Latency of evoked neuromagnetic M100 reflects perceptual and acoustic stimulus attributes

The latency of components of the auditory evoked neuromagnetic field has been shown to reflect, or encode, stimulus attributes. In particular, the M100 component, occurring approximately 100 ms post stimulus onset has a latency that depends on stimulus pitch, spectral complexity and presentation level. This study used magnetoencephalography to record neuromagnetic fields evoked by presentation of two-tone complexes consisting of various proportions of 100 Hz and 1 kHz energy. These are perceived categorically, as evidenced by classification and reaction time measurements. It is found that the M100 latency also varies categorically, that is, characterized by two plateau regions with a sharp interface. Thus, we find that not only does the M100 latency reflect acoustic attributes of a stimulus, but also such perceptual characteristics.     

Effect of serotonin on the contractile activity of the cat duodenum

In cats, distention of an isolated segment of the ileum with a saline injection elicited its contraction which could be abolished with blockade of muscarinic receptors. Serotonine acting from the ileum lumen enhanced the response, whereas acting from the vascular bed induced a contractile response which could be decreased with the beta-adrenoreceptor-blocking agent propranolol. The findings suggest a possibility of the serotonine participation in realisation of peristaltic reflex, the character of its modulating effect being dependent on activation of excitatory cholinergic and inhibitory nonadrenergic neurons.