Using Live and Video Stimuli to Localize Face and Object Processing Regions of the Canine Brain

Previous research to localize face areas in dogs’ brains has generally relied on static images or videos. However, most dogs do not naturally engage with two-dimensional images, raising the question of whether dogs perceive such images as representations of real faces and objects. To measure the equivalency of live and two-dimensional stimuli in the dog’s brain, during functional magnetic resonance imaging (fMRI) we presented dogs and humans with live-action stimuli (actors and objects) as well as videos of the same actors and objects. The dogs (n = 7) and humans (n = 5) were presented with 20 s blocks of faces and objects in random order. In dogs, we found significant areas of increased activation in the putative dog face area, and in humans, we found significant areas of increased activation in the fusiform face area to both live and video stimuli. In both dogs and humans, we found areas of significant activation in the posterior superior temporal sulcus (ectosylvian fissure in dogs) and the lateral occipital complex (entolateral gyrus in dogs) to both live and video stimuli. Of these regions of interest, only the area along the ectosylvian fissure in dogs showed significantly more activation to live faces than to video faces, whereas, in humans, both the fusiform face area and posterior superior temporal sulcus responded significantly more to live conditions than video conditions. However, using the video conditions alone, we were able to localize all regions of interest in both dogs and humans. Therefore, videos can be used to localize these regions of interest, though live conditions may be more salient.

Spatial tuning of face part representations within face-selective areas revealed by high-field fMRI

Regions sensitive to specific object categories as well as organized spatial patterns sensitive to different features have been found across the whole ventral temporal cortex (VTC). However, it is unclear that within each object category region, how specific feature representations are organized to support object identification. Would object features, such as object parts, be represented in fine-scale spatial tuning within object category-specific regions? Here, we used high-field 7T fMRI to examine the spatial tuning to different face parts within each face-selective region. Our results show consistent spatial tuning of face parts across individuals that within right posterior fusiform face area (pFFA) and right occipital face area (OFA), the posterior portion of each region was biased to eyes, while the anterior portion was biased to mouth and chin stimuli. Our results demonstrate that within the occipital and fusiform face processing regions, there exist systematic spatial tuning to different face parts that support further computation combining them.

Implementation of wheelchair controller using mouth and tongue gesture

In this paper, a simple human-machine interface allowing people with severe disabilities to control a motorized wheelchair using mouth and tongue gesture is presented. The development of the proposed system consists of three principal phases: the first phase is mouth detection which performed by using haar cascade to detect the face area and template matching to detect mouth and tongue gestures from the lower face region. The second phase is command extraction; it is carried by determining the mouth and tongue gesture commands according to the detected gesture, the time taken to execute the gestures, and the previous command which is stored in each frame. Finally, the gesture commands are sent to the wheelchair as instruction using the Bluetooth serial port. The hardware used for this project were; laptop with universal serial bus (USB) webcam as a vision-based control unit, Bluetooth module to receive instructions comes from the vision control unit, standard joystick used in case of emergency, joystick emulator which delivers to the control board signals similar to the signals that are usually generated by the standard joystick, and ultrasonic sensors to provide safe navigation. The experimental results showed the success of the proposed control system based on mouth and tongue gestures.

Does the Occipital Face Area Contribute to Holistic Face Processing?

<p>Face perception depends on a network of brain areas that selectively respond to faces over non-face stimuli. These face-selective areas are involved in different aspects of face perception, but what specific process is implemented in a particular region remains little understood. A candidate processisholistic face processing, namely the integration of visual information across the whole of an upright face. In this thesis, I report two experimentsthat examine whether the occipital face area (OFA), a face-selective region in the inferior occipital gyrus, performs holistic processing for categorising a stimulus as a face. Both experiments were conducted using online, repetitive transcranial magnetic stimulation (TMS) to disrupt activity in the brain while participants performed face perception tasks. Experiment 1 was a localiser in which participants completed two face identification tasks while receiving TMS at OFA or vertex. Participants’ accuracy decreased for one of the tasks as a result of OFA but not vertex stimulation. This result confirms that OFA could be localised and its activity disrupted. Experiment 2 was a test of holistic processing in which participants categorised ambiguous two-tone images as faces or non-faces while TMS was delivered to OFA or vertex. Participants’ accuracy and response times were unchanged as a result of either stimulation. This result suggests that the OFA is not engaged in holistic processing for categorising a stimulus as a face. Overall, the currentresults are more consistent with previous studies suggesting that OFA is involved in processing of local face features/details rather than the whole face.</p>

