the sense of self-agency which is assumed to be based on a dysfunction of neuronal processes in several areas of the prefrontal cortex (Daprati et al., 1997; Frith, 1992). 

I will now turn to the extended or narrative self. The extended or narrative self is extended in time, that is, it includes memories of the past and intentions towards the future. It is supposed to be a more or less coherent self or self-image which is constituted through narration, that is, through the various stories we tell about ourselves. Importantly, it is strongly associated with episodic autobiographical memory. The narrative self establishes continuity between our past and our future. It is a self with individual identity which encompasses continuous experience. On the background of the aforementioned model of the minimal self this conception of the narrative self raises questions concerning the relation between the minimal and the narrative self: Do we have to comprehend the extended self a succession of momentary minimal selves? Or can we assume minimal selves as being abstractions from a more substantial continuity that is the more genuine self? One early and famous answer to these questions was given by David Hume (1739) in his "Treatise on Human Nature". According to Hume, the extended self is a bundle of impressions strung together by the imagination. Thus, the extended self is a fiction, albeit a useful one since it lends a practical continuity to life. The narrative theory of the self is a contemporary reading of this view. One version of the narrative theory of the extended self was supposed by Dennett (1991). Referring to the finding that neuronal processing is distributed across a variety of brain regions he claims that we cannot suppose a real "neuronal center of experience" Thus, he concludes that there can be no real simplicity of experience at one time and no real identity across time that might be labeled the self. According to Dennett, we could at best refer to a minimal biological self as something real, but this is nothing more than a principle of organization which involves the distinction between self and non-self and is found throughout living nature. Obviously, this is not sufficient for the generation of coherence and continuity across time observed at the level of human experience. It is language which enables us to render our experiences coherent and continuous across extended time periods. By means of telling stories we create what we call our selves and extend our biological boundaries to encompass a life of meaningful experience. Dennett defines the self as an "abstract center of narrative gravity". Thus, according to this definition, an individual self consists of the abstract and moveable point where the various stories that the individual tells about himself, or that others tell about him, meet up. This view at least has two basic implications: Firstly, we cannot prevent ourselves from "inventing" our selves, and secondly, the self is nothing substantially real, but rather an empty abstraction. This figure illustrates Dennett's view of the self as the center of narrative gravity built up at the point were the various stories referencing an individual meet up. This example which is reduced of the high complexity typically characterizing self-referential narratives, depicts the self as being composed of the narrative of being a spouse, the stories I tell about myself, the narrative of being a parent, the narrative of being a sports fanatic, the stories that others tell about me, and the narrative of being a teacher. A related view of the self was suggested in the context of neuroscience. However, this view from neuroscience has lead to conclusions which are different from Dennett's conclusions in at least one important aspect. It was Michael Gazzaniga (1995, 1998) who introduced the model of the "left hemisphere interpreter" in the context of ongoing debates on the phenomenon of consciousness and interpretative capacities of the human brain. Gazzaniga's basic assumption suggests that one function of the brain's left hemisphere is to generate narratives by means of an "interpreter". This "interpreter" is supposed to be some kind of capacity, or a set of mechanisms, residing in the left hemisphere of the human brain. It is assumed to weave together autobiographical facts and inventive fiction in order to produce a personal narrative that enables the sense of a continuous self. Gazzaniga concludes from his model of the "left hemisphere interpreter" that the self is not a fiction since the normal functioning of the "brain's interpreter" tries to make sense of what actually happens to the individual. Nonetheless, he has to concede that the narrative self in the non-pathological case might be a "bit fictional" (Gazzaniga & Gallagher, 1998, p. 713) since we cannot prevent ourselves from enhancing our personal narratives with elements that smooth over discontinuities and discrepancies in our self-constitution. This view is in good accordance with approaches to the narrative self developed in social psychology. The statement of Fivush (1998) characterizes the basic assumptions generated in social psychology with respect to the interrelations of the narrative self and episodic autobiographical memory. The generation of continuity along the axis of one's life and the generation of a more or less coherent self-image are supposed to be accomplished by means of storytelling in social contexts. It is some kind of conversational remembering (Edwards & Potter, 1991) of personal past experiences which is assumed to allow for the unfolding of the extended self. The extended self is constantly re-interpreted by the narrative process which establishes coherence with respect to at least four dimensions: temporal coherence, spatial coherence, thematic coherence, and social cultural coherence. From this approach, social psychologists generally conclude that both the narrative self and the personal life history are fictional. However, one can argue that this conclusion does not take into consideration the role of the proper functioning of episodic autobiographical memory as a necessary condition for non-fictional aspects of the narrative self. Firstly, episodic autobiographical memory is involved in providing a sense of time: It allows for mental time travel (Tulving & Markowitsch, 1998), that