Scene-selective coding by single neurons in the human parahippocampal cortex.

Imaging, electrophysiological, and lesion studies have shown a relationship between the parahippocampal cortex (PHC) and the processing of spatial scenes. Our present knowledge of PHC, however, is restricted to the macroscopic properties and dynamics of bulk tissue; the behavior and selectivity of single parahippocampal neurons remains largely unknown. In this study, we analyzed responses from 630 parahippocampal neurons in 24 neurosurgical patients during visual stimulus presentation. We found a spatially clustered subpopulation of scene-selective units with an associated event-related field potential. These units form a population code that is more distributed for scenes than for other stimulus categories, and less sparse than elsewhere in the medial temporal lobe. Our electrophysiological findings provide insight into how individual units give rise to the population response observed with functional imaging in the parahippocampal place area.

Breathing above the brain stem: volitional control and attentional modulation in humans.

Whereas the neurophysiology of respiration has traditionally focused on automatic brain stem processes, higher brain mechanisms underlying the cognitive aspects of breathing are gaining increasing interest. Therapeutic techniques have used conscious control and awareness of breathing for millennia with little understanding of the mechanisms underlying their efficacy. Using direct intracranial recordings in humans, we correlated cortical and limbic neuronal activity as measured by the intracranial electroencephalogram (iEEG) with the breathing cycle. We show this to be the direct result of neuronal activity, as demonstrated by both the specificity of the finding to the cortical gray matter and the tracking of breath by the gamma-band (40-150 Hz) envelope in these structures. We extend prior observations by showing the iEEG signal to track the breathing cycle across a widespread network of cortical and limbic structures. We further demonstrate a sensitivity of this tracking to cognitive factors by using tasks adapted from cognitive behavioral therapy and meditative practice. Specifically, volitional control and awareness of breathing engage distinct but overlapping brain circuits. During volitionally paced breathing, iEEG-breath coherence increases in a frontotemporal-insular network, and during attention to breathing, we demonstrate increased coherence in the anterior cingulate, premotor, insular, and hippocampal cortices. Our findings suggest that breathing can act as an organizing hierarchical principle for neuronal oscillations throughout the brain and detail mechanisms of how cognitive factors impact otherwise automatic neuronal processes during interoceptive attention. NEW & NOTEWORTHY Whereas the link between breathing and brain activity has a long history of application to therapy, its neurophysiology remains unexplored. Using intracranial recordings in humans, we show neuronal activity to track the breathing cycle throughout widespread cortical/limbic sites. Volitional pacing of the breath engages frontotemporal-insular cortices, whereas attention to automatic breathing modulates the cingulate cortex. Our findings imply a fundamental role of breathing-related oscillations in driving neuronal activity and provide insight into the neuronal mechanisms of interoceptive attention.

On-line, voluntary control of human temporal lobe neurons.

Daily life continually confronts us with an exuberance of external, sensory stimuli competing with a rich stream of internal deliberations, plans and ruminations. The brain must select one or more of these for further processing. How this competition is resolved across multiple sensory and cognitive regions is not known; nor is it clear how internal thoughts and attention regulate this competition. Recording from single neurons in patients implanted with intracranial electrodes for clinical reasons, here we demonstrate that humans can regulate the activity of their neurons in the medial temporal lobe (MTL) to alter the outcome of the contest between external images and their internal representation. Subjects looked at a hybrid superposition of two images representing familiar individuals, landmarks, objects or animals and had to enhance one image at the expense of the other, competing one. Simultaneously, the spiking activity of their MTL neurons in different subregions and hemispheres was decoded in real time to control the content of the hybrid. Subjects reliably regulated, often on the first trial, the firing rate of their neurons, increasing the rate of some while simultaneously decreasing the rate of others. They did so by focusing onto one image, which gradually became clearer on the computer screen in front of their eyes, and thereby overriding sensory input. On the basis of the firing of these MTL neurons, the dynamics of the competition between visual images in the subject's mind was visualized on an external display.

The psychology of corporate rights: Perception of corporate versus individual rights to religious liberty, privacy, and free speech.

