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Dystonias are frequent,often therapy-refractory movement
disorders.Primary dystonias prevail,whose pathophysiology is
unknown.Dystonic mutant dt sz hamsters represent a model for
primary dystonia.In previous studies (a)striatal interneuron
density was determined to be low,and spontaneous firing rates in
striatal output neurons high and (b)sodium currents in output
neurons were particularly resistant to pharmacological blockade.
Here,we explored whether these phenomena impact on cortico-
striatal communication.Evoked activity (neocortical afferent
stim)was recorded intra-and extracellularly from the striatum in
combined cortico-striatal slice preparations from dystonic and
control animals.Extracellular recordings revealed a higher
proportion of population spikes at saturating stimulation strength
(80%vs.57%),a left-shift of the input/output curve (population
spike amplitude 1.6 vs 1.0 mV),more frequent paired-pulse
accentuation (54%vs.21%of slices)and LTP (75%vs.54%of
slices after tetanic stiumlation)in slices from dystonic animals.
Cellular properties as input resistance,time constant,resting
membrane potential,action potential amplitude and firing patterns
were not different between control and dt sz tissue.In conclusion,
striatal responses to afferent stimulation showed a tendency
towards a higher excitability level in dystonic hamster slices.