The effects of practice and visual feedback on mandibular border movements

Twenty healthy subjects were studied on the effects of training on mandibular border movements. Maximum left (LL) and right (RL) lateral excursions, maximum protrusive movement (PT), maximum mouth opening (MO), the difference between left and right excursions (R-L), midline deflection (DF) during opening and closing and midline deviation of the jaw (MOD) at maximum opening position of mandibular border tracing with or without practicing and visual feedback were compared among various sessions. No significant difference has been found on the amount of border extension under the influence of training. However, 70 to 85% of the subjects had some improvement after verbal instruction practicing, while only 50 to 65% of the same subjects showed improvement through visual feedback. It is suggested that doing research related to the jaw border movement on healthy subjects does not have to train them to obtain comparable data. On the other hand, since repeated border tracing in healthy subjects did not worsen the results, practicing or visual feedback training might ascertain a repeatable border tracing.     

Foraging navigation of hornets studied in natural habitats and laboratory experiments

Foraging flights have been studied in three species of hornets (Vespa mandarinia, V. simillima and V. analis) in the field and the laboratory. Hornets seem to use multiple navigational cues for visiting a familiar feeding place. They could orient towards the feeding place immediately after they rose in air from the nest without directly viewing the feeder. They could visit the feeding place after dark at a luminosity 8 lux. These data suggest that they can navigate for some distance with few external cues. Hornets also seem to rely on visual cues for their mid-range navigation. They used some structures on their way as navigational landmarks to negotiate. Individual hornets are supposed to have their own landmarks. Olfactory cues seem to be used to find a new feeding place or to recruit other member. In the approach flight hornets seemed to use multiple visual cues such as the visual characteristics of the feeder and the wider scenery around the feeder. Even if the feeder in training was removed during the test, they flew with a smooth course as if they were pin-pointing the missing feeder, but without sitting on the ground. Hornets learnt how to fly to reach the feeder without external cues after passing by the last visual landmark under conditions with extremely poor visual cues. The present work suggests that hornets retain multiple navigational cues during repeated foraging behavior, and which cues they use seems to depend upon environmental conditions.     

Complex alimentary motor conditioned reflex reactions in cats and dogs]

The ability of animals to perform a complex motor task representing a model of compensatory discrete tracing was investigated in dogs and cats. Elongation of a light spot on an oscilloscope screen into a vertical line served as a signal of motor reaction. The reaction consisted in several movements, each of which reduced the initial signal change by 1/2, 1/3, 1/4 or 1/5 of its value. Alimentary reinforcement was given only after a reduction of the signal to its initial level. Signals with a different number of steps of transition to their initial state were presented at random. It was found that learned animals were capable of a stable behaviour of a compensatory discrete tracing type. A hypothesis has been advanced about a probabilistic participation of visual control in the realization of tracing motor behaviour.     

The Importance of Lateral Connections in the Parietal Cortex for Generating Motor Plans

Substantial evidence has highlighted the significant role of associative brain areas, such as the posterior parietal cortex (PPC) in transforming multimodal sensory information into motor plans. However, little is known about how different sensory information, which can have different delays or be absent, combines to produce a motor plan, such as executing a reaching movement. To address these issues, we constructed four biologically plausible network architectures to simulate PPC: 1) feedforward from sensory input to the PPC to a motor output area, 2) feedforward with the addition of an efference copy from the motor area, 3) feedforward with the addition of lateral or recurrent connectivity across PPC neurons, and 4) feedforward plus efference copy, and lateral connections. Using an evolutionary strategy, the connectivity of these network architectures was evolved to execute visually guided movements, where the target stimulus provided visual input for the entirety of each trial. The models were then tested on a memory guided motor task, where the visual target disappeared after a short duration. Sensory input to the neural networks had sensory delays consistent with results from monkey studies. We found that lateral connections within the PPC resulted in smoother movements and were necessary for accurate movements in the absence of visual input. The addition of lateral connections resulted in velocity profiles consistent with those observed in human and non-human primate visually guided studies of reaching, and allowed for smooth, rapid, and accurate movements under all conditions. In contrast, Feedforward or Feedback architectures were insufficient to overcome these challenges. Our results suggest that intrinsic lateral connections are critical for executing accurate, smooth motor plans.     

