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PubMed2002

Electrical stimulation induced lumbar medial branch referral patterns.

STUDY DESIGN: Fluoroscopically guided, minimum threshold electrical stimulation of the right first, second, third, and fourth lumbar medial branches and the fifth lumbar dorsal ramus in each of eight healthy test subjects was performed. The stimulation thresholds and referral patterns were recorded. A composite drawing of the referral patterns was created. The composite drawings were compared to documented referral patterns already published by other authors. OBJECTIVE: To determine the referral patterns of the lumbar medial branches and the fifth lumbar dorsal ramus. HYPOTHESIS: The lumbar medial branch referral patterns created by minimum threshold electrical stimulation may differ from those obtained after zygapophysial joint (Z-joint) injections. SUMMARY OF BACKGROUND DATA: Lumbar Z-joint referral patterns have been identified following provocative Z-joint injections. There are no reports of lumbar medial branch referral patterns. METHODS: The right L1 through L4 medial branch of the posterior primary ramus and the right L5 dorsal ramus in each of eight healthy volunteer males (n=40), without a history of back pain, were electrically stimulated under fluoroscopic imaging. All subjects were blinded to the level of stimulation, and each individual mapped out the referral area on a human line drawing at the time of each stimulus. The referral patterns after electrical stimulation and the stimulation thresholds were recorded. These referral patterns were compared to referral patterns recorded during provocative Z-joint injections by other authors. CONCLUSION: All of the subjects' mapped referral sites coincided with each other, creating a well defined composite drawing. These referral zones are different than those reported after injection of the lumbar Z-joint, which may have clinical and therapeutic implications. These referral maps may provide the clinician with additional insight when evaluating a patient with lumbar, flank, or gluteal pain of undetermined etiology.

Journal Article↗
PubMed1989

Spinal cord segments containing key elements of the central pattern generators for three forms of scratch reflex in the turtle.

The immobilized, low-spinal turtle produces 3 forms of the fictive scratch reflex in response to tactile stimulation of specific sites on its body surface (Robertson et al., 1985). We used complete transections of the spinal cord at different rostrocaudal levels to reveal the minimum length of spinal cord sufficient to produce each scratch form. Additional transections revealed the progressive loss of elements of the motor pattern and the eventual loss of rhythmogenesis. We have identified, therefore, spinal cord segments containing key elements of each scratch form's central pattern generator (CPG). The turtle spinal cord consists of 8 cervical segments (C1-C8), 10 dorsal segments (D1-D10), 2 sacral segments (S1, S2) and about 16 caudal segments (Ca1-Ca16; Kusuma et al., 1979). The cell bodies of motor neurons innervating the hindlimb muscles are located in the hindlimb enlargement, segments D8-S2 (Ruigrok and Crowe, 1984). The receptive field for the rostral scratch is innervated by segments D3-D6; the pocket scratch receptive field is innervated by segments D6-D8; the caudal scratch receptive field is innervated by segments S2, Ca1, and more caudal segments (Mortin and Stein, 1985). A rostral scratch motor pattern could be produced with as few as 5 or 6 segments, i.e., segments D5-D9 or D3-D8. The anterior 3 segments of the hindlimb enlargement, D8-D10, could produce a pocket scratch motor pattern. A single segment, either D7 or D8, is capable of rhythmogenesis in response to stimulation of sites in its part of the pocket receptive field. A caudal scratch motor pattern could be produced by D8-End (the hindlimb enlargement and more caudal segments). The posterior 40-80% of the hindlimb enlargement is not necessary for the production of a rostral or pocket motor pattern. The anterior segment of the enlargement is necessary for the production of a normal caudal scratch motor pattern. Key elements of the CPG for each of the 3 scratch forms reside in segments D7-D10. The pattern-generating capacity of the anterior half of the hindlimb enlargement is greater than the posterior half; such an asymmetric distribution of pattern-generating elements in the enlargement of the spinal cord has been described for cat scratching (Deliagina et al., 1983). These results are consistent with the hypothesis that the CPGs producing different motor patterns for the hindlimb share neuronal elements (Grillner, 1981; Robertson et al., 1985; Currie and Stein, 1988, 1989).

Animals↗
PubMed1988

Abnormal breathing patterns in patients with mitral stenosis: a possible compensatory role.

