-
Holmes Sims posted an update 4 hours, 8 minutes ago
As we move through our environment, our visual system is presented with optic flow, a potentially important cue for perception, navigation and postural control. How does the brain anticipate the optic flow that arises as a consequence of our own movement? Converging evidence suggests that stimuli are processed differently by the brain if occurring as a consequence of self-initiated actions, compared to when externally generated. However, this has mainly been demonstrated with auditory stimuli. It is not clear how this occurs with optic flow. We measured behavioural, neurophysiological and head motion responses of 29 healthy participants to radially expanding, vection-inducing optic flow stimuli, simulating forward transitional motion, which were either initiated by the participant’s own button-press (“self-initiated flow”) or by the computer (“passive flow”). Self-initiation led to a prominent and left-lateralized inhibition of the flow-evoked posterior event-related alpha desynchronization (ERD), and a stabilisation of postural responses. Neither effect was present in control button-press-only trials, without optic flow. Additionally, self-initiation also produced a large event-related potential (ERP) negativity between 130-170 ms after optic flow onset. Furthermore, participants’ visual induced motion sickness (VIMS) and vection intensity ratings correlated positively across the group – although many participants felt vection in the absence of any VIMS, none reported the opposite combination. Finally, we found that the simple act of making a button press leads to a detectable head movement even when using a chin rest. Taken together, our results indicate that the visual system is capable of predicting optic flow when self-initiated, to affect behaviour.Subarachnoid hemorrhage (SAH) can cause acute neuronal injury and chronic neurocognitive deficits; biomarkers reflecting its associated neuronal injury are of potential prognostic value. Sortilin, a member of the vacuolar protein sorting 10p (Vps10p) family, is enriched in neurons and is likely involved in neurodegenerative diseases. Here, we explored sortilin in the cerebrospinal fluid (CSF) as a potential biomarker for early neuronal injury after SAH. Sortilin levels in the CSF of SAH patients (n = 11) and controls (n = 6) were analyzed by immunoblot. SAH rats surviving 3-72 h (h) were evaluated neurologically, with their brain and CSF samples examined histologically and biochemically. Sortilin protein ~100 kDa was detected in the CSF from SAH patients only, with its levels correlated to Hunt-Hess scale. Rats in the SAH groups showed poorer Garcia score and beam balancing capability than sham controls. Sortilin ~100 kDa was detectable in the CSF of the SAH, but not sham, animals. Levels of sortilin ~100 kDa and fragments ~40 kDa in cortical lysates were elevated in the SAH relative to control rats. Levels of cortical glial fibrillary acidic protein (GFAP) were also elevated in the SAH rats. In immunohistochemistry, the pattern of sortilin labeling in the brain was largely comparable between the SAH and control rats, whereas an increased astrocytic GFAP immunolabeling was evident in the former. Together, these results suggest that SAH can cause an early and remarkable rise of sortilin products in CSF, likely reflecting neuronal change. Sortilin could be further explored as a potential biomarker in some brain disorders.Although pleasantness is intrinsically related to the perception of odors it is difficult to objectively assess odor-induced pleasantness. To evaluate the effects of odors of different valences on the contingent negative variation (CNV) in a younger and an older population. Data from 62 participants (27 men, 35 women) were included. Two age groups with Age group 1 (YOUNG) had 30 subjects within age 18-30 years and age group 2 (OLD) had 32 subjects with age >40 years. Pre-testing was performed to acquaint subjects with the experimental tasks and their environment. Subjects received “Sniffin’ Sticks” odor identification tests and a standardized medical history to ascertain normosmia. see more In addition, they also took questionnaires relating to importance of the sense of smell and personality traits. CNV was elicited with two auditory stimuli, S1 followed by S2 at an interval of 2.4 s. Subjects were asked to push a button as fast as possible after they perceived S2. EEG was recorded from 4 positions of the 10-20 system (Fp2, Fz, Cz, and Pz). Four odors plus odorless air was presented in randomized order. The following main results emerged (1) Consistent with the literature CNV showed a typical topographical distribution with the largest amplitude over the front-central recording sites. (2) 69% of subjects had consistent CNV for all conditions. (3) for some odor conditions CNV amplitudes exhibit a weak relation to odor pleasantness and associations with calmness. (4) CNV amplitude correlated negatively with reaction times. Overall, the results suggest the usefulness of CNV as an electrophysiological measure of cognition. However, in the present context, concomitantly applied odors of different hedonic tones exerted only minor effects on CNV. Thus, we conclude that odors have little or no effect on CNV.The discovery of the essential requirement for kisspeptin and subsequently neurokinin B signalling for human reproductive function has sparked renewed interest in the neuroendocrinology of reproduction. A key discovery has been a population of cells co-expressing both these neuropeptides and dynorphin in the hypothalamus, directly regulating gonadotropin hormone releasing hormone (GnRH) secretion and thus pituitary secretion of gonadotropins. These neurons also project to the vasomotor centre, and their overactivity in estrogen deficiency results in the common and debilitating hot flushes of the menopause. Several antagonists to the neurokinin 3 receptor, for which neurokinin B is the endogenous ligand, have been developed, and are entering clinical studies in human reproductive function and clinical trials. Even single doses can elicit marked declines in testosterone levels in men, and their use has elicited evidence of the regulation of ovarian follicle growth in women. The most advanced indication is the treatment of menopausal vasomotor symptoms, where these drugs show remarkable results in both the degree and speed of symptom control.