08 - Midbrain

Cross references:       

K&W provides a good picture and a brief discussion
 of the midbrain (mesencephalon) on [K&W:53-54]. 

The superior colliculus of the midbrain is considered
to be the site of the highest level of sensory-motor
integration in the precortical brain, and its internal
structure is more complex than any other part of the
precortical brain.  It receives direct input from the
eyes and indirect input from all other sense
modalities via secondary neurons from all sensory
nuclei.  Its primary output is to the mesencephalic
locomotor region (MLR). 

The MLR is embedded in, and part of, the middle and
upper portions of the reticular formation.  It
supplements the spinal locomotor generator (SLG) by
controlling the movement of the four limbs in the
context of side-to-side body motion which is still
controlled by the SLG. 

Searching Pub Med <http://www.pubmed.gov> for
"mesencephalic locomotor" brought up 201 references.
I've included four below, just in case you're curious.
None is definitive, so this appears to be an area of
ongoing research.  The first link leads, not only to
an abstract, but also to the full article. 

Differential contribution of reticulospinal cells to
the control of locomotion induced by the mesencephalic
locomotor region.
J Neurophysiol. 2003 Sep;90(3):1714-27. Epub 2003 May


To link to the full article, click on the dark
rectangle that says:

    Free full text of article at

The other three links lead to abstracts. 

Excitatory and inhibitory postsynaptic potentials in
alpha-motoneurons produced during fictive locomotion
by stimulation of the mesencephalic locomotor region.
J Neurophysiol. 1985 Jun;53(6):1345-55.


Controlled locomotion in the mesencephalic cat:
distribution of facilitatory and inhibitory regions
within pontine tegmentum.
J Neurophysiol. 1978 Nov;41(6):1580-91.


Role of pontine tegmentum for locomotor control in
mesencephalic cat.
J Neurophysiol. 1977 Mar;40(2):284-95.