ABSTRACT
Eye movements alter the relationship between the visual and auditory spatial scenes. Signals related to eye movements affect neural pathways from the ear through auditory cortex and beyond, but how these signals contribute to computing the locations of sounds with respect to the visual scene is poorly understood. Here, we evaluated the information contained in eye movement-related eardrum oscillations (EMREOs), pressure changes recorded in the ear canal that occur in conjunction with simultaneous eye movements. We show that EMREOs contain parametric information about horizontal and vertical eye displacement as well as initial/final eye position with respect to the head. The parametric information in the horizontal and vertical directions can be modeled as combining linearly, allowing accurate prediction of the EMREOs associated with oblique (diagonal) eye movements. Target location can also be inferred from the EMREO signals recorded during eye movements to those targets. We hypothesize that the (currently unknown) mechanism underlying EMREOs could impose a two-dimensional eye-movement-related transfer function on any incoming sound, permitting subsequent processing stages to compute the positions of sounds in relation to the visual scene.
Subject(s)
Eye Movements , Saccades , Movement , Ocular Physiological Phenomena , SoundABSTRACT
PURPOSE: This study aims to assess the efficacy and safety of intranasal (IN) esketamine as maintenance antidepressant therapy in patients who have demonstrated clinical improvement with off-label intravenous (IV) racemic ketamine for treatment-resistant depression (TRD). METHODS: This is a retrospective case series of 10 consecutive outpatients with TRD who all had a clinically meaningful response when treated with IV racemic ketamine and were then switched to IN esketamine for maintenance therapy. Patient outcomes were assessed with the Montgomery-Åsberg Depression Rating Scale, Patient Health Questionnaire 9, and Clinical Global Impression of Improvement scale at each visit. Adverse effects were assessed at each treatment. FINDINGS: Results indicated that 9 patients either maintained the benefit or showed greater improvement when transitioned to IN esketamine for antidepressant maintenance therapy. One patient had worsening of depression due to an acute psychosocial stressor but still improved from baseline IV racemic ketamine treatment. Six patients returned to work or pursued employment, and 4 patients with suicidal ideation remitted during IV racemic ketamine treatment and had no recurrence of suicidality with IN esketamine. No serious adverse reactions or tolerability issues were observed. IMPLICATIONS: This case series reports the outcomes of 10 severely ill patients with TRD who had a clinically meaningful response to IV racemic ketamine and demonstrated a maintenance of effect or continued improvement when transitioned to IN esketamine. Although this finding needs to be replicated in larger, controlled studies, this report provides promising results for patients who have safely and effectively switched to Food and Drug Administration-approved IN esketamine after receiving acute or maintenance depression treatment with off-label IV racemic ketamine.
