The behavioral origins of phylogenic responses and ontogenic habits.

An examination of innate behavior and its possible origins suggests parallels with the formation of habitual behavior. Inflexible but adaptive responses-innate reflexive behavior, Pavlovian conditioned responses, and operant habits-may have evolved from variable behavior in phylogeny and ontogeny. This form of "plasticity-first" scientific narrative was unpopular post-Darwin but has recently gained credibility in evolutionary biology. The present article seeks to identify originating events and contingencies contributing to such inflexible but adaptive behavior at both phylogenic and ontogenic levels of selection. In ontogeny, the development of inflexible performance (i.e., habit) from variable operant behavior is reminiscent of the genetic accommodation of initially variable phylogenic traits. The effects characteristic of habit (e.g., unresponsiveness to reinforcer devaluation) are explicable as the result of a conflict between behaviors at distinct levels of selection. The present interpretation validates the practice of seeking hard analogies between evolutionary biology and operant behavior. Finding such parallels implies the validity of a claim that organismal behavior, both innate and learned, is a product of selection by consequences. A complete and coherent account of organismal behavior may ultimately focus on functional selective histories in much the same way evolutionary biology does with its subject matter.

A Tale of Two Rats: The Backstory of a Clever Cartoon.

A well-known cartoon among psychologists and behavior analysts depicts two rats in a Skinner box, leaning over a response lever as one says to the other, "Boy, do we have this guy conditioned, every time I press the bar down he drops a pellet in." Anyone who has ever conducted an experiment, worked with a client, or taught someone can relate to the cartoon's message of reciprocal control between subject and experimenter, client and therapist, and teacher and student. This is the tale of that cartoon and its impact. It begins mid-20th-century at Columbia University, then a hotbed of behavioral psychology, which bears an intimate connection to the cartoon's appearance. The tale expands from Columbia to follow the lives of its creators from their undergraduate days there to their deaths decades later. The infusion of the cartoon into American psychology begins with B. F. Skinner, but, over the years, it also has appeared in introductory psychology textbooks and in iterative form in mass media outlets such as the World Wide Web and magazines like The New Yorker. The heart of the tale, however, was stated in the second sentence of this abstract. The tale ends with a review of how reciprocal relations like those depicted by the cartoon's creators have influenced research and practice in behavioral psychology.

Protocols for the Evaluation of Neurodevelopmental Alterations in Rabbit Models In Vitro and In Vivo.

The rabbit model is gaining importance in the field of neurodevelopmental evaluation due to its higher similarity to humans in terms of brain development and maturation than rodents. In this publication, we detailed 14 protocols covering toxicological relevant endpoints for the assessment of neurodevelopmental adverse effects in the rabbit species. These protocols include both in vitro and in vivo techniques, which also cover different evaluation time-points, the neonatal period, and long-term examinations at postnatal days (PNDs) 50-70. Specifically, the protocols (P) included are as follows: neurosphere preparation (GD30/PND0; P2) and neurosphere assay (P3), behavioral ontogeny (PND1; P4), brain obtaining and brain weight measurement at two different ages: PND1 (P5) and PND70 (P12), neurohistopathological evaluations after immersion fixation for neurons, astrocytes, oligodendrocytes and microglia (PND1; P6-9) or perfusion fixation (PND70; P12), motor activity (P11, open field), memory and sensory function (P11, object recognition test), learning (P10, Skinner box), and histological evaluation of plasticity (P13 and P14) through dendritic spines and perineuronal nets. The expected control values and their variabilities are presented together with the information on how to troubleshoot the most common issues related to each protocol. To sum up, this publication offers a comprehensive compilation of reliable protocols adapted to the rabbit model for neurodevelopmental assessment in toxicology.

Conceptual Foundations: Teaching the Historical Development of Radical Behaviorism as a Philosophy of Science.

This article outlines a graduate-level course on the philosophical, conceptual, and historical (PCH) foundations of radical behaviorism, which is the philosophy of science that underlies behavior analysis. As described, the course is for a 15-week semester, and is organized into weekly units. The units in the first half of the course are concerned with the influences of other viewpoints in the history of psychology on the development of behavior analysis and radical behaviorism. The units in the second half are concerned with the PCH foundations of eight basic dimensions of radical behaviorism. Throughout, a course examining the foundations of radical behaviorism is seen as compatible with related courses in the other three domains of behavior analysis-the experimental analysis of behavior, applied behavior analysis, and service delivery-and as integral to the education of all behavior analysts.

