Striatal Beat Frequency Interval Timing Model with Microgravity Stressor

The Striatal Beat Frequency (SBF) model of interval timing uses frontal cortex (FC) neural oscillations to record the state of the brain at the reinforcement time Tc during fixed interval (FI) procedures in the long-term memory (LMEM). The state of the FC oscillators at any given time is stored in a short-term memory (SMEM) buffer. The SBF model uses the spiny neurons of the basal ganglia (BG) as coincidence detectors to produce beats between the content of the SMEM and LMEM. Across multiple species that can perform interval timing, there are two invariant properties: (a) the timing is precise, and (b) it obeys scalar property. The neurobiologically realistic SBF model has been previously used to demonstrate precise and accurate scalar timing. This study explored possible effects on time perception due to microgravity stress. One effect of microgravity we modeled is the shrinking of axons. We hypothesized that shorter axons have two effects: (1) reduce the number of FC oscillators that project to BG, and (2) increase the noise in the timing network because the shorter axons will project to other areas of the brain not intended for processing such inputs. We modeled noise in the FC neural oscillations and LMEM to investigate its effect on the precision and scalar property of timing. We found that interval-timing is accurate, and the spread of timing network output is proportional to the noise intensity.