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At least 505 records · Page 28Linked to original sources
PubMed1986

The squirrel monkey as an experimental model in the study of cerebral organization of emotional vocal utterances.

The different human nonverbal emotional vocal utterances (e.g., laughing, shrieking, moaning) and emotional intonation patterns (e.g., scolding, lamenting, caressing) can be shown to have their acoustic and emotional counterparts in the vocal repertoire of the squirrel monkey. This makes the latter an attractive model for investigations on the neural control of human emotional vocal utterances. Neurophysiological investigations in the squirrel monkey suggest that the cerebral control of emotional vocal utterances is organized hierarchically (Fig. 3). The lowest level - above that of the motor neurons - is represented by the reticular formation of the lateral pons and medulla; here, the motor coordination of laryngeal, respiratory and articulatory movements takes place. The next level is represented by the periaqueductal grey and laterally bordering tegmentum of the caudal midbrain. This area serves to couple specific motivational states to their corresponding vocal expressions. It is a necessary relay station for all vocalization-inducing stimuli. The periaqueductal area receives its input partly from limbic motivation-controlling regions (amygdala, hypothalamus, midline thalamus), partly from sensory pathways (collaterals of spinothalamic tract, fibers from superior and inferior colliculus), and partly from the anterior cingulate cortex. The latter represents the highest level within the system and seems to be responsible for the volitional control of emotional vocal utterances.

Amygdala↗
PubMed1987

Compulsive respiratory stereotypies in children with autistic features: polygraphic recording and treatment with fenfluramine.

Syncopes due to compulsive respiratory stereotypies were studied in eight patients with autistic features. Most had been referred for episodes thought to be intractable epileptic seizures. Polygraphic recording showed two types of syncope, one induced by prolonged apnea and the other by a prolonged Valsalva maneuver. Fenfluramine, 1.5-3 mg/kg per day, was given in an open trial. In four of five cases with frequent Valsalva maneuvers, respiratory stereotypies and syncopes were suppressed for 2-18 months. Patients with periodic apneas were more severely retarded and had less clear benefit. Side effects consisted of dose-dependent sedation and mild weight loss which stabilized without interrupting treatment. We suggest that these syncopes are volitional and may be associated with pleasant sensations. A double-blind placebo-controlled trial of fenfluramine seems warranted in such patients.

Apnea↗
PubMed2007

[The brain-mind debate. Problems in the philosophy of science with regard to psychiatry].

The present interdisciplinary brain-mind debate with regard to neurobiology shows deficits in the criticism of methods and in the precision of language and argumentation. Simplifying localisations of psychic functions, insufficient explanations and over-interpretations in the sense of physical determinism are the consequence. This can be demonstrated in deficits of neurobiological theories of volitional action. Therefore, the current concept of man is less perturbed than is proposed by neurobiologists. For psychiatry besides the neurobiological approach also a separate way of building models seems to be useful if present theoretical psychology and systems science would be regarded. In particular, the systems science of natural systems offers new opportunities to bridge gaps between disciplines involved in the brain-mind debate.

Awareness↗
PubMed2003

On-line compensation for perturbations of a reaching movement is cerebellar dependent: support for the task dependency hypothesis.

Although the cerebellum has been shown to be critical for the acquisition and retention of adaptive modifications in certain reflex behaviors, this structure's role in the learning of motor skills required to execute complex voluntary goal-directed movements still is unclear. This study explores this issue by analyzing the effects of inactivating the interposed and dentate cerebellar nuclei on the adaptation required to compensate for an external elastic load applied during a reaching movement. We show that cats with these nuclei inactivated can adapt to predictable perturbations of the forelimb during a goal-directed reach by including a compensatory component in the motor plan prior to movement initiation. In contrast, when comparable compensatory modifications must be triggered on-line because the perturbations are applied in randomized trials (i.e., unpredictably), such adaptive responses cannot be executed or reacquired after the interposed and dentate nuclei are inactivated. These findings provide the first demonstration of the condition-dependent nature of the cerebellum's contribution to the learning of a specific volitional task.