Visual perception of surface curvature. The spin variation and its physiological implications

In the context of the models of structure from motion visual processing, we propose that the optic-flow field is a source of information for the perception of the curvature of a smooth surface in motion. In particular, it is shown how the spin variation (SV), a second spatial derivative of the retinal velocity field, is mathematically related to the curvature of the surface. Under the hypothesis that the visual system relies on SV to analyse the structure of a moving surface, a neural scheme for SV detection is proposed and psychophysical predictions are developed. Results obtained on artificial images show that the SV scheme presents a rather weak sensitivity to noise in conditions of low image velocity.     

The interest of actin immunocytochemistry in diagnostic histopathology

The immunohistochemical detection of different isoforms of actin provides useful data in the histopathological diagnosis of human tumours. The marked resistance of this protein to fixation and embedding procedures makes it a practical alternative to the ultrastructural search of microfilaments in routine tissue sections. Staining with monoclonal antibodies against alpha smooth muscle actin is helpful in the diagnosis of benign and malignant smooth muscle tumours and allows the differentiation of various types of spindle cell sarcomas. These antibodies are also useful in tracing the myoepithelial cells in normal and various pathological conditions of the breast and salivary glands. Skeletal muscle actin is a reliable marker in the diagnosis of rhabdomyosarcomas. Its use should be combined and complemented with other markers (i.e. desmin; foetal, slow and fast myosins; myoglobin) to monitor the degree of rhabdomyoblastic differentiation of the neoplastic cells in single cases, a parameter of potential prognostic value.     

Which retinal and extra-retinal information is crucial for circular vection?

In contradistinction to conventional wisdom, we propose that retinal image slip of a visual scene (optokinetic pattern, OP) does not constitute the only crucial input for visually induced percepts of self-motion (vection). Instead, the hypothesis is investigated that there are three input factors: 1) OP retinal image slip, 2) motion of the ocular orbital shadows across the retinae, and 3) smooth pursuit eye movements (efference copy). To test this hypothesis, we visually induced percepts of sinusoidal rotatory self-motion (circular vection, CV) in the absence of vestibular stimulation. Subjects were presented with three concurrent stimuli: a large visual OP, a fixation point to be pursued with the eyes (both projected in superposition on a semi-circular screen), and a dark window frame placed close to the eyes to create artificial visual field boundaries that simulate ocular orbital rim boundary shadows, but which could be moved across the retinae independent from eye movements. In different combinations these stimuli were independently moved or kept stationary. When moved together (horizontally and sinusoidally around the subject's head), they did so in precise temporal synchrony at 0.05 Hz. The results show that the occurrence of CV requires retinal slip of the OP and/or relative motion between the orbital boundary shadows and the OP. On the other hand, CV does not develop when the two retinal slip signals equal each other (no relative motion) and concur with pursuit eye movements (as it is the case, e.g., when we follow with the eyes the motion of a target on a stationary visual scene). The findings were formalized in terms of a simulation model. In the model two signals coding relative motion between OP and head are fused and fed into the mechanism for CV, a visuo-oculomotor one, derived from OP retinal slip and eye movement efference copy, and a purely visual signal of relative motion between the orbital rims (head) and the OP. The latter signal is also used, together with a version of the oculomotor efference copy, for a mechanism that suppresses CV at a later stage of processing in conditions in which the retinal slip signals are self-generated by smooth pursuit eye movements.     

Modelling the visual world of a velvet worm

In many animal phyla, eyes are small and provide only low-resolution vision for general orientation in the environment. Because these primitive eyes rarely have a defined image plane, traditional visual-optics principles cannot be applied. To assess the functional capacity of such eyes we have developed modelling principles based on ray tracing in 3D reconstructions of eye morphology, where refraction on the way to the photoreceptors and absorption in the photopigment are calculated incrementally for ray bundles from all angles within the visual field. From the ray tracing, we calculate the complete angular acceptance function of each photoreceptor in the eye, revealing the visual acuity for all parts of the visual field. We then use this information to generate visual filters that can be applied to high resolution images or videos to convert them to accurate representations of the spatial information seen by the animal. The method is here applied to the 0.1 mm eyes of the velvet worm Euperipatoides rowelli (Onychophora). These eyes of these terrestrial invertebrates consist of a curved cornea covering an irregular but optically homogeneous lens directly joining a retina packed with photoreceptive rhabdoms. 3D reconstruction from histological sections revealed an asymmetric eye, where the retina is deeper in the forward-pointing direction. The calculated visual acuity also reveals performance differences across the visual field, with a maximum acuity of about 0.11 cycles/deg in the forward direction despite laterally pointing eyes. The results agree with previous behavioural measurements of visual acuity, and suggest that velvet worm vision is adequate for orientation and positioning within the habitat.     

