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    Mathew Diamond – June 20, 2014

    Neuroscience Seminar Series
    Friday, June 20, 2014 at 11:30 am

    Salle des Conférences (R229), Centre Universitaire des Saints-Pères, 45 rue des Saints-Pères, 75006 Paris

    Mathew Diamond, International School for Advanced Studies, Trieste, Italy.

    Tactile perception and working memory in humans and rats – Psychophysics annd neuronal mechanisms

    Tactile perception and working memory in humans and rats – psychophysics and neuronal mechanisms.

                         The Romo laboratory has shown that primates can store graded sensory stimuli in working memory for subsequent manipulation, but until now there is no demonstration of this capacity in rodents. Here we describe tactile working memory in rats – they compare two “noisy” vibrissal vibrations (termed “base” and “comparison”) separated by an inter stimulus interval. To set a standard against which to interpret rat capacities, humans performed the analogous task by comparing two vibratory stimuli on the fingertip. On average, the tactile acuity and working memory of rats is inferior to that of human subjects, but good rats perform better than humans. Thus, rats exploit a smaller and simpler brain to express unexpected cognitive capacities. We can gain insight into the underlying neuronal operations by recording activity during behavior. Neurons in sensory cortex show a clear coding of stimulus features. Neurons in downstream regions (prefrontal cortex, premotor cortex, hippocampus) are heterogenous; of particular interest are neurons that encode memory and those that compute the upcoming decision as the rat selects between complementary actions. A final understanding will require a systems approach, as we see that cortical regions become coherent in low frequency oscillation as they transfer information.