The basal ganglia integrate cortical and thalamic input to shape motor behaviour, yet how neural activity and metabolic cost are balanced in this circuit — and how that balance is disrupted in disease — remains poorly understood. Using biophysically detailed compartmental models of striatal medium spiny neurons, we compare energy expenditure, firing properties, and dynamic stability between healthy and dopamine-depleted conditions across a range of synaptic drive levels. The aim is to determine whether dopamine depletion, as seen in Parkinson's disease, alters the trade-off between metabolic efficiency and reliable neural signalling, and to identify the cellular mechanisms that underlie any such shift.