The U.S. Supreme Court has increasingly expanded the scope of constitutional rights granted to corporations and other collective entities. Although this tendency receives widespread public and media attention, little empirical research examines how people ascribe rights, commonly thought to belong to natural persons, to corporations. This article explores this issue in 3 studies focusing on different rights (religious liberty, privacy, and free speech). We examined participants' willingness to grant a given right while manipulating the type of entity at stake (from small businesses, to larger corporations, to for-profit and nonprofit companies), and the identity of the right holder (from employees, to owners, to the company itself as a separate entity). We further examined the role of political ideology in perceptions of rights. Results indicated a significant decline in the degree of recognition of entities' rights (the company itself) in comparison to natural persons' rights (owners and employees). Results also demonstrated an effect of the type of entity at stake: Larger, for-profit businesses were less likely to be viewed as rights holders compared with nonprofit entities. Although both tendencies persisted across the ideological spectrum, ideological differences emerged in the relations between corporate and individual rights: these were positively related among conservatives but negatively related among liberals. Finally, we found that the desire to protect citizens (compared with businesses) underlies individuals' willingness to grant rights to companies. These findings show that people (rather than corporations) are more appropriate recipients of rights, and can explain public backlash to judicial expansions of corporate rights.

Evidence for two distinct mechanisms directing gaze in natural scenes.

Various models have been proposed to explain the interplay between bottom-up and top-down mechanisms in driving saccades rapidly to one or a few isolated targets. We investigate this relationship using eye-tracking data from subjects viewing natural scenes to test attentional allocation to high-level objects within a mathematical decision-making framework. We show the existence of two distinct types of bottom-up saliency to objects within a visual scene, which disappear within a few fixations, and modification of this saliency by top-down influences. Our analysis reveals a subpopulation of early saccades, which are capable of accurately fixating salient targets after prior fixation within the same image. These data can be described quantitatively in terms of bottom-up saliency, including an explicit face channel, weighted by top-down influences, determining the mean rate of rise of a decision-making model to a threshold that triggers a saccade. These results are compatible with a rapid subcortical pathway generating accurate saccades to salient targets after analysis by cortical mechanisms.

Brain-Computer Interface using neural network and temporal-spectral features.

Brain-Computer Interfaces (BCIs) are increasingly useful for control. Such BCIs can be used to assist individuals who lost mobility or control over their limbs, for recreational purposes such as gaming or semi-autonomous driving, or as an interface toward man-machine integration. Thus far, the performance of algorithms used for thought decoding has been limited. We show that by extracting temporal and spectral features from electroencephalography (EEG) signals and, following, using deep learning neural network to classify those features, one can significantly improve the performance of BCIs in predicting which motor action was imagined by a subject. Our movement prediction algorithm uses Sequential Backward Selection technique to jointly choose temporal and spectral features and a radial basis function neural network for the classification. The method shows an average performance increase of 3.50% compared to state-of-the-art benchmark algorithms. Using two popular public datasets our algorithm reaches 90.08% accuracy (compared to an average benchmark of 79.99%) on the first dataset and 88.74% (average benchmark: 82.01%) on the second dataset. Given the high variability within- and across-subjects in EEG-based action decoding, we suggest that using features from multiple modalities along with neural network classification protocol is likely to increase the performance of BCIs across various tasks.

Single neuron evidence of inattentional blindness in humans.

Recording directly from the brain of a patient undergoing neurosurgery with electrodes implanted deep in her skull, we identified neurons that change their properties when the patient became consciously aware of content. Specifically, we showed the patient an established clip of a gorilla passing through the screen, unnoticeable, in a classic inattentional blindness task, and identified a neuron in the right amygdala that fired only when the patient was aware of the gorilla. A different neuron coded the moment of insight, when the patient realized that she had missed the salient gorilla in previous trials. A third cluster of neurons fired when the patient was exposed to a post-clip question ("How many passes did you count?") and reflected on the content. Neurons in this cluster altered their response behavior between unaware and aware states. To investigate the interplay between the neurons' activity and characterize the potential cascade of information flow in the brain that leads to conscious awareness, we looked at the neurons' properties change, their activities' alignment and the correlation across the cells. Examining the coherence between the spiking activity of the responsive neurons and the field potentials in neighboring sites we identified an alignment in the alpha and theta bands. This spike-field coherence hints at an involvement of attention and memory circuits in the perceptual awareness of the stimulus. Taken together, our results suggest that conscious awareness of content emerges when there is alignment between individual neurons' activity and the local field potentials. Our work provides direct neural correlate for the psychological process by which one can look at things directly but fail to perceive them with the "mind's eye".

