Journal
JOURNAL OF NEUROSCIENCE
Volume 24, Issue 21, Pages 5031-5043Publisher
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.0357-04.2004
Keywords
inferior colliculus; rate coding; depolarization block; synaptic inhibition; GABA; sensory coding; synaptic depression
Categories
Funding
- NIDCD NIH HHS [R01 DC000189, K08 DC000189, F32 DC000189] Funding Source: Medline
Ask authors/readers for more resources
Neurons in the inferior colliculus (IC) change their firing rates with sound pressure level. Some neurons maintain monotonic increases in firing rate over a wide range of sound intensities, whereas other neurons are monotonic over limited intensity ranges. We examined the conditions necessary for monotonicity in this nucleus in vitro in rat brain slices and in vivo in the unanesthetized rabbit. Our in vitro recordings indicate that concurrent activation of GABA(A) synapses with excitatory inputs facilitates monotonic increases in firing rate with increases in stimulus strength. In the absence of synaptic inhibition, excitatory input to IC neurons causes large depolarizations that result in firing block and nonmonotonicity. In vivo, although GABA(A) synapses decrease the firing rate in all IC neurons, they can have opposing effects on rate-level functions. GABAergic inputs activated by all sound intensities maintain monotonicity by keeping the postsynaptic potential below the level at which depolarization block occurs. When these inputs are blocked, firing block can occur and rate-level functions become nonmonotonic. High-threshold GABAergic inputs, in contrast, cause nonmonotonic responses by decreasing the firing rate at high intensities. Our results suggest that a dynamic regulation of the postsynaptic membrane potential by synaptic inhibition is necessary to allow neurons to respond monotonically to a wide range of sound intensities.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available