Evaluating Cholinergic Receptor Expression in Guinea Pig Primary Auditory and Rostral Belt Cortices After Noise Damage Using [H]Scopolamine and [F]Flubatine Autoradiography.

Noise-induced hearing loss leads to anatomic and physiologic changes in primary auditory cortex (A1) and the adjacent dorsal rostral belt (RB). Since acetylcholine is known to modulate plasticity in other cortical areas, changes in A1 and RB following noise damage may be due to changes in cholinergic receptor expression. We used [H]scopolamine and [F]flubatine binding to measure muscarinic acetylcholine receptor (mAChR) and nicotinic acetylcholine receptor (nAChR) expression, respectively, in guinea pig A1 and RB 3 weeks following unilateral, left ear noise exposure, and a temporary threshold shift in hearing.

Synthesis and pre-clinical evaluation of a potential radiotracer for PET imaging of the dopamine D receptor.

There is considerable interest in using positron emission tomography (PET) imaging to understand the function of dopamine D receptors. Due to high sequence homology with D receptors, development of D-selective PET radiotracers has been challenging. In an effort to overcome this issue, we report the radiosynthesis of a new selective D ligand with carbon-11 ( ), and its initial preclincial evaluation as a potential PET radiotracer for imaging of D receptors.

Noise exposure alters long-term neural firing rates and synchrony in primary auditory and rostral belt cortices following bimodal stimulation.

We previously demonstrated that bimodal stimulation (spinal trigeminal nucleus [Sp5] paired with best frequency tone) altered neural tone-evoked and spontaneous firing rates (SFRs) in primary auditory cortex (A1) 15 min after pairing in guinea pigs with and without noise-induced tinnitus. Neural responses were enhanced (+10 ms) or suppressed (0 ms) based on the bimodal pairing interval. Here we investigated whether bimodal stimulation leads to long-term (up to 2 h) changes in tone-evoked and SFRs and neural synchrony (correlate of tinnitus) and if the long-term bimodal effects are altered following noise exposure.