Dissociable contributions of basolateral amygdala and ventrolateral orbitofrontal cortex to flexible learning under uncertainty.

Reversal learning measures the ability to form flexible associations between choice outcomes with stimuli and actions that precede them. This type of learning is thought to rely on several cortical and subcortical areas, including highly interconnected orbitofrontal cortex (OFC) and basolateral amygdala (BLA), and is often impaired in various neuropsychiatric and substance use disorders. However, unique contributions of these regions to stimulus- and action-based reversal learning have not been systematically compared using a chemogenetic approach and particularly before and after the first reversal that introduces new uncertainty. Here, we examined the roles of ventrolateral OFC (vlOFC) and BLA during reversal learning. Male and female rats were prepared with inhibitory DREADDs targeting projection neurons in these regions and tested on a series of deterministic and probabilistic reversals during which they learned about stimulus identity or side (left or right) associated with different reward probabilities. Using a counterbalanced within-subject design, we inhibited these regions prior to reversal sessions. We assessed initial and pre-post reversal changes in performance to measure learning and adjustments to reversals, respectively. We found that inhibition of vlOFC, but not BLA, eliminated adjustments to stimulus-based reversals. Inhibition of BLA, but not vlOFC, selectively impaired action-based probabilistic reversal learning, leaving deterministic reversal learning intact. vlOFC exhibited a sex-dependent role in early adjustment to action-based reversals, but not in overall learning. These results reveal dissociable roles for BLA and vlOFC in flexible learning and highlight a more crucial role for BLA in learning meaningful changes in the reward environment.

Arytenoid cartilage dislocation mimicking bilateral vocal cord paralysis: A case report.

RATIONALE: Arytenoid dislocation is very rare and may be misdiagnosed as vocal cord paralysis or a self-limiting sore throat. PATIENT CONCERNS: A 70-year-old male (70 kg, 156 cm) was scheduled for transurethral resection of bladder tumors. A McGrath videolaryngoscope, with a basic cuffed Mallinckrodt oral tracheal tube of 7.5 mm internal diameter, was used to successfully intubate his trachea. The duration of surgery was 25 minutes. In the recovery room, he complained of sore throat and dyspnea with inspiratory stridor, which were not resolved after intravenous injection of 10 mg of dexamethasone. DIAGNOSES: The otolaryngological examination revealed midline fixation of the bilateral vocal folds, suggestive of bilateral arytenoid dislocation or bilateral vocal cord palsy. The latter was ruled out because there was no evidence of recurrent laryngeal nerve injury. INTERVENTIONS: Under general anesthesia, a closed reduction was performed using laryngoscopic forceps to apply posterolateral pressure on the arytenoid joints on both sides. Only the dislocation of the left cricoarytenoid joint could be easily reduced, whereas reduction of the right joint was not possible. OUTCOMES: On postoperative day 7, examination with a rigid laryngoscope showed a medially fixed right vocal fold, with full compensation by the left vocal fold. Computed tomography of the neck showed no pathologic findings. Six weeks after surgery, the patient had regained his normal voice with no complications. LESSONS: Although arytenoid dislocation is a rare complication, it should be considered even in patients with uncomplicated tracheal intubation. Early diagnosis and the optimal therapeutic approach are critical for restoration of the patient's original vocal cord function.