Olfactory pattern classification by discrete neuronal network states

Abstract

The categorial nature of sensory, cognitive and behavioural acts indicates that the brain classifies neuronal activity patterns into discrete representations. Pattern classification may be achieved by abrupt switching between discrete activity states of neuronal circuits, but few experimental studies have directly tested this. We gradually varied the concentration or molecular identity of odours and optically measured responses across output neurons of the olfactory bulb in zebrafish. Whereas population activity patterns were largely insensitive to changes in odour concentration, morphing of one odour into another resulted in abrupt transitions between odour representations. These transitions were mediated by coordinated response changes among small neuronal ensembles rather than by shifts in the global network state. The olfactory bulb therefore classifies odour-evoked input patterns into many discrete and defined output patterns, as proposed by attractor models. This computation is consistent with perceptual phenomena and may represent a general information processing strategy in the brain.

Zebrafish Olfactory System

“…In addition to the aforementioned spatial representation of odorant structural features on the OB, several electrophysiological and activity imaging studies proposed the temporal coding of odor quality and intensity and the odor information processing by neuronal populations in the fish OB (Kang and Caprio 1995;Friedrich and Laurent 2001;Friedrich et al 2004;Niessing and Friedrich 2010;Wiechert et al 2010). For details, see reviews by Laberge and Hara (2001), Friedrich (2006), and Friedrich et al (2009).…”

Memories as bifurcations: Realization by collective dynamics of spiking neurons under stochastic inputs

“…Our viewpoint might be helpful for understanding information processing, for instance, in the olfactory system (Bathellier, Buhl, Accolla, & Carleton, 2008;Mazor & Laurent, 2005;Niessing & Friedrich, 2010) or place cells in the hippocampus (Foster & Wilson, 2006;Leutgeb et al, 2005;O'Keefe & Dostrovsky, 1971). In the olfactory system, the response of neural activity to an odorant, which is applied for a long time, is studied with regard to how the response is changed depending on the administration of different odorants and their concentration.…”

Dopaminergic Modulation of Mitral Cells and Odor Responses in the Zebrafish Olfactory Bulb

“…However, it remains unclear how DA is released from interneurons and transmitted to its targets, and how it modulates information processing in the OB. We addressed these issues in the OB of adult zebrafish, which performs multiple computations including a regulation of the total MC activity ) and a discrete decorrelation of MC activity patterns (Friedrich and Laurent, 2001;Friedrich et al, 2004;Niessing and Friedrich, 2010;Wiechert et al, 2010). We find that DA is released by electrical activity and slowly hyperpolarizes MCs via D 2 -like receptors, suggesting volume transmission and/or asynchronous release.…”