The cerebellum monitors errors and entrains executive networks.

Frontal midline θ (Fmθ) activity occurs in medial prefrontal cortices (mPFC), when expected and actual outcomes conflict. Cerebellar forward models could inform the mPFC about this mismatch. To verify this hypothesis we correlated the mPFC activation during a visuomotor tracking task (VM) with performance accuracy, in control and cerebellum-lesioned participants. Additionally, purely visual (V), motor (M) and a motor plus visual tasks (V + M) were performed. An Independent Component, with a mid-frontal topography scalp map and equivalent dipole location in the dorsal anterior cingulate cortex accounted for Fmθ. In control participants Fmθ power increased during VM, when the error level crossed a threshold, but not during V + M, M and V. This increase scaled with tracking error. Fmθ power failed to increase during VM in cerebellar participants, even at highest tracking errors. Thus, in control participants, activation of mPFC is induced when a continuous monitoring effort for online error detection is required. The presence of a threshold error for enhancing Fmθ, suggests the switch from an automatic to an executive tracking control, which recruits the mPFC. Given that the cerebellum stores forward models, the absence of Fmθ increases during tracking errors in cerebellar participants indicates that cerebellum is necessary for supplying the mPFC with prediction error-related information. This occurs when automatic control falters, and a deliberate correction mechanism needs to be triggered. Further studies are needed to verify if this alerting function also occurs in the context of the other cognitive and non-cognitive functions in which the cerebellum is involved.

Psychobiological evidence of the stress resilience fostering properties of a cosmetic routine.

Everyday life psychosocial stressors contribute to poor health and disease vulnerabilty. Means alternative to pharmacotherapy that are able to foster stress resilience are more and more under the magnifying glass of biomedical research. The aim of this study was to test stress resilience fostering properties of the self-administration of a cosmetic product enriched with essential oils. On day 0, fourty women, 25-50 years old, self-administered both the enriched cosmetic product (ECP) and a placebo one (PCP). Then, women were randomized for daily self-administration (from day 1 to 28) of either ECP (n = 20) or PCP (n = 20). On day 29, subjects underwent a psychosocial stress test (PST). Autonomic (heart rate and its variability) and neuroendocrine (salivary cortisol) parameters were assessed both on day 0 and 29. All subjects filled a number of psychological questionnaires in order to quantify anxiety, perceived stress, and mood profile, and were videorecorded during PST for non-verbal behavior evaluation. A single application of ECP produced an acute potentiation of cardiac parasympathetic modulation, which was not observed when placebo was used. Prolonged self-administration of ECP induced: (i) a dampening of the cortisol rise produced by PST, (ii) a reduction of state anxiety, (iii) a favorable change in mood profile, and (iv) a reduction of non-verbal behavior patterns that signal anxiety, motivational conflict and avoidance. In conclusion, this study suggests that the self-administration of a cosmetic cream enriched with essential oils should be considered as a stress resilience fostering strategy due to its favorable physiological, neuroendocrine and psychological effects.

Effects of bicuculline application on the somatosensory responses of secondary vestibular neurons.

Limb somatosensory signals modify the discharge of vestibular neurons and elicit postural reflexes, which stabilize the body position. The aim of this study was to investigate the contribution of the γ-amino-butyric-acid (GABA) to the responsiveness of vestibular neurons to somatosensory inputs. The activity of 128 vestibular units was recorded in anesthetized rats in resting conditions and during sinusoidal foreleg rotation around the elbow or shoulder joints (0.026-0.625Hz, 45° peak amplitude). None of the recorded units was influenced by elbow rotation, while 40% of them responded to shoulder rotation. The selective GABAA antagonist receptor, bicuculline methiodine (BIC), was applied by microiontophoresis on single vestibular neurons and the changes in their activity at rest and during somatosensory stimulation was studied. In about half of cells the resting activity increased after the BIC application: 75% of these neurons showed also an increased response to somatosensory inputs whereas 17% exhibited a decrease. Changes in responsiveness in both directions were detected also in the units whose resting activity was not influenced by BIC. These data suggest that the responses of vestibular neurons to somatosensory inputs are modulated by GABA through a tonic release, which modifies the membrane response to the synaptic current. It is also possible that a phasic release of GABA occurs during foreleg rotation, shaping the stimulus-elicited current passing through the membrane. If this is the case, the changes in the relative position of body segments would modify the GABA release inducing changes in the vestibular reflexes and in learning processes that modify their spatio-temporal development.