Personality similarity predicts synchronous neural responses in fMRI and EEG data.

Successful communication and cooperation among different members of society depends, in part, on a consistent understanding of the physical and social world. What drives this alignment in perspectives? We present evidence from two neuroimaging studies using functional magnetic resonance imaging (fMRI; N = 66 with 2145 dyadic comparisons) and electroencephalography (EEG; N = 225 with 25,200 dyadic comparisons) to show that: (1) the extent to which people's neural responses are synchronized when viewing naturalistic stimuli is related to their personality profiles, and (2) that this effect is stronger than that of similarity in gender, ethnicity and political affiliation. The localization of the fMRI results in combination with the additional eye tracking analyses suggest that the relationship between personality similarity and neural synchrony likely reflects alignment in the interpretation of stimuli and not alignment in overt visual attention. Together, the findings suggest that similarity in psychological dispositions aligns people's reality via shared interpretations of the external world.

Selectivity of pyramidal cells and interneurons in the human medial temporal lobe.

Neurons in the medial temporal lobe (MTL) respond selectively to pictures of specific individuals, objects, and places. However, the underlying mechanisms leading to such degree of stimulus selectivity are largely unknown. A necessary step to move forward in this direction involves the identification and characterization of the different neuron types present in MTL circuitry. We show that putative principal cells recorded in vivo from the human MTL are more selective than putative interneurons. Furthermore, we report that putative hippocampal pyramidal cells exhibit the highest degree of selectivity within the MTL, reflecting the hierarchical processing of visual information. We interpret these differences in selectivity as a plausible mechanism for generating sparse responses.

Goal-Concordant Care in the Era of Advanced Stroke Therapies.

Stroke is a leading cause of disability and mortality worldwide. Recent advances in stroke care now enable patients with severe ischemic stroke owing to large vessel occlusion to safely undergo endovascular thrombectomy (EVT) up to 24 hours since their time of last known well, with the goal of improving functional outcomes by recanalization of the occluded vessel and reperfusion of downstream ischemic brain tissue. The objective of this analysis is to highlight clinical and ethical challenges related to ensuring goal-concordant care in this era of unprecedented advances in acute stroke care. Specifically, there is a salient challenge of whether advanced therapies such as EVT may be justifiably considered comfort focused, given their potential to preempt accumulated neurologic disability and suffering at the end of life. Through the lens of a patient case, we discuss key challenges, lessons learned, and suggestions for future care and research endeavors at the intersection of acute stroke care and palliative care principles. Although therapies such as thrombolysis and EVT may be considered aggressive prima facie, their potential to ameliorate additional disability and potential suffering at the end of life prompt close consideration of the proper role of these therapies on a case-by-case basis in the context of comfort-focused care. Modification to the workflow for EVT evaluations may facilitate goal-concordant care and timely resource allocation, especially for cases that involve hospital-to-hospital transfers for advanced stroke care.

Responses of human medial temporal lobe neurons are modulated by stimulus repetition.

Recent studies have reported the presence of single neurons with strong responses to visual inputs in the human medial temporal lobe. Here we show how repeated stimulus presentation--photos of celebrities and familiar individuals, landmark buildings, animals, and objects--modulates the firing rate of these cells: a consistent decrease in the neural activity was registered as images were repeatedly shown during experimental sessions. The effect of repeated stimulus presentation was not the same for all medial temporal lobe areas. These findings are consistent with the view that medial temporal lobe neurons link visual percepts to declarative memory.

Social Media Perceptions of Legacy-Making: A Qualitative Analysis.

