Local orchestration of distributed functional patterns supporting loss and restoration of consciousness in the primate brain.

A central challenge of neuroscience is to elucidate how brain function supports consciousness. Here, we combine the specificity of focal deep brain stimulation with fMRI coverage of the entire cortex, in awake and anaesthetised non-human primates. During propofol, sevoflurane, or ketamine anaesthesia, and subsequent restoration of responsiveness by electrical stimulation of the central thalamus, we investigate how loss of consciousness impacts distributed patterns of structure-function organisation across scales. We report that distributed brain activity under anaesthesia is increasingly constrained by brain structure across scales, coinciding with anaesthetic-induced collapse of multiple dimensions of hierarchical cortical organisation. These distributed signatures are observed across different anaesthetics, and they are reversed by electrical stimulation of the central thalamus, coinciding with recovery of behavioural markers of arousal. No such effects were observed upon stimulating the ventral lateral thalamus, demonstrating specificity. Overall, we identify consistent distributed signatures of consciousness that are orchestrated by specific thalamic nuclei.

Neural encoding of musical expectations in a non-human primate.

The appreciation of music is a universal trait of humankind.1,2,3 Evidence supporting this notion includes the ubiquity of music across cultures4,5,6,7 and the natural predisposition toward music that humans display early in development.8,9,10 Are we musical animals because of species-specific predispositions? This question cannot be answered by relying on cross-cultural or developmental studies alone, as these cannot rule out enculturation.11 Instead, it calls for cross-species experiments testing whether homologous neural mechanisms underlying music perception are present in non-human primates. We present music to two rhesus monkeys, reared without musical exposure, while recording electroencephalography (EEG) and pupillometry. Monkeys exhibit higher engagement and neural encoding of expectations based on the previously seeded musical context when passively listening to real music as opposed to shuffled controls. We then compare human and monkey neural responses to the same stimuli and find a species-dependent contribution of two fundamental musical features-pitch and timing12-in generating expectations: while timing- and pitch-based expectations13 are similarly weighted in humans, monkeys rely on timing rather than pitch. Together, these results shed light on the phylogeny of music perception. They highlight monkeys' capacity for processing temporal structures beyond plain acoustic processing, and they identify a species-dependent contribution of time- and pitch-related features to the neural encoding of musical expectations.

Ethnoprimatology of the Shipibo of the upper Ucayali River, Perú.

In the Anthropocene, primate conservation can only take place when considering human culture, perspectives, and needs. Such approaches are increasingly important under the growing impact of anthropogenic activities and increasing number of threatened primates. The Amazon rainforest, rich in cultural and biological diversity, where indigenous people play a crucial role in primate conservation, provides ample opportunity to study human-primate interactions and the sociocultural context in which they occur. Human activities threaten the Amazon's fragile ecosystems and its primates, which play a key role in its maintenance and regeneration. This study focuses on one of the largest indigenous groups in the Peruvian Amazon: the Shipibo. Interviews and participant observation were used to investigate local perceptions of animal presence and depletion, food preferences, and how primates are incorporated into daily life and culture. Since time immemorial and still today, primates remain important in Shipibo culture, mythology, and subsistence. Local Shipibo participants consistently identified the presence of 13 species of primate. Primates were among the preferred species for consumption, pet keeping, and held a fundamental role in mythology, traditional knowledge, and storytelling. Large-bodied primates were often mentioned as being locally extinct, with reports and observations suggesting increasing consumption of smaller-bodied primates. Commonly perceived reasons for primate depletion include noise disturbance, hunting, and population growth, often in parallel. This study sheds light on the cultural context of an area rich in biodiversity, where primates, essential for ecological balance and integral to Shipibo lives and identity, are being depleted. We highlight the need for an inclusive ethnoprimatological approach to conserving primates and preserving indigenous heritage while improving local livelihoods.

Critical test of the assumption that the hypothalamic entopeduncular nucleus of rodents is homologous with the primate internal pallidum.