[Endovascular versus conventional vascular surgery--old-fashioned thinking? Part 2: carotid artery stenosis and peripheral arterial occlusive disease]. / Endovaskuläre vs. konventionelle Gefäßchirurgie--antiquiertes Denken? Teil 2: Karotisstenose und periphere arterielle Verschlusskrankheit.

Endovascular therapy has widely replaced conventional open vascular surgical reconstruction. For this reason, both techniques were widely considered to be competing approaches. Evidence-based data from randomized prospective trials, meta-analyses and clinical registries, however, demonstrated that both techniques should be used to complement each other. It became increasingly more evident that the use of either procedure depends on the underlying disease and the anatomical conditions, whereby a combination of both (hybrid approach) may be the preferred option in certain situations. This review focuses on the treatment of patients with carotid artery stenosis, intermittent claudication, critical limb ischemia and acute limb ischemia.

[Endovascular versus conventional vascular surgery - old-fashioned thinking? Part 1: interventions on the aorta]. / Endovaskuläre vs. konventionelle Gefäßchirurgie - antiquiertes Denken? Teil 1: Eingriffe an der Aorta.

Endovascular therapy has widely replaced conventional open vascular surgical reconstruction. For this reason both techniques were widely considered to be competing approaches. Evidence-based data from randomized prospective trials, meta-analyses and clinical registries, however, demonstrated that both techniques should be used to complement each other. It became increasingly more evident that the use of either procedure depends on the underlying disease and the anatomical conditions, whereby a combination of both (hybrid approach) may be the preferred option in certain situations. This review focuses on the treatment of complicated acute type B aortic dissection, descending thoracic aortic aneurysms, thoracoabdominal aortic aneurysms as well as asymptomatic and ruptured abdominal aortic aneurysms.

Effects of body to head rotation on the labyrinthine responses of rat vestibular neurons.

Vestibulospinal reflexes elicited by head displacement in space depend on the direction of body displacement, because the neuronal responses to labyrinthine stimulation are tuned by neck displacement: a directional tuning takes place in the medial cerebellum and in spinal motoneurons, while a gain and a basal activity tuning can be observed in the reticular formation, a target structure of the medial cerebellum. In the present study, we investigated whether also the response of vestibular nuclear neurons (another target of the medial cerebellum) to labyrinthine stimulation is tuned by neck displacement and which parameters of the response are modulated by it. In urethane-anaesthetized Wistar rats, single-unit activity was recorded from the vestibular nuclei at rest and during wobble of the whole animal at 0.156 Hz. This stimulus tilted the animal's head by a constant amplitude (5°), in a direction rotating at a constant velocity over the horizontal plane, either in clockwise or counter clockwise direction. The gain and the direction of neuronal responses to wobble were evaluated through Fourier analysis, in the control position (with coincident head and body axes) and following a body-to-head rotation of 5-30° over the horizontal plane, in both directions. Most of the vestibular neurons modified their response gain and/or their basal activity following body-to-head rotation, as it occurs in the reticular formation. Only few neurons modified their response direction, as occurs in the cerebellum and in spinal motoneurons. The different behaviour of cerebellar neurons and of their vestibular and reticular target cells, suggests that the role played by the cerebellum in the neck tuning of vestibulospinal reflexes has to be reconsidered.

A new technique to investigate vestibulo-spinal reflexes.

Vestibulospinal reflexes can be elicited in humans by low amplitudes direct (galvanic) currents lasting tens of milliseconds and applied across the two mastoids bones, which can be delivered by particular stimulators. The stimulus induces a perception of body sway and a postural response appropriate to counteract the perceived sway. Both the direction of the perceived and induced body sway are modulated by the orientation of the head with respect to the body. This phenomenon is due to the fact that integration of vestibular and neck signals allows to correctly infer the direction of body sway from the labyrinthine input, which is instead related to direction of head motion. The modulation of stimulus-elicited body sway by neck rotation could be utilised for testing the effectiveness of neck proprioceptive signals in modifying the reference frame for labyrinthine signals from the head to the body. In the present experiments we showed that labyrinthine stimulation can be performed also by using train of pulses of 1 msec duration, which can be delivered by virtually all stimulators allowed for human use. Moreover, we developed a simple technique for visualising the time course of the changes in the direction of the postural response, based on the evaluation of the velocity vector of subject's centre of pressure. This method could be exploited in order to the test the efficacy of neck proprioceptive information in modifying the reference frame for processing vestibular signals in both physiological and pathological condition.

