  The presence of diffuse Focal Axonal Swellings (FAS) is a hallmark cellular
feature in many neurodegenerative diseases and traumatic brain injury. Among
other things, the FAS have a significant impact on spike-train encodings that
propagate through the affected neurons, leading to compromised signal
processing on a neuronal network level. This work merges, for the first time,
three fields of study: (i) signal processing in excitatory-inhibitory (EI)
networks of neurons via population codes, (ii) decision-making theory driven by
the production of evidence from stimulus, and (iii) compromised spike-train
propagation through FAS. As such, we demonstrate a mathematical architecture
capable of characterizing compromised decision-making driven by cellular
mechanisms. The computational model also leads to several novel predictions and
diagnostics for understanding injury level and cognitive deficits, including a
key finding that decision-making reaction times, rather than accuracy, are
indicative of network level damage. The results have a number of translational
implications, including that the level of network damage can be characterized
by the reaction times in simple cognitive and motor tests.
