Neuromodulation
of Cortical Plasticity
Sensory experience alters the functional
organization of cortical networks. Previous studies using behavioral training
motivated by aversive or rewarding stimuli have demonstrated that cortical
plasticity is specific to salient inputs in the sensory environment. Sensory
experience associated with electrical activation of the nucleus basalis (NB)
generates similar input specific plasticity. By directly engaging plasticity
mechanisms and avoiding extensive behavioral training, NB stimulation makes it
possible to efficiently explore how specific sensory features contribute to
cortical plasticity. Our recent experiments have documented that cortical
networks employ a variety of distinct strategies to improve the representation
of the sensory environment. Different combinations of receptive field,
temporal, and spectrotemporal plasticity were generated in primary auditory
cortex neurons depending on the pitch, modulation rate and order of sounds
paired with NB stimulation. Simple tones led to map expansion, while modulated
tones altered the maximum cortical following rate. Exposure to complex acoustic
sequences led to the development of combination sensitive responses. This
remodeling of cortical response characteristics may reflect changes in
intrinsic cellular mechanisms, synaptic efficacy, and local neuronal
connectivity. The intricate relationship between the pattern of sensory
activation and cortical plasticity suggests that network-level rules alter the
functional organization of cortex to generate the most behaviorally useful
representation of the sensory environment.
Current treatment of neurological disease is limited
to pharmacological, surgical, or behavioral intervention. Our ability to influence cortical plasticity
by manipulating the sensory environment suggests that it may be possible to
similarly manipulate plasticity mechanisms in human patients and aid recovery
from brain damage.
·
Preference for FM
Sweep Direction and Rate
·
Experience-Dependent
Changes in Cortical Synchronization