Does the Occipital Face Area Contribute to Holistic Face Processing?

<p>Face perception depends on a network of brain areas that selectively respond to faces over non-face stimuli. These face-selective areas are involved in different aspects of face perception, but what specific process is implemented in a particular region remains little understood. A candidate processisholistic face processing, namely the integration of visual information across the whole of an upright face. In this thesis, I report two experimentsthat examine whether the occipital face area (OFA), a face-selective region in the inferior occipital gyrus, performs holistic processing for categorising a stimulus as a face. Both experiments were conducted using online, repetitive transcranial magnetic stimulation (TMS) to disrupt activity in the brain while participants performed face perception tasks. Experiment 1 was a localiser in which participants completed two face identification tasks while receiving TMS at OFA or vertex. Participants’ accuracy decreased for one of the tasks as a result of OFA but not vertex stimulation. This result confirms that OFA could be localised and its activity disrupted. Experiment 2 was a test of holistic processing in which participants categorised ambiguous two-tone images as faces or non-faces while TMS was delivered to OFA or vertex. Participants’ accuracy and response times were unchanged as a result of either stimulation. This result suggests that the OFA is not engaged in holistic processing for categorising a stimulus as a face. Overall, the currentresults are more consistent with previous studies suggesting that OFA is involved in processing of local face features/details rather than the whole face.</p>

Effects of High-Definition Transcranial Direct Current Stimulation Over the Left Fusiform Face Area on Face View Discrimination Depend on the Individual Baseline Performance

A basic human visual function is to identify objects from different viewpoints. Typically, the ability to discriminate face views based on in-depth orientation is necessary in daily life. Early neuroimaging studies have identified the involvement of the left fusiform face area (FFA) and the left superior temporal sulcus (STS) in face view discrimination. However, many studies have documented the important role of the right FFA in face processing. Thus, there remains controversy over whether one specific region or all of them are involved in discriminating face views. Thus, this research examined the influence of high-definition transcranial direct current stimulation (HD-tDCS) over the left FFA, left STS or right FFA on face view discrimination in three experiments. In experiment 1, eighteen subjects performed a face view discrimination task before and immediately, 10 min and 20 min after anodal, cathodal and sham HD-tDCS (20 min, 1.5 mA) over the left FFA in three sessions. Compared with sham stimulation, anodal and cathodal stimulation had no effects that were detected at the group level. However, the analyses at the individual level showed that the baseline performance negatively correlated with the degree of change after anodal tDCS, suggesting a dependence of the change amount on the initial performance. Specifically, tDCS decreased performance in the subjects with better baseline performance but increased performance in those with poorer baseline performance. In experiments 2 and 3, the same experimental protocol was used except that the stimulation site was the left STS or right FFA, respectively. Neither anodal nor cathodal tDCS over the left STS or right FFA influenced face view discrimination in group- or individual-level analyses. These results not only indicated the importance of the left FFA in face view discrimination but also demonstrated that individual initial performance should be taken into consideration in future research and practical applications.

Beautiful People in the Brain of the Beholder

In the paper discussed in this chapter, the authors were interested in the neural underpinnings for facial beauty and whether such responses were automatic. In a functional magnetic resonance imaging study over two sessions, the authors asked participants to make beauty and identity judgments on a series of computer-generated faces. When people judged beauty, the authors found that neural activity varied parametrically to the degree of facial attractiveness in the fusiform face area and the lateral occipital complex, as well as in parts of parietal and frontal cortices. When people made familiarity judgments, the authors observed the same modulation of neural activity within occipital cortex to the degree of attractiveness in the faces. The data suggested that human brains automatically respond to facial beauty even when people might be attending to other aspects of the faces they apprehend.

