Impact of the biopsychosocial model of disability on the medicolegal assessment of personal injury.

Background: The objective of this paper was to determine whether the medicolegal assessment of injured and disabled persons is based on the biopsychosocial model of disability proposed by the International Classification of Functioning, Disability, and Health.

Methods: We searched for the word disability and other keywords, occurring alone or in combination as well as the meaning given to the word "disability" in two Belgian legal databases (JURA and STRADALEX) for the period from 1960 to 2020.

Results: The use of the term disability has increased over time, more so from 2001 to 2010, in areas of public health law, labor relations, and personal injury law.

Spontaneous eye blinks in horses (Equus caballus) are modulated by attention.

Spontaneous eye blinks are brief closures of both eyelids. The spontaneous eye blink rate (SEBR) exceeds physiological corneal needs and is modulated by emotions and cognitive states, including vigilance and attention, in humans. In several animal species, the SEBR is modulated by stress and antipredator vigilance, which may limit the loss of visual information due to spontaneous eye closing.

Horses (Equus caballus) facial micro-expressions: insight into discreet social information.

Facial micro-expressions are facial expressions expressed briefly (less than 500 ms) and involuntarily. Described only in humans, we investigated whether micro-expressions could also be expressed by non-human animal species. Using the Equine Facial action coding system (EquiFACS), an objective tool based on facial muscles actions, we demonstrated that a non-human species, Equus caballus, is expressing facial micro-expressions in a social context.

Paradoxical scalp lateralization of the P100 cognitive somatic potential in humans: a magnetic field study.

In somatic selective attention, electrical brain mapping disclosed a P100 cognitive electrogenesis with a scalp field paradoxically lateralized ipsilaterally to the target finger stimulus. We used 64 sensors magnetoencephalography (MEG) and source localization software in six normal humans to identify the P100 neural generator. Calculated dipole sources for P100 were iteratively compared with the recorded MEG data.

Finger kinaesthesia: cognitive electrogeneses to attended joint input.

Study of brain mechanisms subserving perception of passive finger movements revealed an unexpected contrast between cutaneous and deep inputs from fingers. Selective attention to tactile inputs from finger tips did not change the first response of primary area 3b, but elicited a cognitive P40 in second order postcentral cortex. For finger joint inputs, attention enhanced the very first cortical response elicited by thalamo-cortical input in postcentral area 2 whereby finger kinaesthesia information was integrated with the cutaneous features information received from primary somatic areas via corticocortical connections.

The challenge of non-invasive cognitive physiology of the human brain: how to negotiate the irrelevant background noise without spoiling the recorded data through electronic averaging.

Brain mechanisms involved in selective attention in humans can be studied by measures of regional blood flow and metabolism (by positron emission tomography) which help identify the various locations with enhanced activities over a period of time of seconds. The physiological measures provided by scalp-recorded brain electrical potentials have a better resolution (milliseconds) and can reveal the actual sequences of distinct neural events and their precise timing. We studied selective attention to sensory inputs from fingers because the brain somatic representations are deployed over the brain convexity under the scalp thereby making it possible to assess distinct stages of cortical processing and representation through their characteristic scalp topographies.

Failure to recognise objects by active touch (astereognosia) results from lesion of parietal-cortex representation of finger kinaesthesis.

The inability to identify objects by manipulation with eyes closed (astereognosia) results from a focal cortical lesion of the second order parietal area 2, which integrates inputs from finger joints with tactile information.

Cognitive N140 electrogenesis and concomitant 40 Hz synchronization in mid-dorsolateral prefrontal cortex (area 46) identified in non-averaged human brain potentials.

The mid-dorsolateral prefrontal area 46 has working memory functions for putting current cognitive processing into context and for updating relevant information on a trial-by-trial basis. Using non-averaged human brain responses to a target finger stimulus attended by the subject, we identified the cognitive prefrontal N140 electrogenesis with the Z method which numerically assesses the detailed consistency between scalp topographies of any single response and a grand average template. The cognitive N140 was present between 100 and 180 ms at the scalp contralateral to the attended target finger stimulus.

Unconscious attention manifested in non-averaged human brain potentials by optional short-latency cognitive electrogeneses without subsequent P300.

The cognitive unconscious is distinct from the psychoanalytic unconscious and is defined in experimental psychology as including mental processes which can influence behavior while remaining outside phenomenal awareness. We analyzed its physiological basis in scalp-recorded averaged and non-averaged human brain potentials evoked by near-threshold somatic (finger) sensory stimuli while the subject attended a non-somatic task. The early N20 electrogenesis in parietal area 3b, which was present and did not change across conditions, is thought to reflect automatic procedural processing of stimulus features.

Focal enhancement of chaotic strange attractor dimension in the left semantic (Wernicke) human cortex during reading without concomitant change in vigilance level.

Non-averaged scalp-recorded brain potentials were analyzed in four right-handed humans while they were either silently reading a book, or in idle alert conditions. The dimensionality of chaotic strange attractors was estimated from the EEG at each of 14 scalp electrodes, using the point correlation dimension PD2 algorithm. When the subject was fully alert but not engaged in any specific task, PD2 was between 5.

Human perceptual processing: inhibition of transient prefrontal-parietal 40 Hz binding at P300 onset documented in non-averaged cognitive brain potentials.

Non-averaged scalp-recorded human brain potentials were analyzed during selective attention to somatic (finger) sensory stimuli. Distinct cognitive electrogeneses were identified by numerical assessment of their scalp topographical congruities with appropriate templates. The P300 electrogenesis and the 40 Hz neuronal oscillations disclosed, at different scalp sites, variations in timing from trial to trial.

Non-averaged human brain potentials in somatic attention: the short-latency cognition-related P40 component.