The globus pallidus (GP) of primates is divided conventionally into distinct internal and external parts. The literature repeats since 1930 the opinion that the homolog of the primate internal pallidum in rodents is the hypothalamic entopeduncular nucleus (embedded within fiber tracts of the cerebral peduncle). To test this idea, we explored its historic fundaments, checked the development and genoarchitecture of mouse entopeduncular and pallidal neurons, and examined relevant comparative connectivity data. We found that the extratelencephalic mouse entopeduncular structure consists of four different components arrayed along a dorsoventral sequence in the alar hypothalamus. The ventral entopeduncular nucleus (EPV), with GABAergic neurons expressing Dlx5&6 and Nkx2-1, lies within the hypothalamic peduncular subparaventricular area. Three other formations-the dorsal entopeduncular nucleus (EPD), the prereticular entopeduncular nucleus (EPPRt ), and the preeminential entopeduncular nucleus (EPPEm )-lie within the overlying paraventricular area, under the subpallium. EPD contains glutamatergic neurons expressing Tbr1, Otp, and Pax6. The EPPRt has GABAergic cells expressing Isl1 and Meis2, whereas the EPPEm population expresses Foxg1 and may be glutamatergic. Genoarchitectonic observations on relevant areas of the mouse pallidal/diagonal subpallium suggest that the GP of rodents is constituted as in primates by two adjacent but molecularly and hodologically differentiable telencephalic portions (both expressing Foxg1). These and other reported data oppose the notion that the rodent extratelencephalic entopeduncular nucleus is homologous to the primate internal pallidum. We suggest instead that all mammals, including rodents, have dual subpallial GP components, whereas primates probably also have a comparable set of hypothalamic entopeduncular nuclei. Remarkably, there is close similarity in some gene expression properties of the telencephalic internal GP and the hypothalamic EPV. This apparently underlies their notable functional analogy, sharing GABAergic neurons and thalamopetal connectivity.

Intravitreal Neuroglobin Mitigates Primate Experimental Glaucomatous Structural Damage in Association with Reduced Optic Nerve Microglial and Complement 3-Astrocyte Activation.

Current management of glaucomatous optic neuropathy is limited to intraocular pressure control. Neuroglobin (Ngb) is an endogenous neuroprotectant expressed in neurons and astrocytes. We recently showed that exogenous intravitreal Ngb reduced inflammatory cytokines and microglial activation in a rodent model of hypoxia. We thus hypothesised that IVT-Ngb may also be neuroprotective in experimental glaucoma (EG) by mitigating optic nerve (ON) astrogliosis and microgliosis as well as structural damage. In this study using a microbead-induced model of EG in six Cynomolgus primates, optical coherence imaging showed that Ngb-treated EG eyes had significantly less thinning of the peripapillary minimum rim width, retinal nerve fibre layer thickness, and ON head cupping than untreated EG eyes. Immunohistochemistry confirmed that ON astrocytes overexpressed Ngb following Ngb treatment. A reduction in complement 3 and cleaved-caspase 3 activated microglia and astrocytes was also noted. Our findings in higher-order primates recapitulate the effects of neuroprotection by Ngb treatment in rodent EG studies and suggest that Ngb may be a potential candidate for glaucoma neuroprotection in humans.

Functional network properties of the auditory cortex.

The auditory system transforms auditory stimuli from the external environment into perceptual auditory objects. Recent studies have focused on the contribution of the auditory cortex to this transformation. Other studies have yielded important insights into the contributions of neural activity in the auditory cortex to cognition and decision-making. However, despite this important work, the relationship between auditory-cortex activity and behavior/perception has not been fully elucidated. Two of the more important gaps in our understanding are (1) the specific and differential contributions of different fields of the auditory cortex to auditory perception and behavior and (2) the way networks of auditory neurons impact and facilitate auditory information processing. Here, we focus on recent work from non-human-primate models of hearing and review work related to these gaps and put forth challenges to further our understanding of how single-unit activity and network activity in different cortical fields contribution to behavior and perception.