Rastreando possíveis elos científicos entre Claude Bernard e B. F. Skinner, / Investigating possible scientific connections between Claude Bernard and B. F. Skinner

Resumo Vários estudos rastreando possíveis fontes que teriam norteado Skinner na construção do Behaviorismo sugeriram, de modo pouco preciso, elos científicos entre Claude Bernard e Skinner. Considerando o assunto, este trabalho realizou um comparativo sistemático entre ambos os autores, através das seguintes categorias: (1) interação organismo-ambiente; (2) mentalismo; (3) indução-dedução; e (4) delineamento do sujeito único. Embora diferenças tenham sido encontradas entre as categorias (1), a análise de variáveis externas, e na (2), rejeição de explicações sem bases científicas, essas diferenças estão presentes em ambas as teorias. Na categoria (3), Skinner e Bernard apresentaram posicionamento distintos. Quanto à análise do delineamento intrassujeito, ambos denotaram várias compatibilidades, diferenciando-se, principalmente, por conta de seus objetivos epistêmicos.

Abstract Several studies tracking down possible sources that would have given direction to Skinner in the development of Behaviorism, suggested an inaccurate scientific link between Claude Bernard and Skinner. Considering this subject, this work performed a systematic comparison between both authors, through the following categories: (1) organism-environment interaction; (2) mentalism; (3) induction-deduction; and method of the single case. Although differences have been found, in category (1), the analysis of the external variables, and in (2), rejection of explanation without scientific basis, were detected in both theories. In category (3), Skinner and Bernard show different opinions. As to the analysis of the intrasubject design, both detonated several compatibilities, differing, mainly because of its epistemic objectives.

C-3s and Model Ts: The Machines behind Two Lovely Farewells.

B. F. Skinner's 1976 editorial "Farewell my LOVELY," eulogizing the passing of the cumulative record as a primary form of data analysis, borrowed its title from a 1936 E. B. White essay of the same name. In it, White, a well-known 20th century essayist and children's book author, eulogized the Model T Ford. This article considers the parallels between the machine behind the cumulative record-the cumulative recorder-and White's Model T. The cumulative recorder considered for comparison is the Ralph Gerbrands Company Model C-3, widely considered by scientists of the time to be the best of the cumulative recorders that proliferated between the 1950s and the 1990s. On a much more modest scale, the C-3 became as popular, visible, distinct, and important in research laboratories devoted, but not limited, to the experimental analysis of behavior as was the Model T on the roads of early 20th century America. Not only were there parallels in manufacture and marketing, but, more importantly, in reliability, durability and ease of function of these two machines that changed the respective practices and culture of behavioral psychology and the world.

Standing on the Shoulders of a Giant: Remembrances of Jack Michael, Part 1.

In 1959, Jack Michael and his PhD student Ted Ayllon published "The Psychiatric Nurse as a Behavioral Engineer" (Ayllon & Michael, 1959). That study was Ayllon's doctoral dissertation and was the first empirical demonstration of how the principles of behavior (e.g., reinforcement, extinction, satiation) could be applied to solve clinical problems. That research was the beginning of what would soon be called "behavior modification," and later, "applied behavior analysis." Jack's foundational contributions to behavior analysis continued for 5 decades. In recognition of his life's work, his former students and close associates John Mabry, Grayson Osborne, Jon Bailey, Mark Sundberg, and J. Vincent Carbone offer tributes to Jack. These tributes tell the story of Jack's early teaching career, his students, his work, and how he inspired others to become behavior analysts. Six more tributes will appear in the fall issue of The Analysis of Verbal Behavior and will provide insight into Jack's work and other activities in the later part of his career. Those tributes will be from Jack's former students and close associates Hank Schlinger, Dave Palmer, Carl Sundberg, John and Barb Esch, Anna Petursdottir, and Caio Miguel.

Automated Operant Conditioning Devices for Fish. Do They Work?

