The temporoparietal junction (TPJ) is a brain region where the temporal and parietal lobes converge. Located near the lateral sulcus, it integrates diverse information. The TPJ receives input from various systems, including the thalamus, limbic system, and sensory modalities such as visual, auditory, and somatosensory inputs. This connectivity underlies its involvement in human cognition and perception.
Its Primary Functions
The TPJ plays a central role in Theory of Mind (ToM), the ability to understand and predict others’ mental states (beliefs, intentions, and desires). This cognitive capacity allows individuals to interpret social cues, such as gaze direction and goal-directed actions, and is fundamental for successful social communication. Studies indicate that both the left and right TPJ are involved in representing mental states, with the right TPJ showing particular activity in distinguishing between one’s own mental states and those of others.
The TPJ also contributes to empathy and perspective-taking, involving understanding and sharing others’ feelings and viewing situations from different viewpoints. The right TPJ is linked to perspective-taking, especially when one’s own viewpoint differs from another’s. This region helps to elaborate and integrate sensorimotor and cognitive information from both oneself and others, supporting both emotional and cognitive aspects of empathy.
The ability to differentiate between self-generated thoughts and actions and those originating from others, known as self-other distinction, is another function supported by the TPJ. This mechanism is thought to be domain-general, meaning it applies across various social-cognitive tasks. The TPJ, particularly its dorsal part, helps to enhance task-relevant representations when self-related and other-related information might conflict.
Beyond social cognition, the TPJ is involved in attention reorienting, shifting attention to unexpected or salient stimuli. The right TPJ is part of a ventral attentional control network that reorients attention to unexpected but task-relevant objects. While its role in initiating this reorientation is debated, the TPJ’s activity increases when new information does not match existing expectations, suggesting its involvement in updating internal models of context.
Beyond Social Cognition: Other Important Roles
The TPJ contributes to multisensory integration, combining information from different senses for a cohesive world perception. This integration is crucial for maintaining an internal representation of verticality, incorporating visual, vestibular, and somatic inputs related to gravity. Functional magnetic resonance imaging studies show TPJ activity reflects changes in self-location and first-person perspective, which are influenced by visuo-tactile and visuo-vestibular conflicts.
The TPJ also plays a part in spatial awareness and navigation, helping us understand our position and move through our environment. It integrates various sensory inputs to construct a coherent spatial map. Damage to this region can impair the ability to orient oneself or navigate effectively within familiar or unfamiliar places.
The TPJ contributes to bodily self-awareness, our coherent sense of our body and its position in space. This region integrates sensory information, emotions, and memories to construct a body schema and body image. Disturbances in the TPJ can lead to unusual subjective experiences related to the bodily self, such as feeling disembodied.
When the TPJ is Affected
Dysfunction of the temporoparietal junction can manifest in various neurological conditions. In autism spectrum disorder (ASD), individuals often experience social cognition challenges, and studies suggest TPJ structural and functional differences may contribute to these difficulties. Specifically, the right dorsal TPJ in autistic adolescents has shown reduced connectivity with the left Crus II of the cerebellum, potentially impacting social deficits.
In schizophrenia, the TPJ is implicated in altered theory of mind processes and self-other distinction. Patients may exhibit hypoactivity in the medial prefrontal cortex and hyperactivity in the TPJ during theory of mind tasks, sometimes leading to over-attribution of mental states. Reduced activity in the left TPJ and its connectivity to language-related areas have also been linked to auditory hallucinations in schizophrenia.
Neurological damage from conditions like stroke can also affect the TPJ, leading to symptoms such as spatial neglect, where individuals fail to attend to stimuli on one side of space. Damage to the right TPJ is associated with severe forms of hemispatial neglect, which is a disruption of attention and awareness. This can result in difficulties in shifting attention or understanding others’ viewpoints.
Disruptions in the TPJ, particularly concerning bodily self-awareness, are linked to phenomena like out-of-body experiences (OBEs). During an OBE, an individual feels they are perceiving their body and the world from outside their physical body. Research suggests that OBEs can be induced by stimulating the TPJ and are associated with a failure to integrate proprioceptive, tactile, and visual information related to one’s own body.