Some spikes are more informative than others.

Editor's Note: These short, critical reviews of recent papers in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to summarize the important findings of the paper and provide additional insight and commentary. For more information on the format and purpose of the Journal Club, please see What is the language of the brain when it links perception and behavior? Studies in the past have suggested that there are subsets of " most informative " neurons for perception and behavior (for review, see Parker and Newsome, 1998), and recent findings have revealed that perception and behavior can both be induced with the stimulation of only a small number of neurons (Houweling and Brecht, 2008; Huber et al., 2008). Well-known examples of selective subsets of neurons are found in the direction-, disparity-, and speed-tuning properties of cortical motion-sensitive neurons in middle temporal area (MT) of the monkey brain (for review, see Born and Bradley, 2005). As a popular cortical area to investigate the link between perception and action, neuronal activity in area MT has been studied using different analytic measures such as spike rates, local field potentials, oscillations, and response latencies, but the information density of the neuronal activity is usually analyzed between, rather than within, single neurons. The known disso-ciation between more and less informative neurons, however, raises the question whether the amount of information carried by the neural activity within a single neuron could also be nonuniformly distributed. A recent study by Masse and Cook (2008) published in The Journal of Neuroscience addresses this question and demonstrates that for a motion detection task, some spikes generated by neurons in MT are indeed more informative about the stimulus content than others. Importantly , the more informative spikes are also more closely related to the monkey's response behavior. These novel findings suggest a relationship between spikes, stimuli, and behavior that varies on a relatively short timescale within a single neuron. Masse and Cook (2008) used datasets from several studies in which the activity of single neurons in area MT was recorded while monkeys detected the onset of coherent motion in a dynamic random dot pattern. Importantly, the motion stimulus was updated relatively slowly (every 27 ms), causing the neurons to discharge in an oscillatory manner with a frequency that matched the stimulus updates. Based on this oscillatory firing pattern, the authors subdivided the neuronal responses based on whether …