The growing use of teleosts in comparative cognition and in neurobiological research has prompted many researchers to develop automated conditioning devices for fish. These techniques can make research less expensive and fully comparable with research on warm-blooded species, in which automated devices have been used for more than a century. Tested with a recently developed automated device, guppies (Poecilia reticulata) easily performed 80 reinforced trials per session, exceeding 80% accuracy in color or shape discrimination tasks after only 3-4 training session, though they exhibit unexpectedly poor performance in numerical discrimination tasks. As several pieces of evidence indicate, guppies possess excellent numerical abilities. In the first part of this study, we benchmarked the automated training device with a standard manual training procedure by administering the same set of tasks, which consisted of numerical discriminations of increasing difficulty. All manually-trained guppies quickly learned the easiest discriminations and a substantial percentage learned the more difficult ones, such as 4 vs. 5 items. No fish trained with the automated conditioning device reached the learning criterion for even the easiest discriminations. In the second part of the study, we introduced a series of modifications to the conditioning chamber and to the procedure in an attempt to improve its efficiency. Increasing the decision time, inter-trial interval, or visibility of the stimuli did not produce an appreciable improvement. Reducing the cognitive load of the task by training subjects first to use the device with shape and color discriminations, significantly improved their numerical performance. Allowing the subjects to reside in the test chamber, which likely reduced the amount of attentional resources subtracted to task execution, also led to an improvement, although in no case did subjects match the performance of fish trained with the standard procedure. Our results highlight limitations in the capacity of small laboratory teleosts to cope with operant conditioning automation that was not observed in laboratory mammals and birds and that currently prevent an easy and straightforward comparison with other vertebrates.

Psychological operationisms at Harvard: Skinner, Boring, and Stevens.

Contemporary discussions about operational definition often hark back to Stanley S. Stevens' classic papers on psychological operationism. Still, he was far from the only psychologist to call for conceptual hygiene. Some of Stevens' direct colleagues at Harvard-most notably B. F. Skinner and E. G. Boring-were also actively applying Bridgman's conceptual strictures to the study of mind and behavior. In this paper, I shed new light on the history of operationism by reconstructing the Harvard debates about operational definition in the years before Stevens published his seminal articles. Building on a large set of archival evidence from the Harvard University Archives, I argue that we can get a more complete understanding of Stevens' contributions if we better grasp the operationisms of his former teachers and direct colleagues at Harvard's Department of Philosophy and Psychology.

Standing on the Shoulders of a Giant: Remembrances of Jack Michael, Part 2.

In Part 1 of these remembrances of Jack Michael, we briefly described Jack's history in terms of how he became a behavior analyst (Sundberg & Schlinger, 2021). We pointed out that he was one of the first to apply the principles of behavior analysis discovered in the experimental laboratory to the area of rehabilitation. In so doing, Jack was perhaps the first applied behavior analyst. In Part 1, some of his former students and close associates from his early years at the University of Houston, Arizona State University, and Western Michigan University-John Mabry, Grayson Osborne, Jon Bailey, Mark Sundberg, and J. Vincent Carbone-provided their personal tributes to Jack. In Part 2, we offer six more tributes that-with one exception, that of Ted Ayllon-provide insight into Jack's work in the latter part of his career. In addition to Ted Ayllon, these tributes are from Jack's students and close associates Hank Schlinger, Dave Palmer, John and Barb Esch, Carl Sundberg, and Caio Miguel. The authors provide insights not only into their views about Jack but also into their own lives. Collectively, they paint a picture of people from different backgrounds that all found their way to Jack Michael and to behavior analysis. To a person, they describe how their behavior, whether as scientists, practitioners, or both, was radically transformed as a result, and how they attribute that change largely to Jack's influence.

Jack Michael, Behavior Analyst.

Jack Michael was the quintessential behavior analyst. Despite his reputation as a theoretician and expert in verbal behavior and on Skinner's book Verbal Behavior, Jack was actually an applied behavior analyst in the literal sense before anyone had coined the term. Prior to becoming one of Jack's doctoral students at Western Michigan University, I was a behavior-analytic neophyte. After I graduated and began my own teaching (modeled after Jack's behavior-analytic method of teaching) and thinking and writing about behavior analysis, I found myself talking and thinking like Jack. He had a similar behavior changing effect not only on many of his other students, but also on others who had the good fortune to know him.

The Role of Theory in Behavior Analysis: A Response to Unfinished Business, Travis Thompson's Review of Staddon's New Behaviorism (2nd edition).

