Session Detail

Pupil size, as a component of orienting, changes rapidly in response to local salient events in the environment. A growing body of evidence suggests that the midbrain superior colliculus (SC) encodes stimuli based upon saliency to coordinate the orienting response. Although the SC is causally involved in the initiation of saccadic eye movements and shifts of attention, its role in coordinating other components of orienting is less understood. Here, we examined how pupil dynamics are modulated by the SC and stimulus saliency. While requiring subjects to maintain central fixation, we presented a salient visual, auditory, or audiovisual stimulus. Transient pupil dilation was elicited after presentation of salient stimuli, and the timing and magnitude of evoked pupillary responses were modulated by stimulus contrast, with significantly faster and larger pupillary responses observed for more salient stimuli. Furthermore, the pupillary responses elicited by audiovisual stimuli were well predicted by a linear summation of each modality response. To establish the role of the SC on this behavior, we electrically stimulated the intermediate SC layers varying stimulation parameters in monkeys trained to perform oculomotor tasks. Transient pupil dilation was elicited by SC microstimulation, and this dilation was qualitatively similar to that evoked after presentation of salient stimuli. If the orienting responses of saccade and pupil size are coordinated through the SC, these two responses should be highly correlated. Varying stimulation parameters systematically modulated evoked saccadic as well as pupillary responses, with trial-by-trial correlation between two responses. Together, our results demonstrated 1) the saliency modulation of pupillary responses, and 2) the SC coordinates pupillary responses and saccades. Because the SC receives convergent signals from multisensory, arousal, cognitive areas, the SC-pupil pathway provides a novel neural substrate underlying not only pupil orienting responses, but also the pupillary modulation by cognitive and arousal processes.

 

Detecting imminent collision is essential for survival. Recent studies revealed subcortical circuits responding to looming stimulus in rodents. Little is known about how human subcortical visual pathways process collision information. Using fMRI, we studied how the superior colliculus (SC) and pulvinar of thalamus respond to potential collision information. Visual stimuli depicting an incoming ball towards the subject were presented with 3D LED monitors. The incoming ball appeared in one of the four quadrants of visual field. Within each quadrant, the trajectory of incoming ball varied slightly to either hit the center of face, hit the eye, near-miss or miss the head of observers. subjects responded whether the ball was on a collision course with their head or not. Behavioral results show that subjects performed slightly better detecting collision (hit vs. miss) for stimuli in the upper visual field than in the lower visual field. FMRI data showed that the superficial layers of the SC were sensitive to the looming information from the contralateral visual field, especially when the looming object came from the upper visual field and was on a collision course leading to a direct hit at the center of the subject head. A sub-region in the ventral Pulvinar was also sensitive to the incoming object on a collision course from the contralateral side, showing the strongest response when the incoming object would hit the subjects’ contralateral eye (on the same side of the incoming object). These results suggest that human SC and Pulvinar are closely involved in processing incoming objects potentially on a collision course.

 

Abstract: The response inhibition function related neural signals have arrived from inferior frontal gyrus (IFG) and pre-supplementary motor (preSMA). Response inhibition-related neuronal signals are widespread in the human brain, and there is no specific way to detect their association with other brain regions. Consequently, due to the lack of functional and structural networks across the different brain areas during response inhibition mechanism. We developed a human brain neural network during response inhibition with joint visual and auditory stimuli. The visual and auditory modalities work together to help the identification of a right sources of the events in some circumstances, such as car driving, walking, sport, and shooting. Therefore, to measure the human brain activities changes with visual and auditory modalities in laboratory settings, we performed an auditory stop signal presentation followed by left- and right-hand response inhibition controls. However, the inter-trial coherence (ITC) method was used to evaluate the effect of an auditory modality information processing on visual modality by cortical phase synchrony at frontal, temporal and occipital brain areas. Our results revealed significant phase synchronization in the frequency range of delta (1-4Hz) and theta (4-8Hz) bands at the temporal brain area. Therefore, we suggest this may be a brain signatures of visual event-related response in auditory cortex during left and right-hand response inhibition functions. In addition, strong activation and synchronization were shown in delta (1-4Hz), theta (4-8Hz) and alpha (8-13Hz) bands in the occipital cortex with the visual stimuli. Moreover, in human brain network, highest EEG coherence values were perceived in frontal lobe (F3-F4) compare to other cortices. The higher EEG activation in frontal cortex may be related to response inhibition function. These results delivered new perceptions during the inhibition function of multisensory brain regions with visual and auditory modalities information processing, respectively.

 

Twenty adults (10 males and 10 females, age ranged from 19 to 29) with normal or corrected normal vision and reported no abnormal neurological history participated. In the study, faces of seven basic emotions were tested in separate blocks and presented in pairs. The participants were asked to judge if the two faces in each trial were identical as in the same emotion or as from the same person. The results found that the brain activation of identity task were higher than those of the emotion task. The activation of the second faces were higher than those of the first faces. We found a difference in early processes between the emotion and identity tasks. It was found differences in viewing male and female stimuli at 60-83 ms and at BA7, BA18, BA31, BA37, BA10, and Right Cerebrum. The results of 300-500 found higher activation in processing male faces in identity task than in emotion task in BA13 at insular cortex. The findings of the present study suggests an early perception of emotion information which is implemented in phylogenetically ancient brain structures of subcortical nuclei(Tamietto & de Gelder, 2010). The brain activity found primarily in emotion-related area such as insular might be a result of processing emotional components facial expressions.

 

Individuals in the early-stage of the relationship are generally deeply committed to their partners without active self-control. This 'addictive' state in the early-stage, which is supported by the reward system in the brain (Aron et al., 2005), is believed to be suitable for maintenance of such a new relationship (for a review, Fisher et al., 2016). This observation naturally leads to the idea that the prefrontal executive control, which plays a crucial role in maintenance of a monogamous relationship, is less required in individuals in the early-stage of the relationship than those in the long-term lasting relationship. To test this hypothesis, we asked male participants in a romantic relationship to perform go/no-go task during functional magnetic resonance imaging (fMRI) scanning, which is a well-validated task to measure right VLPFC activity implicated in executive control. Subsequently, they were engaged in a date-rating task in which they rated how much they wanted to date unfamiliar females. We found that individuals with higher right VLPFC activity regulated the interest for dates with females better. Importantly, this relationship was found only in the individuals with a long-term partner. Our findings extend previous findings of executive control in maintenance of the monogamous relationship by highlighting the role of VLPFC which varies according to the stage of the romantic relationship.