The breathing patterns of 37 patients with mitral stenosis were investigated in standing position by Konno-Mead analysis. Hemodynamic parameters were measured by cardiac catheterization, pulmonary function variables by pulmonary function testings and distribution of pulmonary perfusion by Tc-99m-MAA scintigraphy. Seventeen patients displayed rib cage dominant breathing patterns, and 6 patients displayed paradoxical breathing patterns, whereas 14 patients displayed normal breathing patterns. None of these patients exhibited an abdomen dominant breathing pattern. The patients with abnormal breathing patterns (rib cage dominant or paradoxical) displayed significantly higher values of pulmonary arterial pressure (p less than 0.01), capillary wedge pressure (p less than 0.01), total pulmonary vascular resistance (p less than 0.01) and mitral valve gradient (p less than 0.05) as well as smaller mitral valve area (p less than 0.05) and lower values of both in PaO2 (p less than 0.05) and diffusing capacity (p less than 0.05) than patients with normal breathing patterns. Abnormal distribution of pulmonary perfusion with hyperperfusion in the upper zone of the lung were found to be associated with the abnormal breathing patterns. Since rib cage dominant and paradoxical breathing patterns are known to increase ventilation in the upper zone of the lung, these abnormal breathing patterns may represent a compensatory mechanism serving to match ventilation and perfusion.

Adult↗
PubMed1987

The Japanese characteristic of type A behavior pattern.

This was a retrospective study of 285 patients with coronary heart disease and 393 healthy subjects. They were administered a questionnaire composed of 15 items regarding traditional coronary risk factors and 45 items concerning behavior patterns. The 45 multiple-choice questions were computed by multiple regression analysis to develop a coronary-prone behavior pattern score. As a result, the traditional risk factors were reconfirmed and the behavior pattern scores were found to be significantly different between the two groups. The behavior pattern scores were uncorrelated with other risk factors except for cigarettes smoked daily by 40-49 year-old males. Hence, specific behavior patterns can be said to be an independent coronary risk factor also among the Japanese. In order to investigate the relationship between those behavior patterns and the Type A behavior pattern, factor analysis (normal varimax method) was conducted. Comparing three major factors among Americans, Japanese-Americans and Japanese, hard-working and workaholic tendencies were found to be more stressed rather than the hard-driving and competitive components among the Japanese. This property might be a reflection of the Japanese culture which stresses harmonious relationships rather than individualism and competitiveness. As such, it is seen that Type A behavior pattern is necessarily modified according to culture and nationality. Therefore, the authors propose the term "Japanese Type A behavior pattern" for distinction of the modified form of Type A behavior pattern.

Adult↗
PubMed1985

Pattern recognition in bone dysplasias.

Genetically different bone dysplasias may manifest themselves in similar patterns of skeletal abnormalities. It is proposed to group these similar dysplasias in 'families' for two reasons: 1 The knowledge of developmental patterns shared by different genetic disorders cautions the diagnostician and encourages a two-step procedure: a) provisional recognition of a pattern and b) more careful analysis of the pattern to reach a final, specific diagnosis. 2 Families of bone dysplasias may be the result of similar pathogenetic mechanisms. Once the mechanism is discovered in one member of the family, a search for similar mechanisms in others may be rewarding. An example of such a pattern is dysostosis multiplex. It is found in a family of disorders caused by defects of complex carbohydrate degradation. The present study delineates four more patterns and their families: the achondroplasia pattern, spondyloepiphyseal dysplasia congenita pattern, the Larsen/OPD pattern and the Stickler/Kniest pattern.

Achondroplasia↗
PubMed1993

New developments in speech pattern element hearing aids for the profoundly deaf.