Projections from the cortex of the superior temporal sulcus to the dorsal lateral geniculate and pregeniculate nuclei in the macaque monkey

Cortical projections from the visual region and adjacent polysensory region of the superior temporal sulcus (STs) to the lateral geniculate body (LGb) were investigated in the macaque monkey using an autoradiographic tracing method. Solutions of tritiated aminoacids were injected into different parts of the caudal half of the STs of five animals. A survival time of 7 days was allowed. Labels were found in both subdivisions of the LGb: the dorsal lateral geniculate nucleus (DLGn) and the pregeniculate nucleus (PGn). In particular, part of the visual cortical region adjacent to the middle temporal area (MT) projects into the DLGn as well as the PGn, whereas the MT itself and the superior temporal polysensory region project into the PGn only. Afferents to the DLGn terminate in the magnocellular layers and in their adjoining interlaminar zones, completely sparing the parvocellular layers. Afferents to the PGn terminate in separate regions of this nucleus; the MT and adjacent visual cortices project into the internal layer of the PGn, whereas the polysensosy region of the STs projects into the external retinorecipient layer of the PGn. Possible functional implications of these projections are discussed.     

Visual localization during eye tracking on steady background and during steady fixation on moving background

Experiments were performed to clarify the role of the background motion on the retina in the phenomenon of mislocation of brief visual stimuli during smooth eye tracking. It was found that these visual stimuli were mislocated also relative to a moving background during steady eye fixation. The magnitude of mislocation during pursuit eye movements and during steady fixation was influenced by the stimulus intensity, the background/eye velocity and the place of stimulus presentation in respect to the background; the influence having the same features in both cases. However, the magnitudes of mislocation under the two conditions were quantitatively different. The validity of a hypothesis that the eye movement itself plays no role in the process of localization, and, that this process is based on retinal information only, is considered.     

The coordinated mapping of visual space and response features in visual cortex

Whether general principles can explain the layouts of cortical maps remains unresolved. In primary visual cortex of ferret, the relationships between the maps of visual space and response features are predicted by a "dimension-reduction" model. The representation of visual space is anisotropic, with the elevation and azimuth axes having different magnification. This anisotropy is reflected in the orientation, ocular dominance, and spatial frequency domains, which are elongated such that their directions of rapid change, or high-gradient axes, are orthogonal to the high-gradient axis of the visual map. The feature maps are also strongly interdependent-their high-gradient regions avoid one another and intersect orthogonally where essential, so that overlap is minimized. Our results demonstrate a clear influence of the visual map on each feature map. In turn, the local representation of visual space is smooth, as predicted when many features are mapped within a cortical area.     

Myosin filament structure in vertebrate smooth muscle

The in vivo structure of the myosin filaments in vertebrate smooth muscle is unknown. Evidence from purified smooth muscle myosin and from some studies of intact smooth muscle suggests that they may have a nonhelical, side-polar arrangement of crossbridges. However, the bipolar, helical structure characteristic of myosin filaments in striated muscle has not been disproved for smooth muscle. We have used EM to investigate this question in a functionally diverse group of smooth muscles (from the vascular, gastrointestinal, reproductive, and visual systems) from mammalian, amphibian, and avian species. Intact muscle under physiological conditions, rapidly frozen and then freeze substituted, shows many myosin filaments with a square backbone in transverse profile. Transverse sections of fixed, chemically skinned muscles also show square backbones and, in addition, reveal projections (crossbridges) on only two opposite sides of the square. Filaments gently isolated from skinned smooth muscles and observed by negative staining show crossbridges with a 14.5-nm repeat projecting in opposite directions on opposite sides of the filament. Such filaments subjected to low ionic strength conditions show bare filament ends and an antiparallel arrangement of myosin tails along the length of the filament. All of these observations are consistent with a side-polar structure and argue against a bipolar, helical crossbridge arrangement. We conclude that myosin filaments in all smooth muscles, regardless of function, are likely to be side-polar. Such a structure could be an important factor in the ability of smooth muscles to contract by large amounts.     

