Reflexes In Dogs Research Articles

Intraobserver and interobserver agreement of 8 segmental reflexes in healthy dogs.

No available literature supports the claim that the patellar and withdrawal (flexor) reflexes are the only reliable segmental reflexes in dogs. Measure intra- and interobserver agreement of 8 segmental reflexes in dogs without clinical evidence of orthopedic or neurologic disease. One-hundred and one client- or staff-owned dogs between 1 and 10 years of age with no clinical evidence of orthopedic disease, myelopathy, or neuromuscular disease. Descriptive study. The intraobserver proportion of agreement (%) of responses to selected segmental reflexes in right versus left limbs by 3 observers was calculated and reported. The interobserver agreement of 2 observers of responses to selected reflexes was estimated by calculating proportions of agreement, kappa values, and 95% confidence intervals. A segmental reflex with an acceptable agreement was defined as that with a proportion of agreement ≥90% and a Kappa value ≥0.61 in both limbs. The intraobserver proportion of agreement for all 3 observers was high (≥95%) for the extensor carpi radialis, withdrawal, patellar, and cranial tibial reflexes. Between observers 1 and 3 and observers 2 and 3, the interobserver proportion of agreement was high (≥ 92%) for the extensor carpi radialis (κ 0.66, not determined [ND]), withdrawal (both limbs, κ ND), patellar (κ ND), and cranial tibial reflexes (κ ND). The extensor carpi radialis, withdrawal, patellar, and cranial tibial reflexes had a higher proportion of agreement and kappa values between 2 observers.

Comparison of propofol infusion rate required to abolish swallowing or pedal withdrawal reflexes in dogs.

In a prospective, randomized, experimental non-blinded study, the continuous infusions rates of propofol required to prevent swallowing (P-SR) or pedal withdrawal reflex (P-WR) were evaluated in healthy premedicated dogs. Dogs were randomly assigned to one of two treatments at weekly intervals. Following premedication with a combination of acepromazine and methadone, anesthesia was induced with propofol (4.00 mg kg-1 per min) and was maintained for 90 min. The propofol infusion rate was increased or decreased by 0.05 mg kg-1 per min based on positive or negative swallowing (P-SR) or pedal withdrawal reflexes (P-WR). Propofol induction doses were 2.12 ± 0.43 mg kg-1 (P-SR) and 2.14 ± 0.31 mg kg-1 (P-WR), which were not significantly different. The mean (±SD) propofol infusion rate was significantly higher for P-WR (0.26 ± 0.10 mg kg-1 per min) when compared to P-SR (0.22 ± 0.12 mg kg-1 per min). During the last 30 min, the mean propofol infusion rates were 0.09 ± 0.02 and 0.18 ± 0.03 mg kg-1 per min for P-SR and P-WR, respectively. There were no significant differences between treatments with respect to heart rate (HR), respiratory rate, arterial blood pressure, end-tidal CO2 partial pressure, hemoglobin oxygen saturation, partial pressures of oxygen or pH. Transient apnea lasting up to three minutes was observed in three dogs with each treatment. Propofol infusion rate of 0.22 ± 0.12 mg kg-1 per min can be used in premedicated dogs requiring tracheal intubation and undergoing mechanical ventilation, non-painful procedures or painful procedures with local anesthetic techniques.

Effect of medetomidine, midazolam, ketamine, propofol and isoflurane on spinal reflexes in healthy dogs.

