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Isting models CC122 site primarily based on tuning for external variables have been neuron-preferred, in opposition towards the M1 data. Having said that, current models with robust internal dynamics have been condition-preferred, in agreement with the data. Model success or failure depended not on parameter selection or match good quality, but on model class. We conclude that tensor structure is informative relating to the predominant origin of timevarying activity, and may be utilized to test certain hypotheses. Within the present case, the tensor structure of M1 datasets is constant with only a subset of existing models.Outcomes Time-varying response structureWe analyzed nine physiological datasets: 3 recorded from V1 in the course of presentation of visual stimuli, 4 recorded from M1 in the course of reaching tasks, and two recorded from muscle populations through the identical reaching tasks. Each dataset employed multiple circumstances: distinct stimuli/reaches. Every single neuron’s response was averaged across trials inside a condition and smoothed to generate a firing price as a function of time. Some recordings had been simultaneous and a few had been sequential, but in all instances the exact same set of conditions was employed for each neuron. Stimuli have been by no means tailored to person neurons (e.g., to their preferred direction or receptive field). This permits for evaluation on the accurate population response, indexed by neuron, condition, and time. For the muscle populations, electromyographic (EMG) voltages have been converted to a smooth function of intensity versus time by means of standard rectification PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/20192687 and filtering. Muscle populations have been then analyzed in the same way as neural populations, but individual elements have been muscle tissues rather than neurons. We analyzed ten further datasets simulated utilizing current models of M1. We very first concentrate on two datasets: 1 from V1 (Fig 1A) and one particular from M1 (Fig 1B). The V1 dataset was recorded using a 96-electrode array from an anesthetized monkey viewing one-second films of all-natural scenes (25 films, 50 trials every single). The M1 dataset was recorded applying a pair of implanted 96-electrode arrays, spanning the arm representation of key motor cortex plus the straight away adjacent area of dorsal premotor cortex (all final results had been similar if principal motor and premotor cortex had been treated separately). Neural responses have been recorded through a delayed attain activity: the monkey touched a central spot on a screen, was presented with a target, then executed a attain following a go cue. We analyzed data for 72 conditions (Fig 1B, insets), every single involving a unique reach distance and curvature (typical of 28 trials per situation) [30]. Both V1 and M1 neurons displayed temporally complex response patterns (Fig 1). Every single colored trace plots the trial-averaged firing price more than time for 1 situation: a specific film (Fig 1A) or attain (Fig 1B). V1 neurons exhibited multiphasic responses all through the stimulus. M1 neurons exhibited multiphasic activity more than a 700 ms period that started shortly immediately after the go cue. Tight standard error bars (not displayed) confirmed that temporal response structure was statistically trusted in lieu of the outcome of sampling noise. In M1 it has been debated whether such structure primarily reflects external variables which include reach kinematics or mainly reflects internal dynamics. Both hypotheses can claim assistance from surface-level capabilities ofPLOS Computational Biology | DOI:10.1371/journal.pcbi.1005164 November 4,4 /Tensor Structure of M1 and V1 Population ResponsesFig 1. Illustration on the stimuli/ta.