The existence of chaotic attractors for discrete time series, derived
from the occurrences of spikes during electrophysiological recordings,
was investigated, The time series included between 800 and 5200 point
s per analyzed record. The spike trains were recorded in the substanti
a nigra pars reticulata (n = 13) and in the auditory thalamus (n = 14)
. The experiments were performed on anesthetized rats during spontaneo
us activity and during auditory stimulation. According to standard met
hods of dynamical systems theory, an embedding space was constructed u
sing delay coordinates. The embedding and correlation dimensions were
computed by means of the correlation integrals. For 7 of 27 samples, a
deterministic structure with a low embedding dimension (ranging betwe
en 2 and 6) and a correlation dimension between 0.14 and 3.3 could be
determined. Evidence was found that the sensory stimulation may affect
the chaotic behavior, Single units recorded simultaneously from the s
ame electrode tip may display different chaotic dynamics, even with a
similar time-locked response to the stimulus onset.