Travis Thompson's lengthy review of Staddon's The New Behaviorism requires several corrections and extensions. This response discusses Staddon's analysis of Herrnstein's matching law and concludes that Thompson misinterprets a gentle critique as a paean. The response goes on to defend the utility of models and "internal states" (i.e., postulated processes that are not directly measurable) as "formal representation[s] of the data reduced to a minimal number of terms," a position similar to one of B. F. Skinner's statements. The response ends with a defense of Skinner's empirical brilliance, but a critique of his sweeping societal prescriptions.

Interpretação: Um Objetivo e um Método da Ciência de B. F. Skinner / Interpretation: An Aim and a Method of B. F. Skinner's Science

Resumo Este artigo tem por finalidade geral apresentar a visão de Skinner sobre a interpretação, seja como objetivo ou como método. Além disso, tem como propósitos específicos (a) definir a interpretação, conforme Skinner, (b) apontar quando e como o autor defende a sua realização, (c) relacionar a interpretação a outros objetivos e métodos propostos por Skinner e (d) indicar contribuições e limites da interpretação, segundo o autor. Para isso, examinamos 35 textos de Skinner ligados ao assunto, publicados entre 1931 e 1990. Seja como objetivo ou como método, mostramos que a interpretação oferece contribuições teóricas, metodológicas e tecnológicas à ciência de Skinner, ainda que ela apresente limites relacionados à sua natureza inferencial e especulativa, bem como ao seu caráter plausível e, às vezes, temporário.

Abstract This paper has the general purpose of presenting Skinner's vision of interpretation, both as aim and method. Besides, it has as specific purposes (a) to define interpretation, according to Skinner; (b) to indicate when and how the author defends its accomplishment; (c) to relate interpretation with other aims and methods proposed by Skinner; (d) to indicate contributions and limits of interpretation, according to the author. In this regard, we examined 35 texts of Skinner related to the subject, published between 1931 and 1990. Both as aim and method, we show that interpretation offers theoretical, methodological, and technological contributions to Skinner's science, although it presents limits related to its inferential and speculative nature, as well as to its plausible and sometimes temporary format.

O Besouro na Caixa de Skinner, / The Beetle in Skinner's Box

Resumo A literatura tem indicado algumas aproximações entre as propostas de Skinner e Wittgenstein, como, por exemplo, a crítica às concepções tradicionais de linguagem psicológica. Wittgenstein assenta essa crítica na impossibilidade de uma linguagem privada, enquanto Skinner a faz por meio do conceito de eventos privados. Contudo, esse conceito parece não ser consistente com a proposta de Wittgenstein. Partindo dessa hipótese, este artigo pretende reavaliar o papel do conceito de eventos privados no comportamentalismo skinneriano à luz das discussões críticas de Wittgenstein. Para isso, é feita uma comparação entre as propostas de Wittgenstein e de Skinner, evidenciando que o conceito de eventos privados é suscetível às críticas de Wittgenstein às concepções tradicionais da linguagem psicológica.

Abstract The literature has indicated some approximations between Skinner's and Wittgenstein's proposals, such as a critical standpoint on traditional psychological language conceptions. For Wittgenstein, the critique refers to the impossibility of a private language. On the other hand, Skinner's critique culminates in defense of the concept of private events. However, this concept seems inconsistent with Wittgenstein's proposal. Based on this assumption, this paper aims to reevaluate the role of the concept of 'private events' in Skinnerian behaviorism in the light of Wittgenstein's critical discussions. For this, Wittgenstein's and Skinner's proposals were systematically compared. It is concluded that the concept of private events is not to escape Wittgenstein's criticisms of the traditional psychological language.

SPiDbox: design and validation of an open-source "Skinner-box" system for the study of jumping spiders.