Mapping the primate thalamus: systematic approach to analyze the distribution of subcortical neuromodulatory afferents.

Neuromodulatory afferents to thalamic nuclei are key for information transmission and thus play critical roles in sensory, motor, and limbic processes. Over the course of the last decades, diverse attempts have been made to map and describe subcortical neuromodulatory afferents to the primate thalamus, including axons using acetylcholine, serotonin, dopamine, noradrenaline, adrenaline, and histamine. Our group has been actively involved in this endeavor. The published descriptions on neuromodulatory afferents to the primate thalamus have been made in different laboratories and are not fully comparable due to methodological divergences (for example, fixation procedures, planes of cutting, techniques used to detect the afferents, different criteria for identification of thalamic nuclei…). Such variation affects the results obtained. Therefore, systematic methodological and analytical approaches are much needed. The present article proposes reproducible methodological and terminological frameworks for primate thalamic mapping. We suggest the use of standard stereotaxic planes to produce and present maps of the primate thalamus, as well as the use of the Anglo-American school terminology (vs. the German school terminology) for identification of thalamic nuclei. Finally, a public repository of the data collected under agreed-on frameworks would be a useful tool for looking up and comparing data on the structure and connections of primate thalamic nuclei. Important and agreed-on efforts are required to create, manage, and fund a unified and homogeneous resource of data on the primate thalamus. Likewise, a firm commitment of the institutions to preserve experimental brain material is much needed because neuroscience work with non-human primates is becoming increasingly rare, making earlier material still more valuable.

Homo medicus: The transition to meat eating increased pathogen pressure and the use of pharmacological plants in Homo.

The human lineage transitioned to a more carnivorous niche 2.6 mya and evolved a large body size and slower life history, which likely increased zoonotic pathogen pressure. Evidence for this increase includes increased zoonotic infections in modern hunter-gatherers and bushmeat hunters, exceptionally low stomach pH compared to other primates, and divergence in immune-related genes. These all point to change, and probably intensification, in the infectious disease environment of Homo compared to earlier hominins and other apes. At the same time, the brain, an organ in which immune responses are constrained, began to triple in size. We propose that the combination of increased zoonotic pathogen pressure and the challenges of defending a large brain and body from pathogens in a long-lived mammal, selected for intensification of the plant-based self-medication strategies already in place in apes and other primates. In support, there is evidence of medicinal plant use by hominins in the middle Paleolithic, and all cultures today have sophisticated, plant-based medical systems, add spices to food, and regularly consume psychoactive plant substances that are harmful to helminths and other pathogens. We propose that the computational challenges of discovering effective plant-based treatments, the consequent ability to consume more energy-rich animal foods, and the reduced reliance on energetically-costly immune responses helped select for increased cognitive abilities and unique exchange relationships in Homo. In the story of human evolution, which has long emphasized hunting skills, medical skills had an equal role to play.

Mapping the primate thalamus: historical perspective and modern approaches for defining nuclei.

The primate thalamus has been subdivided into multiple nuclei and nuclear groups based on cytoarchitectonic, myeloarchitectonic, connectional, histochemical, and genoarchitectonic differences. Regarding parcellation and terminology, two main schools prevailed in the twentieth century: the German and the Anglo-American Schools, which proposed rather different schemes. The German parcellation and terminology has been mostly used for the human thalamus in neurosurgery atlases; the Anglo-American parcellation and terminology is the most used in experimental research on the primate thalamus. In this article, we review the historical development of terminological and parcellation schemes for the primate thalamus over the last 200 years. We trace the technological innovations and conceptual advances in thalamic research that underlie each parcellation, from the use of magnifying lenses to contemporary genoarchitectonic stains during ontogeny. We also discuss the advantages, disadvantages, and practical use of each parcellation.

Anatomical organization of forebrain circuits in the primate.

