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Z. Zhu, K. Lin, T. Kasamatsu; Asymmetrical response modulation between cell pair in cat striate cortex. Journal of Vision 2002;2(7):104. doi: 10.1167/2.7.104.
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© ARVO (1962-2015); The Authors (2016-present)
Receptive-field responses, dynamically regulated by the excitation-inhibition balance operative in a given network, are either facilitated or suppressed by collinear flankers in a contrast-dependent manner. The flanker effects are widely spread in visual space up to 12 deg., though direct interactions between cell pairs as measured by cross-correllograms are usually limited to ∼1 mm in visual cortex. To understand the nature of neural events taking place at flanker site and the dynamic interactions between two cells, we want to simultaneously register single-cell activity from cell-pairs with non-overlapped receptive fields. A pair of microelectrodes extracellularly registered single-cell activity from two cells separated by 2 mm or more. While concurrently stimulating two receptive fields with two optimally fitted Gabors, one Gabor can be treated as the target for one cell, but as the flanker for the other cell, and vice versa. The strength and property of reciprocal modulation was assessed in terms of the following attributes: firing thresholds, orientation difference, and the relative location between the two receptive fields. Interactions between two identified cells having non-overlapped receptive fields depended on both their global orientation (collinear or not) and orientation difference. The mutual interaction strength between collinear cells seemed to be stronger than that between non-collinear cell pairs. Modes of the interactions were very complicated. The modulatory effect of one cell on another was often found to be different from the effect in the reverse direction, including both modulation strength and property (facilitation or suppression), regardless of whether the cell pair was collinear or not. Our results showed that long-range lateral interactions in the cortex are reciprocated but not necessarily symmetrical. This means that even if two cells are shown to be interacting, they can exert an asymmetric modulatory influence upon each other. Support: NEI grant EY 11711
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