Sometimes it is necessary to use sedatives or even general anaesthetics to examine animals with spinal cord injuries. These drugs may affect spinal reflexes, alter the outcome of neurological examinations, and make it difficult to diagnose location of the lesion. The aim of this study was to evaluate the effects of five pre-anaesthetic and anaesthetic agents commonly used in clinics on spinal reflexes in dogs. Ten native adult dogs were participated in three groups. In all groups, the dogs were premedicated with medetomidine and midazolam; then, in the first group, ketamine, in the second group, propofol and in the third group, isoflurane were used for induction of anaesthesia. The spinal reflexes were evaluated before injection, 15 min after medetomidine, 20 min after midazolam, and at 15, 30, 45 and 60 min after induction of anaesthesia. Medetomidine did not reduce monosynaptic reflexes (patellar and cranial tibial reflexes) but increased them while it had no effect on the polysynaptic limb withdrawal reflexes. Midazolam had no effect on the spinal reflexes; Ketamine did not affect the patellar, cranial tibial and extensor carpi radialis reflexes, but reduced polysynaptic pain-related reflexes; and propofol and isoflurane abolished the all spinal reflexes. Medetomidine, midazolam and ketamine have no effect on reducing monosynaptic reflexes (patellar and cranial tibial reflexes) and may be used for neurological examination of restless animals in the clinic. Propofol and isoflurane eliminated all spinal reflex responses and are not suitable for neurological examinations.

Developing a predictive model for spinal shock in dogs with spinal cord injury.

BackgroundReduced pelvic limb reflexes in dogs with spinal cord injury typically suggests a lesion of the L4‐S3 spinal cord segments. However, pelvic limb reflexes might also be reduced in dogs with a T3‐L3 myelopathy and concurrent spinal shock.Hypothesis/ObjectivesWe hypothesized that statistical models could be used to identify clinical variables associated with spinal shock in dogs with spinal cord injuries.AnimalsCohort of 59 dogs with T3‐L3 myelopathies and spinal shock and 13 dogs with L4‐S3 myelopathies.MethodsData used for this study were prospectively entered by partner institutions into the International Canine Spinal Cord Injury observational registry between October 2016 and July 2019. Univariable logistic regression analyses were performed to assess the association between independent variables and the presence of spinal shock. Independent variables were selected for inclusion in a multivariable logistic regression model if they had a significant effect (P ≤ .1) on the odds of spinal shock in univariable logistic regression.ResultsThe final multivariable model included the natural log of weight (kg), the natural log of duration of clinical signs (hours), severity (paresis vs paraplegia), and pelvic limb tone (normal vs decreased/absent). The odds of spinal shock decreased with increasing weight (odds ratio [OR] = 0.28, P = .09; confidence interval [CI] 0.07‐1.2), increasing duration (OR = 0.44, P = .02; CI 0.21‐0.9), decreased pelvic limb tone (OR = 0.04, P = .003; CI 0.01‐0.36), and increased in the presence of paraplegia (OR = 7.87, P = .04; CI 1.1‐56.62).Conclusions and Clinical ImportanceA formula, as developed by the present study and after external validation, could be useful for assisting clinicians in determining the likelihood of spinal shock in various clinical scenarios and aid in diagnostic planning.

Effect of Sedation on the Neurological Examination of the Patellar and Withdrawal Reflexes in Healthy Dogs.

Introduction: Pain, temperament, fear, and anxiety can prevent safe and accurate evaluation of common neurologic reflexes in dogs. When sedation is used it is unknown how the neurological examination, and specifically patellar and withdrawal reflexes are affected, and, if present, how long any effect might last. The purpose of this study is to investigate the effect of sedation on the evaluation of select common limb spinal reflexes in healthy dogs.Material and Methods: Fourteen healthy dogs with normal neurologic exams were included. After placing joint landmarks, patellar reflex and pelvic and thoracic limb withdrawal reflexes were tested. Joint angles were measured, obtaining reflex angle endpoints, change in angle, and change in time to reflex completion. These measurements were recorded at different time points: prior to sedation (awake timepoint), 15 and 30 min following administration of standardized sedation protocol of dexmedetomidine and butorphanol, and 15 and 30 min following administration of a standardized reversal agent, atipamazole.Results: For patellar reflex, the stifle end angle increased from 91.5 to 108.55 degrees (p < 0.0001) 15 min following sedation, and remained increased at 104.5 degrees (p < 0.0001) 30 min following sedation. Stifle change in angle increased from 9.6 to 24.4 degrees (p < 0.0001) 15 min following sedation, and remained increased at 20.85 degrees (p < 0.0001) and 11 degrees (p = 0.012) at 30 min sedation and 15 min reversal. Tarsal joint in pelvic withdrawal and elbow in thoracic withdrawal reflexes did not differ in at any timepoint of sedation or reversal when compared with the awake timepoint, for end angle or change in angle. The increases in end angle and change in angle for patellar reflex generated a change in time for patellar reflex from 0.12 s (awake) to 0.129 s (15 min sedation) which was statistically significant (p = 0.041). Change in time did not differ for pelvic withdrawal or thoracic withdrawal.Discussion/Conclusions: Reflexes were elicited in all dogs under sedation. Sedation does not affect the evaluation of the withdrawal reflex on any limb but improves the visualization of the patellar reflex in this group of neurologically normal dogs.