The primate forebrain is a complex structure. Thousands of connections have been identified between cortical areas, and between cortical and sub-cortical areas. Previous work, however, has suggested that a number of principles can be used to reduce this complexity. Here, we integrate four principles that have been put forth previously, including a nested model of neocortical connectivity, gradients of connectivity between frontal cortical areas and the striatum and thalamus, shared patterns of sub-cortical connectivity between connected posterior and frontal cortical areas, and topographic organization of cortical-striatal-pallidal-thalamocortical circuits. We integrate these principles into a single model that accounts for a substantial amount of connectivity in the forebrain. We then suggest that studies in evolution and development can account for these four principles, by assuming that the ancestral vertebrate pallium was dominated by medial, hippocampal and ventral-lateral, pyriform areas, and at most a small dorsal pallium. The small dorsal pallium expanded massively in the lineage leading to primates. During this expansion, topological, adjacency relationships were maintained between pallial and sub-pallial areas. This maintained topology led to the connectivity gradients seen between cortex, striatum, pallidum, and thalamus.

Cortical depth profiles of auditory and visual 7 T functional MRI responses in human superior temporal areas.

Invasive neurophysiological studies in nonhuman primates have shown different laminar activation profiles to auditory vs. visual stimuli in auditory cortices and adjacent polymodal areas. Means to examine the underlying feedforward vs. feedback type influences noninvasively have been limited in humans. Here, using 1-mm isotropic resolution 3D echo-planar imaging at 7 T, we studied the intracortical depth profiles of functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) signals to brief auditory (noise bursts) and visual (checkerboard) stimuli. BOLD percent-signal-changes were estimated at 11 equally spaced intracortical depths, within regions-of-interest encompassing auditory (Heschl's gyrus, Heschl's sulcus, planum temporale, and posterior superior temporal gyrus) and polymodal (middle and posterior superior temporal sulcus) areas. Effects of differing BOLD signal strengths for auditory and visual stimuli were controlled via normalization and statistical modeling. The BOLD depth profile shapes, modeled with quadratic regression, were significantly different for auditory vs. visual stimuli in auditory cortices, but not in polymodal areas. The different depth profiles could reflect sensory-specific feedforward versus cross-sensory feedback influences, previously shown in laminar recordings in nonhuman primates. The results suggest that intracortical BOLD profiles can help distinguish between feedforward and feedback type influences in the human brain. Further experimental studies are still needed to clarify how underlying signal strength influences BOLD depth profiles under different stimulus conditions.

Suppressive effects of ketamine on auditory steady-state responses in intact, awake macaques: A non-human primate model of schizophrenia.

Auditory steady-state responses (ASSRs) are recurrent neural activities entrained to regular cyclic auditory stimulation. ASSRs are altered in individuals with schizophrenia, and may be related to hypofunction of the N-methyl-D-aspartate (NMDA) glutamate receptor. Noncompetitive NMDA receptor antagonists, including ketamine, have been used in ASSR studies of rodent models of schizophrenia. Although animal studies using non-human primates are required to complement rodent studies, the effects of ketamine on ASSRs are unknown in intact awake non-human primates. In this study, after administration of vehicle or ketamine, click trains at 20-83.3 Hz were presented to elicit ASSRs during recording of electroencephalograms in intact, awake macaque monkeys. The results indicated that ASSRs quantified by event-related spectral perturbation and inter-trial coherence were maximal at 83.3 Hz after vehicle administration, and that ketamine reduced ASSRs at 58.8 and 83.3 Hz, but not at 20 and 40 Hz. The present results demonstrated a reduction of ASSRs by the NMDA receptor antagonist at optimal frequencies with maximal responses in intact, awake macaques, comparable to ASSR reduction in patients with schizophrenia. These findings suggest that ASSR can be used as a neurophysiological biomarker of the disturbance of gamma-oscillatory neural circuits in this ketamine model of schizophrenia using intact, awake macaques. Thus, this model with ASSRs would be useful in the investigation of human brain pathophysiology as well as in preclinical translational research.