Functional pain in hospitalised and school children.

AIM: Aim of the study was to recognise the role of psychological disagreement in children and adolescents suffering from functional pain. METHODS: Two groups of children, adolescents and their parents were interviewed: group H (hospitalized patients), group S (students, at school). Suitable investigations excluded organic lesions. The following data were analysed: 1) presence of pain in relation with: i) sex and age; ii) relation with parents, brothers, other relatives, schoolfellows; 2) efficacy of possible treatments. RESULTS: Group H: 194 patients, median age 10 years; 134 referred pain: 62 out of 92 males and 72 out of 102 females; location of pain: abdomen, limbs, head, back. Family disagreements: 36, functional pain 32; schoolfellows disagreements 114, functional pain 79. Correlations of pain with sex, increasing age, family and schoolfellows disagreements: non statistically significant. Group S: 246 students, median age: 13 years; 188 referred pain: 78 out of 118 males and 110 out of 128 females; pain was statistically more frequent in females, it increased with age. Location of pain: limbs, abdomen, head, back. Family disagreements: 31, functional pain 28, schoolfellows disagreements 140, functional pain 114. Correlations of pain with family and schoolfellows disagreements: non-statistically significant. Several parents gave answers which were different from their children's. Pharmacological and dietary interventions failed to obtain regression of pain. CONCLUSION: In both groups, the referred disagreements were not statistically different among children with functional pain and those without pain; such psychological distress was not the only factor causing functional pain. The empiric treatment adopted was inefficacious.

Effects of trunk-to-head rotation on the labyrinthine responses of rat reticular neurons.

Vestibulospinal reflexes elicited by head displacement become appropriate for body stabilization owing to the integration of neck input by the cerebellar anterior vermis. Due to this integration, the preferred direction of spinal motoneurons' responses to animal tilt rotates by the same angle and by the same direction as the head over the body, which makes it dependent on the direction of body displacement rather than on head displacement. It is known that the cerebellar control of spinal motoneurons involves the reticular formation. Since the preferred directions of corticocerebellar units' responses to animal tilt are tuned by neck rotation, as occuring in spinal motoneurons, we investigated whether a similar tuning can be observed also in the intermediate station of reticular formation. In anaesthetized rats, the activity of neurons in the medullary reticular formation was recorded during wobble of the whole animal at 0.156 Hz, a stimulus that tilted the animal's head by a constant amplitude (5°), in a direction rotating clockwise or counter clockwise over the horizontal plane. The response gain and the direction of tilt eliciting the maximal activity were evaluated with the head and body axes aligned and during a maintained body-to-head displacement of 5-20° over the horizontal plane, in either direction. We found that the neck displacement modified the response gain and/or the average activity of most of the responsive neurons. Rotation of the response direction was observed only in a minor percentage of the recorded neurons. The modifications of reticular neurons' responses were different from those observed in the P-cells of the cerebellar anterior vermis, which rarely showed gain and activity changes and often exhibited a rotation of their response directions. In conclusion, reticular neurons take part in the neck tuning of vestibulospinal reflexes by transforming a head-driven sensory input into a body-centred postural response. The present findings prompt re-evaluation of the role played by the reticular neurons and the cerebellum in vestibulospinal reflexes.

Transjugular Intrahepatic Portosystemic Shunt and Laparoscopic Colorectal Resection: the ideal minimally-invasive management for the treatment of colorectal cancer in severe cirrhotic patients. A case report and literature review.