Algorithms↗
PubMed2005

Cortico-motoneuronal output to intrinsic hand muscles is differentially influenced by static changes in shoulder positions.

We investigated whether shoulder position influenced the recruitment properties of the abductor digiti minimi muscle (ADM) and first dorsal interosseous muscle (FDI). ADM and FDI motor evoked potentials (MEPs) in response to transcranial magnetic stimulation (TMS) were obtained in seven healthy volunteers at two different static positions of the shoulder joint (30 degrees adduction vs 30 degrees abduction) while the arm was passively supported at shoulder level (90 degrees in the horizontal plane) and the elbow joint was fixed at 90 degrees . ADM and FDI voluntary activity was also examined during (1) externally paced finger abductions at 2 Hz in the two different shoulder positions (EMG(ADM) and EMG(FDI) was back-averaged time-locked to the end of finger abduction) and (2) maximal voluntary abduction of the little finger and the index finger. Maximal EMG power and force were analysed in the two shoulder positions. H-reflexes from ADM and FDI were also obtained in two subjects. The ADM stimulus-response curve to TMS showed that the slope and plateau level were significantly reduced with the shoulder at 30 degrees abduction. In contrast, the FDI stimulus-response curve to TMS was not influenced by shoulder position. The back-averaged EMG(ADM) showed a significant decrease in peak amplitude and area with the shoulder at 30 degrees abduction, while no change in EMG(FDI) was observed under the same condition. Similarly, maximal EMG(ADM) and force exertion by the little finger were significantly reduced with the shoulder at 30 degrees abduction, while no such effect was observed for FDI. ADM H-reflex, but not FDI, was also decreased with shoulder abduction. These results indicate that the corticospinal pathway to ADM is less accessible to TMS and to voluntary command when the shoulder is placed at 30 degrees abduction. In contrast, activation of FDI, whether by TMS or by volition, is not influenced by shoulder position. This finding suggests that there are differences in the corticospinal innervation to ADM and FDI, possibly due to the different role of these muscles in hand function.

Adult↗
PubMed2000

Cortical potentials related to the nogo decision.

The go/nogo reaction time task has been frequently used to assess volitional inhibition. Psychophysiological studies of the correlates of the go/nogo decision have almost exclusively been concerned with N2 and P3 potentials of the event-related potentials (ERPs). However, in studies where the EMG onset latency was available, it was obvious that this latency was shorter than or at least equal to the latencies of the studied cerebral potentials. In this study, by concurrent recording of the EEG and EMG activity we aimed to better define the temporal relationship between cortical activity and motor response. Particularly, we wanted to identify the early (i.e. pre EMG-onset) electrophysiological correlates of the nogo decision. We used a modified S1-S2 paradigm that involved a two-stage go/nogo decision. In this task both S1 and S2 were informative and required the subject to make a decision, but the nature of the decision differed. The decision at S1 involved whether to prepare a movement, whereas the decision at S2 involved whether to initiate or inhibit an already prepared response. To better visualise the nogo decision related components of the ERPs, the go ERPs were subtracted from the corresponding nogo ERPs and difference ERPs were formed. Before EMG onset, a small negative component common to both go/nogo difference traces and corresponding roughly with the N1 wave was detected. It is suggested that this early negativity may be a more specific electrophysiological reflection of the nogo decision proper.

Adult↗
PubMed1998

Fast, anticipatory smooth-pursuit eye movements appear to depend on a short-term store.