Biochronology of South African hominin-bearing sites: A reassessment using cercopithecid primates.

Despite recent advances in chronometric techniques (e.g., Uranium-Lead [U-Pb], cosmogenic nuclides, electron spin resonance spectroscopy [ESR]), considerable uncertainty remains regarding the age of many Plio-Pleistocene hominin sites, including several in South Africa. Consequently, biochronology remains important in assessments of Plio-Pleistocene geochronology and provides direct age estimates of the fossils themselves. Historically, cercopithecid monkeys have been among the most useful taxa for biochronology of early hominins because they are widely present and abundant in the African Plio-Pleistocene record. The last major studies using cercopithecids were published over 30 y ago. Since then, new hominin sites have been discovered, radiometric age estimates have been refined, and many changes have occurred in cercopithecid taxonomy and systematics. Thus, a biochronological reassessment using cercopithecids is long overdue. Here, we provide just such a revision based on our recent study of every major cercopithecid collection from African Plio-Pleistocene sites. In addition to correlations based on shared faunal elements, we present an analysis based on the dentition of the abundant cercopithecid Theropithecus oswaldi, which increases in size in a manner that is strongly correlated with geological age (r2 ∼0.83), thereby providing a highly accurate age-estimation tool not previously utilized. In combination with paleomagnetic and U-Pb data, our results provide revised age estimates and suggest that there are no hominin sites in South Africa significantly older than ∼2.8 Ma. Where conflicting age estimates exist, we suggest that additional data are needed and recall that faunal estimates have ultimately proved reliable in the past (e.g., the age of the KBS Tuff).

Self-medication in nonhuman primates: A systematic evaluation of the possible function of the use of medicinal plants.

Animal self-medication is thought to provide an adaptive advantage, as species would actively respond to a disease state or homeostatic imbalances. In wild nonhuman primates, it is challenging to differentiate plant use as part of the diet or as medication, especially because self-medication can be preventive or therapeutic. Here, we aimed to compile the available potential evidence on primate self-medication modes, investigating which proposed requirements are fulfilled for each plant species reported to date. We systematically reviewed the scientific literature on plant use for potential self-medication in wild nonhuman primates. To construct the extensive database, we extracted data on the primate species, study area, plant/plant's part used, the requirement(s) met for demonstrating self-medication modes, and self-medicative behavioral patterns. We also updated available information on plant's biological compounds and/or physical characteristics, pharmacological properties, and ethnomedical uses. We identified 575 plant species (135 families), used by 25 primate species (9 families). Plants were used by Old World monkeys (46.5%, n = 268 plant species), followed by apes (41%, n = 235), New World monkeys (13.4%, n = 77), and prosimians (1%, n = 6). We found three general types of self-medicative behaviors: ingestion (including, but not limited to, leaf-swallowing, seed-swallowing, and bitter pith chewing), topical (fur-rubbing), and nest fumigation. Plant uses were associated with antiparasitic, antibacterial, antimalarial, anti-inflammatory, insect repellent, among other properties. Self-medication is widespread in nonhuman primate species across Central and South America, Africa, Madagascar, and Asia. Long-term field research efforts and studies integrating different research sites and topics are urgent to advance our knowledge into the evolution of plant selection, medical traditions, and to bring insights into potentially novel medicinal plants and bioactive compounds to treat emergent or established primate and human diseases.

Increasing the Reuse of Protein Non-Naïve Nonhuman Primates in Pharmaceutical Drug Discovery and Development: An Overview and Industry Position on the Challenges and Benefits.