Background: Individuals with life-limiting illnesses experience psychotherapeutic benefits of transmitting their life's history to loved ones; however, the scope and depth of what warrants preservation and who ought to undertake such activity remains less clear. Furthermore, individuals with conditions that afflict the brain face barriers regarding the timing and structure of such interventions. We analyzed data from an online social media forum to understand perceptions of legacy-making. Methods: This is a qualitative descriptive study of Slashdot, a social media website with a focus on science, technology, and politics. In August 2010, a Slashdot user inquired about a loved one with a life-limiting illness and asked for opinions on how to preserve the individual's memories. We conducted a content analysis of the individual comments related to digital legacy-making to identify common themes. Results: Slashdot users contributed 527 replies to the initial inquiry. Users often included bereaved individuals who offered input on the need to preserve information about a loved one, the modalities in which to preserve, and what type of content to preserve. Three key themes emerged related to legacy-making: (1) capture the individual's essence and avoid the minutia, (2) live for now to avoid prolonged suffering, and (3) recognize the equal benefits to all who memorialize. Conclusions: Users in a social media forum articulated the value of capturing their loved ones' essence for posterity, which many believed would help them to avoid prolonged grief. These findings have implications for the development and timing of personalized psychosocial interventions as well as informing application development of evidence-based digital legacy systems.

Latency and selectivity of single neurons indicate hierarchical processing in the human medial temporal lobe.

Neurons in the temporal lobe of both monkeys and humans show selective responses to classes of visual stimuli and even to specific individuals. In this study, we investigate the latency and selectivity of visually responsive neurons recorded from microelectrodes in the parahippocampal cortex, entorhinal cortex, hippocampus, and amygdala of human subjects during a visual object presentation task. During 96 experimental sessions in 35 subjects, we recorded from a total of 3278 neurons. Of these units, 398 responded selectively to one or more of the presented stimuli. Mean response latencies were substantially larger than those reported in monkeys. We observed a highly significant correlation between the latency and the selectivity of these neurons: the longer the latency the greater the selectivity. Particularly, parahippocampal neurons were found to respond significantly earlier and less selectively than those in the other three regions. Regional analysis showed significant correlations between latency and selectivity within the parahippocampal cortex, entorhinal cortex, and hippocampus, but not within the amygdala. The later and more selective responses tended to be generated by cells with sparse baseline firing rates and vice versa. Our results provide direct evidence for hierarchical processing of sensory information at the interface between the visual pathway and the limbic system, by which increasingly refined and specific representations of stimulus identity are generated over time along the anatomic pathways of the medial temporal lobe.

Faces and text attract gaze independent of the task: Experimental data and computer model.

Previous studies of eye gaze have shown that when looking at images containing human faces, observers tend to rapidly focus on the facial regions. But is this true of other high-level image features as well? We here investigate the extent to which natural scenes containing faces, text elements, and cell phones-as a suitable control-attract attention by tracking the eye movements of subjects in two types of tasks-free viewing and search. We observed that subjects in free-viewing conditions look at faces and text 16.6 and 11.1 times more than similar regions normalized for size and position of the face and text. In terms of attracting gaze, text is almost as effective as faces. Furthermore, it is difficult to avoid looking at faces and text even when doing so imposes a cost. We also found that subjects took longer in making their initial saccade when they were told to avoid faces/text and their saccades landed on a non-face/non-text object. We refine a well-known bottom-up computer model of saliency-driven attention that includes conspicuity maps for color, orientation, and intensity by adding high-level semantic information (i.e., the location of faces or text) and demonstrate that this significantly improves the ability to predict eye fixations in natural images. Our enhanced model's predictions yield an area under the ROC curve over 84% for images that contain faces or text when compared against the actual fixation pattern of subjects. This suggests that the primate visual system allocates attention using such an enhanced saliency map.

Polar Similars: Using Massive Mobile Dating Data to Predict Synchronization and Similarity in Dating Preferences.

