Temporal coding

In several insect types the presence of oscillations among AL neural assemblies have been demonstrated. The main experimental animal for these investigations has been the locust. In these experiments it has been shown how synchronous oscillations allow a temporal coding of odor information. These experiments will be further elaborated in the following paragraphs. 

Studying odor-evoked activity in PNs often reveal different temporal features. Temporal coding has been most thoroughly studied in the locust (Laurent et al., 2001) and if not otherwise noted the results in this section refer to work in the locust system. A spike train may include periods of excitation and inhibition in different combinations. Spike profiles are often both odor and neuron specific and reproducible at repeated stimulations (Laurent and Davidowitz, 1994 Laurent et al., 1996). The inhibitory phases of the spike sequences should be generated by inhibitory input from LNs. However, application of picrotoxin (PTX), which... 

In addition to the spatial representations of odorant structural features on the surface of the OB, several electrophysiological studies proposed the temporal coding of odor quality and intensity by neuronal populations in the fish OB (Kang and Caprio 1995 Friedrich and Laurent 2001). For details, see the reviews by Laberge and Hara (2001) and Friedrich (2002). 

W.C. Lemon and W.M. Getz, Rate code input produces temporal code output from cockroach antermal lobes, BioSystems 58 (2000) 151-8. 

Among all animals, insects have one of the simplest olfactory systems. In particular the first stage of this system, the antennal lobe (AL), has been shown to encode odours. Many experimental data, and in particular from the work of Laurent s group from Caltech , have shown that subsets of AL projection neurons (PNs) - whose activity is projected on higher structures -get synchronized in presence of an olfactory stimulus and that these subsets change in time in an odour-specific manner. Such a transient synchronization encoding scheme or spatio-temporal code has already been reproduced and studied by means of a biologically detailed model of the insect antennal lobe... 

Therefore, the network exhibits a spatio-temporal code of the stimulus, in the sense that at any LFP oscillation, an assembly of precisely firing PNs is... 

In this paper we have proposed a simplified model of the insect AL in order to explore the neural code in olfaction. A possible role of the AL is to transform a multidimensional input vector representing the odorant stimulus into a spatio-temporal code given by a sequence of quasi-synchronized assemblies of PNs, in which each PN is individually phase-locked to the LFP. 

Temporal coding in intercellnlar conunnnication from cAMP signalling in Dictyostelium to pnisatile hormone secretion... 

Buzsaki, G., R. Llinas, W. Singer, A. Berthoz Y. Christen (eds.) 1994. Temporal Coding in the Brain. Springer, Berlin. 

Temporal coding, 515-19 see also Frequency encoding Thalamic neurons, 17 birhythmicity in. Ill multiple oscillations in, 109-13,504 Theoretical models, role of, 2,3,491,493 Thermodynamics of irreversible processes, 5... 

Hallock, R.M., Di Lorenzo, P.M. Temporal coding in the gustatory system. Neurosci. Biobe-havioral. Rev. 30, 1145-1160 (2006)... 

---