is, it provides us with the ability to mentally travel back to our personal past experiences. Secondly, it has a direct link into emotion processing. Thus, it comprises the emotional evaluation of personal life experiences with respect to our selves. Additionally, Tulving (1995) proposed that episodic autobiographical memory is associated with a specific kind of consciousness which he named "autonoetic consciousness". The notion of autonoetic consciousness depicts the form of self-awareness typically accompanying episodic autobiographical memory retrieval and which is assumed to be contingent on brain structures of the prefrontal cortex. Studies of amnesic patients have repeatedly demonstrated that specific impairments of episodic autobiographical memory - in particular those resulting from damage to areas of the prefrontal cortex and limbic structures - can lead to changes in the patients' personality and self-concepts, to a deficient ability of temporal sequencing and emotion processing, or even to an inability to develop and maintain some kind of stable self-referential cognition. Obviously, impaired functioning of episodic autobiographical memory affects our ability to generate a more or less coherent self-structure or self-image which is extended in time as it includes a sense of a continuity between our past and our future. In a recent functional neuroimaging study, Vogeley et al. (2001) aimed at elucidating the neural mechanisms of theory of mind and taking a self-perspective using functional magnetic resonance imaging (fMRI). Increased neural activity associated with taking a self-perspective was found in the medial prefrontal cortex (the frontal pole) and in the right temporoparietal junction area. Our own fMRI data revealed activation of the frontal pole to be related to the retrieval of positively valenced autobiographical memories. Can we assume activation of this area during the recollection of positively valenced personal past episodes (compared to the retrieval of negatively valenced memories) to be associated with taking a self-perspective, as well? We then would have to ask why positively valenced memories should be stronger associated with taking a self-perspective than negatively valenced memories. One highly speculative explanation would suggest that the subjects' identification with positive autobiographical memories is per se stronger than identification with negative ones. Possibly, remembering positively valenced personal past experiences might be associated with an immediate, pre-reflective, and non-observational access to the self. In contrast, access to negatively valenced autobiographical memories might be not as immediate as access to positive ones but rather could imply a conscious act of reflection associated with some kind of an observer perspective leading to a less pronounced formation of a self-perspective. Based on our functional neuroimaging data we can assume that negative autobiographical memories are kept more distant than positive ones. Interestingly, additional increased neural activity associated with positively valenced autobiographical memories was observed in limbic regions - in particular in the amygdala and the hippocampus - and in the retrosplenial cortex. These activations are supposed to indicate a higher level of emotional re-experiencing for positive than for negative memories, thus, supporting the view that recollection of positively valenced autobiographical memories is associated with an immediate and emotional pre-reflective access to the self whereas recollection of negative memories are rather kept distant. The formation of some kind of observational distance during retrieval of negative memories might be suggested to prevent the pronounced specification of a self-perspective as seen during the recollection of positively valenced personal past experiences. Finally, I want to discuss the interrelations between the minimal ('core') self and the narrative ('autobiographical') self. Damasio (1999) captured some of the difficulties one has to face while trying to find suitable expressions for the interrelations between the minimal and the narrative self. These difficulties are primarily due to complexities characterizing the interconnections among episodic autobiographical memory and the narrative self. Episodic memory obviously is indispensable for the construction of the extended narrative self. However, episodic autobiographical memory is subject to constant remodeling under the influence of factors that include both an individual's acquired and innate dispositions. Additionally, episodic autobiographical memory is affected by the narrative process itself and the social and cultural environments an individual lives in. Nonetheless, the registration of episodic autobiographical memory as my memory of myself is contingent on a minimal but constantly reiterated sense of self that I recognize, without error, as myself. In some respects this may depend on narrowly defined, embodied capabilities and feelings. In other regards, we have to take into account that the core features of the minimal self might be constantly re-interpreted by the narrative process, as well. In an essay on the biology of consciousness, Damasio (1998) refers to these issues in terms of a distinction between a "core consciousness" and an "extended consciousness" which has highly similar implications than that between the minimal self and the narrative self. According to Damasio's approach, the extended consciousness also depends on the core consciousness. However, both forms of consciousness principally perform precisely the same mental operations: They place mental contents into an individual perspective, confer ownership to such contents, and give the owner the sense of an ability to act on them. Obviously, the conceptions of the self developed by different researchers in a variety of different research disciplines are characterized by a number of differences and similarities. However - as I attempted to illustrate in my talk - these conceptions coincide with regard to several main structural and theoretical implications of the self. Thus, interdisciplinary research between philosophers, psychologists, and neuroscientists might open new ways for the development of deeper insights and more sophisticated conceptions of self-referential information processing.