Leveraging a massive dataset of over 421 million potential matches between single users on a leading mobile dating application, we were able to identify numerous characteristics of effective matching. Effective matching is defined as the exchange of contact information with the likely intent to meet in person. The characteristics of effective match include alignment of psychological traits (i.e., extroversion), physical traits (i.e., height), personal choices (i.e., desiring the same relationship type), and shared experiences. For nearly all characteristics, the more similar the individuals were, the higher the likelihood was of them finding each other desirable and opting to meet in person. The only exception was introversion, where introverts rarely had an effective match with other introverts. When investigating the preliminary stages of the choice process we looked at the consistency between the choice of men/women, the time it took users to make these binary choices, and the tendency of yes/no decisions. We used a biologically inspired choice model to estimate the decision process and could predict the selection and response time with nearly 60% accuracy. Given that people make their initial selection in no more than 11 s, and ultimately prefer a partner who shares numerous attributes with them, we suggest that users are less selective in their early preferences and gradually, during their conversation, converge onto clusters that share a high degree of similarity in characteristics.

Advance care planning in Parkinson's disease: ethical challenges and future directions.

Recent discoveries support the principle that palliative care may improve the quality of life of patients with Parkinson's disease and those who care for them. Advance care planning, a component of palliative care, provides a vehicle through which patients, families, and clinicians can collaborate to identify values, goals, and preferences early, as well as throughout the disease trajectory, to facilitate care concordant with patient wishes. While research on this topic is abundant in other life-limiting disorders, particularly in oncology, there is a paucity of data in Parkinson's disease and related neurological disorders. We review and critically evaluate current practices on advance care planning through the analyses of three bioethical challenges pertinent to Parkinson's disease and propose recommendations for each.

Lauren Slater 's Blue Dreams: The Science and the Story of the Drugs that Changed Our Minds.

In 1988, Lauren Slater became one of the first patients in the US to take Prozac. She also emerged as one of its most poetic chroniclers when she detailed her heady, complex love affair with the drug in "Prozac Diary" (1998). Thirty years since that first book, Slater explores the discovery, invention, science, and people behind today's drugs that define mind, emotion, and behavior, from the earliest, Thorazine and Lithium, to Ecstasy, "magic mushrooms," and through today's most cutting-edge memory drugs and neural implants.

Observers are consistent when rating image conspicuity.

Human perception of an image's conspicuity depends on the stimulus itself and the observer's semantic interpretation. We investigated the relative contribution of the former, sensory-driven, component. Participants viewed sequences of images from five different classes-fractals, overhead satellite imagery, grayscale and colored natural scenes, and magazine covers-and graded each numerically according to its perceived conspicuity. We found significant consistency in this rating within and between observers for all image categories. In a subsequent recognition memory test, performance was significantly above chance for all categories, with the weakest memory for satellite imagery, and reaching near ceiling for magazine covers. When repeating the experiment after one year, ratings remained consistent within each observer and category, despite the absence of explicit scene memory. Our findings suggest that the rating of image conspicuity is driven by image-immanent, sensory factors common to all observers.

Comparing social attention in autism and amygdala lesions: effects of stimulus and task condition.

The amygdala plays a critical role in orienting gaze and attention to socially salient stimuli. Previous work has demonstrated that SM a patient with rare bilateral amygdala lesions, fails to fixate and make use of information from the eyes in faces. Amygdala dysfunction has also been implicated as a contributing factor in autism spectrum disorders (ASD), consistent with some reports of reduced eye fixations in ASD. Yet, detailed comparisons between ASD and patients with amygdala lesions have not been undertaken. Here we carried out such a comparison, using eye tracking to complex social scenes that contained faces. We presented participants with three task conditions. In the Neutral task, participants had to determine what kind of room the scene took place in. In the Describe task, participants described the scene. In the Social Attention task, participants inferred where people in the scene were directing their attention. SM spent less time looking at the eyes and much more time looking at the mouths than control subjects, consistent with earlier findings. There was also a trend for the ASD group to spend less time on the eyes, although this depended on the particular image and task. Whereas controls and SM looked more at the eyes when the task required social attention, the ASD group did not. This pattern of impairments suggests that SM looks less at the eyes because of a failure in stimulus-driven attention to social features, whereas individuals with ASD look less at the eyes because they are generally insensitive to socially relevant information and fail to modulate attention as a function of task demands. We conclude that the source of the social attention impairment in ASD may arise upstream from the amygdala, rather than in the amygdala itself.