[ExI] Neuroscience Question

[Neil Halelamien]

An interesting bit of trivia: It was recently discovered that whales also
have spindle cells. This is likely an example of convergent evolution, as
none of the species along the genetic tree traversal between great apes and
whales seem to have spindle-like cells. And no, they don't seem to be
present in dolphins.

http://sciencenow.sciencemag.org/cgi/content/full/2006/1127/1
http://www3.interscience.wiley.com/cgi-bin/abstract/113473213/ABSTRACT?CRETRY=1&SRETRY=0

On 7/11/07, Jeff Miller <jwmillerusa at gmail.com> wrote:
>
> The exceptional neuron type is called a "spindle" neuron. I will quote
> briefly from Koch's "The Quest for Consciousness":
>
> "... In fact, small and large excitatory pyramidal neurons and spiny
> stellate cells, as well as inhibitory basket, nonspiny stellate cells,
> double bouquet neurons, and other members of the diverse menagerie of
> inhibitory neurons, are found in all mammals.
>
> The sole exception, so far, are spindle neurons, a class of giant cells
> restricted to two neocortical regions in the frontal lobe. Found in high
> densities in humans, they are much sparser in the great apes and
> altogether absent in monkeys, cats, and rodents. A few tantalizing hints
> point toward their possible involvement in self monitoring and self
> awareness.
>
> ...
>
> Spindle neurons, the Korkzieher cells of von Economo and Koskinas (1925),
> are characterized by elongated and large cell bodies in the lower part of
> layer 5, the output layer of the cortex (Nimchinsky et al., 1999). Absent
> in newborn infants, their numbers stabilize in adults at about 40,000
> neurons in the anterior cingulate cortex and 100,000 or so in FI, another
> frontal area. These regions are involved in self-evaluation, monitoring,
> and attentional control."
>
>
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