Protocol for assessment of the pupillary light reflex in dogs without chemical restraint: preliminary investigation.

To explore the use of a modified pupillometry technique in dogs without chemical restraint. Following dark adaptation, pupillary light reflexes were assessed in six dogs with sudden acquired retinal degeneration syndrome, in the unaffected eye of eight dogs with unilateral primary glaucoma ("predisposed"), and in 11 healthy dogs. Responses to red, blue and white lights were recorded and relative pupil sizes subsequently determined based on video recordings of each test. Mean testing time was 2.3minutes (range 1.8 to 3.1 minutes), excluding time for dark adaptation. Baseline pupil size in dogs with sudden acquired retinal degeneration syndrome was greater than in normal and predisposed eyes. Pupil constriction was reduced in predisposed compared to normal and sudden acquired retinal degeneration syndrome eyes when stimulated with high-intensity blue light. Compared to normal eyes, those with sudden acquired retinal degeneration syndrome had reduced pupil constriction when stimulated with low- and high-intensity red light, low-intensity blue light and white light. Quantitative measures of pupil function were obtained from healthy and diseased eyes without the need for chemical restraint. Further investigations are warranted to validate the technique and evaluate its use in the management of canine glaucoma.

Comparison of interobserver agreement between the evaluation of bicipital and the patellar tendon reflex in healthy dogs

The reliability of reflex-assessment is currently debatable, with current literature regarding the patellar tendon reflex (PTR) as highly reliable, while the biceps tendon reflex (BTR) is regarded to be of low reliability in the dog. Such statements are, however, based on subjective observations rather than on an empirical study. The goals of this study were three-fold: (1) the quantification of the interobserver agreement (IA) on the evaluation of the canine bicipital (BTR) and patellar tendon (PTR) reflex in healthy dogs, (2) to compare the IA of the BTR and PTR evaluation and (3) the identification of intrinsic (sex, age, fur length, weight) and extrinsic (observer´s expertise, body side) risk factors on the IA of both reflexes. The observers were subdivided into three groups based on their expected level of expertise (neurologists = highest -, practitioners = middle–and veterinary students = lowest level of expertise). For the BTR, 54 thoracic limbs were analyzed and compared to the evaluation of the PTR on 64 pelvic limbs. Each observer had to evaluate the reflex presence (RP) (present or absent) and the reflex activity (RA) using a 5-point ordinal scale. Multiple reliability coefficients were calculated. The influence of the risk factors has been calculated using a mixed regression-model. The Odds Ratio for each factor was presented. The higher the level of expertise the higher was the IA of the BTR. For RP(BTR), IA was highest for neurologists and for RA(BTR) the IA was lowest for students. The level of expertise had a significant impact on the degree of the IA in the evaluation of the bicipital tendon reflex: for the RA(BTR), practitioners had a 3.4-times (p = 0.003) and students a 7.0-times (p < 0.001) higher chance of discordance. In longhaired dogs the chance of disagreement was 2.6-times higher compared to shorthaired dogs in the evaluation of RA(BTR) (p = 0.003). Likewise, the IA of the RP(PTR) was the higher the higher the observers´ expertise was with neurologists having significantly highest values (p < 0.001). The RA(PTR) has been evaluated more consistent by practitioners and students than the RA(BTR). For practitioners this difference was significant (< 0.01). Our data suggests that neurologists assess the bicipital and patellar tendon reflex in dogs most reliably. None of the examined risk factors had a significant impact on the degree of IA in the evaluation of RP(PTR), while students had a 4.4-times higher chance of discordance when evaluating the RA(PTR) compared to the other groups. This effect was significant (p < 0.001). Neurologists can reliably assess the bicipital and patellar tendon reflex in healthy dogs. Observer´s level of expertise and the fur length of the dog affect the degree of IA of RA(BTR). The influence of the observer´s expertise is higher on the evaluation of the BTR than on the PTR.

