Anterior insula and inferior frontal gyrus: where ventral and dorsal visual attention systems meet

Abstract

The clinical link between spatial and non-spatial attentional aspects in patients with hemispatial neglect is well known; in particular, an increase in alerting can transitorily help to allocate attention towards the contralesional side. In models of attention, this phenomenon is postulated to rely on an interaction between ventral and dorsal cortical networks, subtending non-spatial and spatial attentional aspects, respectively. However, the exact neural underpinnings of the interaction between these two networks are still poorly understood. In the present study, we included 80 right-hemispheric patients with subacute stroke (50% women; age range: 24–96), 33 with and 47 without neglect, as assessed by paper–pencil cancellation tests. The patients performed a computerized task in which they were asked to respond as quickly as possible by button-press to central targets, which were either preceded or not preceded by non-spatial, auditory warning tones. Reaction times in the two different conditions were measured. In neglect patients, a warning tone, enhancing activity within the ventral attentional ‘alerting’ network, could boost the reaction (in terms of shorter reaction times) of the dorsal attentional network to a visual stimulus up to the level of patients without neglect. Critically, using voxel-based lesion-symptom mapping analyses, we show that this effect significantly depends on the integrity of the right anterior insula and adjacent inferior frontal gyrus, i.e., right-hemispheric patients with lesions involving these areas were significantly less likely to show shorter reaction times when a warning tone was presented prior to visual target appearance. We propose that the right anterior insula and inferior frontal gyrus are a critical hub through which the ventral attentional network can ‘alert’ and increase the efficiency of the activity of the dorsal attentional network.

Minimal phrase composition revealed by intracranial recordings

“…Lastly, anterior insula, pars triangularis and IFS subserve the integration of linguistic input with visual referents. Anterior insula and the IFS have been argued to be the convergence zones of the ventral and dorsal attentional networks (Cazzoli et al, 2021), and our results align with previous models (Willems et al, 2008).…”

“…Lastly, anterior insula and inferior frontal sulcus subserve the integration of language input with the visual referent. Both of these regions have been argued to be the convergence zones of the ventral (anterior insula) and dorsal (IFS) attentional networks (Cazzoli et al, 2021), which may explain their recruitment in this attention-based semantic-visual task. Task-evoked pupillary dynamics have also been linked to the insula (Kucyi and Parvizi, 2020); given our picture-matching task, these dynamics may also partly underscore our findings.…”

Development of a Search Task Using Immersive Virtual Reality: Proof-of-Concept Study

“…Additionally, several adaptations in design and task mechanics were performed. First, as patients with neglect process visual information slower [ 44 , 45 ], the landscape of the gameplay would be too complex; therefore, in order to reduce the number of distractive elements, the trees in the background and the clouds in the sky were removed from the game scenery (see Figure 2 ). Second, based on the recommendations of clinicians, the minimal speed of the targets was lowered from 2 °/second to 0.1 °/second; this manipulation generally lowered the difficulty level as well as reduced the need for fast head movements that could promote side effects.…”

Prefrontal contributions to the stability and variability of thought and conscious experience

“…1) are considered to support the early automatic identification of salient information originating exteroceptively, interoceptively, or within the thought stream [5,20,[279][280][281]. Such initial automatic salience assessments allow important information to become amplified throughout neurocognitive hierarchies [279] through increased attention [282] and cognitive control [283]. The salience and ventral attentional networks, therefore, may underlie increased automatic constraints on thought.…”

“…When treated as a single network, both "salience network" and "ventral attention network" have been used as designation labels. Of their multiple subregions, the anterior insula is commonly referred to under either designation label [172,279,280,282], the ACC mentioned more frequently during discussion of the salience network [69,172,232,279,286], and the temporoparietal junction and inferior frontal gyrus mentioned more frequently during discussion of the ventral attention network [280,282,[287][288][289]. While we acknowledge the significant overlap between the salience network and the ventral attention network, here we treat them as separable networks when discussing how their PFC nodes may contribute to mental state dynamics.…”