1. Non-averaged scalp-recorded brain potentials were studied in humans during selective attention to randomly intermixed series of stimuli to fingers. Physiological tests were use for validating the presence or absence of the short-latency cognition-related P40 electrogeneses in parietal cortex in the response to a single-target stimulus (P40 signifies a positive polarity of about 40 ms peak latency).

Transcutaneous magnetic stimulation of descending tracts in the cervical spinal cord in humans.

Percutaneous magnetic stimulation in humans allows non-invasive stimulation of deeply situated nervous structures with little, if any, discomfort and has proven its utility for brain stimulation. At the level of the vertebral canal, magnetic stimulation readily elicits muscle responses through activation of the motor spinal roots, but there has been no evidence for direct stimulation of the spinal cord itself. The present results document the feasibility of directly stimulating descending systems of the cervical spinal cord which synaptically activate motoneurones.

Differential voluntary programming of fingers extensor commands revealed by non-invasive transcranial magnetic stimulation of the human brain.

Slightly suprathreshold magnetic stimuli were delivered over the left scalp while a normal human subject attended a sensory signal which called for a motor response of right fingers in a reaction time paradigm. The cortico-motoneuronal systems of the two muscles producing finger extension disclosed a remarkable physiological differentiation. Brain magnetic stimulation delivered just before the subject's motor response revealed cortico-motoneuronal facilitation for one extensor muscle and concomitant inhibition for the other, depending on the verbal instructions that had been given to the subject before the experimental trial.

New application of the Z estimator to identify the cognitive P300 in non-averaged human brain potentials.

Electronic averaging is currently used for displaying event-related potentials such as P300 from the electroencephalogram (EEG). However, there is a growing need for upgraded methods allowing cognitive components to be identified in single trial brain responses. The Z estimation method has been adapted for the topographic testing of non-averaged scalp recordings.

Consciousness.

Consciousness offers a major challenge to the neurosciences. Even though consciousness is by definition subjective and private to the organism concerned, we consider it to be an intrinsic feature of biological processes in the brain. As such, it should be viewed in the Darwinian perspective of natural selection which implies that the conscious brain function does have survival value and cannot be a mere epiphenomenon.

The point correlation dimension: performance with nonstationary surrogate data and noise.

The dynamics of many biological systems have recently been attributed to low-dimensional chaos instead of high-dimensional noise, as previously though. Because biological data are invariably nonstationary, especially when recorded over a long interval, the conventional measures of low-dimensional chaos (e.g.

Transient phase-locking of 40 Hz electrical oscillations in prefrontal and parietal human cortex reflects the process of conscious somatic perception.

Electrical potential oscillations in the range of 35-45 Hz (gamma waves) have recently been shown to occur rather ubiquitously in the brain of awake humans. During selective somatic attention, we demonstrate a transient phase-locking of the gamma waves generated in the contralateral prefrontal and parietal cortical areas that we had previously shown to be involved in such selective attention tasks. In line with other microphysiological evidence obtained on mammalian visual cortex, this selective functional synchronization between critical human brain areas (as far as about 9 cm apart) is proposed to reflect the transient 'binding' of discrete cognitive features that are processed in distributed neuronal assemblies of the brain whereby the conscious perception of an object or event can be achieved.

A method for identifying short-latency human cognitive potentials in single trials by scalp mapping.

Studies of scalp-recorded brain event-related potentials in humans currently depend on the electronic averaging of many responses to the stimulus. In non-averaged single responses, it is sometimes possible to see late components such as the so-called P300, but not the shorter latency components that are much smaller and masked in background noise. We tried to identify short-latency cognitive potentials evoked by finger stimulation by comparing single trial responses that are concomitantly recorded at the contralateral and ipsilateral parietal scalp respectively.

Right or left ear reference changes the voltage of frontal and parietal somatosensory evoked potentials.

Short-latency cortical somatosensory evoked potentials (SEPs) to left median nerve stimulation were recorded with either the left or right earlobe as reference. With a right earlobe reference the voltage of the parietal N20 and P27 was reduced while the voltage of the frontal P20 and N30 was enhanced. The effects were consistent, but their size varied with the SEP component considered and also among the subjects.

Nasopharyngeal recordings of somatosensory evoked potentials document the medullary origin of the N18 far-field.

Because the nasopharyngeal electrode provides non-invasive access to the ventral brain-stem at the medullo-pontine level we used it for recording somatosensory evoked potentials (SEPs) to median nerve stimulation (non-cephalic reference). After the P9 and P11 far-fields, the nasopharyngeal SEPs disclosed a negative-going component which was interpreted as the near-field equivalent of the P14 scalp far-field generated in the caudal part of the medial lemniscus. Nasopharyngeal SEPs also revealed a large N18 with voltage and features strikingly similar to those of the scalp-recorded N18 far-field.

Prime mover muscle in finger lift or finger flexion reaction times: identification with transcranial magnetic stimulation.

When recording the onset of the electromyographic (EMG) voluntary response in reaction time (RT) studies, the electrodes should be placed on the muscle which is first and foremost involved in executing the response. It is thus necessary to identify which is the prime mover muscle among active synergic muscles. This has been investigated for index finger lift or flexion RTs by delivering a magnetic stimulus to motor cortical areas prior to the subject's voluntary response.

Reaction times recording methods: reliability and EMG analysis of patterns of motor commands.

Different methods for estimating reaction times (RTs) from either finger flexion or finger extension responses have been evaluated. The onset of finger movement was recorded with a photoelectric method and the results are compared with RT measures based on microswitch closure or onset of electromyographic (EMG) activity in the prime move muscle. EMG analysis showed the voluntary motor commands to present a characteristic ballistic pattern in RTs.