Conversion of pancreatic α cells into insulin-producing cells modulated by β-cell insufficiency and supplemental insulin administration

The emergence of bihormonal (BH) cells expressing insulin and glucagon has been reported under diabetic conditions in humans and mice. Whereas lineage tracing studies demonstrated that glucagon-producing α cells can be reprogrammed into BH cells, the underlying dynamics of the conversion process remain poorly understood. In the present study, we investigated the identities of pancreatic endocrine cells by genetic lineage tracing under diabetic conditions. When β-cell ablation was induced by alloxan (ALX), a time-dependent increase in BH cells was subsequently observed. Lineage tracing experiments demonstrated that BH cells originate from α cells, but not from β cells, in ALX-induced diabetic mice. Notably, supplemental insulin administration into diabetic mice resulted in a significant increase in α-cell-derived insulin-producing cells that did not express glucagon. Furthermore, lineage tracing in Ins2^Akita diabetic mice demonstrated a significant induction of α-to-β conversion. Thus, adult α cells have plasticity, which enables them to be reprogrammed into insulin-producing cells under diabetic conditions, and this can be modulated by supplemental insulin administration.     

Anticipatory Smooth Eye Movements in Autism Spectrum Disorder

Smooth pursuit eye movements are important for vision because they maintain the line of sight on targets that move smoothly within the visual field. Smooth pursuit is driven by neural representations of motion, including a surprisingly strong influence of high-level signals representing expected motion. We studied anticipatory smooth eye movements (defined as smooth eye movements in the direction of expected future motion) produced by salient visual cues in a group of high-functioning observers with Autism Spectrum Disorder (ASD), a condition that has been associated with difficulties in either generating predictions, or translating predictions into effective motor commands. Eye movements were recorded while participants pursued the motion of a disc that moved within an outline drawing of an inverted Y-shaped tube. The cue to the motion path was a visual barrier that blocked the untraveled branch (right or left) of the tube. ASD participants showed strong anticipatory smooth eye movements whose velocity was the same as that of a group of neurotypical participants. Anticipatory smooth eye movements appeared on the very first cued trial, indicating that trial-by-trial learning was not responsible for the responses. These results are significant because they show that anticipatory capacities are intact in high-functioning ASD in cases where the cue to the motion path is highly salient and unambiguous. Once the ability to generate anticipatory pursuit is demonstrated, the study of the anticipatory responses with a variety of types of cues provides a window into the perceptual or cognitive processes that underlie the interpretation of events in natural environments or social situations.     

Extrinsic cells, immunoreactive to Ca-binding protein, as sources of thalamic visual centres in tortoises

Extrinsic sources of calcium-binding proteins involved in immunoreactive innervation of the visual thalamic nuclei Rot and GLd in turtles (Testudo horsfieldi and Emys orbicularis) were studied using HRP tracing method and immunohistochemistry. In 1.5-4.5 months after monocular enucleation calbindin (Calb)-, parvalbumin (Parv)- and calretinin (Calr)-labeling was found in fragments of degenerated retinal fibers in the contralateral optic tract and in some retinorecipient structures (optic tectum, GLd and GLv). Changes in GLd were detected in its neuropil part. in 2.0-3.5 months after unilateral ablation of tectum and pretectum, the densities of Parv-, Calb- and Aclr-immunoreactivity terminals and fibers were diminisched in the ipsilateral n. Rot, with the maximum effect seen in Parv. Following HRP injection into the visual thalamus (Rot and GLd), retrogradely labeled cells with Parv label only, were revealed in the ventrothalamic nucleus Enta, pretectal nucleus Ptv, and in all types of Ca-binding proteins (CaBPr) in separately labeled cells of the optic tectum. Thus, it has been shown that thalamic visual centers in turtles have multiple extrinsic cells, which serve as sources of CaBPr projections. The present data suggest that organization of CaBPr inputs to visual thalamus in reptiles (turtle) and higher amniotes are fundamentally similar.     

猫外侧膝状体神经元HRP示踪结合生长抑素的免疫组织化学研究

本文采用HRP逆行示踪的方法,在猫视皮质的17区多点微量注射30％HRP,逆行标记外侧膝状体核（LGN）至视皮质的中继神经元,继用免疫金银法作生长抑素（SS）免疫组织化学,试图双标记LGN的中断神经元。结果显示：光镜下HRP标记细胞与SS是性细胞清晰可辨,HRP标记细胞内为较粗的棕色颗粒,分布于胞浆和树突基部;而SS免疫阳性细胞内的颗粒为银染黑色颗粒;HRP和SS双标记神经元内,上述两种颗粒共存,警备LGN的A、A1和C板层均有SS免疫阳性凶的分布;HRP标记细胞分布于A和A1板层;双标记神经元位于A和A1板层;C板层未见。本文结合以前的研究认为,SS在LGN至视皮质传导通路中的作用,可能与视觉信息的传递和调制有关。     