Anticipatory smooth pursuit before the expected appearance of a moving target can reduce the initial retinal blur caused by the 100-ms delay of visual feedback. Humans, though, can only voluntarily generate smooth velocities up to about 5 degrees/s without a moving target. However, previous experiments have shown that repetitive brief presentations of a moving target every few seconds appear to charge an internal store, the contents of which can later be released to generate higher velocity anticipatory movements. This store's longevity was assessed here by repetitively presenting a moving target for 500 ms at different known intervals up to 7.2 s. Target motion at 25 degrees/s or 50 degrees/s was tested, with presentations in alternate directions or the same direction. Anticipatory velocity, measured 100 ms after target onset, decreased with increasing interval for all target motion conditions. A decrease was still seen when accurate timing cues were given before each presentation, suggesting that the drive for anticipatory pursuit is held in a short-term store lasting a few seconds which can enhance the low velocities produced by volition alone. The results also demonstrate that high-velocity anticipatory pursuit helps to overcome the temporal delays in the system and allows target velocity to be matched at an earlier time.

Adult↗
PubMed2001

Is breath-hold time an objective index of exertional dyspnoea in humans?

Since dyspnoeic sensation (delta) increases progressively with work rate (WR) and the duration of a volitional breath-hold (tBH) shortens, we wished to explore whether tBH might correlate sufficiently closely with delta to provide a quantitative and descriptor-free index of respiratory sensation during dynamic exercise. Nine healthy males exercised on a cycle ergometer at a series of constant WRs, above and below the lactate threshold. Ventilatory and gas exchange variables were measured breath-by-breath. At each WR, breath-holds to the limit of tolerance were taken; delta was recorded (visual-analog scale) immediately prior to and throughout each breath-hold. During breath-holds, delta increased with time as a "break-away" monoexponential characteristic, reaching the maximum (100%) at the break-point. Despite end-tidal partial pressure of carbon dioxide at the break-point being higher and end-tidal partial pressure of oxygen being lower with increasing WR, the relationship between WR and tBH declined curvilinearly (i.e. with large falls in tBH occurring in the low WR range, but far smaller reductions at higher WRs). The tBH/minute ventilation relationship had a similar form. The relationship between pre-breath-hold delta and tBH was also complex: the large reductions in tBH in the low WR range were associated with only modest increases in pre-BH delta while, at higher WRs, the progressively smaller decrements in tBH were associated with progressively larger increases in delta. We therefore conclude that breath-hold duration is unlikely to provide a useful correlate of exertional dyspnoea during dynamic exercise. Furthermore, the relative prolongation of tBH at high WRs (accounting for the more-extreme levels of end-tidal gas tensions) may reflect the attention-diverting influence of the exercise per se.

Adult↗
PubMed2005

Sexually violent predator evaluations: empirical evidence, strategies for professionals, and research directions.

Several states have passed civil commitment laws that allow the precautionary detention of sex offenders who have completed their criminal sentences. Over 2,500 sex offenders have been committed across states with such statutes and several thousand more sex offenders have been evaluated. Most statutes call for an evaluation of risk by a mental health professional and, although each state statute is worded differently, three main elements common to sexually violent predator evaluations are used to guide evaluators: mental abnormality, volitional capacity, and likelihood of future sexual violence. The current article presents empirical evidence for the main tenants of these forensic evaluations, provides recommendations for evaluators in light of current limitations of evidence, and offers suggestions for future research in this area of forensic assessment.

Commitment of Persons with Psychiatric Disorders↗
PubMed1986

Recruitment threshold force and its changing type of motor units during voluntary contraction at various speeds in man.

The motor unit discharges in human hand muscles were recorded during voluntary isometric contraction. Bipolar wire electrodes were inserted in the right adductor pollicis muscle (AP) and first dorsal interosseous muscle (FDI) for the recordings. Motor unit activities from these muscles were investigated when subjects exerted voluntary force to each target force at various speeds. On 27 motor units of AP and 28 motor units of FDI, ramp RTF and ballistic RTF were compared. Furthermore, RTF changes of motor units with the different force speeds were investigated. It is clear that the RTF of the motor units during ballistic contractions were lower than those during ramp contraction. The processes of motor unit RTF changes were classified into 3 types: RTF of type I motor units were relatively low and decreased slightly even when force speed increased widely; RTF of type II motor units were relatively high and decreased irregularly; and RTF of type III motor units, which appeared rarely, decreased their relatively high RTF with increases of force speed increment. It is suggested that the volitional outflow related with the force speed change to the spinal motor pool might cause the different RTF change effects in the various motor units.