BACKGROUND: Skinner-box systems are fundamental in behavioural research. They are objective, reliable and can be used to carry out procedures otherwise impossible with manual methodologies. Recently, jumping spiders have caught the interest of scientists for their remarkable cognitive abilities. However, inquiries on their learning abilities are still few, since we lacked a proper methodology capable of overcoming the inherent difficulties that this family poses when carrying out a conditioning protocol. NEW METHOD: In this paper, a new, automated, open-source Skinner-box, intended for the study of jumping spiders is presented. The system is 3d printable, cheap, fully open-source; is controlled with a Raspberry Pi Zero by a Python script. Since spiders are too lightweight to activate large physical object, the SPiDbox employs photo-sensors. RESULTS: To validate the methodology, 30 Phidippus regius underwent a training procedure for a simple discrimination task to validate the effectiveness of the system. The spiders managed to learn the task, establishing the effectiveness of the SPiDbox. COMPARISON WITH EXISTING METHODS: This automated training appears to be more reliable and effective than traditional methodologies. Moreover, its highly scalable, as many SPiDboxes could be used in parallel. CONCLUSIONS: The SPiDbox appears to be an effective system to train jumping spiders, opening up the possibility to study learning in increasingly more complex tasks, possibly extending our understanding of jumping spiders' cognitive abilities.

Systematic Review of Verbal Operants in Speech Generating Device Research from Skinner's Analysis of Verbal Behavior.

Skinner's (1957) book Verbal Behavior is a critical tool in designing effective communication programs for individuals with limited speech. The purpose of this systematic review was to analyze the speech generating device (SGD) research literature from Skinner's taxonomy of primary verbal operants. An extraction procedure yielded 56 studies published between 1995 and 2018, with a total of 221 participants, most of whom had autism spectrum disorder (ASD) or an intellectual and developmental disability (IDD). The large majority of SGD studies (42) targeted multiply controlled mands, whereas only a handful of studies targeted verbal operants that were not mands. Few studies employed procedures for fading contrived sources of stimulus control to promote spontaneous responding, and few studies targeted more sophisticated, topography-based responses (e.g., typing, speech). Results of the review highlight the need for better dissemination of Skinner's Verbal Behavior, the need for research to evaluate effects of SGD in teaching a greater variety of spontaneous verbal operants, and the need to focus on application of SGD with populations beyond individuals with ASD and IDD.

Concepções sobre o Behaviorismo radical nas publicações da Folha de S. Paulo / Conceptions about radical Behaviorism in Folha de S. Paulo's publications / Concepciones acerca del Conductismo radical en las publicaciones de Folha de S. Paulo

Frequentemente, o behaviorismo radical e a análise do comportamento são apresentados na mídia por meio de estereótipos negativos, possivelmente atravancando a difusão de suas propostas aos potenciais beneficiários. Com base nisso, o objetivo deste trabalho é caracterizar as publicações do jornal Folha de S.Paulo sobre behaviorismo radical e análise do comportamento desde a sua fundação em 192, até 2015. Para tal, 227 parágrafos presentes no jornal que continham os termos Skinner ou behaviorismo foram selecionados para análise. De forma geral, foram encontrados trechos contendo críticas ao behaviorismo radical que expuseram equívocos históricos e conceituais, problematizaram o este campo de estudo, apresentaram algum aspecto correto e/ou apresentaram o termo "behaviorismo" de forma genérica. Foram identificados tópicos especialmente mal compreendidos: a análise do comportamento como legitimadora do controle, ultrapassada pelas teorias cognitivistas, capaz de explicar apenas comportamentos simples ou de animais não-humanos e interessada apenas em comportamentos observáveis. Recomenda-se que behavioristas radicais comuniquem suas propostas com ênfase em seu caráter de denúncia do controle como uma característica inerente às relações comportamentais de uma ciência viva em constante desenvolvimento e de uma abordagem interessada em lidar com quaisquer comportamentos, que aconteçam dentro ou fora da pele...(AU)

Often radical behaviorism and behavior analysis are presented in the media by means of negative stereotypes, thus possibly making harder the diffusion of its proposals to potential target audience. Taking that into account, this paper categorized publications from the newspaper Folha de S.Paulo since its foundation, in 1921, until 2015, regarding radical behaviorism and behavior analysis. To reach such goal, 227 paragraphs were selected containing the terms Skinner or behaviorism from the newspaper. In general, excerpts that criticized radical behaviorism, parts that exposed historical and conceptual misconception, that problematized radical behaviorism, that showed some correct aspect and that presented the term behaviorism in a generic way were found. Some specially misunderstood topics were identified: the view of behavior analysis as an approach that defends control, outdated and overcome by cognitive theories, is only capable of explaining simple human or non-human behavior and interested in observable behavior. We recommend behavior analysts that communicate their proposals with an emphasis on control as an inherent characteristic of behavioral relations to take into account it is a constantly evolving science and an approach interested in dealing with any behavior, whether occurring over or under the skin...(AU)

