Effects of Pulvinar Inactivation on Spatial Decision-making between Equal and Asymmetric Reward Options

Abstract

Abstract■ The ability to selectively process visual inputs and to decide between multiple movement options in an adaptive manner is critical for survival. Such decisions are known to be influenced by factors such as reward expectation and visual saliency. The dorsal pulvinar connects to a multitude of cortical areas that are involved in visuospatial memory and integrate information about upcoming eye movements with expected reward values. However, it is unclear whether the dorsal pulvinar is critically involved in spatial memory and reward-based oculomotor decision behavior. To examine this, we reversibly inactivated the dorsal portion of the pulvinar while monkeys performed a delayed memory saccade task that included choices between equally or unequally rewarded options. Pulvinar inactivation resulted in a delay of saccade initiation toward memorized contralesional targets but did not affect spatial memory. Furthermore, pulvinar inactivation caused a pronounced choice bias toward the ipsilesional hemifield when the reward value in the two hemifields was equal. However, this choice bias could be alleviated by placing a high reward target into the contralesional hemifield. The bias was less affected by the manipulation of relative visual saliency between the two competing targets. These results suggest that the dorsal pulvinar is involved in determining the behavioral desirability of movement goals while being less critical for spatial memory and reward processing. ■

Subcortical Shape Changes, Hippocampal Atrophy and Cortical Thinning in Future Alzheimer's Disease Patients

“…Further significant shape alterations were found in the VP, VL and lateral posterior nuclei connecting the structure with the somatosensory, motor, premotor and prefrontal and temporal and parietal cortices (Behrens et al, 2003; De bourbon-Teles et al, 2014). Consistent with these extensive connections, thalamic regions affected from shape alterations in MCI-CB and MCI-CC have been linked with memory and frontal executive, attention, visuospatial perception, and emotion processing (Wilke et al, 2013; Saalmann, 2014; De bourbon-Teles et al, 2014; Arend et al, 2015), with all of these functions being impaired early in AD (Klekociuk et al, 2014). …”

Electrical Microstimulation of the Pulvinar Biases Saccade Choices and Reaction Times in a Time-Dependent Manner

“…Pulvinar lesions in humans or monkeys do not result in primary visual or saccade generation deficits (Bender and Butter, 1987; Bender and Baizer, 1990; Van der Stigchel et al, 2010; Wilke et al, 2010, 2013), although a modest lesion-induced increase of contralesional saccade latencies has been reported (Rafal et al, 2004; Wilke et al, 2013). More pronounced are “higher-order” spatial attention and decision-making impairments (Robinson and Petersen, 1992; Saalmann and Kastner, 2011).…”

“…More pronounced are “higher-order” spatial attention and decision-making impairments (Robinson and Petersen, 1992; Saalmann and Kastner, 2011). Specifically, structural and reversible lesions in the vPul and/or dPul impair the ability to shift visual attention toward the contralesional hemifield and result in an ipsilesional spatial exploration and saccade choice bias (Rafal and Posner, 1987; Karnath et al, 2002; Arend et al, 2008; Snow et al, 2009; Wilke et al, 2010, 2013; Zhou et al, 2016). Although these lesion/inactivation studies provide strong evidence that normal pulvinar functioning is crucial for the selection of saccade goals in the presence of competing targets, they cannot resolve at which processing stage pulvinar exerts its effect on saccade behavior.…”

Electrical Stimulation of the Pulvinar Disrupts Control of Spatially Directed Actions

“…Indeed, inactivation studies have provided some insights into pulvinar function, indicating that the nucleus might be involved in identifying action-relevant stimuli, allocating or maintaining spatial attention, and initiating directed movements. Unilateral inactivation of the dorsal pulvinar results in spatial neglect, contralesional saccadic slowing, a bias toward choosing ipsilesional targets, and impaired saccadic and manual motor control (Petersen et al, 1987;Wilke et al, 2010Wilke et al, , 2013, whereas injections of the GABA receptor antagonist bicuculline result in saccadic response time effects consistent with enhanced attentional orientation toward the contralateral visual field (Petersen et al, 1987). However, these studies are limited by the timescale of pharmacological perturbation.…”