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Natural Stimuli Evoke Dynamic Sequences of States in Sensory Cortical Ensembles. Lauren Jones, Alfredo Fontanini, Brian Sadacca, Paul Miller, and Donald Katz. Authors:. Lauren Jones – Ph.D. Studied the rodent whisker somatosensory system at University of Maryland School of Medicine
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Natural Stimuli Evoke Dynamic Sequences of States in Sensory Cortical Ensembles Lauren Jones, Alfredo Fontanini, Brian Sadacca, Paul Miller, and Donald Katz
Authors: • Lauren Jones – Ph.D. • Studied the rodent whisker somatosensory system at University of Maryland School of Medicine • Alfredo Fontanini – MD, Ph.D. • Previous research at Caltech in the olfactory cortex • Brian Sadacca – Ph.D. Student • Graduated from University of Pittsburgh where he studied the vestibular system • Paul Miller – Volen Center for Complex Systems • Donald Katz – Lab at Brandeis University, MA
Methods • Female rats anesthetized • Microelectrodes inserted bilaterally into the gustatory cortex along with intraoral cannulae • Rats received 40 µl of 100 mM NaCl, 100 mM sucrose, 100 mM citric acid, or 1 mM quinone HCl • Neuron considered a taste neuron if response was different for at least one taste (38%) • Hidden Markov Models (HMM) • Detect coherent rate patterning in populations of simultaneously recorded neurons • Peristimulus Time Histograms (PSTHs) • Across trial averages – sequentially recorded neurons
PSTHs • In pairs of trials with similar response magnitudes, variability is still high.
Progression through 3 – 4 firing rate states • Brief transitions not identified as a certain state • Transition from one state to another is a result of the coordinated activity of many neurons • During transition, 51% of neurons per ensemble changed firing rates • Timing of states may change but the sequence remains the same • States are stimulus specific State Sequences
Trial/Taste Shuffling • Gradual rate changes should not increase the duration of transitions • Trial Shuffled and Trial/Taste Shuffled is much slower than the original or simulated data • Fast change of state in sequences is characteristic of ensemble sensory responses
Conclusions • State sequences were reliable and stimulus specific • States were recognizable only with simultaneously recorded ensembles • State sequences provide more information than averages • PSTHs obscure the rapid transitions observed in ensemble analysis • “Sensory neurons act as parts of a systems-level dynamic process.”