We analyze the time resolved spike statistics of a solitary and two mutually interacting chaotic semiconductor lasers whose chaos is characterized by apparently random, short intensity spikes. Repulsion between two successive spikes is observed, resulting in a refractory period which is largest at laser threshold. For time intervals between spikes greater than the refractory period, the distribution of the intervals follows a Poisson distribution. The spiking pattern is highly periodic over time windows corresponding to the optical length of the external cavity, with a slow change of the spiking pattern as time increases. When zero-lag synchronization between the two lasers is established, the statistics of the nearly perfectly matched spikes are not altered. The similarity of these features to those found in complex interacting neural networks, suggests the use of laser systems as simpler physical models for neural networks.PACS numbers: 05.45. Xt, 42.65.Sf, 42.55.Px Semiconductor lasers, subjected to optical feedback, display chaotic behavior [1]. The chaotic behavior consists of a very short and random spiking of the laser intensity with the time between spikes depending on how far above lasing threshold the laser is. Two chaotic lasers can be synchronized with each other and this has allowed them to be excellent candidates for novel broadband [2, 3, 4, 5, 6] communication devices. Different configurations, such as delayed optoelectronic [7,8] or coherent optical injection [8,9,10,11] have been used for synchronization of the two lasers. Using optical feedback, configurations consisting of unidirectional [7,8] or mutual coupling [5,6,8,9,10,11] and variations of the strength of the self and coupling feedback have been shown to result in different synchronization states. The lasers can synchronize in a leader-laggard or anticipated mode, as well as in two different synchronization states; achronal or generalized synchronization [12,13,14] where the cross correlation is time shifted by the feedback delay time but neither laser acts as a preferred leader or laggard, or isochronal synchronization (zero-lag) where there is no time delay between the two lasers' chaotic signals [5,6,15,16,17].Zero-lag synchronization of lasers was recently extended to a cluster consisting of three semiconductor lasers, mutually coupled along a line, in such a way that the central laser element acts as a relay of the dynamics between the outer elements [18,19]. The zero-lag synchronized dynamics of remotely located chaotic signal sources has sparked an interest in such systems in part because they have features also seen in biological and neural transmission networks. Though the time scales for the two phenomena are vastly different; lasers spiking on 100 ps time scale while neurons spike on ms time scales, much of the dynamics and spiking statistics appear to have common behavior. Here we report on the spiking optical pattern of solitary and two mutually coupled chaotic lasers, observed on a time scale which resolves the individu...