Evaluation of different premedicants in canine anaesthesia

Fifteen experimental trials were made in fifteen dogs in three different groups to study the degree of sedation produced by different premedicants, to evaluate and to compare their effects on various clinical parameters including different reflexes in dogs. These animals were premedicated with xylazine (1.1mg/kg), atropine (0.05mg/kg)-xylazine (1.1mg/kg) and diazepam (0.2mg/kg)-xylazine (1.1mg/kg) to observe their effect on different clinical and anaesthetic parameters. Diazepam-xylazine combination produced deep sedation while mild sedation was recorded with atropine-xylazine premedication. Respiration rate, heart rate and rectal temperature significantly decreased (P&lt;0.05) in dogs of all three groups after fifteen minutes of premedication. Diazepam-xylazine produced marked reduction (P&lt;0.05) on clinical parameters while atropine-xylazine produced mild to moderate reduction (P&lt;0.05) on clinical parameters in dogs. All experimental dogs in different groups were anaesthetized with ketamine hydrochloride after fifteen minutes of premedication. The respiration rate, heart rate and rectal temperature reduced significantly (P&lt;0.05) in xylazine-ketamine, atropinexylazine- ketamine and diazepam-xylazine-ketamine combination at 5, 10 and 15 min after induction when compared with pre-induction control values. The longest duration of anaesthesia (61.6 minutes) was obtained with diazepam-xylazine-ketamine combination while the shortest anaesthetic period (28.4 minutes) was observed in xylazine-ketamine combination. Diazepam-xylazine-ketamine combination produced longest recovery period (56.4 minutes) while the shortest recovery period (46.2 minutes) was observed with xylazineketamine combination. Atropine-xylazine-ketamine combination appears to be a safe combination for anaesthesia in dogs.Res. Agric. Livest. Fish.4(3): 209-214, December 2017