Two new developments in speech pattern processing hearing aids will be described. The first development is the use of compound speech pattern coding. Speech information which is invisible to the lipreader was encoded in terms of three acoustic speech factors; the voice fundamental frequency pattern, coded as a sinusoid, the presence of aperiodic excitation, coded as a low-frequency noise, and the wide-band amplitude envelope, coded by amplitude modulation of the sinusoid and noise signals. Each element of the compound stimulus was individually matched in frequency and intensity to the listener's receptive range. Audio-visual speech receptive assessments in five profoundly hearing-impaired listeners were performed to examine the contributions of adding voiceless and amplitude information to the voice fundamental frequency pattern, and to compare these codings to amplified speech. In both consonant recognition and connected discourse tracking (CDT), all five subjects showed an advantage from the addition of amplitude information to the fundamental frequency pattern. In consonant identification, all five subjects showed further improvements in performance when voiceless speech excitation was additionally encoded together with amplitude information, but this effect was not found in CDT. The addition of voiceless information to voice fundamental frequency information did not improve performance in the absence of amplitude information. Three of the subjects performed significantly better in at least one of the compound speech pattern conditions than with amplified speech, while the other two performed similarly with amplified speech and the best compound speech pattern condition. The three speech pattern elements encoded here may represent a near-optimal basis for an acoustic aid to lipreading for this group of listeners. The second development is the use of a trained multi-layer-perceptron (MLP) pattern classification algorithm as the basis for a robust real-time voice fundamental frequency extractor. This algorithm runs on a low-power digital signal processor which can be incorporated in a wearable hearing aid. Aided lipreading for speech in noise was assessed in the same five profoundly hearing-impaired listeners to compare the benefits of conventional hearing aids with those of an aid which provided MLP-based fundamental frequency information together with speech+noise amplitude information. The MLP-based pattern element aid gave significantly better performance in the reception of consonantal voicing contrasts from speech in pink noise than that achieved with conventional amplification and consequently, it also gave better overall performance in audio-visual consonant identification.(ABSTRACT TRUNCATED AT 400 WORDS)

Algorithms↗
PubMed1993

[Temporal stimulus structure, gestalt perception and electrodermal reaction pattern].

The presentation of tones with alternating interstimulus intervals (ISIs) of 10 and 70 s leads to an electrodermal response pattern with an increase in magnitude after long and a decrease after short ISIs. The present study investigated whether there is a relation between the occurrence of the response pattern and the perception of stimuli as a pattern and, furthermore, whether the greater response to the stimulus after the long ISI is due to the greater information content of this stimulus (announcing the occurrence of the pair of tones). Four groups, each consisting of 12 subjects, were subjected to a 1 s, 1000 Hz tone of 90 dB(A) intensity over 21 trials. Group I received the tones in randomized sequences of 10 and 70 s, groups II and III received alternating ISIs of 10 and 70 s. While in group II the regularity of the stimulus pattern was interrupted by the presentation of an extra stimulus, group III was confronted with a stimulus omission. As a control condition, group IV received regularly alternating tones with ISIs of 10 and 70 s. Skin conductance and heart rate were recorded as dependent physiological variables. The perception of the stimulus patterns was measured by means of a questionnaire. The electrodermal response pattern found in earlier studies was replicated, and this pattern even occurred in the random group when 10 and 70 s ISIs appeared directly after each other. The presentation of the extra stimulus and the stimulus omission did not have any effect. For heart rate, a deceleration to tones after long ISIs and an acceleration to tones after short ISIs was found. Subjective pattern perception and electrodermal response patterns did not coincide. In general, the results can be interpreted as showing that the relationship between the ISIs seems to be of importance for the occurrence of the response pattern.

Adult↗
PubMed1996

The interaction of imposed and inherent olfactory mucosal activity patterns and their composite representation in a mammalian species using voltage-sensitive dyes.

From amphibian data, two mechanisms that could underlie the encoding of odorants by the mucosal activity patterns they engender are as follows (1) receptors with similar odorant selectivities could be aggregated spatially on the mucosa (inherent patterns); (2) in analogy to gas chromatography, as odorants are drawn along the surface of the mucosa the strongly sorbed ones could be deposited preferentially upstream, whereas the weakly sorbed ones could be distributed more evenly (imposed patterns). Do both of these possible coding mechanisms operate in mammals and, if so, how do they interact in giving composite patterns (imposed + inherent)? Fluorescence changes in di-4-ANEPPS applied to rat mucosas were monitored by a 10 x 10 pixel photodiode array. To observe the inherent patterns, three odorants of varying sorbabilities first were puffed uniformly onto the entire mucosa mounted in a Delrin chamber. To bring out the imposed patterns, the chamber was then sealed to replicate anatomically the rat's nasal cavity, and these same odorants were drawn at three flow rates along the mucosal flow path. The results demonstrated for the first time the existence of imposed patterns in a mammal. The strongly sorbed odorants, unlike the weakly sorbed one, showed marked imposed patterns. Within physiological limits, increasing the flow rate decreased the magnitude of the imposed patterns. One might consider strategies that the olfactory process could use either to negate or to take advantage of the chromatographic effect, because the lability of the composite patterns with changing stimulus conditions raises questions about their role in odorant encoding.