El análisis conductual y el conductismo radical son presentados a menudo en los medios de comunicación mediante estereotipos negativos, posiblemente dificultando la difusión de sus propuestas a los potenciales beneficiarios. Basándose en esto, el objetivo de este trabajo fue caracterizar las publicaciones del diario Folha de S.Paulo sobre el análisis conductual y el conductismo radical desde su fundación, en 1921, hasta 2015. Para ello, se seleccionaran para análisis 227 párrafos presentes en el diario, que contenían las palabras Skinner o conductismo. En general, se encontraron extractos que hicieron críticas al conductismo radical, que expusieron equívocos históricos y conceptuales, que problematizaron el conductismo radical, que presentaron algún aspecto correcto y que presentaron el término "conductismo" de manera genérica. Se identificó tópicos especialmente incomprendidos: la perspectiva de análisis de la conducta como un enfoque psicológico defensor del control, ultrapasada y superada por las teorías cognitivistas, capaz de explicar solo los comportamientos simples o de animales no humanos e interesada solamente en comportamientos observables. Se recomienda que conductistas radicales comuniquen sus propuestas con énfasis en su carácter de denuncia del control como una característica inherente a las relaciones comportamentales, de una ciencia viva, en desarrollo continuo, y de un enfoque psicológico interesado en tratar cualquier comportamiento, que ocurra dentro o fuera de la piel...(AU)

Didática Magna e Walden II: Comênio, Skinner e o impossível na educação e na política / Didáctica Magna y Walden II: Comenio, Skinner y lo imposible en la educación y la política / The Great Didactic and Walden II: Comenius, Skinner and the impossible in education and politcs

Neste artigo cotejamos concepções político-educacionais de Comênio e Skinner presentes, respectivamente, na Didática Magna e em Walden II. Problematizamos se o fato dos autores superestimarem o método de ensino - como se este fosse uma infalível garantia de êxito educacional - seria suficiente para irmaná- los. Seguindo a ideia de que é estruturalmente impossível controlar os efeitos da educação, constatamos que em Comênio, mas não em Skinner, ocorre um significativo arrefecimento de tal pretensa infalibilidade metodológica. Essa divergência entre os autores deriva do modo distinto com que cada um concebe a política e lida com as finalidades e impossibilidades da política e da educação.

En este artículo cotejamos concepciones político-educativas de Comenio y Skinner presentes en Didáctica Magna y Walden II. Problematizamos si el hecho de que los autores exageran en la valorización del método - como si fuera una infalible garantía de éxito en la educación - sería suficiente para hermanarlos. Siguiendo la idea de que es estructuralmente imposible controlar los efectos de la educación, constatamos que en Comenio, pero no en Skinner, ocurre un enfriamiento de tal pretendida infalibilidad metodologica. Esta divergencia deriva del modo distinto como cada autor concibe la política y se ocupa de las finalidades e imposibilidades de la política y de la educación.

In this paper, we compare the educational-political conceptions of Comenius and Skinner, presents in The Great Didactic and Walden II. We problematize if their overestimation of the teaching method - as if it were an infallible assurance of education success - is a sufficient criteria to take their theory as siblings. Following the idea that it is structurally impossible to control the effects of education, we verify that in Comenius, different from Skinner, occurs an expressive decline of such methodological infallibility. This difference derives from their radically distinct way to conceive politic and to deal with the aims and impossibilities of politics and education.

Association between calf muscle oxygen saturation with ambulatory function and quality of life in symptomatic patients with peripheral artery disease.

