Gating of attentional effort through the central thalamus

Abstract

The central thalamus plays an important role in the regulation of arousal and allocation of attentional resources in the performance of even simple tasks. To assess the contribution of central thalamic neurons to short-term adjustments of attentional effort, we analyzed 166 microelectrode recordings obtained from two rhesus monkeys performing a visuomotor simple reaction time task with a variable foreperiod. Multiunit responses showed maintained firing rate elevations during the variable delay period of the task in ∼24% of recording sites. Simultaneously recorded local field potentials demonstrated significant decreases in power at ∼10-20 Hz and increases in power at 30-100 Hz during the delay period when compared against precue baselines. Comparison of the spectral power of local field potentials during the delay period of correct and incorrect trials showed that, during incorrect trials, similar, but reduced, shifts of spectral power occurred within the same frequency bands. Sustained performance of even simple tasks requires regulation of arousal and attention that combine in the concept of "attentional effort". Our findings suggest that central thalamic neurons regulate task performance through brief changes in firing rates and spectral power changes during task-relevant short-term shifts of attentional effort. Increases in attentional effort may be reflected in changes within the central thalamic local populations, where correct task performance associates with more robust maintenance of firing rates during the delay period. Such ongoing fluctuations of central thalamic activity likely reflect a mix of influences, including variations in moment-to-moment levels of motivation, arousal, and availability of cognitive resources.

Within- and Between-Session Changes in Neural Activity During Emotion Processing in Unipolar and Bipolar Depression

“…By contrast, our primary findings regarding abnormal attenuation of an insular-striato-thalamic system among BD compared to the other two groups suggests that part of the pathophysiology of BD could involve the additional, and abnormal, habituation of this system, potentially subserving attention, sustained arousal, and behavioral responses to emotional stimuli as function of the perceived salience of those stimuli (35–40). Our previous findings indicated elevated left-sided striatal and ventrolateral prefrontal cortical activity during uncertain reward anticipation in individuals with BD relative to HC and UD (41–43).…”

Sleep after practice reduces the attentional blink

“…Indeed, sleep spindles can modulate membrane potential in cortical neurons and induce short- and long-term potentiation in neocortical pyramidal cells (for a review, see Genzel et al, 2014). Spindles, which are generated in the thalamocortical network, may improve selective attention in the AB task by strengthening the thalamocortical loop, thereby increasing its effectiveness in allocating attentional resources (Portas et al, 1998; Schiff et al, 2013). In other words, it is possible that during a period of sleep following the AB training, active potentiation of relevant information (e.g., the temporal structure and contents of an AB task) can strengthen the attentional network for that information, enhancing the ability to allocate attentional resources in time.…”

The neurobiology of thalamic amnesia: Contributions of medial thalamus and prefrontal cortex to delayed conditional discrimination

“…These nuclei thus seem organized to modulate the activity of broadly distributed cortical and basal ganglia circuits in conjunction with behavior state (Haber and Calzavara, 2009;Jones, 2009;Schiff, 2008;van der Werf et al, 2002). Recordings of neuronal activity in primates have revealed precisely timed activity of neurons in IL and paralaminar regions of central thalamus related to behaviorally significant events (Matsumoto et al, 2001;Minamimoto and Kimura, 2002;Schiff et al, 2013;Wyder et al, 2003). Functional imaging has similarly shown activation of central thalamus during alert, wakeful states (Paus, 2000), particularly when demands are increased on attention or working memory (Burianova and Grady, 2007;Chee and Choo, 2004;Kinomura et al, 1997).…”

“…Our results demonstrate that thalamic and PFC neurons exhibit precisely coordinated responses that encode diverse behavioral events in rats performing a flexible DNMTP task and they show that reversible inactivation of medial thalamus disrupts this activity in PFC. Our working hypothesis is that medial thalamus has an organizing or gating function, coordinating the activity of PFC with distributed cortical, limbic, and basal ganglia pathways that give rise to cognitive functions such as decision making, inhibitory control, supervisory attentional processes, and memory that are important for complex goal-directed behavior (León-Domínguez et al, 2013;Saalmann, 2014;Schiff et al, 2013).…”