Insular Cortex Mediates Attentional Capture by Behaviorally Relevant Stimuli after Damage to the Right Temporoparietal Junction

The disengagement deficit after right-hemisphere damage: Distinct roles of lateral frontal and parietal damage

An influential model of spatial attention postulates three main attention-orienting mechanisms: disengagement, shifting, and engagement. Early research linked disengagement deficits with superior parietal damage, regardless of hemisphere or presence of spatial neglect. Subsequent studies supported the involvement of more ventral parietal regions, especially in the right hemisphere, and linked spatial neglect to deficient disengagement from ipsilateral cues. However, previous lesion studies faced serious limitations, such as small sample sizes and the lack of brain-injured controls without neglect. Additionally, some studies employed symbolic cues or used long cue-target intervals, which may fail to reveal impaired disengagement. We here used a machine-learning approach to conduct lesion-symptom mapping (LSM) on 89 patients with focal cerebral lesions to the left (LH) or right (RH) cerebral hemisphere. A group of 54 healthy participants served as controls. The paradigm used to uncover disengagement deficits employed non-predictive cues presented in the visual periphery and at short cue-target intervals, targeting exogenous attention. The main factors of interest were group (healthy participants, LH, RH), target position (left, right hemifield) and cue validity (valid, invalid). LSM-analyses were performed on two indices: the validity effect, computed as the absolute difference between reaction times (RTs) following invalid compared to valid cues, and the disengagement deficit, determined by the difference between contralesional and ipsilesional validity effects. While LH patients showed general slowing of RTs to contralesional targets, only RH patients exhibited a disengagement deficit from ipsilesional cues. LSM associated the validity effect with a right lateral frontal cluster, which additionally affected subcortical white matter of the right arcuate fasciculus, the corticothalamic pathway, and the superior longitudinal fasciculus. In contrast, the disengagement deficit was related to damage involving the right temporoparietal junction. Thus, our results support the crucial role of right inferior parietal and posterior temporal regions for attentional disengagement, but also emphasize the importance of lateral frontal regions, for the reorienting of attention.

Disengagement of attention with spatial neglect: A systematic review of behavioral and anatomical findings

The present review examined the consequences of focal brain injury on spatial attention studied with cueing paradigms, with a particular focus on the disengagement deficit, which refers to the abnormal slowing of reactions following an ipsilesional cue. Our review supports the established notion that the disengagement deficit is a functional marker of spatial neglect and is particularly pronounced when elicited by peripheral cues. Recent research has revealed that this deficit critically depends on cues that have task-relevant characteristics or are associated with negative reinforcement. Attentional capture by task-relevant cues is contingent on damage to the right temporo-parietal junction (TPJ) and is modulated by functional connections between the TPJ and the right insular cortex. Furthermore, damage to the dorsal premotor or prefrontal cortex (dPMC/dPFC) reduces the effect of task-relevant cues. These findings support an interactive model of the disengagement deficit, involving the right TPJ, the insula, and the dPMC/dPFC. These interconnected regions play a crucial role in regulating and adapting spatial attention to changing intrinsic values of stimuli in the environment.

Task relevance and negative reward modulate the disengagement deficit of patients with spatial neglect

Though motivational value is a recognized trigger of approach and avoidance behavior, less is known about the potential of reward to capture attention. We here explored whether positive or negative reward modulates the characteristic deficit of patients with left spatial neglect to disengage attention from an ipsilesional distracter. We built our study on recent observations showing that the disengagement deficit is exaggerated for distracters with target-defining features, indicating that task-relevance captures attention. Patients with left neglect and matched healthy controls were asked to react to lateralized, colored targets preceded by a peripheral cue. Crucially, the cue either possessed the color of the target and was thus task-relevant, or was followed by a positive, negative, or neutral symbolic reward. Neglect patients only exhibited a disengagement deficit when cues were task-relevant or were followed by a negative reward. This finding indicates that attentional selection is driven by task-relevance and negative reward, possibly through interactions between limbic and attention networks.

From Action to Cognition: Neural Reuse, Network Theory and the Emergence of Higher Cognitive Functions

The aim of this article is to discuss the logic and assumptions behind the concept of neural reuse, to explore its biological advantages and to discuss the implications for the cognition of a brain that reuses existing circuits and resources. We first address the requirements that must be fulfilled for neural reuse to be a biologically plausible mechanism. Neural reuse theories generally take a developmental approach and model the brain as a dynamic system composed of highly flexible neural networks. They often argue against domain-specificity and for a distributed, embodied representation of knowledge, which sets them apart from modular theories of mental processes. We provide an example of reuse by proposing how a phylogenetically more modern mental capacity (mental rotation) may appear through the reuse and recombination of existing resources from an older capacity (motor planning). We conclude by putting arguments into context regarding functional modularity, embodied representation, and the current ontology of mental processes.