Does spatial distribution of boutons relate to orientation preference in layer IV spiny neurons?

Does spatial distribution of boutons relate to orientation preference in la

yer IV spiny neurons?

Fuyuki KARUBE and Zoltán F. KisvárdayLaboratory for Cortical Systems Neuroscience,

Medical and Health Science Center (MHSC),

University of Debrecen, HUNGARY

Materials and Methods

• Adult cats (2.3 - 3.2 kg) were used. • Visual stimuli

Moving luminance gratings (square waves; frequency, 0.1-0.8 cpd; velocity, 2 Hz).

• ImagingCortex (A18) was illuminated at 605 nm light. Int

rinsic signals were captured with a CCD camera. • Extracellular recordings to identify receptive field properti

es.• Tracer injections for extracellular staining• Reconstruction of stained single cells by Neurolucida.

Time course of intrinsic signal

From Grinvald and Bonhoeffer

Start visual stimulation

Stop stimulation

Arb

itrar

y un

its

Time after stimuli onset (s)

Activity dependent changes in [oxyHb] and [deoxyHb]

Optical imaging of intrinsic signal

From Grinvald and Bonhoeffer

Avtivated area by vertical gratings

Analysis of map structure for orientation preference

Orientation preference patches elongated along iso-elevation line in visual field

Reconstructions of layer IV spiny neurons

Dendrites were drawn in black, axons in red.

Bouton distribution pattern relative to orientation preference

Within 400m diameter

Local

Distal

Bouton distribution in iso-,oblique-, and cross-orientation patches

Tentative LM and AP-elongated cells on orientation preference map

Quantification of bouton distribution

Bouton distribution to cortical dimensions and preferred orientations

conclusion

• Layer IV spiny neurons showed various bouton distribution from cell to cell.

half of them preferred iso-orientation, another half did cross-orientation.

• Orientation patches elongated with LM (or iso-elevation) axis. Thus, spatial distribution of boutons of single cells can affect connectivity between iso- or cross-orientation preference patches.

Tangential viewCoronal view