Action Potentials↗
PubMed1982

Readiness-potentials preceding unrestricted 'spontaneous' vs. pre-planned voluntary acts.

The nature of readiness-potentials (RPs) that may be associated with fully endogenous, 'freely' voluntary acts was investigated. Restriction on when to act were eliminated and instructions fostered 'spontaneity.' The 'self-initiated' RPs exhibited in these conditions were categorizable into two (possibly three) types, all of which could be exhibited by the same subject. Type I had an early onset at about -1050 +/- 175 msec and a long ramp-like form, resembling self-paced RPs. In type II the main negative shift began at about -575 +/- 150 msec, and at about -240 +/- 50 msec in type III. Type II partially resembled the similarly timed NS' component in self-paced RPs. For acts produced at known, preset times, in which freedom of choice was eliminated but planning to act was required, RPs resembled self-initiated type I RPs and self-paced RPs. All RPs were maximal at the vertex, especially type II even though it was also bilaterally asymmetrical. These distributions suggest that cortical areas other than area 4 and 6 contribute importantly, especially to type II. All RPs, whether in self-initiated or pre-planned acts, appear related specifically to preparation for a motor action. When task-related skin stimuli replaced self-initiated movements, under similar conditions of attentiveness (and expectancy), there were either no or relatively small event-preceding-slow potential shifts. All post-stimulus P300 waves were very large. Two volitional processes are postulated: process I is associated with development of pre-planning or preparation to act in the near future (seconds), whether voluntary choice is present (type I RPs) or absent (pre-set RPs); process II, with an onset at roughly 0.5 sec before the act, is associated more uniquely with voluntary choice and with the more specific as well as endogenous urge or intention to act; it can be present in the comparative absence of or in sequence and overlapping with process I.

Brain↗
PubMed1990

Emotional facial paresis with striatocapsular infarction.

Emotional facial paresis (EFP) refers to hemifacial paresis of emotionally evoked or spontaneous smiling or weeping with preserved volitional movements of the face. The anatomical location for this phenomenon has been controversial. We report a 15-year-old boy with EFP. Follow-up MRI demonstrated infarction limited to the head of the caudate, putamen and anterior limb of the internal capsule on the contralateral side. This case lends support for selective damage at a striatal or capsular site in the production of EFP.

Adolescent↗
PubMed1984

Hemispheric dominance for intentional and automatic processes? A test of the Luria and Simernitskaya hypothesis.

Luria and Simernitskaya ( Neuropsychologia 15, 175-178, 1977) proposed a functional division between the cerebral hemispheres in terms of automatic vs volitional operations. The present study of two types of memory in brain-damaged patients did not support the hypothesis. The results were consistent with the well-established theory of material-specific deficits following unilateral lesions.

Aged↗
PubMed1986

Alcoholism as an addiction: the disease concept reconsidered.

The concept of alcoholism as a disease is compared to the concept of addiction in regard to individual intentionality, the resultant social and legal accountability and especially the total phenomenology of the addictive process. It is held that alcoholism is essentially an addiction like any other that if active, can culminate in various diseases and in death but that its most significant and characteristic volitional disorder: starting to drink when sober, is not explained by the disease concept. The concept of alcoholism as a disease is basically due to a reversal of the perception of cause and effect and has thereby impoverished full understanding and treatment of the entire process of addictive emotionality, addictive relationships and the addictive way of life. The disease concept can contribute best by inclusion to describe the results of active alcoholism but not as an explanation. This means we must turn to the concept of addiction to provide more accurate guidance in the development of adequate domestic and societal responses to alcoholism and especially for more adequate management methods for the physician confronted with the many overt and hidden forms of alcoholism in daily practice.

Alcoholism↗
PubMed2006

Temporal dynamics of auditory and visual bistability reveal common principles of perceptual organization.

