Parietal cortex and representation of the mental Self

Abstract

For a coherent and meaningful life, conscious self-representation is mandatory. Such explicit ''autonoetic consciousness'' is thought to emerge by retrieval of memory of personally experienced events (''episodic memory''). During episodic retrieval, functional imaging studies consistently show differential activity in medial prefrontal and medial parietal cortices. With positron-emission tomography, we here show that these medial regions are functionally connected and interact with lateral regions that are activated according to the degree of self-reference. During retrieval of previous judgments of Oneself, Best Friend, and the Danish Queen, activation increased in the left lateral temporal cortex and decreased in the right inferior parietal region with decreasing self-reference. Functionally, the former region was preferentially connected to medial prefrontal cortex, the latter to medial parietal. The medial parietal region may, then, be conceived of as a nodal structure in self-representation, functionally connected to both the right parietal and the medial prefrontal cortices. To determine whether medial parietal cortex in this network is essential for episodic memory retrieval with self-representation, we used transcranial magnetic stimulation over the region to transiently disturb neuronal circuitry. There was a decrease in the efficiency of retrieval of previous judgment of mental Self compared with retrieval of judgment of Other with transcranial magnetic stimulation at a latency of 160 ms, confirming the hypothesis. This network is strikingly similar to the network of the resting conscious state, suggesting that self-monitoring is a core function in resting consciousness.A ll subjective experience may be seen as self-conscious in the weak sense that there is something it feels like for the subject to have that experience. We may at times be selfconscious in a deep way, for example, when we are engaged in figuring out who we are and what we are going to do with our lives, a distinctly human experience giving organization, meaning, and structure to life. In its absence, our representation of ourselves and our world becomes kaleidoscopic and our life chaotic (1).Such explicit ''autonoetic consciousness'' is thought to emerge by retrieval of memory of personally experienced events (episodic memory) (2, 3). The cerebral activation pattern of episodic memory retrieval differs from that of semantic retrieval (retrieval of common knowledge by ''familiarity''): e.g., activation of medial parietal cortex is characteristic of the former and activation of left lateral temporal lobe is characteristic of the latter (4). First, we hypothesize that the cerebral activity pattern of retrieval of previous judgments of a person is determined not only by the episodic retrieval nature of the task, but also by the degree of self-reference of the judgment to be retrieved. Second, we hypothesize that the regions activated by retrieval of judgment of the mental Self are functionally interacting. This network would give a distinc...

What is self-specific? Theoretical investigation and critical review of neuroimaging results.

“…Indeed, autobiographical memory appears as a privileged database for finding precise examples of encounters with others (i.e., episode witnessing the way a known person behaves in a social context), and this kind of example may be especially needed to draw a general representation of the personality of someone one knows less than oneself or to predict his or her behavior. This account would also well explain increased left temporal pole activity for others' versus self personality assessment in the study of Lou et al (2004). Interestingly, Mitchell et al (2006) demonstrated that a functional dissociation could be made within the prefrontal cortex: Representing minds of similar others would be associated with ventromedial prefrontal cortex activation, while representing minds of dissimilar others would be associated with dorsomedial prefrontal cortex activation.…”

Preceding attention and the dorsomedial prefrontal cortex: Process specificity versus domain dependence

“…Involvement of attention has also been suspected to account for DMPFC activation in tasks requiring evaluation as for example emotional judgment [Gusnard et al, 2001;Lane et al, 1997;Phan et al, 2002], moral judgment [Greene and Haidt, 2002;Moll et al, 2005], and reappraisal [Kalisch et al, 2006;Ochsner et al, 2002Ochsner et al, , 2004Ochsner and Gross, 2005]. Finally, attentional processes may also be involved in other tasks associate with DMPFC activation like theory of mind, memory retrieval, verbal decision, sexual arousal, face recognition, and mentalizing [Beauregard et al, 2001;Ferretti et al, 2005;Fossati et al, 2003;Frith, 2002;Frith andFrith, 1999, 2003;Gallagher and Frith, 2003;Johnson et al, 2002;Kampe et al, 2003;Kjaer et al, 2002;Lou et al, 2004;Macrae et al, 2004;Maddock et al, 2003;Mitchell et al, 2005;Platek et al, 2004;Stoléru et al, 1999].…”

“…This research has identified the medial prefrontal cortex, and in particular the dorsal medial prefrontal cortex (DMPFC), as one of the key regions in processing mental states. For example, the DMPFC has been shown to be activated in various conditions like emotional judgment [Gusnard et al, 2001;Lane et al, 1997;Phan et al, 2002], moral judgment [Greene and Haidt, 2002;Moll et al, 2005], theory of mind tasks [Frith, 2002;Frith andFrith, 1999, 2003;Gallagher and Frith, 2003;Kampe et al, 2003], memory retrieval tasks [Fossati et al, 2003;Lou et al, 2004;Macrae et al, 2004;Maddock et al, 2003], self-related processing [Kelley et al, 2002;Northoff et al, 2006;Wicker et al, 2003;Zysset et al, 2002], mentalizing tasks [Mitchell et al, 2005], verbal decision tasks [Johnson et al, 2002;Kjaer et al, 2002], sexual stimuli [Beauregard et al, 2001;Ferretti et al, 2005;Karama et al, 2002;Park et al, 2001;Stoléru et al, 1999], or face recognition [Platek et al, 2004]. The involvement of the DMPFC in a variety of different tasks (judgment, retrieval, recognition, decision) and in different domains (verbal, facial, social, moral, emotional, sexual) raises the question for its functional organization: is neural activity in the DMPFC instantiated by a particular task, i.e., process, remaining independent of the different domains or is it rather determined by a specific domain rather than by a particular task, i.e., process?…”

Zazen meditation and no-task resting EEG compared with LORETA intracortical source localization

“…This default mode network (DMN) consists of regions in the medial prefrontal cortex, the posterior cingulate cortex (PCC) and precuneus, the angular gyrus and the left superior and middle frontal gyri, hippocampus and parahippocampus (Buckner et al 2008;Gusnard et al 2001;Raichle et al 2001). The brain areas constituting the DMN are of special interest for the study of meditation as their activity has been linked to mind wandering (Mason et al 2007), episodic memories (Buckner et al 2008;Greicius et al 2004) and conceptual processing (Binder et al 1999), all important for maintaining the sense of self Lou et al 2004). As all these processes are affected by meditation, the DMN brain regions are key areas where brain electric differences between Zazen and no-task resting would be expected.…”