Posts Tagged ‘Dilation’

Einstein in four *spatial* dimension

Why many physicists chose to define the universe in terms of the physical properties of a time or space-time dimension instead of four *spatial* dimensions is puzzling because, as was shown in the earlier article "Defining time" Sept 20, 2007 there is no observational evidence supporting it having physical properties.  Gravity and space-time But even […]

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Neural correlates of single-vessel haemodynamic responses in vivo

Neural activation increases blood flow locally. This vascular signal is used by functional imaging techniques to infer the location and strength of neural activity. However, the precise spatial scale over which neural and vascular signals are correlated is unknown. Furthermore, the relative role of synaptic and spiking activity in driving haemodynamic signals is controversial. Previous studies recorded local field potentials as a measure of synaptic activity together with spiking activity and low-resolution haemodynamic imaging. Here we used two-photon microscopy to measure sensory-evoked responses of individual blood vessels (dilation, blood velocity) while imaging synaptic and spiking activity in the surrounding tissue using fluorescent glutamate and calcium sensors. In cat primary visual cortex, where neurons are clustered by their preference for stimulus orientation, we discovered new maps for excitatory synaptic activity, which were organized similarly to those for spiking activity but were less selective for stimulus orientation and direction. We generated tuning curves for individual vessel responses for the first time and found that parenchymal vessels in cortical layer 2/3 were orientation selective. Neighbouring penetrating arterioles had different orientation preferences. Pial surface arteries in cats, as well as surface arteries and penetrating arterioles in rat visual cortex (where orientation maps do not exist), responded to visual stimuli but had no orientation selectivity. We integrated synaptic or spiking responses around individual parenchymal vessels in cats and established that the vascular and neural responses had the same orientation preference. However, synaptic and spiking responses were more selective than vascular responses—vessels frequently responded robustly to stimuli that evoked little to no neural activity in the surrounding tissue. Thus, local neural and haemodynamic signals were partly decoupled. Together, these results indicate that intrinsic cortical properties, such as propagation of vascular dilation between neighbouring columns, need to be accounted for when decoding haemodynamic signals.


Described herein are methods for enhancing airway dilation and/or relieving bronchoconstriction, e.g., to treat obstructive lung diseases such as asthma and COPD, by administering bitter tastants to subjects in need thereof. Also described herein are m…

Why something rather than nothing.

TweetThe Big Bang theory suggests that matter and antimatter should have been produced in equal quantities.  Since collisions between matter and antimatter result in their mutual annihilation there should not be any ordinary matter, and its antimatter equivalent left in the universe.  However, it is obvious this did not happen because no galaxies or intergalactic [...]

Recreational Cocaine Use Linked To Heart Attack Conditions

Alan McStravick for – Your Universe Online

I said to a guy, “Tell me, what is it about cocaine that makes it so wonderful,” and he said, “Because it intensifies your personality.” I said, “Yes, but what if you’re an [explet…

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