Ivan Pavlov and the Moral Physiology of Self

Ivan Pavlov and the Moral Physiology of Self Kirill Rossiianov Translated by Nicholas Seay Daniel P. Todes, Ivan Pavlov: A Russian Life in Science. xiii + 855 pp. Oxford: Oxford University Press, 2014. ISBN-13 978-0199925193. £27.49. In many respects, Daniel Todes’s new book serves as a shining example of an academic biography. He makes use of a great number of previously unknown archival materials to put forth a history of the scientific research of Ivan Petrovich Pavlov. This research would earn Pavlov the 1904 Nobel Prize in Physiology and Medicine and eventually turn his name into a symbol of rational control of the human psyche. By using these new archival sources, Todes allows his readers to better imagine not only Pavlov but also an entire generation of educated Russians. This is especially true for the first two sections of the book, “The Seminarian Chooses Science, 1849–1875” and “The Wilderness Years, 1875–1890.” Pavlov’s attraction to the works of the highly esteemed Dmitrii Pisarev, whose popularity soared during the 1860s and 1870s, goes a long way toward explaining his decision to become a physiologist, despite the many obstacles he faced. It also accounts for Pavlov’s strong belief in the ability of the natural sciences to solve many of the important issues of human life. In the sections “Man of Tsarist Science, 1891–1904” and “Nobelist in the Silver Age, 1904–1914,” Todes analyzes Pavlov’s research on the physiology of digestion, which brought him the Nobel Prize, and his subsequent shift away from that research for a new and very ambitious project—the study of conditional and unconditional reflexes in dogs.1 Through this new project, Pavlov aspired to find the “key” to understanding the human psyche. Todes then shows, in the fifth part of the book “War and Revolution, 1914–1921,” how the catastrophes of World War I, the Russian Revolution, and the Russian Civil [End Page 203] War for all intents and purposes brought this research to a complete halt. After these cataclysmic events, however, Pavlov was able to continue his studies on a much greater scale, thanks to the generous support of the Bolsheviks. As Todes shows in the sixth section of the book, “Prosperous Dissident,” Pavlov received this support despite his open criticism of the Bolsheviks’ politics and conceptions of society. In part 7, “Icon of Soviet and World Science,” Todes explores how Pavlov’s study of the human mind brought him worldwide fame. He also discusses a bitter disappointment in Pavlov’s life and career: the ideas that were dearest to Pavlov were misunderstood not only by the general public but also by other scientists, who misinterpreted his theory as a mere variant of behaviorism. The essence of Todes’s book is founded on his attempt to understand Pavlov’s values, which in no small measure shaped the nature of his research. The key to understanding Pavlov’s Weltanschauung is the Russian word pravil´nost´, which Pavlov defined as regularity, lawfulness, and correctness. Following such logic, the worst thing that can await one in life is sluchainost´, which Todes translates as “chance, accident, or randomness.” Suffering from an unbalanced and quick-tempered personality, Pavlov, like many who are nervous and temperamental, was inclined to apply the values of pravil´nost´ not only to his own life but also to the lives of those around him. By the end of the 1870s, Pavlov was already working as a young assistant doctor to Professor Sergei Botkin. At this point in his career, he was able to organize the work done in Botkin’s laboratory in a new way; eventually he came to pride himself on his managerial skills. Having founded his own laboratory in 1891, Pavlov started to conduct new research on the nervous regulation of the activity of the digestive glands. He frequently used the metaphor of the factory, highlighting similarities between the properly functioning body and his own laboratory. Like the factory and the laboratory, the human body relied on the division and coordination of labor. The effects of the psyche on the activity of the digestive glands in dogs turned out to be as undeniable as they were irregular...

Alfaxalone Anaesthesia Facilitates Electrophysiological Recordings of Nociceptive Withdrawal Reflexes in Dogs (Canis familiaris).

Naturally occurring canine osteoarthritis represents a welfare issue for affected dogs (Canis familiaris), but is also considered very similar to human osteoarthritis and has therefore been proposed as a model of disease in humans. Central sensitisation is recognized in human osteoarthritis sufferers but identification in dogs is challenging. Electromyographic measurement of responses to nociceptive stimulation represents a potential means of investigating alterations in central nociceptive processing, and has been evaluated in conscious experimental dogs, but is likely to be aversive. Development of a suitable anaesthetic protocol in experimental dogs, which facilitated electrophysiological nociceptive withdrawal reflex assessment, may increase the acceptability of using the technique in owned dogs with naturally occurring osteoarthritis. Seven purpose bred male hound dogs underwent electromyographic recording sessions in each of three states: acepromazine sedation, alfaxalone sedation, and alfaxalone anaesthesia. Electromyographic responses to escalating mechanical and electrical, and repeated electrical, stimuli were recorded. Subsequently the integral of both early and late rectified responses was calculated. Natural logarithms of the integral values were analysed within and between the three states using multi level modeling. Alfaxalone increased nociceptive thresholds and decreased the magnitude of recorded responses, but characteristics of increasing responses with increasing stimulus magnitude were preserved. Behavioural signs of anxiety were noted in two out of seven dogs during recordings in the acepromazine sedated state. There were few significant differences in response magnitude or nociceptive threshold between the two alfaxalone states. Following acepromazine premedication, induction of anaesthesia with 1–2 mg kg-1 alfaxalone, followed by a continuous rate infusion in the range 0.075–0.1 mg kg-1 min-1 produced suitable conditions to enable assessment of spinal nociceptive processing in dogs, without subjecting them to potentially aversive experiences. This methodology may be appropriate for obtaining electrophysiological nociceptive withdrawal reflex data in client-owned dogs with naturally occurring osteoarthritis.

Chronic Interactions Between Carotid Baroreceptors and Chemoreceptors in Obesity Hypertension.