Animals↗
PubMed2000

Extracellular matrix environment influences chondrogenic pattern formation in limb bud micromass culture: experimental verification of theoretical models.

Various theoretical models have been proposed to explain the periodicity in the pattern of limb chondrogenesis, but experimental comparison of these models have seldom been performed properly. In the present study, micromass culture of limb bud mesenchyme cells was undertaken to test the validity of three theoretical models: the reaction-diffusion model, the cell sorting model, and the mechanochemical model. Computer simulations were undertaken to predict the factors that can affect the coarseness of the chondrogenic pattern. According to the predictions, we performed micromass culture of limb mesenchyme in collagen and agarose gel. Then we carried out time-lapse observation to analyze the cell movement during pattern formation. From computer simulations it was theoretically predicted that changes in the surrounding extracellular matrix should alter the periodicity of the chondrogenic pattern in vitro, and we found that pattern changes actually occurred under different culture conditions. When compared with the culture in a liquid medium, the chondrogenic pattern became less coarse when the cells were cultured in collagen or agarose gel, and the pattern change appeared to be independent of the cell differentiation. Time-lapse observation revealed a decrease in cell motility when the cells were cultured in gel. It was found that both the reaction-diffusion and cell sorting models fit the pattern change produced and that the mechanochemical model is not primarily important in the chondrogenic pattern formation in vitro.

Agar↗
PubMed2006

Inheritance of sutural pattern at the pterion in Rhesus monkey skulls.

Five of the bones that characteristically comprise the cranial vault articulate on the lateral aspect of the skull at or near the cephalometric landmark referred to as the pterion. The pattern of articulation in the sutures associated with these bones varies among and within primate species and has been used as a criterion for classification in taxonomic studies, as well as in archeological and forensic studies. Within species, the sutural patterns found within the region of the pterion have remarkable consistency, which lead to the hypothesis that these patterns have a genetic basis. Sutural pattern variations were investigated at the pterion in 422 skulls from 66 rhesus monkey families with known genealogies from the long-standing colony on Cayo Santiago. Four specific types of articulation patterns were recorded. The results demonstrated that the most common suture pattern at the pterion of Cayo Santiago rhesus monkeys (86%; similar to that seen in some other anthropoid species but not humans and some apes) was characterized by an articulation between the temporal bone and parietal bone. Articulation between the sphenoid and parietal bones (type SP) accounted for 14% of the specimens and was concentrated in a dozen families. Mothers with the SP phenotype had a high incidence of offspring with SP phenotypes. Most non-SP mothers having SP offspring had siblings or family members from previous generations with the SP type. This is the first study to examine variation in sutural patterns at the pterion in pedigrees. Variation of sutural patterns shows familial aggregation, suggesting that this variation is heritable. Future work will be focused on defining the inheritance patterns of variation at the pterion, with the ultimate objective of identifying the specific genes involved and their mechanism of action.

Animals↗
PubMed2005

Amino acid coupling patterns in thermophilic proteins.

Structural analysis is useful in elucidating structural features responsible for enhanced thermal stability of proteins. However, due to the rapid increase of sequenced genomic data, there are far more protein sequences than the corresponding three-dimensional (3D) structures. The usual sequence-based amino acid composition analysis provides useful but simplified clues about the amino acid types related to thermal stability of proteins. In this work, we developed a statistical approach to identify the significant amino acid coupling sequence patterns in thermophilic proteins. The amino acid coupling sequence pattern is defined as any 2 types of amino acids separated by 1 or more amino acids. Using this approach, we construct the rho profiles for the coupling patterns. The rho value gives a measure of the relative occurrence of a coupling pattern in thermophiles compared with mesophiles. We found that thermophiles and mesophiles exhibit significant bias in their amino acid coupling patterns. We showed that such bias is mainly due to temperature adaptation instead of species or GC content variations. Though no single outstanding coupling pattern can adequately account for protein thermostability, we can use a group of amino acid coupling patterns having strong statistical significance (p values < 10(-7)) to distinguish between thermophilic and mesophilic proteins. We found a good correlation between the optimal growth temperatures of the genomes and the occurrences of the coupling patterns (the correlation coefficient is 0.89). Furthermore, we can separate the thermophilic proteins from their mesophilic orthologs using the amino acid coupling patterns. These results may be useful in the study of the enhanced stability of proteins from thermophiles-especially when structural information is scarce. Proteins 2005. (c) 2005 Wiley-Liss, Inc.

