Convergent evidence suggests that corticostriatal interactions act as a gate to

Convergent evidence suggests that corticostriatal interactions act as a gate to select the input to working memory (WM). gate WM’s output. These results support the output gating hypothesis and suggest that contextual representations in PFC influence striatum to select which information in WM drives responding. Introduction Cognitive control requires a balance between two incompatible demands: flexibly updating goals versus robustly maintaining them. One answer to this dilemma is to separate the neural mechanisms for working memory (WM) maintenance from those that update the information that is to be maintained i.e. a WM “gate”. This computational division of labor is usually thought to have anatomical correlates with prefrontal cortex (PFC) supporting maintenance and basal ganglia (BG) supporting gating (Braver and Cohen 2000 Frank et al. 2001 Gruber et al. 2006; Frank and O’Reilly 2006 Cools et al. 2007 From this perspective disinhibition of cortico-striato-thalamic loops enables the selective updating of task-relevant information into P276-00 WM. Once maintained information supported by PFC is usually available to exert a top-down bias on posterior neocortex (Desimone and Duncan 1995 This type of selective control over the input to WM – termed “input gating” – relies on dopaminergic corticostriatal systems (Frank and O’Reilly 2006 Moustafa et al. 2008 Cools et al. 2010 Murty et al. 2011 McNab and Klingberg 2008 However not everything in WM will be relevant for behavior at any one point in time. Rather it is also adaptive to control which representations within WM can influence attention and behavior and when. Such selection from within WM or “singling out” of WM representations (Oberauer and Hein 2012 is usually resource-demanding and PFC-dependent (e.g. Rowe et al. 2000 Bunge et al. 2002 Hester et al. 2007 Tamber-Rosenau et al. 2011 Nevertheless relative to control over the input to WM little evidence exists regarding this type of selection process and its relationship to cognitive control. One hypothesis is usually that selection from within WM can be conceived of as a gating function analogous to that described above for WM updating. From this perspective an “output gate” may control the flow of information within WM between an actively maintained but inert state to one that is capable of exerting a top down influence on behavior. In other words for any given WM representation when the output gate is closed that representation would be maintained but would not have a top down influence. Conversely when the output gate is opened the maintained representation provides a top down contextual signal. Output gating is usually a shared treatment for the problem of selection from within WM across Rabbit polyclonal to CBL. many computational models (Hochreiter and Schimidhuber 1997 Hazy et al. 2007 Brown et al. 2007 Kriete and P276-00 Noelle 2011 Chatham et al. 2011 Eliasmith et al 2012; Frank and Badre 2012 Collins and Frank 2013 Huang et al. 2013 Like input gating output gating may be hypothesized to arise from cortico-striato-thalamic loops wherein candidate contextual representations maintained in PFC act as input to dorsal striatum which in turn amplifies one of these representations via its pallado-thalamic disinhibitory loop (Hazy et al. 2007 Kriete and Noelle 2011 Chatham et al. 2011 Collins and Frank 2013 Kriete et al. 2013 This putative output gating dynamic for selection of a WM representation P276-00 is an extension of more established interactions between cortex and dorsal striatum during selection of a candidate motor plan P276-00 (e.g. Mink 1996; Graybiel 1998 Gurney et al. 2001; Brown et al. 2004 According to this general class of accounts some potential stimulus-response action plan represented by premotor cortex is usually “gated out” by striatum and thereby becomes the motor plan executed by primary motor cortex. However the hypothesis that comparable frontostriatal interactions could support selection of a WM representation currently lacks support. The present study seeks to fill this gap. To test output gating of WM we focus on hierarchical control tasks requiring the use of conditional rules (e.g. the shape of a stimulus cues whether to attend to the size or color of a stimulus and size or color then determine which response must be made.) In the brain simpler rules that directly map a stimulus to a response tend to recruit more caudal frontal cortex than rules involving higher-order contingencies (Koechlin et al. 2003 Badre and D’Esposito 2007 Badre et al. 2009 2010 with a.