scholarly journals Neural Responses in Parietal and Occipital Areas in Response to Visual Events Are Modulated by Prior Multisensory Stimuli

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e84331 ◽  
Author(s):  
Hamish Innes-Brown ◽  
Ayla Barutchu ◽  
David P. Crewther
Keyword(s):  
Neural Responses ◽  
Visual Events

scholarly journals All-or-none visual categorization in the human brain

2019 ◽  
Author(s):  
Talia L. Retter ◽  
Fang Jiang ◽  
Michael A. Webster ◽  
Bruno Rossion
Keyword(s):  
Human Brain ◽  
Visual Presentation ◽  
Neural Responses ◽  
Behavioral Measures ◽  
Visual Categorization ◽  
Visual Events ◽  
Face Categorization ◽  
Wide Range ◽  
The Face ◽  
Spatio Temporal

AbstractWhether visual categorization, i.e., specific responses to a certain class of visual events across a wide range of exemplars, is graded or all-or-none in the human brain is largely unknown. We address this issue with an original frequency-sweep paradigm probing the evolution of responses between the minimum and optimal presentation times required to elicit both neural and behavioral face categorization responses. In a first experiment, widely variable natural images of nonface objects are progressively swept from 120 to 3 Hz (8.33 to 333 ms duration) in rapid serial visual presentation sequences; variable face exemplars appear every 1 s, enabling an implicit frequency-tagged face-categorization electroencephalographic (EEG) response at 1 Hz. In a second experiment, faces appear non-periodically throughout such sequences at fixed presentation rates, while participants explicitly categorize faces. Face-categorization activity emerges with stimulus durations as brief as 17 ms for both neural and behavioral measures (17 – 83 ms across individual participants neurally; 33 ms at the group level). The face-categorization response amplitude increases until 83 ms stimulus duration (12 Hz), implying graded categorization responses. However, a strong correlation with behavioral accuracy suggests instead that dilution from missed categorizations, rather than a decreased response to each face stimulus, may be responsible. This is supported in the second experiment by the absence of neural responses to behaviorally uncategorized faces, and equivalent amplitudes of isolated neural responses to only behaviorally categorized faces across presentation rates, consistent with the otherwise stable spatio-temporal signatures of face-categorization responses in both experiments. Overall, these observations provide original evidence that visual categorization of faces, while being widely variable across human observers, occurs in an all-or-none fashion in the human brain.

scholarly journals Implicit Agency in Observed Actions: Evidence for N1 Suppression of Tones Caused by Self-made and Observed Actions

2015 ◽  
Vol 27 (4) ◽  
pp. 752-764 ◽  
Author(s):  
Simandeep K. Poonian ◽  
Jessica McFadyen ◽  
Jessica Ogden ◽  
Ross Cunnington
Keyword(s):  
Interval Estimation ◽  
The Self ◽  
Sense Of Agency ◽  
Neural Responses ◽  
Top Down ◽  
Intentional Binding ◽  
Visual Events ◽  
Neural Processes ◽  
The World ◽  
Sensory Consequence

Every day we make attributions about how our actions and the actions of others cause consequences in the world around us. It is unknown whether we use the same implicit process in attributing causality when observing others' actions as we do when making our own. The aim of this research was to investigate the neural processes involved in the implicit sense of agency we form between actions and effects, for both our own actions and when watching others' actions. Using an interval estimation paradigm to elicit intentional binding in self-made and observed actions, we measured the EEG responses indicative of anticipatory processes before an action and the ERPs in response to the sensory consequence. We replicated our previous findings that we form a sense of implicit agency over our own and others' actions. Crucially, EEG results showed that tones caused by either self-made or observed actions both resulted in suppression of the N1 component of the sensory ERP, with no difference in suppression between consequences caused by observed actions compared with self-made actions. Furthermore, this N1 suppression was greatest for tones caused by observed goal-directed actions rather than non-action or non-goal-related visual events. This suggests that top–down processes act upon the neural responses to sensory events caused by goal-directed actions in the same way for events caused by the self or those made by other agents.

Visual evoked responses to a gamma-frequency flicker are enhanced in acute schizophrenia

2011 ◽  
Vol 26 (S2) ◽  
pp. 1494-1494
Author(s):  
I. Riecansky ◽  
T. Kasparek ◽  
J. Rehulova ◽  
S. Katina ◽  
R. Prikyl
Keyword(s):  
Psychotic Disorders ◽  
Alpha Band ◽  
Neural Responses ◽  
Acute Schizophrenia ◽  
Gamma Frequency ◽  
Visual Events ◽  
Healthy Control ◽  
Gamma Frequencies ◽  
40 Hz ◽  
Visual Evoked

Disturbances of visual perception, such as illusions and hallucinations, are a hallmark of psychotic disorders. In perceptual processes, synchronous neuronal activity in gamma frequencies (> 30 Hz) is considered to play a major role. Steady-state visual evoked potentials (ssVEP) allow for testing the ability of the visual cortex to support synchronous neural responses to periodically flickering light. We employed photic stimulation at 40 Hz in order to specifically drive cortical gamma synchrony. In acute schizophrenia patients, compared to healthy control subjects, we found significantly increased evoked synchrony at 40 Hz, but decreased synchrony in the alpha band (8–13 Hz). Linear decomposition of ssVEP waveforms separated the activity of independent neural sources and revealed their different dynamics in the patients and the controls. The results indicate an aberrant processing of transient visual events in acute schizophrenia.

Specificity of Neural Responses to Emotion

2013 ◽  
Author(s):  
Luke J. Chang ◽  
Peter J. Gianaros ◽  
Steve Manuck ◽  
Anjali Krishnan ◽  
Tor D. Wager
Keyword(s):  
Neural Responses

What you morph is not what you get: Subjective and neural responses to facial expressions of emotion depend on perceived intensity/arousal (not on amount of morphing)

2020 ◽  
Author(s):  
Fernando Ferreira-Santos ◽  
Mariana R. Pereira ◽  
Tiago O. Paiva ◽  
Pedro R. Almeida ◽  
Eva C. Martins ◽  
...  
Keyword(s):  
Facial Expressions ◽  
Electrophysiological Study ◽  
Objective Measure ◽  
Event Related Potential ◽  
Supporting Evidence ◽  
Emotional Intensity ◽  
Neural Responses ◽  
Facial Stimuli ◽  
Facial Expressions Of Emotion ◽  
Processing Techniques

The behavioral and electrophysiological study of the emotional intensity of facial expressions of emotions has relied on image processing techniques termed ‘morphing’ to generate realistic facial stimuli in which emotional intensity can be manipulated. This is achieved by blending neutral and emotional facial displays and treating the percent of morphing between the two stimuli as an objective measure of emotional intensity. Here we argue that the percentage of morphing between stimuli does not provide an objective measure of emotional intensity and present supporting evidence from affective ratings and neural (event-related potential) responses. We show that 50% morphs created from high or moderate arousal stimuli differ in subjective and neural responses in a sensible way: 50% morphs are perceived as having approximately half of the emotional intensity of the original stimuli, but if the original stimuli differed in emotional intensity to begin with, then so will the morphs. We suggest a re-examination of previous studies that used percentage of morphing as a measure of emotional intensity and highlight the value of more careful experimental control of emotional stimuli and inclusion of proper manipulation checks.

Sign in / Sign up

Export Citation Format

Share Document