Amino Acid Sequence↗
PubMed2002

Pattern formation in reaction-diffusion models with nonuniform domain growth.

Recent examples of biological pattern formation where a pattern changes qualitatively as the underlying domain grows have given rise to renewed interest in the reaction-diffusion (Turing) model for pattern formation. Several authors have now reported studies showing that with the addition of domain growth the Turing model can generate sequences of patterns consistent with experimental observations. These studies demonstrate the tendency for the symmetrical splitting or insertion of concentration peaks in response to domain growth. This process has also been suggested as a mechanism for reliable pattern selection. However, thus far authors have only considered the restricted case where growth is uniform throughout the domain. In this paper we generalize our recent results for reaction-diffusion pattern formation on growing domains to consider the effects of spatially nonuniform growth. The purpose is twofold: firstly to demonstrate that the addition of weak spatial heterogeneity does not significantly alter pattern selection from the uniform case, but secondly that sufficiently strong nonuniformity, for example where only a restricted part of the domain is growing, can give rise to sequences of patterns not seen for the uniform case, giving a further mechanism for controlling pattern selection. A framework for modelling is presented in which domain expansion and boundary (apical) growth are unified in a consistent manner. The results have implications for all reaction-diffusion type models subject to underlying domain growth.

Animals↗
PubMed1999

Interactions between the foot and the head patterning systems in Hydra vulgaris.

The Cnidarian, hydra, is an appealing model system for studying the basic processes underlying pattern formation. Classical studies have elucidated much basic information regarding the role of development gradients, and theoretical models have been quite successful at describing experimental results. However, most experiments and computer simulations have dealt with isolated patterning events such as the dynamics of head regeneration. More global events such as interactions among the head, bud, and foot patterning systems have not been extensively addressed. The characterization of monoclonal antibodies with position-specific labeling patterns and the recent cloning and characterization of genes expressed in position-specific manners now provide the tools for investigating global interactions between patterning systems. In particular, changes in the axial positional value gradient may be monitored in response to experimental perturbation. Rather than studying isolated patterning events, this approach allows us to study patterning over the entire animal. The studies reported here focus on interactions between the foot and the head patterning systems in Hydra vulgaris following induction of a foot in close proximity to a head, axial grafting of a foot closer to the head, or doubling the amount of basal tissue by lateral grafting of an additional peduncle-foot onto host animals. Resulting positional value changes as monitored by antigen (TS19) and gene (ks1 and CnNK-2) expression were assessed in the foot, head, and intervening tissue. The results of the experiments indicate that positional values changed rapidly, in a matter of hours, and that there were reciprocal interactions between the foot and the head patterning systems. Theoretical interpretations of the results in the form of computer simulations based on the reaction-diffusion model are presented and predict many, but not all, of the experimental observations. Since the lateral grafting experiment cannot, at present, be simulated, it is discussed in light of what has been learned from the axial grafting experiments and their simulations.

Animals↗
PubMed1999

Three-dimensional structure analysis of PROSITE patterns.

Pattern matches for each of the sequence patterns in PROSITE, a database of sequence patterns, were searched in all protein sequences in the Brookhaven Protein Data Bank (PDB). The three-dimensional structures of the pattern matches for the 20 patterns with the largest numbers of hits were analysed. We found that the true positives have a common three-dimensional structure for each pattern; the structures of false positives, found for six of the 20 patterns, were clearly different from those of the true positives. The results suggest that the true pattern matches each have a characteristic common three-dimensional structure, which could be used to create a template to define a three-dimensional functional pattern.

Adenosine Triphosphate↗
PubMed2000

Searching the protein structure databank with weak sequence patterns and structural constraints.

