[Abstract Title]. - Society for Neuroscience

sensitive dye Fura-2 were loaded in a patch pipette and electroporated into astrocytes selected in
layer 2/3. High intracellular concentrations of both dyes were obtained and remained stable for
more than one hour without any detectable photodamage in low-light level imaging conditions.
Local application of ATP induced Ca 2+ spikes in Fura-2 loaded astrocytes while local application
of glutamate produced an increase in cytosolic Na + in SBFI-loaded astrocytes, indicating intact
cellular responses after SCE. To check whether endogenous release of glutamate would produce
similar effects, we placed a concentric stimulation electrode in layer 4 of the same cortical
column. Short trains of 10-20V pulses induced Na + increases in layer 2/3 astrocytes that were
blocked by tetrodotoxin. EAATs inhibitors threo-β-benzyloxyaspartate and dihydrokainic acid
impaired evoked astrocytic Na + responses evidencing a predominant role of glutamate uptake
mechanisms. In conclusion, SCE is a powerful tool for optical imaging of physiological
responses in the slice model. The responses recorded in intact circuits are reminiscent of
metabolic waves described in primary cultures of astrocytes.
Disclosures: C.M. Lamy , None; J. Chatton, None.
Poster
241. Glial Neuronal Interactions
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 241.19/H1
Topic: B.11.a. Synapses
Support: NIH R01 NS054736-01
Title: Geometric and physiological properties of functional connectivity patterns arising in
spontaneously forming neuron networks
Authors: *K. W. CHIAO, G. A. SILVA;
UC San Diego, La Jolla, CA
Abstract: Spontaneously forming neuronal networks provide a useful model system for probing
mechanisms giving rise to and regulating intrinsic spontaneous activity. In addition, the
application of electrophysiological and pharmacological manipulations, combined with optical
imaging with calcium and voltage sensitive dyes, allow for the dissection of network dynamics
into its component connectivities. Well-studied synapses provide examples of the range of
diversity in synaptic connections, which include differences in both the onset (bursting,
continuous, or delayed) and sustained (irregular, accommodating, non-accommodating, or
stuttering) pattern of activity generated in the post-synaptic cell. The propensity of dissociated