Pathways for Emotions and Attention Converge on the Thalamic Reticular Nucleus in Primates

Abstract

How do emotional events readily capture our attention? To address this question we used neural tracers to label pathways linking areas involved in emotional and attentional processes in the primate brain (Macaca mulatta). We report that a novel pathway from the amygdala, the brain's emotional center, targets the inhibitory thalamic reticular nucleus (TRN), a key node in the brain's attentional network. The amygdalar pathway formed unusual synapses close to cell bodies of TRN neurons, and had more large and efficient terminals than pathways from the orbitofrontal cortex and the thalamic mediodorsal nucleus, which similarly innervated extensive TRN sites. The robust amygdalar pathway provides a mechanism for rapid shifting of attention to emotional stimuli. Acting synergistically, pathways from the amygdala and orbitofrontal cortex provide a circuit for purposeful assessment of emotional stimuli. The different pathways to TRN suggest distinct mechanisms of attention to external and internal stimuli that may be differentially disrupted in anxiety and mood disorders and may be selectively targeted for therapeutic interventions.

Neurocognitive bases of emotion regulation development in adolescence

“…Adolescents with conduct problems and low callous-unemotional traits (reactive-aggressive subtype) were disproportionately slowed in making the dot/no dot decision in the presence of fearful eyes relative to typically developing controls; and slower reaction times in the presence of fearful eyes in this group were associated with increased left amygdala response. This group also showed increased neural responses during the presentation of fearful eyes in subgenual ACC and OFC relative to controls; two regions involved in directing attention to affective stimuli (Zikopoulos & Barbas, 2012) and integrating emotion and cognitive control (Pessoa, 2008). These findings suggest that emotion may disproportionately interfere with executive processes in adolescents with reactive-aggressive conduct problems, although future studies could additionally examine interactions between prefrontal and limbic circuitry to uncover more detail as to the mechanisms of poor implicit emotion regulation in this group.…”

Affect-biased attention as emotion regulation

“…Recent neuroanatomical research has given rise to neural models that implicate amygdala-thalamic connectivity in rapid orienting of attention to salient locations of a scene, thereby accounting for enhanced activation of regions tuned to salient stimuli and inhibition of distractors [35,39]. We suggest that biases in this system towards specific categories of stimuli underlie affectively biased competition.…”

“…Because patterns of amygdala activation serve as well-documented neural markers of preferential responses to stimulus salience, our review of the empirical literature focuses on the amygdala; however, it is important to note that other regions, including the orbitofrontal cortex (OFC) and the pulvinar and inhibitory reticular nuclei of the thalamus, are also important hubs [35][36][37]. In conjunction with reciprocally connected regions of the amygdala, these regions also play key roles in integrating information from multiple cortical and subcortical regions to tag stimulus salience and direct attention to preferential features of the environment [35,37].…”

“…We suggest that biases in this system towards specific categories of stimuli underlie affectively biased competition. In contrast, more extended network interactions including the OFC are suggested to underlie other attentional processes, such as effortful attentional switching or disengagement [35]. However, there is also evidence that affective salience may bias attention without suppression of competing stimuli in a manner distinct from biased competition [40].…”

The thalamic reticular nucleus: A functional hub for thalamocortical network dysfunction in schizophrenia and a target for drug discovery

“…In addition, recently discovered TRN afferents from the amygdala (Zikopoulos and Barbas, 2012) implicate the TRN in imparting emotional salience to thalamic filtering of sensory information.…”