By depositing a high instant energy in a small focal volume, the probability for multi-photon absorption, and the occurrence of other nonlinear optical effects is increased. Such localized energy deposition may serve for three-dimensionally confined sample ablation (Berns 1981). Using sub-nanosecond pulsed UV laser light instead, the average power at the sample required for optical dissection can be further reduced while, sharply confining the photo-damage to the focal volume. The laser dissector based on a sub-nanosecond pulsed UV-A source, permit to perform three dimensionally confined ablation just like systems based on two-photon absorption processes. However, it has the advantage of delivering extremely low average power (few µW) to the sample, thereby minimizing undesirable thermal effects.By laser dissection and concurrent calcium imaging it is possible to estimate the extracellular solution influx in to the dissected neurite.