Rebecca Saxe

Uniquely human social cognition.

Recent data identify distinct components of social cognition associated with five brain regions. In posterior temporal cortex, the extrastriate body area is associated with perceiving the form of other human bodies. A nearby region in the posterior superior temporal sulcus is involved in interpreting the motions of a human body in terms of goals. A distinct region at the temporo-parietal junction supports the uniquely human ability to reason about the contents of mental states. Medial prefrontal cortex is divided into at least two subregions. Ventral medial prefrontal cortex is implicated in emotional empathy, whereas dorsal medial prefrontal cortex is implicated in the uniquely human representation of triadic relations between two minds and an object, supporting shared attention and collaborative goals.

It's the Thought That Counts Specific Brain Regions for One Component of Theory of Mind

Evidence from developmental psychology suggests that representing the contents of other peoples thoughts and beliefs depends on a component of reasoning about other minds (theory of mind) that is distinct from the earlier-developing mental-state concepts for goals, perceptions, and feelings. To provide converging evidence, the current study investigated the substrate of the late-developing process in adult brains. Three regions—the right and left temporo-parietal junction and the posterior cingulate—responded selectively when subjects read about a protagonists thoughts, but not when they read about other subjective, internal states or other socially relevant information about a person. By contrast, the medial prefrontal cortex responded equivalently in all of these story conditions, a result consistent with a broader role for medial prefrontal cortex in general social cognition. These data support the hypothesis that the early- and late-developing components of theory of mind rely on separate psychological and neural mechanisms, and that these mechanisms remain distinct into adulthood.

The neural basis of the interaction between theory of mind and moral judgment

Is the basis of criminality an act that causes harm, or an act undertaken with the belief that one will cause harm? The present study takes a cognitive neuroscience approach to investigating how information about an agents beliefs and an actions consequences contribute to moral judgment. We build on prior developmental evidence showing that these factors contribute differentially to the young childs moral judgments coupled with neurobiological evidence suggesting a role for the right temporoparietal junction (RTPJ) in belief attribution. Participants read vignettes in a 2 × 2 design: protagonists produced either a negative or neutral outcome based on the belief that they were causing the negative outcome (“negative” belief) or the neutral outcome (“neutral” belief). The RTPJ showed significant activation above baseline for all four conditions but was modulated by an interaction between belief and outcome. Specifically, the RTPJ response was highest for cases of attempted harm, where protagonists were condemned for actions that they believed would cause harm to others, even though the harm did not occur. The results not only suggest a general role for belief attribution during moral judgment, but also add detail to our understanding of the interaction between these processes at both the neural and behavioral levels.

Divide and conquer: A defense of functional localizers

Numerous functionally distinct regions of cortex (e.g., V1, MT, the fusiform face area) can be easily identified in any normal human subject in just a few minutes of fMRI scanning. However, the locations of these regions vary across subjects. Investigations of these regions have therefore often used a functional region of interest (fROI) approach in which the region is first identified functionally in each subject individually, before subsequent scans in the same subjects test specific hypotheses concerning that region. This fROI method, which resembled long-established practice in visual neurophysiology, has methodological, statistical, and theoretical advantages over standard alternatives (such as whole-brain analyses of group data): (i) because functional properties are more consistently and robustly associated with fROIs than with locations in stereotaxic space, functional hypotheses concerning fROIs are often the most straightforward to frame, motivate, and test, (ii) because hypotheses are tested in only a handful of fROIs (instead of in tens of thousands of voxels), advance specification of fROIs provides a massive increase in statistical power over whole-brain analyses, and (iii) some fROIs may serve as candidate distinct components of the mind/brain worth investigation as such. Of course fROIs can be productively used in conjunction with other complementary methods. Here, we explain the motivation for and advantages of the fROI approach, and we rebut the criticism of this method offered by Friston et al. (Friston, K., Rotshtein, P., Geng, J., Sterzer, P., Henson, R., in press. A critique of functional localizers. NeuroImage).

A region of right posterior superior temporal sulcus responds to observed intentional actions

Human adults and infants identify the actions of another agent based not only on its intrinsic perceptual features, but critically on the contingent relationship between its motion path and the environmental context [Trends Cogn. Sci. 7 (1995) 287; Cognition 72 (2003) 237]. Functional neuroimaging studies of the perception of agents and intentional actions, on the other hand, have mostly focussed on the perception of intrinsic cues to agency, like a face or articulated body motion (e.g. [J. Neurosci. 17 (1997) 4302; Neuroimage 8 (1998) 221; Trends Cogn. Sci. 4 (2000) 267; Nat. Neurosci. 3 (2000) 80; Neuroimage 13 (2001) 775; Proc. Natl. Acad. Sci. U.S.A. 98 (2001) 11656; Neuron 35 (2002) 1167; Neuron 34 (2002) 149, Neuroscience 15 (2003) 991; J. Neurosci. 23 (2003) 6819; Philos. Trans. R Soc. Lond. B. Biol. Sci. 358 (2003) 435]. Here we describe a region of the right posterior superior temporal sulcus that is sensitive not to articulated body motion per se, but to the relationship between the observed motion and the structure of the surrounding environment. From this and other aspects of the regions response, we hypothesize that this region is involved in the representation of observed intentional actions.