When dealing with natural scenes, sensory systems have to process an often messy and ambiguous flow of information. A stable perceptual organization nevertheless has to be achieved in order to guide behavior. The neural mechanisms involved can be highlighted by intrinsically ambiguous situations. In such cases, bistable perception occurs: distinct interpretations of the unchanging stimulus alternate spontaneously in the mind of the observer. Bistable stimuli have been used extensively for more than two centuries to study visual perception. Here we demonstrate that bistable perception also occurs in the auditory modality. We compared the temporal dynamics of percept alternations observed during auditory streaming with those observed for visual plaids and the susceptibilities of both modalities to volitional control. Strong similarities indicate that auditory and visual alternations share common principles of perceptual bistability. The absence of correlation across modalities for subject-specific biases, however, suggests that these common principles are implemented at least partly independently across sensory modalities. We propose that visual and auditory perceptual organization could rely on distributed but functionally similar neural competition mechanisms aimed at resolving sensory ambiguities.

Acoustic Stimulation↗
PubMed1999

Abnormalities of imaged motor sequences in children with developmental coordination disorder.

The chronometry of real and imagined movements was investigated in a group of children with developmental coordination disorder (DCD) and a group of matched controls. The visually-guided pointing task was used to investigate the speed for accuracy trade-offs that occur as target size is varied for both real and imagined performance. In the control group, the speed for accuracy trade-off for both real and imagined performance conformed to Fitts' law. In the DCD group only real movements conformed to Fitts' law. This pattern of performance suggests that children with DCD have an impairment in the ability to generate internal representations of volitional movements. This may reflect part of a general impairment in the processing of efference copy in DCD.

Analysis of Variance↗
PubMed2004

Neural control mechanisms for normal versus parkinsonian gait.

The non-invasive methods which can be applied to the study of the cerebral control mechanisms for human gait are limited because of technical constraints. In particular, the subject's head has to be fixed for most measurements. Despite this problem, SPECT-detected, rCBF activation studies have shown that the cerebral cortex participates in the control of the normal volitional walking of healthy human subjects. The active brain areas include the foot and trunk regions of the primary sensorimotor cortex, and the supplementary motor area (SMA), lateral premotor cortex, and cingulated gyrus. Selected subcortical structures also exhibit walking-related activity, including the dorsal brainstem and cerebellum. These same regions are active in patients with Parkinson's disease (PD), but significantly less so in the right SMA, left precuneus, and right cerebellar hemisphere. For the "kinesie paradoxale" of PD patients, the right lateral premotor area plays an important role in the visually induced gait improvement brought on by adding transverse lines to the walking path.

Brain↗
PubMed2005

Genes and experience shape brain networks of conscious control.

One aspect of consciousness involves voluntary control over thoughts and feelings, often called will. Progress in neuroimaging and in sequencing the human genome makes it possible to think about voluntary control in terms of a specific neural network that includes midline and lateral frontal areas. A number of cognitive tasks involving conflict as well as the control of emotions have been shown to activate these brain areas. Studies have traced the development of this network in the ability to regulate cognition and emotion from about 2.5 to 7 years of age. Individual differences in this network have been related to parental reports of the ability of children to regulate their behavior, to delay reward and to develop a conscience. In adolescents these individual differences predict the propensity for antisocial behavior. Differences in specific genes are related to individual efficiency in performance of the network, and by neuroimaging, to the strength of its activation of this network. Future animal studies may make it possible to learn in detail how genes influence the common pattern of development of self-regulation made possible by this network. Moreover, a number of neurological and psychiatric pathologies involving difficulties in awareness and volition show deficits in parts of this network. We are now studying whether specific training experiences can influence the development of this network in 4-year-old children and if so, for whom it is most effective. Voluntary control is also important for the regulation of conscious input from the sensory environment. It seems likely that the same network involved in self-regulation is also crucial for focal attention to the sensory world.

Brain↗