Results section “Adaptation to changes in stimulus variance… The rate-level curves associated with higher stimulus variances tended to have shallower GSK2118436 slopes or saturated at lower spike rates…. … If the neurons responded to the increase in variance with a pure scaling of their rate response functions then we would expect the slopes

and the firing rates at the 50% points to decrease, and we would not expect the abscissa of the 50% to change…… The firing rates at the 50% points (and therefore the maximum firing rates) were always greatest for the stimuli with the lowest variance (the black diamonds in figure 6D are always below their corresponding green squares and red circles). But the 50% points for higher variance stimuli occurred typically at higher stimulus amplitudes (the black diamonds in figure 6D are usually to the right of their corresponding green squares and red selleck circles). This was due, not to the whole rate level curve shifting as we had seen when the HPRs were shifted, but instead because the rate level curves obtained with the higher variance stimuli often leveled off later than those obtained with lower variance stimuli, as can be seen in the examples shown in Fig.

6B and supplementary figure 2 C and D. Increasing stimulus variance did not appear to produce threshold shifts. We mentioned earlier that the slope of rate-level function can be considered as a measure of ‘neuronal response gain’. Maravall and colleagues (2007) concluded from their results that gain scales with stimulus variance. Expressed mathematically, this means that the gain (or slope) g observed at given stimulus variance v should be proportional to v, i.e. (5) Consequently, if we assume that gain scales inversely with variance (a < 1 and log(a) is negative), then we expect a scatter plot of the log of unit gain against the log of stimulus variance should fall along a line of slope -1, offset by the log of the Cell press unit’s gain factor a…… The distribution peaks at minus one,

as one might expect if gain does indeed scale inversely with variance. “
“Early-life stress induces several neuropsychological disorders in adulthood, including depression. Such disorders may be induced by functional alteration of the glutamatergic system. However, their underlying mechanisms have not yet been fully clarified. Furthermore, the involvement of glucocorticoids, which are representative stress hormones, has not yet been fully clarified. In this study, we used maternal deprivation (MD) mice as an early-life-stress model, and studied the changes in the glutamatergic system in adulthood. The glutamate concentration and neuronal activity in the somatosensory cortex (SSC) increased under basal conditions in MD mice. Stressful physical stimulation (SPS) increased the concentration of corticosterone, but not of glutamate, in the control mouse SSC.