A method is described in which proteins that match PROSITE patterns are filtered by the root-mean-square deviation of the local 3D structures of the probe and target over the pattern components. This was found to increase the discrimination between true and false members of the protein family but was dependent on how unique the structural features in the pattern were compared to equivalent fragments extracted from the structure databank (for example; if the pattern fell in an alpha-helix, then discrimination was poor.) We then generalised the sequence patterns (by widening the range of amino acid residues allowed at each position) and monitored how well the structural information helped retain specificity. While the discrimination of the pure sequence pattern had generally disappeared at information content values less than ten bits, the discrimination of the combined sequence structure probe remained high at this point before following a similar decay. The displacement between these curves indicates that the structural component is, on average, equivalent to about ten bits. The sequence patterns were also filtered using the structure comparison program SAP, giving a global, rather than local "view" of the proteins. This allowed the information content of the sequence patterns to become even less specific but raised problems of whether some proteins encountered with the same fold but no PROSITE pattern should constitute family members.

Amino Acid Motifs↗
PubMed1980

Responsiveness of inferotemporal single units to visual pattern stimuli in monkeys performing discrimination.

Four monkeys were trained to choose two rewarded stimuli from four two-dimensional patterns presented successively, and the responsiveness of single units to these patterns was investigated. Eighty-three of 214 units (39%) recorded from the dorsolateral portion of the inferotemporal cortex were responsive; nearly half responded to all four patterns, irrespective of pattern shape and of whether the stimuli were rewarded or not. A few units were responsive to only one of the patterns, regardless of size, color, or luminance, and unresponsiveness to components of the response-eliciting patterns was indicated in some of these units. The activity of most units response to two or three patterns was dependent on pattern shapes rather than the learnt meaning of the patterns.

Animals↗
PubMed1980

Neocognitron: a self organizing neural network model for a mechanism of pattern recognition unaffected by shift in position.

A neural network model for a mechanism of visual pattern recognition is proposed in this paper. The network is self-organized by "learning without a teacher", and acquires an ability to recognize stimulus patterns based on the geometrical similarity (Gestalt) of their shapes without affected by their positions. This network is given a nickname "neocognitron". After completion of self-organization, the network has a structure similar to the hierarchy model of the visual nervous system proposed by Hubel and Wiesel. The network consists of an input layer (photoreceptor array) followed by a cascade connection of a number of modular structures, each of which is composed of two layers of cells connected in a cascade. The first layer of each module consists of "S-cells", which show characteristics similar to simple cells or lower order hypercomplex cells, and the second layer consists of "C-cells" similar to complex cells or higher order hypercomplex cells. The afferent synapses to each S-cell have plasticity and are modifiable. The network has an ability of unsupervised learning: We do not need any "teacher" during the process of self-organization, and it is only needed to present a set of stimulus patterns repeatedly to the input layer of the network. The network has been simulated on a digital computer. After repetitive presentation of a set of stimulus patterns, each stimulus pattern has become to elicit an output only from one of the C-cells of the last layer, and conversely, this C-cell has become selectively responsive only to that stimulus pattern. That is, none of the C-cells of the last layer responds to more than one stimulus pattern. The response of the C-cells of the last layer is not affected by the pattern's position at all. Neither is it affected by a small change in shape nor in size of the stimulus pattern.

Cognition↗
PubMed1986

A neural network model for selective attention in visual pattern recognition.

A neural network model of the mechanism of selective attention in visual pattern recognition is proposed and simulated on a digital computer. When a complex figure consisting of two patterns or more is presented to the model, it is segmented into individual patterns, and each pattern is recognized separately. Even if one of the patterns to which the model is paying selective attention is affected by noise or defects, the model can recall the complete pattern from which the noise has been eliminated and the defects corrected. It is not necessary for perfect recall that the stimulus pattern should be identical in shape to the training pattern. Even though the pattern is distorted in shape or changed in size, it can be correctly recognized and the missing portions restored. The model consists of a hierarchical neural network which has efferent as well as afferent connections between cells. The afferent and the efferent signals interact with each other in the network: the efferent signals, that is, the signals for selective attention, have a facilitating effect on the afferent ones, and, at the same time, the afferent signals gate efferent signal flow. When some feature in the stimulus is not extracted in the afferent paths, the threshold for detection of that feature is automatically lowered by decreasing the efficiency of inhibition, and the model tries to extract even vague traces of the undetected feature.

Afferent Pathways↗