Chemosensation in anxiety: the trigeminal system matters.

The presence of a perceptual bias due to anxiety is well demonstrated in cognitive and sensory task for the visual and auditory modality. Event-related potentials, by their specific measurement of neural processes, have strongly contributed to this evidence. There is still no consensus as to whether such a bias exists in the chemical senses; chemosensory event-related potentials (CSERPs) are an excellent tool to clarify the heterogeneous results, especially since the Late Positive Component (LPC) may be an indicator of emotional involvement after chemosensory stimulation. This research examined the association between state and trait anxiety and the amplitude and latency of pure olfactory and mixed olfactory-trigeminal LPC. In this study, 20 healthy participants (11 women) with a mean age of 24.6 years (SD = 2.6) completed a validated questionnaire to measure anxiety (STAI), and CSERP was recorded during 40 pure olfactory stimulations (phenyl ethanol) and 40 mixed olfactory-trigeminal stimulations (eucalyptol). LPC latency and amplitude were measured at Cz (electrode located at midline central) for each participant. We observed a significant negative correlation between LPC latencies and the state anxiety scores for the mixed olfactory-trigeminal condition (r(18) = -0.513; P = 0.021), but not for the pure olfactory condition. We did not observe any effect on LPC amplitudes. This study suggests that a higher level of state anxiety is related to a more rapid perceptual electrophysiological response for mixed olfactory-trigeminal stimuli but not for pure odors.

Verbal Episodic Memory Alterations and Hippocampal Atrophy in Acute Mild Traumatic Brain Injury.

Episodic memory deficit is a symptom frequently observed after a mild traumatic brain injury (mTBI). However, few studies have investigated the impact of a single and acute mTBI on episodic memory and structural cerebral changes. To do so, we conducted two experiments. In the first, we evaluated verbal episodic memory by using a word recall test, in 52 patients with mTBI (mean age 33.1 [12.2] years) 2-4 weeks after a first mTBI, compared with 54 healthy controls (31.3 [9.2] years) and followed both groups up for 6 months. In the second, we measured hippocampal volume in a subset of 40 participants (20 patients with mTBI, 20 controls) from Experiment 1 using magnetic resonance imaging (MRI; T1-weighted images) and correlated memory performance scores to hippocampal volume. Experiment 1 showed significantly reduced verbal episodic memory within the first month after an mTBI and a tendency for a reduction 6 months later, more pronounced for men. In Experiment 2, patients with mTBI exhibited a generally reduced hippocampal volume; however, we did not observe any linear correlation between hippocampal volume and memory scores. These results suggest that one single mTBI is associated with both episodic memory alteration and reduced volume of the hippocampus in the acute phase. Future studies are needed to elucidate the link between both measures.