OBJECTIVE: The objective of this study was to determine whether calf muscle hemoglobin oxygen saturation (Sto2) obtained during a standardized treadmill test is associated with ambulatory function and health-related quality of life (HRQoL) in patients with symptomatic peripheral artery disease (PAD). We hypothesized that a rapid decline in calf muscle Sto2 during walking is associated with impaired ambulatory function and HRQoL and that these associations are independent of ankle-brachial index (ABI). METHODS: Calf muscle Sto2, peak walking time, and claudication onset time were obtained during a treadmill test in 151 symptomatic men and women with PAD. Patients were further characterized by demographic variables, comorbid conditions, cardiovascular risk factors, ABI, 6-minute walk distance, daily ambulatory activity, Walking Impairment Questionnaire (WIQ) score, and Medical Outcomes Study 36-Item Short Form Health Survey physical function score to assess HRQoL. RESULTS: The median calf muscle Sto2 value at rest was 52%, which declined to 22% after only 1 minute of walking during the treadmill test and reached a minimum value of 9% after a median time of 87 seconds of walking. Of the various calf muscle Sto2 measurements obtained during the treadmill test, the exercise time to the minimum calf muscle Sto2 value (log transformed) had the strongest univariate associations with peak walking time (r = 0.56; P < .001), claudication onset time (r = 0.49; P < .001), 6-minute walk distance (r = 0.31; P < .001), WIQ distance score (r = 0.33; P < .001), WIQ speed score (r = 0.39; P < .001), WIQ stair-climbing score (r = 0.37; P < .001), and Medical Outcomes Study 36-Item Short Form Health Survey physical function score (r = 0.32; P < .001). In adjusted multiple regression models, these associations persisted (P < .001) after adjustment for demographic measures, cardiovascular risk factors, comorbid conditions, and ABI. CONCLUSIONS: More rapid decline in oxygen saturation of the calf musculature during walking, indicative of impaired microcirculation, is predictive of impaired ambulatory function and HRQoL in patients with symptomatic PAD. Of particular importance, these associations are independent of ABI and other common health burdens, highlighting the clinical relevance that the microcirculation has on ambulatory function and HRQoL in patients with symptomatic PAD.

A low-cost, wireless near-infrared spectroscopy device detects the presence of lower extremity atherosclerosis as measured by computed tomographic angiography and characterizes walking impairment in peripheral artery disease.

BACKGROUND: Patients with peripheral artery disease (PAD) who experience intermittent claudication report a range of symptoms. Patients with symptoms other than classically described intermittent claudication may be at the highest risk for functional decline and mobility loss. Therefore, technologies allowing for characterization of PAD severity are desirable. Near-infrared spectroscopy (NIRS) allows for measurements of muscle heme oxygen saturation (StO2) during exercise. We hypothesized lower extremities affected by PAD would exhibit distinct NIRS profiles as measured by a low-cost, wireless NIRS device and that NIRS during exercise predicts walking limitation. METHODS: We recruited 40 patients with PAD and 10 control participants. All patients with PAD completed a computed tomographic angiography, 6-minute walk test, and a standardized treadmill test. Controls completed a 540-second treadmill test for comparison. StO2 measurements were continuously taken from the gastrocnemius during exercise. Variables were analyzed by Fischer's exact, χ2, Wilcoxon rank-sum, and Kruskal-Wallis tests as appropriate. Correlations were assessed by partial Spearman correlation coefficients adjusted for occlusive disease pattern. RESULTS: Patients with PAD experienced claudication onset at a median of 108 seconds with a median peak walking time of 288 seconds. The baseline StO2 was similar between PAD and control. The StO2 of PAD and control participants dropped below baseline at a median of 1 and 104 seconds of exercise, respectively (P < .0001). Patients with PAD reached minimum StO2 earlier than control participants (119 seconds vs 522 seconds, respectively; P < .001) and experienced a greater change in StO2 at 1 minute of exercise (-73.2% vs 8.3%; P < .0001) and a greater decrease at minimum exercise StO2 (-83.4% vs -16.1%; P < .0001). For patients with PAD, peak walking time, and 6-minute walking distance correlated with percent change in StO2 at 1 minute of exercise (r = -0.76 and -0.67, respectively; P < .001) and time to minimum StO2 (r = 0.79 and 0.70, respectively; P < .0001). CONCLUSIONS: In this initial evaluation of a novel, low-cost NIRS device, lower extremities affected by PAD exhibited characteristic changes in calf muscle StO2, which differentiated them from healthy controls and were strongly correlated with walking impairment. These findings confirm and expand on previous work demonstrating the potential clinical value of NIRS devices and the need for further research investigating the ability of low-cost NIRS technology to evaluate, diagnose, and monitor treatment response in PAD.