Late Pleistocene and Holocene climates as viewed from Verlore Vlei

Main articleEvidence from a number of sites along the lower reaches of the Verlore Vlei and the adjacent coastline is interpreted as reflecting considerable environmental change since about 18 000 B.P. In particular seven points are relevant.Non

Individual differences in recogn-eye-zing faces: Behavioural and neural underpinnings of face recognition in neurotypical and autistic adults

Attention to another’s eyes and face recognition are necessary building blocks for efficient social communication. Neurotypical adults show an attentional bias for the eye region and strong face recognition performance. In contrast, adults with an autism spectrum disorder (ASD) often have pervasive difficulties looking at the eyes and recognizing others. These behavioural tendencies have led researchers to propose the eye avoidance and indifference theories of face recognition: implicating disruptions in eye sensitivity as a potential source of face recognition difficulties, although a direct link has yet to be established at the individual level. Holistic integration also plays a key role in neurotypical face recognition, although the temporal neurodynamics of autistic holistic integration remain unclear. Addressing this clinically relevant gap in the literature and acknowledging the within-group heterogeneity reported for both autistic and neurotypical adults, this dissertation presents four empirical studies evaluating feature saliency during face perception and its relationship with face recognition accuracy in adults with and without an ASD. Chapter 2 presents one of the first evaluations establishing direct associations between fixations to internal facial features during face encoding and recognition accuracy (d′) across incidental and intentional task demands. Results demonstrate incidental recognition accuracy is positively associated with left eye and nasion fixation patterns but is negatively impacted by increased fixations to the nose. Intentional recognition accuracy, on the other hand, negatively correlates with fixations directed towards non-core features and sub-clinical autistic traits. Chapter 3 then extends this research into a clinical ASD population and neurotypical control adults, evaluating face recognition performance from a neurodiversity perspective. Despite between-group analyses revealing autistic adults spend less time looking at faces during encoding, neurotypical and autistic adults’ eye movements do not differ in their fixation patterns towards internal features nor in their recognition accuracy scores. Within-group analyses for adults with an ASD reveal a negative association between autism symptomology and intentional face recognition accuracy. To clarify the temporal neurodynamics of early face perception in autism, two ERP experiments were completed by a subset of participants from Chapter 3. N170 peak amplitudes and latencies were measured in response to upright/inverted faces and cars, isolated eye regions, and isolated mouths (Chapter 4) and in response to intact faces with fixation enforced to the left eye, right eye, nasion, nose, or mouth (Chapter 5). Consistent with neurotypical patterns, autistic adults demonstrate preserved markers of eye sensitivity and holistic integration at the N170 level when fixation is enforced. Collectively, this research signifies the importance of the eyes and nasion in supporting neurotypical and autistic face recognition accuracy and emphasizes the importance of accounting for individual differences from a neurodiversity perspective in social cognition research. Considerations for monitoring visual attention to faces and moving towards more individualized methods in neuroimaging studies are also discussed. This research has important clinical implications for the advancement and assessment of face recognition and social cognition abilities in ASD

An eye (region) sensitivity during early face perception: The N170 is modulated by facial context and featural fixation

The N170 is a face-sensitive ERP component that also demonstrates a particular sensitivity to the eyes. Specifically, the N170 responds maximally to isolated eye regions (i.e., two eyes), as well as to eye fixations within a face. Here I compared N170 modulations when facial features (left eye, right eye, nasion, nose, and mouth) were fixated in isolation or within a full face. Fixation on the desired feature was continuously enforced using a gaze-contingent eye-tracking procedure. In order to further assess this eye sensitivity, I also compared the N170 response to single isolated eyes and the classically-used eye region. The N170 was largest and most delayed when features were fixated in isolation, compared to equivalent fixations in a full face. An eye sensitivity within a face context was observed, with larger N170 amplitudes elicited when the left or right eye was fixated. Mouth fixation yielded the smallest and most delayed N170 within a face, and showed the largest amplitude difference between fixation in isolation and fixation within a face. For isolated features, single eyes did not differ from mouths, yielding significantly larger and faster N170 responses compared to isolated noses. Alternatively, isolated eye regions elicited consistently larger and shorter N170 responses compared to single isolated eyes, irrespective of eye or nasion fixation. These results highlight the importance of the eyes in early face perception, and provide compelling support for an interplay between featural and holistic neural mechanisms. These findings also provide novel evidence of an increased sensitivity to the presence of two symmetric eyes within the eye region compared to only one eye, consistent with an eye region detector rather than an eye detector per se

Characterization of the molecular and electrophysiological properties of the T-type calcium channel in human myometrium

