Voluntary physical activity increases maternal care and reduces anxiety- and depression-related behaviours during the postpartum period in mice.

A growing body of evidence suggests voluntary physical activity is associated with decreased stress-related disorders such as anxiety- and depression-like behaviours in both humans and rodents. The postpartum period is also a vulnerable transition time for the development of these neurobehavioural disorders in women. This study aimed to determine whether voluntary physical activity during pregnancy and postpartum period can increase maternal care and decrease anxiety- and depression-related behaviours in postpartum dams. To this end, pregnant mice were exposed to running wheel during their gestational and postpartum periods, and then nest building, active nursing, and licking/grooming behaviours were recorded as maternal care. To assess depression and anxiety-related symptoms, several behavioural tests such as the novelty-suppressed feeding test, tail suspension test, sucrose preference test, social interaction test, forced swim test, open field, elevated plus maze, light-dark box, and elevated zero maze were used. To identify the most important mechanisms behind these behavioural alterations, we measured oxytocin, adrenocorticotropic hormone (ACTH) and corticosterone in the serum and serotonin in the brain of postpartum dams. Our findings showed that running wheel significantly increased maternal care, and decreased depression-like behaviour during the postpartum period through increasing serum oxytocin and brain serotonin levels, whereas it decreased anxiety-like behaviour via attenuating the hypothalamic-pituitaryadrenal (HPA) axis activity by measuring ACTH and corticosterone levels in postpartum dams. Overall, this study suggests that voluntary physical activity during pregnancy and the postpartum period might improve maternal care and decrease anxiety and depression-related behaviours in postpartum dams.

Outcomes of epikeratoplasty for advanced keratoglobus.

PURPOSE: To determine the visual and anatomic outcomes of epikeratoplasty in keratoglobus. METHODS: In an interventional case series, 7 eyes of 6 patients with keratoglobus (KGB), 5 to 39 years of age, underwent epikeratoplasty. Three patients (3 eyes) had blue sclera, joint hypermobility, and consanguineous parents; 3 other patients (4 eyes) had only KGB. In the blue sclera group, all patients had lost the fellow eye because of minor trauma. We used a corneo-scleral button 1 mm larger than corneal diameter as an onlay graft. Orbscan pachymetry was performed before and 3 months after surgery. RESULTS: Mean visual acuity was 20/400 preoperatively and improved to 20/160 postoperatively. Mean central corneal thickness was 200 microm preoperatively, which increased to 800 microm after surgery. Epithelial inclusion cysts developed in 1 patient. Severe interface vascularization was observed in 1 eye of the blue sclera group, which had total Descemet membrane detachment before epikeratoplasty. Neurotrophic ulcer occurred in 1 case, which improved with tarsorrhaphy, punctal occlusion, and medical therapy. CONCLUSION: Epikeratoplasty is a safe and effective procedure in preserving ocular integrity and increasing visual acuity in patients with keratoglobus and should be considered before corneal perforation, which often results in loss of an eye.

Mean field theory for a balanced hypercolumn model of orientation selectivity in primary visual cortex.

We present a complete mean field theory for a balanced state of a simple model of an orientation hypercolumn, with a numerical procedure for solving the mean-field equations quantitatively. With our treatment, one can determine self-consistently both the firing rates and the firing correlations, without being restricted to specific neuron models. Here, we solve the mean-field equations numerically for integrate-and-fire neurons. Several known key properties of orientation selective cortical neurons emerge naturally from the description: Irregular firing with statistics close to - but not restricted to - Poisson statistics; an almost linear gain function (firing frequency as a function of stimulus contrast) of the neurons within the network; and a contrast-invariant tuning width of the neuronal firing. We find that the irregularity in firing depends sensitively on synaptic strengths. If the Fano factor is considerably larger (smaller) than 1 at some stimulus orientation, then it is also larger (resp. maller) than 1 for all other stimulus orientations that elicit firing. We also find that the tuning of the noise in the input current is the same as the tuning of the external input, while that for the mean input current depends on both the external input and the intracortical connectivity.

Response variability in balanced cortical networks.

We study the spike statistics of neurons in a network with dynamically balanced excitation and inhibition. Our model, intended to represent a generic cortical column, comprises randomly connected excitatory and inhibitory leaky integrate-and-fire neurons, driven by excitatory input from an external population. The high connectivity permits a mean field description in which synaptic currents can be treated as gaussian noise, the mean and autocorrelation function of which are calculated self-consistently from the firing statistics of single model neurons. Within this description, a wide range of Fano factors is possible. We find that the irregularity of spike trains is controlled mainly by the strength of the synapses relative to the difference between the firing threshold and the postfiring reset level of the membrane potential. For moderately strong synapses, we find spike statistics very similar to those observed in primary visual cortex.