Local and global stereopsis in the horse.

Although horses have laterally-placed eyes, there is substantial binocular overlap, allowing for the possibility that these animals have stereopsis. In the first experiment of the present study we measured local stereopsis by obtaining monocular and binocular depth thresholds for renal depth stimuli. On all measures, the horses\u27 binocular performance was superior to their monocular. When depth thresholds were obtained, binocular thresholds were several times superior to those obtained monocularly, suggesting that the animals could use stereoscopic information when it was available. The binocular thresholds averaged about 15 min arc. In the second experiment we obtained evidence for the presence of global stereopsis by testing the animals\u27 ability to discriminate between random-dot stereograms with and without consistent disparity information. When presented with such stimuli they showed a strong preference for the cyclopean equivalent of the positive stimulus with the real depth. These results provide the first behavioral demonstration of a full range of stereoscopic skills in a lateral-eyed mammal

EquiFACS: the Equine Facial Action Coding System

Although previous studies of horses have investigated their facial expressions in specific contexts, e.g. pain, until now there has been no methodology available that documents all the possible facial movements of the horse and provides a way to record all potential facial configurations. This is essential for an objective description of horse facial expressions across a range of contexts that reflect different emotional states. Facial Action Coding Systems (FACS) provide a systematic methodology of identifying and coding facial expressions on the basis of underlying facial musculature and muscle movement. FACS are anatomically based and document all possible facial movements rather than a configuration of movements associated with a particular situation. Consequently, FACS can be applied as a tool for a wide range of research questions. We developed FACS for the domestic horse (Equus caballus) through anatomical investigation of the underlying musculature and subsequent analysis of naturally occurring behaviour captured on high quality video. Discrete facial movements were identified and described in terms of the underlying muscle contractions, in correspondence with previous FACS systems. The reliability of others to be able to learn this system (EquiFACS) and consistently code behavioural sequences was high—and this included people with no previous experience of horses. A wide range of facial movements were identified, including many that are also seen in primates and other domestic animals (dogs and cats). EquiFACS provides a method that can now be used to document the facial movements associated with different social contexts and thus to address questions relevant to understanding social cognition and comparative psychology, as well as informing current veterinary and animal welfare practices

Nucleocytoplasmic transport: a thermodynamic mechanism

The nuclear pore supports molecular communication between cytoplasm and nucleus in eukaryotic cells. Selective transport of proteins is mediated by soluble receptors, whose regulation by the small GTPase Ran leads to cargo accumulation in, or depletion from the nucleus, i.e., nuclear import or nuclear export. We consider the operation of this transport system by a combined analytical and experimental approach. Provocative predictions of a simple model were tested using cell-free nuclei reconstituted in Xenopus egg extract, a system well suited to quantitative studies. We found that accumulation capacity is limited, so that introduction of one import cargo leads to egress of another. Clearly, the pore per se does not determine transport directionality. Moreover, different cargo reach a similar ratio of nuclear to cytoplasmic concentration in steady-state. The model shows that this ratio should in fact be independent of the receptor-cargo affinity, though kinetics may be strongly influenced. Numerical conservation of the system components highlights a conflict between the observations and the popular concept of transport cycles. We suggest that chemical partitioning provides a framework to understand the capacity to generate concentration gradients by equilibration of the receptor-cargo intermediary.Comment: in press at HFSP Journal, vol 3 16 text pages, 1 table, 4 figures, plus Supplementary Material include

Towards reconciling structure and function in the nuclear pore complex

The spatial separation between the cytoplasm and the cell nucleus necessitates the continuous exchange of macromolecular cargo across the double-membraned nuclear envelope. Being the only passageway in and out of the nucleus, the nuclear pore complex (NPC) has the principal function of regulating the high throughput of nucleocytoplasmic transport in a highly selective manner so as to maintain cellular order and function. Here, we present a retrospective review of the evidence that has led to the current understanding of both NPC structure and function. Looking towards the future, we contemplate on how various outstanding effects and nanoscopic characteristics ought to be addressed, with the goal of reconciling structure and function into a single unified picture of the NPC

Communicating Auditory Impairments Using Electroacoustic Composition

Changes in human sensory perception can occur for a variety of reasons. In the case of distortions or transformations in the human auditory system, the aetiology may include factors such as medical conditions affecting cognition or physiology, interaction of the ears with mechanical waves, or stem from chemically induced sources, such the consumption of alcohol. These changes may be permanent, intermittent, or temporary. In order to communicate such effects to an audience in an accessible, and easily understood manner, a series of electroacoustic compositions were produced. This concept follows on from previous work on the theme of representing auditory hallucinations. Specifically, these compositions relate to auditory impairments that humans can experience due to tinnitus or through the consumption of alcohol. In the case of tinnitus, whilst much is known about the causes and symptoms, the experience of what it is like to live with tinnitus is less explored and those who have acquired the condition may often feel frustration when trying to convey the experience of ‘what it is like’ for them. In terms of impairment from alcohol consumption, whilst there is much hearsay, little research exists on the immediate and short-term effects of alcohol consumption on the human auditory system, despite over half of the UK population reported as consuming alcohol in 2017. The methodology employed to design these compositions draws upon scientific research findings, including experimental and explorative studies involving human participants, coupled with electroacoustic composition techniques. The pieces are typically constructed by mixing field recordings with synthesised materials and incorporating a range of temporal and frequency domain manipulations to the elements therein. In this way, the listener is able to experience the phenomenon in a recognisable context, where distortions of reality can be emulated to varying degrees. It is intended that these compositions can serve as easily accessible and understood examples of auditory impairments and that they might find utility in the communication of symptoms to those who have never experienced the underlying causes or conditions. This presents opportunities for pieces like these to be used in scenarios such as education and public health awareness campaigns