Hemispheric sensitivity to body stimuli in simple reaction time

Increased visual task difficulty enhances attentional capture by both visual and auditory distractor stimuli

Spatial compatibility and anatomical factors in simple and choice reaction time

OPINION article Front. Hum. Neurosci., 09 December 2011Sec. Cognitive Neuroscience volume 5 - 2011 | https://doi.org/10.3389/fnhum.2011.00162

The authors carried out 2 experiments designed to cast light on the locus of redundancy gain in simple visual reaction time by using a stop-signal paradigm. In Experiment 1, the authors found that single visual stimuli were more easily inhibited than double visual stimuli by an acoustic stop signal. This result is in keeping with the idea that redundancy gain occurs prior to the ballistic stage of the stop-signal task. In Experiment 2, the authors found that the response to an acoustic go signal was more easily inhibited by a double than by a single visual stop signal. This result provides conclusive evidence for a redundancy gain in the stop process--in a process that does not involve a motor response but rather its inhibition.

Reduced P300 responses in criminal psychopaths during a visual oddball task

Event Abstract Back to Event Changes of oscillatory activity during visual oddball task (SEEG study) Robert Roman1*, Milan Brázdil2, J. Chládek3, P. Jurák3, Ivan Rektor2 and M. Kukleta1 1 Department of Physiology, Medical Faculty, Masaryk University, Czechia 2 Department of Neurology, St. Anne Hospital, Masaryk University, Czechia 3 Institute of Scientific Instruments, Academy of Sciences, Czechia Objectives: To study intracerebral distribution and frequency spectrum of event-related desynchronization (ERD) and synchronization (ERS) recorded during discrimination task. Methods: EEG was recorded from 187 cerebral sites in 6 patients suffering from intractable epilepsy during visual oddball task. Patients were instructed to respond only to the target stimulus by pressing the microswitch button. The intertrial variance method of quantification of ERD and ERS was used separately for target and frequent stimuli in individually selected reactive frequency bands (in the theta, alfa, beta and gamma range). Results: ERD and ERS were observed both after target and frequent stimuli repeatedly in the amygdala, hippocampus, parahippocampal gyrus, cingulate gyrus, fusiform gyrus, rectus gyrus, orbitofrontal gyri, superior and middle temporal gyri, middle and inferior frontal gyri. ERD after target stimuli was found in 139 sites – 91 cases in alfa, 69 cases in theta, 86 cases in beta and 15 cases in gamma band. ERS was observed in 86 sites – 42 cases in alfa, 37 cases in theta, 42 cases in beta and 17 cases in gamma band. ERD after frequent stimuli was present in 53 sites – 21 cases in alfa, 9 cases in theta, 23 cases in beta and 5 cases in gamma band. ERS was found in 63 sites – 24 cases in alfa, 9 cases in theta, 39 cases in beta and 4 cases in gamma band. Conclusion: Widespread distribution of decreased and increased oscillatory activity in different frequency bands shows the complexity of neural networks involved in cognitive processing of visual stimuli. More frequent finding of ERD phenomena after target stimuli might probably reflect the enhanced information processing related to the executive functions. Conference: 10th International Conference on Cognitive Neuroscience, Bodrum, Turkey, 1 Sep - 5 Sep, 2008. Presentation Type: Poster Presentation Topic: Brain Electrical Oscillations in Cognition Citation: Roman R, Brázdil M, Chládek J, Jurák P, Rektor I and Kukleta M (2008). Changes of oscillatory activity during visual oddball task (SEEG study). Conference Abstract: 10th International Conference on Cognitive Neuroscience. doi: 10.3389/conf.neuro.09.2009.01.141 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 05 Dec 2008; Published Online: 05 Dec 2008. * Correspondence: Robert Roman, Department of Physiology, Medical Faculty, Masaryk University, Brno, Czechia, roman@med.muni.cz Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Robert Roman Milan Brázdil J. Chládek P. Jurák Ivan Rektor M. Kukleta Google Robert Roman Milan Brázdil J. Chládek P. Jurák Ivan Rektor M. Kukleta Google Scholar Robert Roman Milan Brázdil J. Chládek P. Jurák Ivan Rektor M. Kukleta PubMed Robert Roman Milan Brázdil J. Chládek P. Jurák Ivan Rektor M. Kukleta Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Whole brain event-related functional magnetic resonance imaging (fMRI) techniques were employed to elucidate the cerebral sites involved in processing rare target and novel visual stimuli during an oddball discrimination task. The analyses of the hemodynamic response to the visual target stimuli revealed a distributed network of neural sources in anterior and posterior cingulate, inferior and middle frontal gyrus, bilateral parietal lobules, anterior superior temporal gyrus, amygdala, and thalamus. The analyses of the hemodynamic response for the visual novel stimuli revealed an extensive network of neural activations in occipital lobes and posterior temporal lobes, bilateral parietal lobules, and lateral frontal cortex. The hemodynamic response associated with processing target and novel stimuli in the visual modality were also compared with data from an analogous study in the auditory modality ( Kiehl et al., 2001 ). Similar patterns of activation were observed for target and novel stimuli in both modalities, but there were some significant differences. The results support the hypothesis that target detection and novelty processing are associated with neural activation in widespread neural areas, suggesting that the brain seems to adopt a strategy of activating many potentially useful brain regions despite the low probability that these brain regions are necessary for task performance.