Cultural Neuroaesthetics of Delicate Sadness Induced by Noh Masks

As an investigator of how culture interacts with neuroaesthetics in Japanese art, the author’s goal in the article under discussion is to explore the neural mechanisms involved in the social, affective, and cognitive processes of sadness induced by the Noh mask. Why do seemingly negative emotions, such as sadness, play a critical role in aesthetic experiences in the Noh theater? What brain activity is involved in feeling delicate sadness? Sadness induced by faces involves cortical interactions among various brain areas such as the amygdala, striatum, fusiform face area, and insula. The expectation for reward, hidden in the appreciation of the sad mask, might be a social reward. If so, it may be that appreciating sadness masks engages a common system that drives the expectation of negative rewards. The author ran a functional magnetic resonance imaging study in which participants’ brains were scanned while watching sad Noh masks. Results confirmed predictions, revealing activation of the right amygdala while viewing sad masks.

Architectural Styles as Subordinate Scene Categories

How do the brains of experts and non-experts represent entry-level and subordinate-level categories of buildings and places? In the study reviewed in this chapter, the authors measured the brain activity of architecture and psychology students while they viewed images of buildings of different architectural styles as well as general scenes. From functional magnetic resonance imaging (fMRI) patterns, they were able to decode which architectural style participants viewed. Despite finding a strong behavioral expertise effect for architectural styles between the two groups of participants, the authors could not find any differences in brain activity. Surprisingly, they found that the fusiform face area, which is typically not involved in scene perception, was tightly linked with scene-selective brain regions for the decoding of architectural styles but not for entry-level scenes categories.

Face Processing in Developmental Prosopagnosia: Altered Neural Representations in the Fusiform Face Area

Rationale: Face expertise is a pivotal social skill. Developmental prosopagnosia (DP), i.e., the inability to recognize faces without a history of brain damage, affects about 2% of the general population, and is a renowned model system of the face-processing network. Within this network, the right Fusiform Face Area (FFA), is particularly involved in face identity processing and may therefore be a key element in DP. Neural representations within the FFA have been examined with Representational Similarity Analysis (RSA), a data-analytical framework in which multi-unit measures of brain activity are assessed with correlation analysis.Objectives: Our study intended to scrutinize modifications of FFA-activation during face encoding and maintenance based on RSA.Methods: Thirteen participants with DP (23–70 years) and 12 healthy control subjects (19–62 years) participated in a functional MRI study, including morphological MRI, a functional FFA-localizer and a modified Sternberg paradigm probing face memory encoding and maintenance. Memory maintenance of one, two, or four faces represented low, medium, and high memory load. We examined conventional activation differences in response to working memory load and applied RSA to compute individual correlation-matrices on the voxel level. Group correlation-matrices were compared via Donsker’s random walk analysis.Results: On the functional level, increased memory load entailed both a higher absolute FFA-activation level and a higher degree of correlation between activated voxels. Both aspects were deficient in DP. Interestingly, control participants showed a homogeneous degree of correlation for successful trials during the experiment. In DP-participants, correlation levels between FFA-voxels were significantly lower and were less sustained during the experiment. In behavioral terms, DP-participants performed poorer and had longer reaction times in relation to DP-severity. Furthermore, correlation levels were negatively correlated with reaction times for the most demanding high load condition.Conclusion: We suggest that participants with DP fail to generate robust and maintained neural representations in the FFA during face encoding and maintenance, in line with poorer task performance and prolonged reaction times. In DP, alterations of neural coding in the FFA might therefore explain curtailing in working memory and contribute to impaired long-term memory and mental imagery.