Rises in intracellular calcium are essential for contraction of human myometrial smooth muscle (HMSM) and hence parturition. The T-type calcium channel may play a role in this process. The aim was to investigate the role of the T-Type calcium channel in HMSM by characterizing mRNA expression, protein localization, electrophysiological properties and function of the channel subunits Cav3.1(α1G), Cav3.2(α1H), and Cav3.3(α1I). QRT-PCR, immuno-histochemistry, electrophysiology and invitro contractility were performed on human myometrial samples from term, preterm, labour and not in labour. QRT-PCR analysis of Cav3.1, Cav3.2 and Cav3.3 demonstrated expression of Cav3.1 and Cav3.2 with no significant change (P>0.05) associated with gestation or labour status. Immuno-histochemistry localized Cav3.1 to myometrial and vascular smooth muscle cells whilst Cav3.2 localized to vascular endothelial cells and invading leukocytes. Voltage clamp studies demonstrated a T-type current in 55% of cells. Nickel block of T-type current was voltage sensitive (IC50 of 118.57±68.9 μM at - 30mV). Activation and inactivation curves of ICa currents in cells expressing T-type channels overlapped demonstrating steady state window currents at the resting membrane potential of myometrium at term. Current clamp analysis demonstrated that hyperpolarizing pulses to a membrane potential greater than -80mV elicited rebound calcium spikes that were blocked reversibly by 100μM nickel. Contractility studies demonstrated a reversible decrease in contraction frequency during application of 100μM nickel (P<0.05). We conclude that the primary T-type subunit expressed in some MSMCs is Cav3.1. We found that application of 100 μM nickel to spontaneously contracting human myometrium reversibly slows contraction frequency

Middens and moderns: Shellfishing and the Middle Stone Age of the Western Cape, South Africa

This paper describes some evidence of shellfish gathering from what are arguably among the earliest shell middens in human history. What makes this evidence interesting for scientists involved in explaining human evolutionary events is the fact that it may register a key moment in the emergence of our species. I describe the sites, list some of the archaeological remains, and speculate on the relationship between the evidence for systematic shellfish gathering and the appearance of hominid fossils that almost all palaeoanthropologists would call 'modern'. I have this word in inverted commas because I believe all our definitions of 'modern behaviour', and perhaps even 'modern humans', are self-serving and in need of substantial unpacking. Cynically, modern behaviour is defined as likely to be reflected in the kinds of archaeological remains (worked bone, some or other complex subsistence activity, marked ochre, burial) that we have in hand. It may be better to ask a less loaded question such as what is the history of one of these component behaviours, such as inter-tidal marine food acquisition. The gathering of sessile molluscs is, at first sight, hardly complex, but its nutritional advantages and correlates in the archaeological record might be of considerable significance

Alcohol exposure during late gestation: Multiple developmental outcomes in sheep

Alcohol consumption during pregnancy remains common in many countries. Exposure to even low amounts of alcohol (i.e. ethanol) in pregnancy can lead to the heterogeneous fetal alcohol spectrum disorders (FASD), while heavy alcohol consumption can result in the fetal alcohol syndrome (FAS). FAS is characterized by cerebral dysfunction, growth restriction and craniofacial malformations. However, the effects of lower doses of alcohol during pregnancy, such as those that lead to FASD, are less well understood. In this article, we discuss the findings of recent studies performed in our laboratories on the effects of fetal alcohol exposure using sheep, in which we investigated the effects of late gestational alcohol exposure on the developing brain, arteries, kidneys, heart and lungs. Our studies indicate that alcohol exposure in late gestation can (1) affect cerebral white matter development and increase the risk of hemorrhage in the fetal brain, (2) cause left ventricular hypertrophy with evidence of altered cardiomyocyte maturation, (3) lead to a decrease in nephron number in the kidney, (4) cause altered arterial wall stiffness and endothelial and smooth muscle function and (5) result in altered surfactant protein mRNA expression, surfactant phospholipid composition and pro-inflammatory cytokine mRNA expression in the lung. These findings suggest that fetal alcohol exposure in late gestation can affect multiple organs, potentially increasing the risk of disease and organ dysfunction in later life

Feasibility of Blood Flow Restriction Resistance Exercise for Patients with Intermittent Claudication