Visual deprivation modifies oscillatory activity in visual and auditory centers

Loss of vision may enhance the capabilities of auditory perception, but the mechanisms mediating these changes remain elusive. Here, visual deprivation in rats resulted in altered oscillatory activities, which appeared to be the result of a common mechanism underlying neuronal assembly formation in visual and auditory centers. The power of high-frequency β and γ oscillations in V1 (the primary visual cortex) and β oscillations in the LGN (lateral geniculate nucleus) was increased after one week of visual deprivation. Meanwhile, the power of β oscillations in A1 (the primary auditory cortex) and the power of β and γ oscillations in the MGB (medial geniculate body) were also enhanced in the absence of visual input. Furthermore, nerve tracing revealed a bidirectional nerve fiber connection between V1 and A1 cortices, which might be involved in transmitting auditory information to the visual cortex, contributing to enhanced auditory perception after visual deprivation. These results may facilitate the better understanding of multisensory cross-modal plasticity.     

A Direct Projection from Mouse Primary Visual Cortex to Dorsomedial Striatum

The mammalian striatum receives inputs from many cortical areas, but the existence of a direct axonal projection from the primary visual cortex (V1) is controversial. In this study we use anterograde and retrograde tracing techniques to demonstrate that V1 directly innervates a topographically defined longitudinal strip of dorsomedial striatum in mice. We find that this projection forms functional excitatory synapses with direct and indirect pathway striatal projection neurons (SPNs) and engages feed-forward inhibition onto these cells. Importantly, stimulation of V1 afferents is sufficient to evoke phasic firing in SPNs. These findings therefore identify a striatal region that is functionally innervated by V1 and suggest that early visual processing may play an important role in striatal-based behaviors.     

GSM 900 MHz radiation inhibits ants' association between food sites and encountered cues

The kinetics of the acquisition and loss of the use of olfactory and visual cues were previously obtained in six experimental colonies of the ant Myrmica sabuleti meinert 1861, under normal conditions. In the present work, the same experiments were conducted on six other naive identical colonies of M. sabuleti, under electromagnetic radiation similar to those surrounding GSM and communication masts. In this situation, no association between food and either olfactory or visual cues occurred. After a recovery period, the ants were able to make such an association but never reached the expected score. Such ants having acquired a weaker olfactory or visual score and still undergoing olfactory or visual training were again submitted to electromagnetic waves. Not only did they lose all that they had memorized, but also they lost it in a few hours instead of in a few days (as under normal conditions when no longer trained). They kept no visual memory at all (instead of keeping 10% of it as they normally do). The impact of GSM 900?MHz radiation was greater on the visual memory than on the olfactory one. These communication waves may have such a disastrous impact on a wide range of insects using olfactory and/or visual memory, i.e., on bees.     

Generation and characterization of Csrp1 enhancer-driven tissue-restricted Cre-recombinase mice

Cell type-specific genetic modification using the LoxP/Cre system is a powerful tool for genetic analysis of distinct cell lineages. Because of the unique arterial smooth muscle-restricted expression of a 5.0 kb cysteine-rich protein (Csrp1) enhancer (Lilly et al.,2001, Dev Biol 240:531-547), we hypothesized that a transgenic Cre line would prove useful for the smooth muscle lineage-specific genetic manipulation. Here we describe a transgenic mouse line, ECsrp1(Cre), where Cre is initially specifically expressed in arterial smooth muscle cells. Use of the ROSA26R reporter allele confirmed that Cre-mediated recombination in vascular smooth muscle cells began at approximately E10.0 and was highly proficient. Subsequently, Cre is expressed in restricted skeletal and nonvascular smooth muscle lineages. This lineage tracing data is important for future conditional knockout studies to understand where and when Cre-mediated deletion occurs and where Cre-expressing daughter cells finally localize. Additionally, we crossed the ECsrp1(Cre) mice to the ROSA26(-eGFP-DTA) diphtheria toxin A-expressing mice to genetically ablate ECsrp1(Cre) expressing cells. This ECsrp1(Cre) transgenic line should thus prove useful for genetic analysis of diverse aspects of cardiovascular morphogenesis and as a general smooth muscle lineage deletor line.