Abstract
Recent investigations into the neural mechanisms that underlie temporal perception have revealed that the striatum is an important contributor to interval timing processes, and electrophysiological recording studies have shown that the firing rates of striatal neurons are modulated by the time in a trial at which an operant response is made. However, it remains unclear whether striatal firing rate modulations are related to the passage of time alone (i.e., whether temporal information is represented in an “abstract” manner independent of other attributes of biological importance), or whether this temporal information is embedded within striatal activity related to co-occurring contextual information, such as motor behaviors. This study evaluated these two hypotheses by recording from striatal neurons while rats performed a temporal production task. Rats were trained to respond at different nosepoke apertures for food reward under two simultaneously active reinforcement schedules: a variable-interval (VI-15 s) schedule and a fixed-interval (FI-15 s) schedule of reinforcement. Responding during a trial occurred in a sequential manner composing three phases; VI responding, FI responding, VI responding. The vast majority of task-sensitive striatal neurons (95%) varied their firing rates associated with equivalent behaviors (e.g., periods in which their snout was held within the nosepoke) across these behavioral phases, and 96% of cells varied their firing rates for the same behavior within a phase, thereby demonstrating their sensitivity to time. However, in a direct test of the abstract timing hypothesis, 91% of temporally modulated “hold” cells were further modulated by the overt motor behaviors associated with transitioning between nosepokes. As such, these data are inconsistent with the striatum representing time in an “abstract’ manner, but support the hypothesis that temporal information is embedded within contextual and motor functions of the striatum.
Highlights
The ability to adapt to the temporal structure of events in the seconds to minutes range, interval timing, is critical for behaving in an efficient manner with respect to an unstable, but predictable, environment (Gallistel, 1990; Brunner et al, 1996; Buhusi and Meck, 2005)
We examined whether firing rates differed between and within behavioral phases to ascertain whether temporal aspects and/or motor behaviors modulated striatal activity
Our results are consistent with previous work showing that neural regions that innervate the striatum have all been linked to interval timing (Lejeune et al, 1997; Harrington and Haaland, 1999; Macar et al, 1999, 2004; Komura et al, 2001; Rao et al, 2001; Brody et al, 2003; Ferrandez et al, 2003; Leon and Shadlen, 2003; Nenadic et al, 2003; Coull, 2004; Coull et al, 2004; Sakurai et al, 2004; Janssen and Shadlen, 2005; Tsujimoto and Sawaguchi, 2005; Jahanshahi et al, 2006; Matell et al, 2006a, 2011; Meck, 2006; Shuler and Bear, 2006; Mita et al, 2009)
Summary
The ability to adapt to the temporal structure of events in the seconds to minutes range, interval timing, is critical for behaving in an efficient manner with respect to an unstable, but predictable, environment (Gallistel, 1990; Brunner et al, 1996; Buhusi and Meck, 2005). Besides providing the important ability to predict when specific events should occur, interval timing may be essential for the computational processes underlying associative learning (Gibbon and Balsam, 1981; Miller and Barnet, 1993; Gallistel and Gibbon, 2000; Balsam et al, 2006), adaptive foraging (Kacelnik and Bateson, 1996), and rate estimation (Brunner et al, 1992). Functional neuroimaging work in humans (Ferrandez et al, 2003; Nenadic et al, 2003; Coull, 2004; Harrington et al, 2004; Macar et al, 2004; Pouthas et al, 2005; Tregellas et al, 2006; Livesey et al, 2007; Stevens et al, 2007), lesion studies in rodents (Dietrich et al, 1997; Meck, 2006), and electrophysiological recordings from humans (Macar et al, 1999; Pfeuty et al, 2005), non-human primates (Brody et al, 2003; Leon and Shadlen, 2003; Sakurai et al, 2004; Janssen and Shadlen, 2005; Tsujimoto and Sawaguchi, 2005; Mita et al, 2009) and rodents (Matell et al, 2003, 2011), have implicated a broad network of non-sensory structures in interval timing, including parietal and frontal cortices, the basal
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