Carotid bodies play a critical role in protecting against hypoxemia, and their activation increases sympathetic activity, arterial pressure, and ventilation, responses opposed by acute stimulation of the baroreflex. Although chemoreceptor hypersensitivity is associated with sympathetically mediated hypertension, the mechanisms involved and their significance in the pathogenesis of hypertension remain unclear. We investigated the chronic interactions of these reflexes in dogs with sympathetically mediated, obesity-induced hypertension based on the hypothesis that hypoxemia and tonic activation of carotid chemoreceptors may be associated with obesity. After 5 weeks on a high-fat diet, the animals experienced a 35% to 40% weight gain and increases in arterial pressure from 106±3 to 123±3 mm Hg and respiratory rate from 8±1 to 12±1 breaths/min along with hypoxemia (arterial partial pressure of oxygen=81±3 mm Hg) but eucapnia. During 7 days of carotid baroreflex activation by electric stimulation of the carotid sinus, tachypnea was attenuated, and hypertension was abolished before these variables returned to prestimulation values during a recovery period. After subsequent denervation of the carotid sinus region, respiratory rate decreased transiently in association with further sustained reductions in arterial partial pressure of oxygen (to 65±2 mm Hg) and substantial hypercapnia. Moreover, the severity of hypertension was attenuated from 125±2 to 116±3 mm Hg (45%-50% reduction). These findings suggest that hypoxemia may account for sustained stimulation of peripheral chemoreceptors in obesity and that this activation leads to compensatory increases in ventilation and central sympathetic outflow that contributes to neurogenically mediated hypertension. Furthermore, the excitatory effects of chemoreceptor hyperactivity are abolished by chronic activation of the carotid baroreflex.

Alfaxalone Anaesthesia Facilitates Electrophysiological Recordings of Nociceptive Withdrawal Reflexes in Dogs (Canis familiaris)

Alfaxalone Anaesthesia Facilitates Electrophysiological Recordings of Nociceptive Withdrawal Reflexes in Dogs (Canis familiaris)

Reflex control of sympathetic outflow and depressed baroreflex sensitivity following myocardial infarction

Reflex control of heart rate is frequently impaired following myocardial infarction. This is referred to as depressed baroreflex sensitivity. The aim of these experiments was to assess the function of other autonomic reflexes in dogs with depressed baroreflex sensitivity. Comparisons were made to dogs in whom baroreflex sensitivity was preserved or unchanged after myocardial infarction. Under chloralose–barbiturate anesthesia, reflex control of sympathetic outflow by the sinoaortic baroreceptors was determined by measurement of changes in systolic arterial pressure and efferent renal sympathetic nerve activity during infusion of phenylephrine. Following sinoaortic denervation, reflex control of sympathetic outflow by cardiac receptors with vagal afferent fibers was determined by measurement of changes in pulmonary capillary wedge pressure and renal nerve activity during blood volume expansion.Reflex decreases in renal nerve activity in response to increases in arterial pressure were similar in the two groups of dogs. In contrast, elevation of pulmonary capillary wedge pressure elicited significantly greater reflex decreases in renal nerve activity in dogs with depressed baroreflex sensitivity following myocardial infarction compared to dogs with preserved baroreflex sensitivity. Hemodynamic parameters and infarct sizes were similar in each group.In conclusion, activation of cardiac receptors with vagal afferent fibers elicited greater reflex inhibition of sympathetic outflow in dogs with depressed baroreflex sensitivity following myocardial infarction. These data suggest that these receptors are “sensitized”. These results provide additional support for the hypothesis that depressed reflex control of heart rate following myocardial infarction is related to augmented afferent input from the left ventricle.

