  Synchronization of neural activity in the gamma frequency band is associated
with various cognitive phenomena. Abnormalities of gamma synchronization may
underlie symptoms of several neurological and psychiatric disorders such as
schizophrenia and autism spectrum disorder. Properties of neural oscillations
in the gamma band depend critically on the synaptic properties of the
underlying circuits. This study explores how synaptic properties in
pyramidal-interneuronal circuits affect not only the average synchronization
strength but also the fine temporal patterning of neural synchrony. If two
signals show only moderate synchrony strength, it may be possible to consider
these dynamics as alternating between synchronized and desynchronized states.
We use a model of connected circuits that produces pyramidal-interneuronal
gamma (PING) oscillations to explore the temporal patterning of synchronized
and desynchronized intervals. Changes in synaptic strength may alter the
temporal patterning of synchronized dynamics (even if the average synchrony
strength is not changed). Larger values of local synaptic connections promote
longer desynchronization durations, while larger values of long-range synaptic
connections promote shorter desynchronization durations. Furthermore, we show
that circuits with different temporal patterning of synchronization may have
different sensitivity to synaptic input. Thus, the alterations of synaptic
strength may mediate physiological properties of neural circuits not only
through change in the average synchrony level of gamma oscillations, but also
through change in how synchrony is patterned in time over very short time
scales.