Surgical interventions on gastrointestinal tract are often not well tolerated by patients with cirrhosis and severe portal hypertension, impairing their prognosis if suffering from malignant disease. Combining the benefits of two minimally invasive techniques such as Transjugular intrahepatic portosystemic shunt (TIPS) and Laparoscopic Colorectal Resection (LCR), the complications related to surgical intervention might be reduced and thus, it allows patients with liver disease, to undergo a curative intervention. One patient with cirrhosis and portal hypertension diagnosed with a rectal cancer underwent a meticulous preoperative preparation through placement of TIPS before laparoscopic surgery. TIPS placement was performed without intraprocedure complications. The patient was successfully operated by laparoscopic technique 36 days after TIPS placement without intraoperative bleeding or postoperative complications. Our experience, despite being based on one case, allows us to conclude that decompression of portal system by TIPS, already used in open surgery, may be applicable as a preoperative laparoscopic procedure with equally satisfactory results.

Tuning of human vestibulospinal reflexes by leg rotation.

Changing the foot position modifies the mechanical action exerted by the ankle extensor and flexor muscles over the body. We verified, in two groups of healthy subjects standing with the heels touching or apart, whether a 90° external rotation of the right leg and foot also changes the pattern of vestibulospinal reflexes elicited by electrical stimulation of the labyrinth. With the head oriented forward, leg rotation did not modify the labyrinthine-driven displacements of the center of pressure (CoP). When the head was rotated in the horizontal plane, either to the right or to the left, the CoP displacement increased along the y axis in all subjects. Changes in the x component in most instances appropriate to preserve unmodified the direction of body sway elicited by the stimulus were observed. Right leg rotation increased the basal EMG activity of ankle extensors and flexors on the left side, while the right side activity was unaffected. The EMG responses to labyrinthine stimulation were modified only on the left side, in a way appropriate to correct the effects of the altered torque pattern exerted on the body by right leg muscles. It appears, therefore, that somatosensory signals related to leg rotation and/or copy of the corresponding voluntary motor commands modify the pattern of vestibulospinal reflexes and maintain the postural response appropriate to counteract a body sway in the direction inferred by labyrinthine signals.

Influence of obesity-susceptibility loci (MC4R and INSIG2) on the outcome of weight loss and amelioration of co-morbidity in obese patients treated by a gastric-bypass.

BACKGROUND: Genome-wide association and linkage studies have identified multiple susceptibility loci for obesity. OBJECTIVE: We hypothesized that such loci may affect weight loss and comorbidity amelioration outcomes following a gastric-bypass. DESIGN: A total of 200 obese patients who underwent a gastric bypass surgery were genotyped for single-nucleotide polymorphisms (SNPs) in insulin induced gene 2 (INSIG2) and melanocortin 4 receptor (MC4R) obesity genes. RESULTS: After a follow-up of 18 month, the patients (192) data of weight excess loss (72%) and co-morbidities (Hypertension -62- and Diabetes -39-) were analyzed and compared. 26 Patients with SNP were found (9 MC4R and 17 INSIG2). No significant differences in weight excess loss and amelioration of comorbidities were revealed. CONCLUSIONS: The data suggest no influence of weight excess loss and amelioration of co-morbidities after gastric-bypass by genetic susceptibility.

Can imagery become reality?

Previous studies showed that highly hypnotizable persons imagining a specific sensory context behave according to the corresponding real stimulation and perceive their behaviour as involuntary. The aim of the study was to confirm the hypothesis of a translation of sensory imagery into real perception and, thus, of a true involuntary response. We studied the imagery-induced modulation of the vestibulospinal (VS) reflex earlier component in highly (Highs) and low hypnotizable subjects (Lows), as it is not affected by voluntary control, its amplitude depends on the stimulus intensity, and the plane of body sway depends on the position of the head with respect to the trunk. Results showed that the effects of the "obstructive" imagery of anaesthesia are different from those elicited by the "constructive" imagery of head rotation. Indeed, both Highs and Lows having their face forward and reporting high vividness of imagery experienced anaesthesia and reduced their VS reflex amplitude in the frontal plane, while only Highs changed the plane of body sway according to the imagined head rotation that is from the frontal to the sagittal one. These effects cannot be voluntary and should be attributed to translation of sensory imagery into the corresponding real perception.

A case of fatal emphysematous pyelonephritis presenting as lower limb gaseous gangrene.

