Description
For analyses of complex sounds, many neurons integrate information across different spectral elements via suppressive effects that are distant from the neurons' excitatory tuning. In the mustached bat, suppression evoked by sounds within the first sonar harmonic (23-30 kHz) or in the subsonar band (\textless23 kHz) alters responsiveness to the higher best frequencies of many neurons. This study examined features and mechanisms associated with low-frequency (LF) suppression among neurons of the lateral lemniscal nuclei (NLL). We obtained extracellular recordings from neurons in the intermediate and ventral nuclei of the lateral lemniscus, observing different forms of LF suppression related to the two above-cited frequency bands. To understand the mechanisms underlying this suppression in NLL neurons, we examined the roles of glycinergic and GABAergic input through local microiontophoretic application of strychnine, an antagonist to glycine receptors (GlyRs), or bicuculline, an antagonist to gamma-aminobutyric acid type A receptors (GABA(A)Rs). With blockade of GABA(A)Rs, neurons showed an increase in firing rate to best frequency (BF) and/or LF tones but retained LF suppression of BF sounds. For neurons that displayed LF suppression tuned to
Subject
Acoustic Stimulation; Action Potentials/drug effects; Animals; Auditory Perception/drug effects/*physiology; Bicuculline/pharmacology; Brain Stem/drug effects/*physiology; Chiroptera; GABA Antagonists/pharmacology; GABA-A Receptor Antagonists; GABA-A/metabolism; gamma-Aminobutyric Acid/metabolism; Glycine Agents/pharmacology; Glycine/*physiology; Glycine/antagonists & inhibitors/metabolism; Microelectrodes; Neural Inhibition/drug effects/*physiology; Neurons/drug effects/*physiology; Receptors; Strychnine/pharmacology