Contributions of the striatum to learning, motivation, and performance: an associative account

Abstract

It has long been recognized that the striatum is composed of distinct functional sub-units that are part of multiple cortico-striatal-thalamic circuits. Contemporary research has focused on the contribution of striatal sub-regions to three main phenomena: learning of associations between stimuli, actions and rewards; selection between competing response alternatives; and motivational modulation of motor behavior. Recent proposals have argued for a functional division of the striatum along these lines, attributing, for example, learning to one region and performance to another. Here, we consider empirical data from human and animal studies, as well as theoretical notions from both the psychological and computational literatures, and conclude that striatal sub-regions instead differ most clearly in terms of the associations being encoded in each region.

Dissociating contributions of ventral and dorsal striatum to reward learning

“…In other words, the increased BOLD signal in DLS and DMS correlating with increased trialwise probability of reward receipt may reflect either model-free or model-based Pavlovian learning (or both). This interpretation is in line with previous findings that DLS codes model-free, whereas DMS processes model-based, instrumental learning (Liljeholm and O'Doherty 2012;Wunderlich et al 2012). It suggests that the neural computation underlying Pavlovian learning may be similar to that of instrumental learning (Dayan and Berridge 2014).…”

“…Surprisingly however, recent lesion and functional magnetic resonance imaging (fMRI) studies suggest that dorsomedial striatum (DMS; for a brief anatomic introduction of striatum, see Fig. 1) is implicated in model-based instrumental learning (Liljeholm and O'Doherty 2012;Wunderlich et al 2012). What makes the picture more complex is that, using a task dissociating the two types of learning, Daw et al (2011) found that ventral striatum (VS) signal encodes both model-free and model-based instrumental learning.…”

“…1A). However, Liljeholm and O'Doherty (2012) argued that rather than a direct role in instrumental learning per se, the VS is more involved in Pavlovian learning and that it is the latter that potentially supports instrumental learning (Fig. 1B).…”

Influence of reward motivation on human declarative memory

“…Specifically, the declarative memory system involves the MTL cooperating with the ventromedial prefrontal cortex (Preston and Eichenbaum, 2013), and enables instance learning, the extraction and application of underlying associative or categorical rules (generalization) to new instances, as well as retrieval of ensuing episodic and semantic memories (Hoscheidt et al, 2010). The second non-declarative learning system allows for rapid, feedback-based learning of patterns predicting reward, via the recruitment of the basal ganglia (Delgado and Dickerson, 2012;Poldrack and Foerde, 2008), and is essential for habit learning (Liljeholm and O'Doherty, 2012;Schwabe and Wolf, 2013;Smith and Graybiel, 2013). Both systems are capable of some form of associative learning and generalization, and increasing evidence points toward the collaboration between them in post-encoding episodic memory registration (Ben-Yakov and Dudai, 2011) and retrieval (Scimeca and Badre, 2012).…”

Journal Club: Possible role of the basal ganglia in poor reward sensitivity and apathy after stroke

“…As the BG are involved in both reinforcement learning and motivation, 9 lesions may have influenced these processes separately or together. A task permitting dissociation of learning from reward sensitivity, or the examination of the ).…”