About Kai Schreiber Expertise Mostly questions specific to vision science and eye movements, with some expertise in general neuroscience and cognitive science. Strongest background in mathematical theory, modelling and the theory of perception, but I will try to answer anything that comes my way.
Experience Postdoc in Vision/Oculomotor research.
Organizations UC Berkeley
Publications Journal of Vision, Nature, IEEE Transactions on Biomedical Enginerring
Education/Credentials Dipl Phys (Universtität Tübingen), PhD (Physiology, Univeristy of Toronto), Graduate Program in Neuroscience (University of Toronto)
Expert: Kai Schreiber Date: 7/6/2006 Subject: neuroscience
Question A Neuron partially consists of mylin sheath,i.e it covers the neuron in segments.Here the mylin sheath has the typical property of responding to impulses.So does it have any thing to do with IQ?Does an individual whose neurons are covered with mylin sheath to a large extent possess more IQ than anormal person?
Answer Hi,
myelin sheathing is present not on the neuronal cell body itself, but on the axon projections, ie the nerve fibers. It's main function is to block parts of the axon's wall for ion influx, leaving regularly spaced unsheathed gaps. In an unmyelinated axon, the nerve impuls travels as a wave of depolarization by means of ion movement across the axon wall. In a myelinated axon, the basic mechanism is the same, but because of the blocked segments, the activation of ion channels jumps from gap to gap. This jumping is much faster than normal wavelike signal travel. So myelination speeds up signal transduction across neuronal connections.
The white colour of the fatty myelin, by the way, is why the white matter - the nerve connections - in the brain is white. Gray matter consists of unmyelinated neuronal cell bodies.
As to your question about IQ: as loss of myelination will decrease signal transduction speed, it will lead to a whole host of problems, and indeed sicknesses that express themselves in demyelination, like multiple sclerosis, can show a broad variety of symptoms ranging from motor and sensory problems to depression.
IQ, however, as a general intelligence factor is a contested concept in itself, and has to date not reliably linked to physical parameters of the brain. While it is entirely possible that a slowing of nerve conductance could reduce performance in a specific task, the connection pattern itself, independent of speed, is likely to play as big, if not bigger a role in the overall performance, making the opposite prediction - no change in performance due to slowing of conductance - almost as likely. Though I'd wager it's likely that slowing nerves will produce some performance loss. It's not going to be possible to test either predition, though, so take your pick.
