Motor role of parietal cortex in a monkey model of hemispatial neglect

Abstract

Parietal cortex is central to spatial cognition. Lesions of parietal cortex often lead to hemispatial neglect, an impairment of choices of targets in space. It has been unclear whether parietal cortex implements target choice at the general cognitive level, or whether parietal cortex subserves the choice of targets of particular actions. To address this question, monkeys engaged in choice tasks in two distinct action contexts-eye movements and arm movements. We placed focused reversible lesions into specific parietal circuits using the GABA A receptor agonist muscimol and validated the lesion placement using MRI. We found that lesions on the lateral bank of the intraparietal sulcus [lateral intraparietal area (LIP)] specifically biased choices made using eye movements, whereas lesions on the medial bank of the intraparietal sulcus [parietal reach region (PRR)] specifically biased choices made using arm movements. This double dissociation suggests that target choice is implemented in dedicated parietal circuits in the context of specific actions. This finding emphasizes a motor role of parietal cortex in spatial choice making and contributes to our understanding of hemispatial neglect.

The Role of the Lateral Intraparietal Area in (the Study of) Decision Making

“…In this control task, monkeys chose freely between two saccade targets in the absence of a motion stimulus. Inactivation in LIP shifted choices away from the target in the contralesional hemifield, consistent with previous inactivation studies in monkeys, rodents, and humans (Balan & Gottlieb 2009, Erlich et al 2015, Kerkhoff 2001, Kubanek et al 2015, Wardak et al 2002, Wilke et al 2012, Zirnsak et al 2015), and indicating that neural activity in LIP—although necessary for guiding free choices—is not necessary for the type of perceptual decision traditionally used to elicit decision-correlated activity in LIP.…”

“…Second, the reduction in RT and subtle increase in choices can be explained in multiple forms outside the evidence accumulation framework, for example, as an increase in attention to one choice target over the other. In studies that focus on target selection in the presence of distractor targets, both microstimulation and inactivation in LIP produce behavioral deficits consistent with the results reported by Hanks et al (2006) (Balan & Gottlieb 2009, Cutrell & Marrocco 2002, Dai et al 2014, Kubanek et al 2015, Wardak et al 2002, Zirnsak et al 2015). …”

“…However, it could also be the case that these LIP neurons are in fact usually relied upon, but that other structures are recruited in compensation. This is an intriguing, but we think unlikely, hypothesis, given that inactivation of LIP in other cognitive tasks (e.g., attentional selection, visual search, free choices) does result in reliable behavioral deficits (Balan & Gottlieb 2009, Kubanek et al 2015, Liu et al 2010, Wardak et al 2004, Wilke et al 2012). Such an account would require that LIP be compensated for by other structures in a decision-making task but not in these related tasks—including the free-choice control task in which behavioral disruption was observed (in the same experimental sessions as the motion discrimination task inactivations).…”

Neural bases of self‐ and object‐motion in a naturalistic vision

“…Areas LIP and SFS/FEF are part of the dorsal attention network, invariably activated in studies on saccadic eye movements, visual tracking, or attention (covert or overt) shifts in both monkeys (Ben Hamed, Duhamel, Bremmer, & Graf, 2001Koyama et al, 2004;Kubanek, Li, & Snyder, 2015;Wardak, Hamed, Olivier, & Duhamel, 2012) and humans (Astafiev et al, 2003;Corbetta et al, 1998;Culham et al, 1998;Perry & Zeki, 2000;Petit & Haxby, 1999;Schluppeck et al, 2005Schluppeck et al, , 2006Sereno et al, 2001). Although the activity of these two regions is mainly eye/attention-movement related (see below for a full discussion on the role of eye movements), some of the previous works showed that the activity of these two regions is also related to visual motion (Huang et al, 2015;Pitzalis et al, 2010;.…”

Transcranial ultrasound selectively biases decision-making in primates

“…Here, we characterize the size and polarity of the neuromodulatory e↵ects of ultrasound using a wellestablished task (Oppenheim, 1885;Rorden et al, 1997;Ro et al, 2001;Schiller and Tehovnik, 2003;Kubanek et al, 2015) in awake behaving non-human primates (NHPs). In this task, a subject decides whether to look at a right or a left target, guided by one of the targets appearing slightly earlier than the other target.…”