The IQ Consortium NHP Reuse Working Group (WG) comprises members from 15 pharmaceutical and biotechnology companies. In 2020, the WG developed and distributed a detailed questionnaire on protein non-naïve NHP reuse to the WG member companies. The WG received responses from key stakeholders including principal investigators, facility managers, animal welfare officers and research scientists. This paper's content reflects the consolidated opinion of the WG members and the questionnaire responses on the subject of NHP reuse within nonclinical programs at all stages of research and development. Many of the pharmaceutical companies represented in the working group or participating in the questionnaire have already achieved some level of NHP reuse in their nonclinical programs, but the survey results suggested that there is significant potential to increase NHP reuse further and a need to understand the considerations involved in reuse more clearly. The WG has also focused carefully on the inherent concerns and risks of implementing protein non-naive NHP reuse and has evaluated the best methods of risk assessment and decision-making. This paper presents a discussion on the challenges and opportunities surrounding protein non-naïve NHP reuse and aims to stimulate further industry dialogue on the subject and provide guidance for pharmaceutical companies to establish roadmaps and decision trees enabling increased protein non-naïve NHP reuse. In addition, this paper represents a solid basis for collaborative engagement between pharmaceutical and biotechnology companies with contract research organizations (CROs) to discuss how the availability of protein non-naïve NHP within CROs can be better leveraged for their use within nonclinical studies.

A versatile toolbox for studying cortical physiology in primates.

Lesioning and neurophysiological studies have facilitated the elucidation of cortical functions and mechanisms of functional recovery following injury. Clinical translation of such studies is contingent on their employment in non-human primates (NHPs), yet tools for monitoring and modulating cortical physiology are incompatible with conventional lesioning techniques. To address these challenges, we developed a toolbox validated in seven macaques. We introduce the photothrombotic method for inducing focal cortical lesions, a quantitative model for designing experiment-specific lesion profiles and optical coherence tomography angiography (OCTA) for large-scale (~5 cm2) monitoring of vascular dynamics. We integrate these tools with our electrocorticographic array for large-scale monitoring of neural dynamics and testing stimulation-based interventions. Advantageously, this versatile toolbox can be incorporated into established chronic cranial windows. By combining optical and electrophysiological techniques in the NHP cortex, we can enhance our understanding of cortical functions, investigate functional recovery mechanisms, integrate physiological and behavioral findings, and develop neurorehabilitative treatments. MOTIVATION The primate neocortex encodes for complex functions and behaviors, the physiologies of which are yet to be fully understood. Such an understanding in both healthy and diseased states can be crucial for the development of effective neurorehabilitative strategies. However, there is a lack of a comprehensive and adaptable set of tools that enables the study of multiple physiological phenomena in healthy and injured brains. Therefore, we developed a toolbox with the capability to induce targeted cortical lesions, monitor dynamics of underlying cortical microvasculature, and record and stimulate neural activity. With this toolbox, we can enhance our understanding of cortical functions, investigate functional recovery mechanisms, test stimulation-based interventions, and integrate physiological and behavioral findings.

A computational framework for canonical holistic morphometric analysis of trabecular bone.

Bone is a remarkable, living tissue that functionally adapts to external loading. Therefore, bone shape and internal structure carry information relevant to many disciplines, including medicine, forensic science, and anthropology. However, morphometric comparisons of homologous regions across different individuals or groups are still challenging. In this study, two methods were combined to quantify such differences: (1) Holistic morphometric analysis (HMA) was used to quantify morphometric values in each bone, (2) which could then be mapped to a volumetric mesh of a canonical bone created by a statistical free-form deformation model (SDM). Required parameters for this canonical holistic morphometric analysis (cHMA) method were identified and the robustness of the method was evaluated. The robustness studies showed that the SDM converged after one to two iterations, had only a marginal bias towards the chosen starting image, and could handle large shape differences seen in bones of different species. Case studies were performed on metacarpal bones and proximal femora of different primate species to confirm prior study results. The differences between species could be visualised and statistically analysed in both case studies. cHMA provides a framework for performing quantitative comparisons of different morphometric quantities across individuals or groups. These comparisons facilitate investigation of the relationship between spatial morphometric variations and function or pathology, or both.