Accuracy of the withdrawal reflex for localization of the site of cervical disk herniation in dogs: 35 cases (2004–2007)

To evaluate the accuracy of neurologic examination versus magnetic resonance imaging (MRI) in localization of cervical disk herniation and evaluate the usefulness of withdrawal reflex testing in dogs. Retrospective case series. 35 client-owned dogs with a single-level cervical disk herniation as determined via MRI. 1 of 2 board-certified neurologists performed a complete neurologic examination in each dog. Clinical signs of a cervical lesion included evidence of neck pain and tetraparesis. The withdrawal reflex was used for neuroanatomic localization (C1-C5 or C6-T2). Agreement between results of neurologic and MRI examinations was determined. Agreement between neurologic and MRI diagnoses was 65.8%. In 11 dogs in which the lesion was clinically localized to the C6-T2 segment on the basis of a decreased withdrawal reflex in the forelimbs, MRI revealed an isolated C1-C5 disk lesion. In 1 dog, in which the lesion was suspected to be at the C1-C5 level, MRI revealed a C6-T2 lesion. Cranial cervical lesions were significantly associated with an incorrect neurologic diagnosis regarding site of the lesion. Results suggested that the withdrawal reflex in dogs with cervical disk herniation is not reliable for determining the affected site and that a decreased withdrawal reflex does not always indicate a lesion from C6 to T2.

The emergence of genomic psychology

To say that psychology was born out of biology is not a huge overstatement. Many of the founders of modern psychology were trained in medicine, physiology or the natural sciences, and regarded psychology as the physiology of behaviour. Wilhelm Wundt, who founded modern experimental and cognitive psychology, and published the Principles of Physiological Psychology in 1874, studied medicine and worked as an assistant to the physicist Herrmann von Helmholtz. William James, who is widely regarded as a founder of psychology in the USA, earned a medical degree and, in 1890, published the influential Principles of Psychology , which starts with a chapter on brain function. Ivan Pavlov, whose work in the 1890s on the conditioning of reflexes in dogs gave rise to behaviourism, received his doctorate in the natural sciences. ![][1] Given its roots in the biological sciences, it is not surprising that psychology has absorbed many technical innovations from biological research, although their incorporation has been confined largely to the subfield of biological psychology. This has changed notably over the past 15 years, as investigators have begun to use non‐invasive functional neuroimaging technologies to study human behaviour and psychological processes. Today, this type of analysis cuts across all domains of psychology—clinical, cognitive, developmental and social/health—and represents the lowest level of the reductionist ladder, as it descends from behaviour to neurons. Here, I suggest that the field of psychology is about to undergo another transformation that will affect all of its subfields, and that will push analyses further down to the level of the genome. This transformation is inspired by genomics—defined as the molecular study of the entire genome, as opposed to the genetics of single genes—and by the interactions among genes, and those between genes and the environment. Genomics is more powerful than quantitative genetics—which has produced studies based on … [1]: /embed/graphic-1.gif

Functional regional asymmetry in intrahemisphere coherencein the EEG during conditioning in dogs

The individual characteristics of regional interhemisphere relationships were studied during acquisition of a food-related conditioned reflex in dogs. Electrical activity was recorded from symmetrical anterior (frontal and motor) and posterior (auditory and visual) areas of the brain. Comparison of averaged intrahemisphere EEG coherence values in the left and right hemispheres of the brain revealed individual features of regional interhemisphere relationships. In dogs with the strong type of nervous system, higher levels of EEG coherence in the anterior areas of the cerebral cortex were seen in the left hemisphere, while coherence in the posterior areas was greater in the right hemisphere. The opposite pattern was seen in animals with the weak type of nervous system. Thus, the spatial organization of cortical electrical activity differed in the associative and projection areas.

Increased mechanoreceptor/metaboreceptor stimulation explains the exaggerated exercise pressor reflex seen in heart failure

The following letters are in response to the Point:Counterpoint series “Increased mechanoreceptor/metaboreceptor stimulation explains the exaggerated exercise pressor reflex seen in heart failure” that appears in this issue. To the Editor: The Point:Counterpoint concerning the issue of

Interaction of central Ang II and NO on the cardiac sympathetic afferent reflex in dogs