The aim of this paper was to focus on emphysematous pyelonephritis (EPN), which is a severe disease that is rarely described in intensive care literature, although it is well-considered in urology and radiology journals, with numerous case reports. A 61 year-old diabetic and obese woman admitted to the Intensive Care Unit (ICU) was diagnosed with gas gangrene of the left lower limb. Within a few hours, the patient needed mechanical ventilation and high inotropic support. The abdominal computed tomography (CT) scans showed bilateral renal calculi and gas within the renal parenchyma extending towards the lower limb. Despite aggressive antibiotic therapy, supportive intensive treatment and nephrectomy, the patient died after 5 days. EPN is a rare but severe disease whose early recognition is fundamental for a favorable outcome. Intensivists should reasonably suspect it whenever diabetic patients develop septic conditions and signs of gas collection in the abdomen, pelvis, retroperitoneal space or even in the lower limbs.

Modulation of the postural effects of cognitive load by hypnotizability.

Aim of the experiment was to study whether cognitive load affects postural control more in low (Lows) than in highly hypnotizable (Highs) subjects due to the latter's greater attentional abilities. Standing Highs and Lows underwent an experimental session (closed eyes) consisting of a basal condition and of mental computation in an easy (stable support) and a difficult (unstable support) postural condition. Variability [standard deviation (SD)] and complexity [sample entropy (SampEn)] of the movement of the centre of pressure (CoP), its mean velocity (Velocity), the area swept by the CoP (Area) and the ratio between the CoP trajectory length and area [length for surface (LFS)] were measured. Few hypnotizability-related differences were detected (reduction in the Highs' SD and increases in the Lows' LFS in the difficult postural condition). Thus, the hypnotizability-related postural differences observed in previous studies during sensory alteration could not be accounted mainly by attentional abilities.

Hypnotizability-dependent modulation of postural control: effects of alteration of the visual and leg proprioceptive inputs.

The aim of the experiment was to investigate whether the peculiar attentional/imagery abilities associated with susceptibility to hypnosis might make postural control in highly hypnotizable subjects (Highs) that are less vulnerable to sensory alteration than in individuals with low hypnotic susceptibility (Lows). The movement of the centre of pression (CoP) was monitored in Highs and Lows during alteration of the visual and leg proprioceptive input. The two groups responded differently to eyes closure and to an unstable support and the CoP movement was generally larger and faster in Highs. The stabilogram diffusion analysis indicated a different set point in Highs and Lows and suggested that the former are more independent of specific sensory information than the latter, likely due to different abilities in sensory re-weighting and/or peculiar internal models of postural control. The results are discussed within the general perspective of high pervasiveness of the hypnotizability trait, which modulates cognitive, autonomic and somatic functions.

The cerebellum and sensorimotor coupling: looking at the problem from the perspective of vestibular reflexes.

Cerebellar modules process afferent information and deliver outputs relevant for both reflex and voluntary movements. The response of cerebellar modules to a given input depends on the whole array of signals impinging on them. Studies on vestibular reflexes indicate that the response of the cerebellar circuits to the vestibular input is modified by the integration of multiple visual, vestibular and somatosensory afferent signals. In this way the cerebellum slowly adapts these reflexes when they are not adequate to the behavioural condition and allows their fast modifications when the relative position of the body segments and that of the body in space are changed. Studies on voluntary movements indicate that the cerebellum is responsible for motor learning that consists of the development of new input-output associations. Several theoretical, anatomical and clinical studies are consistent with the hypothesis that the cerebellum allows the delivery of motor commands which vary according to the condition of the motor apparatus. Finally, the cerebellum could change the relation between visual information and aimed reaching movements according to the position of the eyes in the orbit and of the neck over the body. We propose that, due to the large expansion of its cortex, an important function of the cerebellum could be that of expanding the range of sensorimotor associations according to all the factors characterizing the behavioural condition. Indeed, following cerebellar lesion, learning is often lost, the movement results impaired and requires an increased attention. In the light of the recently discovered connections of the cerebellum with the rostral regions of the frontal lobe, it can be suggested that the ability of cerebellar circuits to modify the rules of input-output coupling according to a general context is a fundamental property allowing the cerebellum to control not only motor but also cognitive functions.

Posttraumatic cerebral infarction in patients with moderate or severe head trauma.