Deep brain stimulation of the thalamus restores signatures of consciousness in a nonhuman primate model.

Loss of consciousness is associated with the disruption of long-range thalamocortical and corticocortical brain communication. We tested the hypothesis that deep brain stimulation (DBS) of central thalamus might restore both arousal and awareness following consciousness loss. We applied anesthesia to suppress consciousness in nonhuman primates. During anesthesia, central thalamic stimulation induced arousal in an on-off manner and increased functional magnetic resonance imaging activity in prefrontal, parietal, and cingulate cortices. Moreover, DBS restored a broad dynamic repertoire of spontaneous resting-state activity, previously described as a signature of consciousness. None of these effects were obtained during the stimulation of a control site in the ventrolateral thalamus. Last, DBS restored a broad hierarchical response to auditory violations that was disrupted under anesthesia. Thus, DBS restored the two dimensions of consciousness, arousal and conscious access, following consciousness loss, paving the way to its therapeutical translation in patients with disorders of consciousness.

Diurnal and circadian rhythmicity of the human blood transcriptome overlaps with organ- and tissue-specific expression of a non-human primate.

BACKGROUND: Twenty-four-hour rhythmicity in mammalian tissues and organs is driven by local circadian oscillators, systemic factors, the central circadian pacemaker and light-dark cycles. At the physiological level, the neural and endocrine systems synchronise gene expression in peripheral tissues and organs to the 24-h-day cycle, and disruption of such regulation has been shown to lead to pathological conditions. Thus, monitoring rhythmicity in tissues/organs holds promise for circadian medicine; however, most tissues and organs are not easily accessible in humans and alternative approaches to quantify circadian rhythmicity are needed. We investigated the overlap between rhythmic transcripts in human blood and transcripts shown to be rhythmic in 64 tissues/organs of the baboon, how these rhythms are aligned with light-dark cycles and each other, and whether timing of tissue-specific rhythmicity can be predicted from a blood sample. RESULTS: We compared rhythmicity in transcriptomic time series collected from humans and baboons using set logic, circular cross-correlation, circular clustering, functional enrichment analyses, and least squares regression. Of the 759 orthologous genes that were rhythmic in human blood, 652 (86%) were also rhythmic in at least one baboon tissue and most of these genes were associated with basic processes such as transcription and protein homeostasis. In total, 109 (17%) of the 652 overlapping rhythmic genes were reported as rhythmic in only one baboon tissue or organ and several of these genes have tissue/organ-specific functions. The timing of human and baboon rhythmic transcripts displayed prominent 'night' and 'day' clusters, with genes in the dark cluster associated with translation. Alignment between baboon rhythmic transcriptomes and the overlapping human blood transcriptome was significantly closer when light onset, rather than midpoint of light, or end of light period, was used as phase reference point. The timing of overlapping human and baboon rhythmic transcriptomes was significantly correlated in 25 tissue/organs with an average earlier timing of 3.21 h (SD 2.47 h) in human blood. CONCLUSIONS: The human blood transcriptome contains sets of rhythmic genes that overlap with rhythmic genes of tissues/organs in baboon. The rhythmic sets vary across tissues/organs, but the timing of most rhythmic genes is similar in human blood and baboon tissues/organs. These results have implications for development of blood transcriptome-based biomarkers for circadian rhythmicity in tissues and organs.

Face perception: computational insights from phylogeny.

Studies of face perception in primates elucidate the psychological and neural mechanisms that support this critical and complex ability. Recent progress in characterizing face perception across species, for example in insects and reptiles, has highlighted the ubiquity over phylogeny of this key ability for social interactions and survival. Here, we review the competence in face perception across species and the types of computation that support this behavior. We conclude that the computational complexity of face perception evinced by a species is not related to phylogenetic status and is, instead, largely a product of environmental context and social and adaptive pressures. Integrating findings across evolutionary data permits the derivation of computational principles that shed further light on primate face perception.