Major depression and electrovestibulography.

OBJECTIVES: No electrophysiological neuroimaging or genetic markers have been established that strongly relate to a diagnosis of major depression or its severity. The objective of this paper is to describe the preliminary evaluation of a potential new biomarker for depression utilizing the recording of electrical activity from the outer ear canal referred to as electrovestibulography (EVestG). METHODS: Sensory oto-acoustic features were extracted from EVestG data to compare 31 healthy age- and gender-matched individuals as controls to 43 major depressive disorder (MDD) subjects (22 symptomatic (MDD-S), 21 reduced symptomatic (MDD-R)). The stimulus was a single supine-vertical translation. The six features examined were based on the measured firing pattern interval histogram and the shape of the average field potential response. RESULTS: An unbiased classification accuracy of 85, 87 and 77% was achieved for separating Control from MDD-S, Control from MDD, and MDD-S from MDD-R groups respectively. Features used showed low but significant correlations (P < 0.05) with MADRS and CORE assessments. CONCLUSIONS: The results support the use of separate features for measuring MDD symptomatology versus diagnosing MDD, representing plausible different mechanisms of brain function in MDD-S and MDD-R. The first evidence of the successful application of sensory oto-acoustic features toward diagnosing and measuring the symptomatology of MDD is presented.

A new proposal concerning the botanical origin of Baltic amber.

Baltic amber constitutes the largest known deposit of fossil plant resin and the richest repository of fossil insects of any age. Despite a remarkable legacy of archaeological, geochemical and palaeobiological investigation, the botanical origin of this exceptional resource remains controversial. Here, we use taxonomically explicit applications of solid-state Fourier-transform infrared (FTIR) microspectroscopy, coupled with multivariate clustering and palaeobotanical observations, to propose that conifers of the family Sciadopityaceae, closely allied to the sole extant representative, Sciadopitys verticillata, were involved in the genesis of Baltic amber. The fidelity of FTIR-based chemotaxonomic inferences is upheld by modern-fossil comparisons of resins from additional conifer families and genera (Cupressaceae: Metasequoia; Pinaceae: Pinus and Pseudolarix). Our conclusions challenge hypotheses advocating members of either of the families Araucariaceae or Pinaceae as the primary amber-producing trees and correlate favourably with the progressive demise of subtropical forest biomes from northern Europe as palaeotemperatures cooled following the Eocene climate optimum.

EVestG: a measure for Meniere's Disease.

Meniere's Disease is commonly diagnosed using Electrocochleography (ECOG). EVestG is a variant of ECOG utilizing one or more patient tilts as stimuli in place of the ECOG's repeated tonal clicks. The dynamic measures averaged 'background-onAA' (onAA=acceleration phase of tilt) and background-onBB (onBB=deceleration phase of tilt) of excitatory (ipsilateral tilt) vestibular responses are compared for a small group of age matched Controls (n=18) and Meniere's Disease patients (n=11). Preliminary data provides for an apparent clearer demarcation between Controls and Meniere's patients. Meniere's patients appear to show not only increased Sp/Ap ratios but also a decreased dynamic range of response as measured by the EVestG response measure averaged 'background-onBB'. Increased sample size is required to validate these findings.

EVestG: responses in depressed patients.

Depression is a mood disorder characterized by a sustained period of low mood or loss of interest or pleasure in activities. Dysfunction of the limbic system is implicated in depression. Different areas of this system have bidirectional links with the vestibular nucleus. The diagnosis of depression is subjective. Electrovestibulography (EVestG) might be able to assist in the diagnosis of depression in a more objective way. A dynamic measure of the excitatory (ipsilateral) responses during the background, acceleration and deceleration phases of an active tilt are compared with a small group (n=5) of depressive patients and age matched controls (n=10).

Electrovestibulography: the "DC" potential used to separate Meniere's disease and Benign Paroxysmal Positional Vertigo.

Electrovestibulography (EVestG) is a new diagnostic technique potentially applicable to detecting neurological changes impacting on sensory performance. A complex Morlet wavelet based signal processing technique, a Neural Event Extraction Routine, has been used to extract diagnostically meaningful biomarkers from these EVestG recordings. Separation of Meniere's disease and Benign Paroxysmal Positional Vertigo (BPPV) has been accomplished using a "DC" Biomarker [1]. When using tilt stimuli to evoke a semi circular canal response, otolithic organ responses are also observed. The origin of this "DC" biomarker is likely a multifaceted dipole generated by both semi circular canal and otolithic structures.