So does this explain rodent inflammation is not the same as human inflammation? And the reason that Dr. Michael.Tymianski@uhn.ca has stated that 1000+ neuroprotective trials have failed? It is a damned simple question that will never be answered because we don't have smart enough people in the stroke medical world. Oops, not following Dale Carnegie again.
http://www.alphagalileo.org/ViewItem.aspx?ItemId=171346&CultureCode=en
The human brain’s advanced cognitive capabilities are often
attributed to our recently evolved neocortex. Comparison of human and
rodent brains shows that the human cortex is thicker, contains more
white matter, has larger neurons, and its abundant pyramidal cells
(formerly called “psychic” neurons) have more synaptic connections per
cell as compared to rodents.
However, scientists have yet to determine whether there are important
differences at the biophysical level of the basic building blocks of
the human neocortex, the pyramidal neurons. Do these cells possess
unique biophysical properties that might impact on cortical
computations?
To answer this question, a theoretical team led by Prof. Idan Segev
from the Hebrew University of Jerusalem, working with experimental
colleagues at Vrije Universiteit Amsterdam and Instituto Cajal in
Madrid, built detailed 3D models of pyramidal cells from the human
temporal neocortex. These first-ever detailed models of human neurons
were based on in vitro intracellular physiological and anatomical data
from human cells.
(To collect this data, fresh cortical tissue was obtained from brain
operations at a neurosurgical department in Amsterdam, and additional
data was obtained from light-microscope studies in pyramidal cells from
post mortem studies at the Cajal Institute in Madrid.)
The theoretical study predicted that layer 2/3 pyramidal neurons from
the human temporal cortex would have a specific membrane capacitance
that is half of the commonly accepted “universal” value for biological
membranes (~0.5 µF/cm2 vs. ~1 µF/cm2). Since membrane capacitance
affects how quickly a cell can respond to its synaptic inputs, this
finding has important implications for the transmission of signals
within and between cells. The theoretical prediction regarding the
specific membrane capacitance was then validated experimentally by
direct measurements of membrane capacitance in human pyramidal neurons.
“This is the first direct evidence for the unique electrical
properties of human neurons,” said researcher Guy Eyal, a Ph.D. student
at the Hebrew University’s Department of Neurobiology. “Our finding
shows that low membrane capacitance significantly improves the efficacy
of signal processing and the speed of communication within and between
cortical neurons in the human neocortex, as compared to rodents.”
“The results of this work imply that human cortical neurons are
efficient electrical microchips, compensating for the larger brain and
large cells in humans, and processing sensory information more
effectively,” said Prof. Idan Segev from the Department of Neurobiology
and the Edmond and Lily Safra Center for Brain Sciences at the Hebrew
University. “Indeed, the study shows that already at the level of the
individual building blocks of the nervous system (the nerve cells),
humans are distinct as compared to rodents. More research should be
performed in this direction on non-human primates.”
The researchers suggest the distinctive biophysical membrane
properties of human pyramidal neurons are an outcome of evolutionary
pressure to compensate for the increase in size and distances in the
human brain.
No comments:
Post a Comment