Despite the tight coupling between sensory and motor processing for fine manipulation in humans, it is not yet totally clear which specific properties of the fingers are mapped in the precentral and postcentral gyrus. We used fMRI to compare the morphology, connectivity, and encoding of the motor and tactile finger representations (FRs) in the precentral and postcentral gyrus of 25 5-fingered participants (8 females). Multivoxel pattern and structural and functional connectivity analyses demonstrated the existence of distinct motor and tactile FRs within both the precentral and postcentral gyrus, integrating finger-specific motor and tactile information. Using representational similarity analysis, we found that the motor and tactile FRs in the sensorimotor cortex were described by the perceived structure of the hand better than by the actual hand anatomy or other functional models (finger kinematics, muscles synergies). We then studied a polydactyly individual (i.e., with a congenital 6-fingered hand) showing superior manipulation abilities and divergent anatomic-functional hand properties. The perceived hand model was still the best model for tactile representations in the precentral and postcentral gyrus, while finger kinematics better described motor representations in the precentral gyrus. We suggest that, under normal conditions (i.e., in subjects with a standard hand anatomy), the sensorimotor representations of the 5 fingers in humans converge toward a model of perceived hand anatomy, deviating from the real hand structure, as the best synthesis between functional and structural features of the hand.SIGNIFICANCE STATEMENT Distinct motor and tactile finger representations exist in both the precentral and postcentral gyrus, supported by a finger-specific pattern of anatomic and functional connectivity across modalities. At the representational level, finger representations reflect the perceived structure of the hand, which might result from an adapting process harmonizing (i.e., uniformizing) the encoding of hand function and structure in the precentral and postcentral gyrus. The same analyses performed in an extremely rare polydactyly subject showed that the emergence of such representational geometry is also found in neuromechanical variants with different hand anatomy and function. However, the harmonization process across the precentral and postcentral gyrus might not be possible because of divergent functional-structural properties of the hand and associated superior manipulation abilities.

Simple reaction time is used to evaluate the processing speed and the co-ordination between the sensory and motor systems. Reaction time is influenced by various factors. Therefore, the effect of color stimulus in modulating the reaction time among young Indian males has been investigated in this study. A total of 50 healthy volunteers (young males) of age group 18-28 years were included in the study. The subjects were presented with two visual stimuli viz.; red and green light by using an audio visual reaction time apparatus. Using paired t-test for comparison of visual reaction time between red and green color in young males, it was observed that the response latency for red color was significantly less compared to green color ( P < 0.05). From the present study, it could be suggested that the color stimulus has an impact in modulating the visual reaction time.