Disruption of the right temporoparietal junction with transcranial magnetic stimulation reduces the role of beliefs in moral judgments

When we judge an action as morally right or wrong, we rely on our capacity to infer the actors mental states (e.g., beliefs, intentions). Here, we test the hypothesis that the right temporoparietal junction (RTPJ), an area involved in mental state reasoning, is necessary for making moral judgments. In two experiments, we used transcranial magnetic stimulation (TMS) to disrupt neural activity in the RTPJ transiently before moral judgment (experiment 1, offline stimulation) and during moral judgment (experiment 2, online stimulation). In both experiments, TMS to the RTPJ led participants to rely less on the actors mental states. A particularly striking effect occurred for attempted harms (e.g., actors who intended but failed to do harm): Relative to TMS to a control site, TMS to the RTPJ caused participants to judge attempted harms as less morally forbidden and more morally permissible. Thus, interfering with activity in the RTPJ disrupts the capacity to use mental states in moral judgment, especially in the case of attempted harms.

Associations and dissociations between default and self-reference networks in the human brain.

Neuroimaging has revealed consistent activations in medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC) extending to precuneus both during explicit self-reference tasks and during rest, a period during which some form of self-reference is assumed to occur in the default mode of brain function. The similarity between these two patterns of midline cortical activation may reflect a common neural system for explicit and default-mode self-reference, but there is little direct evidence about the similarities and differences between the neural systems that mediate explicit self-reference versus default-mode self-reference during rest. In two experiments, we compared directly the brain regions activated by explicit self-reference during judgments about trait adjectives and by rest conditions relative to a semantic task without self-reference. Explicit self-reference preferentially engaged dorsal MPFC, rest preferentially engaged precuneus, and both self-reference and rest commonly engaged ventral MPFC and PCC. These findings indicate that there are both associations (shared components) and dissociations between the neural systems underlying explicit self-reference and the default mode of brain function.

Differential selectivity for dynamic versus static information in face-selective cortical regions

Neuroimaging studies have identified multiple face-selective regions in human cortex but the functional division of labor between these regions is not yet clear. A central hypothesis, with some empirical support, is that face-selective regions in the superior temporal sulcus (STS) are particularly responsive to dynamic information in faces, whereas the fusiform face area (FFA) computes the static or invariant properties of faces. Here we directly tested this hypothesis by measuring the magnitude of response in each region to both dynamic and static stimuli. Consistent with the hypothesis, we found that the response to movies of faces was not significantly different from the response to static images of faces from these same movies in the right FFA and right occipital face area (OFA). By contrast the face-selective region in the right posterior STS (pSTS) responded nearly three times as strongly to dynamic faces as to static faces, and a face-selective region in the right anterior STS (aSTS) responded to dynamic faces only. Both of these regions also responded more strongly to moving faces than to moving bodies, indicating that they are preferentially engaged in processing dynamic information from faces, not in more general processing of any dynamic social stimuli. The response to dynamic and static faces was not significantly different in a third face-selective region in the posterior continuation of the STS (pcSTS). The strong selectivity of face-selective regions in the pSTS and aSTS, but not the FFA, OFA or pcSTS, for dynamic face information demonstrates a clear functional dissociation between different face-selective regions, and provides further clues into their function.

Impaired theory of mind for moral judgment in high-functioning autism

High-functioning autism (ASD) is characterized by real-life difficulties in social interaction; however, these individuals often succeed on laboratory tests that require an understanding of another persons beliefs and intentions. This paradox suggests a theory of mind (ToM) deficit in adults with ASD that has yet to be demonstrated in an experimental task eliciting ToM judgments. We tested whether ASD adults would show atypical moral judgments when they need to consider both the intentions (based on ToM) and outcomes of a persons actions. In experiment 1, ASD and neurotypical (NT) participants performed a ToM task designed to test false belief understanding. In experiment 2, the same ASD participants and a new group of NT participants judged the moral permissibility of actions, in a 2 (intention: neutral/negative) × 2 (outcome: neutral/negative) design. Though there was no difference between groups on the false belief task, there was a selective difference in the moral judgment task for judgments of accidental harms, but not neutral acts, attempted harms, or intentional harms. Unlike the NT group, which judged accidental harms less morally wrong than attempted harms, the ASD group did not reliably judge accidental and attempted harms as morally different. In judging accidental harms, ASD participants appeared to show an underreliance on information about a persons innocent intention and, as a direct result, an overreliance on the actions negative outcome. These findings reveal impairments in integrating mental state information (e.g., beliefs, intentions) for moral judgment.

Language processing in the occipital cortex of congenitally blind adults

Humans are thought to have evolved brain regions in the left frontal and temporal cortex that are uniquely capable of language processing. However, congenitally blind individuals also activate the visual cortex in some verbal tasks. We provide evidence that this visual cortex activity in fact reflects language processing. We find that in congenitally blind individuals, the left visual cortex behaves similarly to classic language regions: (i) BOLD signal is higher during sentence comprehension than during linguistically degraded control conditions that are more difficult; (ii) BOLD signal is modulated by phonological information, lexical semantic information, and sentence-level combinatorial structure; and (iii) functional connectivity with language regions in the left prefrontal cortex and thalamus are increased relative to sighted individuals. We conclude that brain regions that are thought to have evolved for vision can take on language processing as a result of early experience. Innate microcircuit properties are not necessary for a brain region to become involved in language processing.