Redrawing The Brain’s Map

 

• Motor homunculus – more complicated than thought

A)  no simple movements – 500 msec

- complex movements à always ended nsame place (even if started in dif places)

B) simple movements – durations of 50 Msec

 

 

 

• Premotor cortex – stimulatable sites ~ motor cortex

à Certain action performed

 

Glia

 

• do not have Voltage mediated channels

• do respond to neuronal stumulation

 

Types

1)    Schwann cells – monitor synaptic activity

-       esp NMJ – control strength by modulation NT release

-       via GTP

2)    Oligodendrocytes

3)    Astrocytes

Communicate w/one another

a)    gap junctions

b)    extracellulr molecules

Modify synaptic strength

Release ATP à P2Y receptors à increase [Ca] intracell

Have glutamate receptors??

 

Supplemental Figure S2. Astrocytes communicate via intracellular Ca2+ waves (rainbow colors). (A) Binding of glutamate causes a rise in intracellular Ca2+ via activation of IP3, which propagates through gap junctions (GJ) with adjacent cells. (B) ATP release from astrocytes may occur through unpaired gap junctions (Hemi), the cystic fibrosis transmembrane conductance regulator (CFTR), ATP-binding cassette transporters (Trans), and other stretch-activated Cl– channels (SaCl). (C) ATP binding to membrane receptors causes a rise in intracellular Ca2+ by activating metabotropic (P2Y) or ionotropic (P2X) receptors. This is associated with the vesicular release of glutamate, and the release of ATP via an unknown mechanism. The K+ released into the extracellular space by neuronal firing is taken up by membrane transporters in astrocytes and distributed by gap junctions through the astrocytic syncytium. The mechanisms of neuron-astrocyte and astrocyte-astrocyte communication are being studied intensely in many laboratories, and multiple signaling mechanisms have been discovered. However, the plasticity of glial cells makes this determination difficult, because of the heterogeneity introduced by developmental, or regional differences in the nervous system, and by differences in culture conditions (S1). VSCC, voltage-sensitive calcium channel, GluR, glutamate receptor, P, Na/K ATPase, T, glu transporter.

 

 

 

4)    Microglia – from bone marrow