Self-regulating arousal via pupil-based biofeedback

The brain's arousal state is controlled by several neuromodulatory nuclei known to substantially influence cognition and mental well-being. Here we investigate whether human participants can gain volitional control of their arousal state using a pupil-based biofeedback approach. Our approach inverts a mechanism suggested by previous literature that links activity of the locus coeruleus, one of the key regulators of central arousal and pupil dynamics. We show that pupil-based biofeedback enables participants to acquire volitional control of pupil size. Applying pupil self-regulation systematically modulates activity of the locus coeruleus and other brainstem structures involved in arousal control. Furthermore, it modulates cardiovascular measures such as heart rate, and behavioural and psychophysiological responses during an oddball task. We provide evidence that pupil-based biofeedback makes the brain's arousal system accessible to volitional control, a finding that has tremendous potential for translation to behavioural and clinical applications across various domains, including stress-related and anxiety disorders.

Force plate gait analysis at the walk and trot in dogs with low-grade hindlimb lameness

OBJECTIVE

To evaluate the accuracy of force plate gait analysis at the walk and trot in dogs with low-grade hindlimb lameness.

MATERIAL AND METHODS

Nineteen healthy dogs and 41 dogs with low-grade unilateral hindlimb lameness due to stifle or hip joint problems were walked and trotted over a force plate. Peak vertical forces (PVF) were recorded, and a symmetry index (SI) was calculated from the PVF of the hindlimbs. 'Cut-off' values were determined from the SI of the normal dogs. These cut-off values were used to discriminate lame dogs from normal ones. Sensitivity and specificity were evaluated for measurements at walk and trot, and the Cohen's Kappa coefficient (k) was used to determine the agreement between clinical lameness and force plate measurements, and between force plate results at walk and trot. Receiver Operating Characteristics (ROC) curve were plotted for both gaits to evaluate accuracy.

RESULTS

The sensitivity of the measurements at walk was 0.63, and specifity was 0.95. The sensitivity of the measurements at trot was 0.90, and specificity was 1.0. Moderate agreement was found between force plate measurements at walk and trot, and between clinical gait assessment and force plate measurements at walk. Good agreement was found between clinical gait assessment and measurements at trot. ROC analyses revealed the trot (94.7% [91.7%; 97.7%]) to be the more accurate test than the walk (85.0% [80.1%; 89.9%]).

CONCLUSION

The trotting gait was more sensitive and accurate than the walking gait for the differentiation of dogs with a low-grade hindlimb lameness from normal ones using force plate gait analysis.

Countertransferential and attitudinal considerations in the treatment of drug abuse and addiction

This article explores countertransferential and attitudinal considerations in relation to their impact on the evaluation, diagnosis, and therapeutic management of drug-dependent individuals. Following a literature survey of the manner in which countertransference has been applied to the treatment of drug dependency, the authors discuss the status of the drug-dependent individual as a psychiatric patient and the resultant treatment implications when such a patient is viewed from within, rather than exclusive of, the mental health treatment delivery system. A number of examples are provided of patient-induced countertransferential reactions, in addition to specific attitudinal factors often present in the treatment of addiction.