02073nas a2200241 4500008004100000022001400041245011100055210006900166260001200235300001100247490000700258520141600265653001001681653000801691653000901699653000801708653001201716653001101728653000801739100001701747700001901764856004801783 2015 eng d a1559-008900aNeuralAct: A Tool to Visualize Electrocortical (ECoG) Activity on a Three-Dimensional Model of the Cortex.0 aNeuralAct A Tool to Visualize Electrocortical ECoG Activity on a c04/2015 a167-740 v133 a
Electrocorticography (ECoG) records neural signals directly from the surface of the cortex. Due to its high temporal and favorable spatial resolution, ECoG has emerged as a valuable new tool in acquiring cortical activity in cognitive and systems neuroscience. Many studies using ECoG visualized topographies of cortical activity or statistical tests on a three-dimensional model of the cortex, but a dedicated tool for this function has not yet been described. In this paper, we describe the NeuralAct package that serves this purpose. This package takes as input the 3D coordinates of the recording sensors, a cortical model in the same coordinate system (e.g., Talairach), and the activation data to be visualized at each sensor. It then aligns the sensor coordinates with the cortical model, convolves the activation data with a spatial kernel, and renders the resulting activations in color on the cortical model. The NeuralAct package can plot cortical activations of an individual subject as well as activations averaged over subjects. It is capable to render single images as well as sequences of images. The software runs under Matlab and is stable and robust. We here provide the tool and describe its visualization capabilities and procedures. The provided package contains thoroughly documented code and includes a simple demo that guides the researcher through the functionality of the tool.
10aBrain10aDOT10aECoG10aEEG10aimaging10aMatlab10aMEG1 aKubanek, Jan1 aSchalk, Gerwin uhttp://www.ncbi.nlm.nih.gov/pubmed/2538164102782nas a2200193 4500008004100000022001400041245009600055210006900151260001200220300001400232490000700246520218000253100001702433700002502450700002402475700002202499700001902521856004802540 2013 eng d a1095-957200aA low-frequency oscillatory neural signal in humans encodes a developing decision variable.0 alowfrequency oscillatory neural signal in humans encodes a devel c12/2013 a795–8080 v833 aWe often make decisions based on sensory evidence that is accumulated over a period of time. How the evidence for such decisions is represented in the brain and how such a neural representation is used to guide a subsequent action are questions of considerable interest to decision sciences. The neural correlates of developing perceptual decisions have been thoroughly investigated in the oculomotor system of macaques who communicated their decisions using an eye movement. It has been found that the evidence informing a decision to make an eye movement is in part accumulated within the same oculomotor circuits that signal the upcoming eye movement. Recent evidence suggests that the somatomotor system may exhibit an analogous property for choices made using a hand movement. To investigate this possibility, we engaged humans in a decision task in which they integrated discrete quanta of sensory information over a period of time and signaled their decision using a hand movement or an eye movement. The discrete form of the sensory evidence allowed us to infer the decision variable on which subjects base their decision on each trial and to assess the neural processes related to each quantum of the incoming decision evidence. We found that a low-frequency electrophysiological signal recorded over centroparietal regions strongly encodes the decision variable inferred in this task, and that it does so specifically for hand movement choices. The signal ramps up with a rate that is proportional to the decision variable, remains graded by the decision variable throughout the delay period, reaches a common peak shortly before a hand movement, and falls off shortly after the hand movement. Furthermore, the signal encodes the polarity of each evidence quantum, with a short latency, and retains the response level over time. Thus, this neural signal shows properties of evidence accumulation. These findings suggest that the decision-related effects observed in the oculomotor system of the monkey during eye movement choices may share the same basic properties with the decision-related effects in the somatomotor system of humans during hand movement choices.1 aKubanek, Jan1 aSnyder, Lawrence, H.1 aBrunton, Bingni, W.1 aBrody, Carlos, D.1 aSchalk, Gerwin uhttp://www.ncbi.nlm.nih.gov/pubmed/2387249502234nas a2200181 4500008004100000245005700041210005200098260001200150300001400162490000600176520172300182100001701905700001901922700002001941700001901961700001901980856005301999 2013 eng d00aThe Tracking of Speech Envelope in the Human Cortex.0 aTracking of Speech Envelope in the Human Cortex c01/2013 ae53398 - 0 v83 aHumans are highly adept at processing speech. Recently, it has been shown that slow temporal information in speech (i.e., the envelope of speech) is critical for speech comprehension. Furthermore, it has been found that evoked electric potentials in human cortex are correlated with the speech envelope. However, it has been unclear whether this essential linguistic feature is encoded differentially in specific regions, or whether it is represented throughout the auditory system. To answer this question, we recorded neural data with high temporal resolution directly from the cortex while human subjects listened to a spoken story. We found that the gamma activity in human auditory cortex robustly tracks the speech envelope. The effect is so marked that it is observed during a single presentation of the spoken story to each subject. The effect is stronger in regions situated relatively early in the auditory pathway (belt areas) compared to other regions involved in speech processing, including the superior temporal gyrus (STG) and the posterior inferior frontal gyrus (Broca's region). To further distinguish whether speech envelope is encoded in the auditory system as a phonological (speech-related), or instead as a more general acoustic feature, we also probed the auditory system with a melodic stimulus. We found that belt areas track melody envelope weakly, and as the only region considered. Together, our data provide the first direct electrophysiological evidence that the envelope of speech is robustly tracked in non-primary auditory cortex (belt areas in particular), and suggest that the considered higher-order regions (STG and Broca's region) partake in a more abstract linguistic analysis.1 aKubanek, Jan1 aBrunner, Peter1 aGunduz, Aysegul1 aPoeppel, David1 aSchalk, Gerwin uhttp://dx.doi.org/10.1371%2Fjournal.pone.0053398