Identical event-related potentials to target and frequent stimuli of visual oddball task recorded by intracerebral electrodes.

Objective: The purpose of this study was to find out whether the simple reaction time was faster for auditory or visual stimulus and the factors responsible for improving the performance of the athlete. Methodology: 14 subjects were as- signed randomly into groups consisting of 2 members. Both the members from each group performed both the visual and auditory tests. The tests were taken from the DirectRT software program from a laptop. The DirectRT software consists of Testlabvisual and Testlabsounds to test the reaction times to visual and auditory stimuli. The 2 members from each group completed both the visual and auditory reaction times, the data was taken and the mean reaction time was calculated excluding the first and last values. Results: The results show that the mean visual reaction time is around 331 milliseconds as compared to the mean auditory reaction time of around 284 milliseconds. Conclusion: This shows that the auditory reaction time is faster than the visual reaction time. And also males have faster reaction times when compared to females for both auditory as well as visual stimuli.

The role of the ipsilateral primary motor cortex in movement control after spinal cord injury: A TMS study

Despite the important role that attending to novel events plays in human behavior, there is limited information about the neuroanatomical underpinnings of this vital activity. This study investigated the relative contributions of the frontal and posterior parietal lobes to the differential processing of novel and target stimuli under an experimental condition in which subjects actively directed attention to novel events. Event-related potentials were recorded from well-matched frontal patients, parietal patients, and non-brain-injured subjects who controlled their viewing duration (by button press) of line drawings that included a frequent, repetitive background stimulus, an infrequent target stimulus, and infrequent, novel visual stimuli. Subjects also responded to target stimuli by pressing a foot pedal. Damage to the frontal cortex resulted in a much greater disruption of response to novel stimuli than to designated targets. Frontal patients exhibited a widely distributed, profound reduction of the novelty P3 response and a marked diminution of the viewing duration of novel events. In contrast, damage to posterior parietal lobes was associated with a substantial reduction of both target P3 and novelty P3 amplitude; however, there was less disruption of the processing of novel than of target stimuli. We conclude that two nodes of the neuroanatomical network for responding to and processing novelty are the prefrontal and posterior parietal regions, which participate in the voluntary allocation of attention to novel events. Injury to this network is indexed by reduced novelty P3 amplitude, which is tightly associated with diminished attention to novel stimuli. The prefrontal cortex may serve as the central node in determining the allocation of attentional resources to novel events, whereas the posterior parietal lobe may provide the neural substrate for the dynamic process of updating one's internal model of the environment to take into account a novel event.

P79-T Sensory-motor integration during a visuomotor sequence learning task

High-γ amplitude (80-150 Hz) represents motor information, such as movement types, on the sensorimotor cortex. In several cortical areas, high-γ amplitudes are coupled with low-frequency phases, e.g., α and θ (phase-amplitude coupling, PAC). However, such coupling has not been studied in the sensorimotor cortex; thus, its potential functional role has yet to be explored. We investigated PAC of high-γ amplitude in the sensorimotor cortex during waiting for and the execution of movements using electrocorticographic (ECoG) recordings in humans. ECoG signals were recorded from the sensorimotor cortices of 4 epilepsy patients while they performed three different hand movements. A subset of electrodes showed high-γ activity selective to movement type around the timing of motor execution, while the same electrodes showed nonselective high-γ activity during the waiting period (>2 s before execution). Cross frequency coupling analysis revealed that the high-γ amplitude during waiting was strongly coupled with the α phase (10-14 Hz) at the electrodes with movement-selective high-γ amplitudes during execution. This coupling constituted the high-γ amplitude peaking around the trough of the α oscillation, and its strength and phase were not predictive of movement type. As the coupling attenuated toward the timing of motor execution, the high-γ amplitude appeared to be released from the α phase to build a motor representation with phase-independent activity. Our results suggest that PAC modulates motor representation in the sensorimotor cortex by holding and releasing high-γ activity in movement-selective cortical regions.