The aim of this study was to test the hypothesis that the central angiotensin II (Ang II) and nitric oxide (NO) systems interact to modulate the cardiac sympathetic afferent reflex (CSAR). All dogs were anesthetized with α-chloralose (100 mg/kg, iv). They were sino-aortic baroreceptor denervated and vagotomized throughout the experiment renal sympathetic nerve activity responses to cardiac sympathetic afferent stimulation and the central gain of the CSAR were measured. Three protocols were performed: (1) intracerebroventricular injection (icv, 3 μg/h or 6 μg/h) of Ang II with and without N ω-nitro- l-arginine methyl ester ( l-NAME) (icv, 1 mg/kg), (2) l-NAME (icv) with and without Ang II (icv, 6 μg/h), and (3) administration of the specific neural NO synthase (nNOS) inhibitor, S-Methyl- l-thiocitrulline (MeTC) (icv, 0.1 or 1 mM, 0.5 ml in 5 min) with and without pretreatment with the angiotensin type 1 receptor antagonist, losartan (icv, 0.125 mg/kg). The primary findings were (1) Ang II alone did not significantly affect the central sensitivity of the CSAR. However, Ang II with l-NAME enhanced this reflex, (2) even though l-NAME alone augmented the CSAR, this excitatory effect was further potentiated in the presence of Ang II and (3) MeTC significantly enhanced the central sensitivity of the CSAR. However, this enhancement did not occur after pretreatment with losartan. These data suggest that Ang II interacts with NO in the brain to modulate the CSAR and that inhibition of NO is required for facilitation of the CSAR by Ang II.

Cough reflex in allergic dogs

This study investigated the effects of antigen challenge on the cough reflex in dogs that were neonatally sensitized to ragweed. Tidal volume (VT), respiratory rate (f), pulmonary resistance (RL), dynamic lung compliance (CDyn) and the number and amplitude (increase in mean peak expiratory pressure) of coughs induced by mechanical stimulation of the intrathoracic trachea were measured in propofol-anesthetized dogs. Aerosolized ragweed challenge had no effect to induce spontaneous cough but increased f and RL and reduced VT and CDyn. Mechanical stimulation of the intrathoracic trachea at this time produced 19±5 coughs with an average increase in cough amplitude of 11±1 cm H2O which differed significantly from the number (9±2 coughs) and amplitude (30±5.5 cm H2O) of mechanically induced coughs after treatment with aerosolized saline. Both the number and amplitude of mechanically induced coughs returned to baseline values by 24–48 h after the ragweed challenge. Similar results were obtained after challenge with aerosolized histamine (0.3–1% histamine) that did not induce spontaneous coughs but increased f, reduced VT and decreased CDyn and increased the number but reduced the amplitude of the mechanically induced coughs. In conclusion, both antigen and histamine bronchoprovocation changed the characteristics of the mechanically induced cough in dogs to a response of increased cough number but reduced mean expiratory cough amplitude.

Effect of Inhibition of NO Synthases on Cardiogenic Depressor Reflexes in Different Animal Species

We studied the role of the nitric oxide (NO) system in the realization of cardiogenic depressor reflexes evoked by stimulation of cardiac receptors by veratrine (reproduction of the Bezold–Jarish reflex). Acute experiments were performed on anesthetized dogs and rats: we tested the effects of inhibition of dissimilar isoforms of NO synthase (NOS) and paid special attention to possible species-related differences in realization of the reflex responses. We found that systemic inhibition of NOS by L-nitro-N-arginine (L-NNA, 30 mg/kg, i.v.) significantly decreased the depressor reflex reaction in dogs. Vasomotor dilatatory reactions of the peripheral vessels underwent considerable modifications and in some cases were converted into vasoconstrictory responses. Selective inhibition of neuronal NOS (nNOS) by 7-nitroindazole (7-NI, 25 mg/kg, i.p.) exerted no effect on the development of cardiogenic depressor reflexes in dogs. At the same time, systemic inhibition of NOS in the course of reproduction of cardiogenic depressor reflexes in rats resulted in intensification of depressor responses, while inhibition of nNOS decreased these reactions. Thus, we first demonstrated the role of NO in the realization of cardiogenic depressor reflexes under in vivo conditions and described species-related peculiarities of the involvement of the NO system in the development of these reflexes. We also demonstrated the dependence of formation of cardiogenic depressor reflexes on the predominant involvement of one NOS type or another.