Intermittent Claudication (IC) is a common and debilitating symptom of peripheral arterial disease (PAD) resulting in significant reduction in exercise performance and quality of life. Supervised exercise programmes are part of first-line treatment for IC proving highly effective for improving exercise performance and alleviating symptoms. Despite this, supervised exercise programmes have poor adherence in part to patients’ inability to tolerate IC related pain during walking exercise highlighting the need for alternative exercise modes. Blood flow restriction resistance exercise (BFR-RE) is a technique that facilitates local muscle hypoxia during resistance exercise to induce hypertrophy, strength, and muscular endurance. BFR-RE presents an exciting alternative modality to improve exercise performance in IC patients though requires research on safety, feasibility, and efficacy. This research explored the acute perceptual, affective, and physiological responses to resistance exercises performed at low-load with BFR (LL-BFR), low-load (LL) and moderate-load (ML) in healthy young and older adults; examined the inter-day reliability of a physical function test battery in IC patients sought to determine suitability of the test battery and smallest worthwhile change for each measure; and conducted a randomised controlled trial to evaluate the safety, feasibility, and efficacy of an 8-week LL-BFR resistance exercise programme in IC patients. No adverse events were recorded during this body of work that was attributed to the protocols or procedures administered. LL-BFR was shown to be more demanding than LL and ML predominately through increased pain (p ≤ 0.024, d = 0.8 – 1.4). However, this did not lead to decrements in affective response and fatigue post exercise. Excellent reliability (≥ 0.92 ICC) of the physical function test battery was observed in IC patients and the minimum likely change (76% chance) was calculated for each measure. The feasibility trial observed high adherence (LL-BFR = 78.3%, LL = 83.8%) and completion rates (LL-BFR = 93%, LL = 87%). Significant clinical improvement (>35 m) in the six-minute walk test (6MWT) was achieved in 86% of patients in LL-BFR but only 46% of patients in LL. Additionally, time to claudication pain during 6MWT was likely increased (44.7 s [20.8, 68.6]) for LL-BFR and likely unchanged (4.4 s [-32.4, 23.6]) for LL. This thesis supports BFR-RE as a safe, feasible and potentially effective exercise mode for IC patients

Evaluating the between-day reliability and likelihood of change of a test battery incorporating vastus lateralis muscle thickness, ankle-brachial pressure index, maximal voluntary torque, and six-minute walk test in patients with claudication

Objective: The study aims to evaluate the between-day reliability of a proposed test battery for patients with claudication that can be used for monitoring the effectiveness of exercise interventions and other therapeutic strategies tailored to this patient population.Methods: Twenty-five men with claudication were recruited. The test battery consisted of the Vastus Lateralis muscle thickness (VL-MT), ankle-brachial pressure index (ABI), unilateral isometric knee extension maximal voluntary torque (MVT) and 6-minute walk test (6MWT). A single investigator conducted the tests for each patient on two separate testing sessions (T1 and T2) 5–7 days apart.Results: Good to excellent reliability was observed for VL-MT (ICC = 0.95, 95% LOA = ±3.10 mm, SEM = 0.81 mm), ABI (ICC = 0.97, 95% LOA = ±0.10, SEM = 0.02), MVT (ICC = 0.97, 95% LOA = ±24.0 N·m, SEM = 6.31 N·m), 6MWT distance (ICC = 0.99, 95% LOA = ±39.6 m, SEM = 11.0 m), 6MWT time to claudication (ICC = 0.99, 95% LOA = ±30.8 s, SEM = 7.8 s), and 6MWT ratings of pain (ICC = 0.87, 95% LOA = ±2.4 CR-10 +, SEM = 0.7 CR-10 +). Analysis derived from reliability data indicates a change of 1.4 mm for VL-MT, 0.14 for ABI, 12 N·m for MVT, 25 m for 6MWT distance, 15 s for 6MWT time to claudication and 1 CR-10 + for 6MWT ratings of pain is required to be interpreted as the minimum ‘likely’ change (76% chance).Conclusions: The test battery provides a reliable assessment of patients with claudication and can be widely used to evaluate the effects of exercise programmes and other therapeutic interventions. For the individual, changes in VL-MT, ABI, MVT, and 6MWT greater than the minimum likely change as a result of an exercise programme or an intervention are likely changes and less influenced by error associated with the test.</p

One versus two eyes makes a difference! Early face perception is modulated by featural fixation and feature context

The final publication is available at Elsevier via https://doi.org/10.1016/j.cortex.2018.08.025 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The N170 event-related potential component is an early marker of face perception that is particularly sensitive to isolated eye regions and to eye fixations within a face. Here, this eye sensitivity was tested further by measuring the N170 to isolated facial features and to the same features fixated within a face, using a gaze-contingent procedure. The neural response to single isolated eyes and eye regions (two eyes) was also compared. Pixel intensity and contrast were controlled at the global (image) and local (featural) levels. Consistent with previous findings, larger N170 amplitudes were elicited when the left or right eye was fixated within a face, compared to the mouth or nose, demonstrating that the N170 eye sensitivity reflects higher-order perceptual processes and not merely low-level perceptual effects. The N170 was also largest and most delayed for isolated features, compared to equivalent fixations within a face. Specifically, mouth fixation yielded the largest amplitude difference, and nose fixation yielded the largest latency difference between these two contexts, suggesting the N170 may reflect a complex interplay between holistic and featural processes. Critically, eye regions elicited consistently larger and shorter N170 responses compared to single eyes, with enhanced responses for contralateral eye content, irrespective of eye or nasion fixation. These results confirm the importance of the eyes in early face perception, and provide novel evidence of an increased sensitivity to the presence of two symmetric eyes compared to only one eye, consistent with a neural eye region detector rather than an eye detector per se.Natural Sciences and Engineering Research Council of Canada || NSERC #418431 Canada Foundation for Innovation || CFI # 213322 Canada Research Chair program || CRC #213322 and 23040