OBJECTIVE: To evaluate the frequency, types, and location of posttraumatic cerebral infarction, to assess if secondary cerebral insults were associated with cerebral infarction, and to determine if cerebral infarction affected patients' outcome. METHODS: We based diagnosis of cerebral infarction on review of brain CT scans. We assessed frequency of secondary cerebral insults, including intracranial hypertension, cerebral hypoperfusion, systolic hypo- and hypertension, arterial blood oxygen desaturation, hypocapnia, and hyperthermia, using clinical charts. We used the Glasgow Outcome Scale to evaluate outcome at 6 months after trauma. RESULTS: Of the 89 patients included, a total of 28 cerebral infarctions were found in 17 cases (19.1%). Infarctions were territorial in 23 (82.1%) and watershed in 5 (17.9%) cases. Territorial infarctions were localized to the middle cerebral artery (n = 9, 32.1%), lenticulostriate arteries (n = 6, 21.4%), posterior cerebral artery (n = 3, 10.7%), anterior cerebral artery (n = 3, 10.7%), thalamoperforating arteries (n = 1, 3.6%), and basilar artery (n = 1, 3.6%) territories. Watershed infarctions were in the boundary (n = 4, 14.3%) and terminal (n = 1, 3.6%) zones. Intracranial hypertension was the only independent variable predicting cerebral infarction (odds ratio [OR] 13.3; 95% CI 2.8 to 62.6). At 6 months after trauma, there was a lower proportion of patients with good outcome among patients with cerebral infarction vs patients without (23.5 and 61.1%; p = 0.005). Cerebral infarction was the only independent predictor of 6-month outcome (OR of good outcome 0.19, 95% CI 0.06 to 0.66). CONCLUSIONS: The risk of developing posttraumatic cerebral infarction may be higher in patients with intracranial hypertension than in those without. Patients with posttraumatic cerebral infarction may be at increased risk of residual disability.

Responses of Purkinje-cells of the cerebellar anterior vermis to stimulation of vestibular and somatosensory receptors.

In decerebrate cats, sinusoidal rotation of the forepaw around the wrist modifies the activity of the ipsilateral forelimb extensor triceps brachii (TB) and leads to plastic changes of adaptive nature in the gain of vestibulospinal (VS) reflexes (VSRs). Both effects are depressed by functional inactivation of the cerebellar anterior vermis, which also decreases the gain of VSRs. In order to better understand the mechanisms of these phenomena, the simple spike activity of Purkinje (P-) cells was recorded from the vermal cortex of the cerebellar anterior lobe during individual and/or combined stimulation of somatosensory wrist, neck and vestibular receptors. About one third of the recorded units were affected by sinusoidal rotation of the ipsilateral forepaw around the wrist axis (0.16 Hz, +/-10 degrees ). Most of these neurons ( approximately 60%) increased their activity during ventral flexion of the wrist and decreased it during the oppositely directed movement, with an average phase lag of -141 degrees with respect to the position of maximal dorsiflexion. The remaining cells ( approximately 40%) were excited during dorsiflexion of the wrist, with an average phase lead of 59 degrees with respect to the extreme dorsal flexion. Both populations showed comparable response gains, with an average value of 0.42+/-0.52, S.D., imp/s/deg. About half of the recorded units were also tested during sinusoidal roll tilt of the animal around the longitudinal axis (0.16 Hz, +/-10 degrees ), leading to stimulation of labyrinthine receptors. When both stimuli were applied simultaneously, the responses to combined stimulation usually corresponded to the sum of individual responses. While the phase distribution of somatosensory responses was clearly bimodal, vestibular responses showed phase angle values uniformly scattered between +/-180 degrees and 0 degrees , so that, during combined stimulation, each neuron could be maximally activated by coupling the two stimuli with a particular phase relation. Finally, a proportion of the recorded neurons was also tested during sinusoidal rotation of the body around its longitudinal axis, with the head fixed in space, leading to stimulation of neck receptors. The proportion of neurons affected by individual stimulation of vestibular or neck receptors (81% and 72%, respectively) was larger than that of wrist-driven neurons. Convergence of signals from vestibular, somatosensory wrist and neck receptors was found in 18% of the neurons analyzed. In conclusion, the results of this study show that somatosensory signals from the forelimb: i) modulate the activity of a sizeable proportion of neurons located within the cerebellar anterior vermis and ii) interact widely with labyrinthine and neck signals at this level. Moreover, iii) this corticocerebellar region is largely dominated by vestibular and neck signals that may be utilized to build up a neuronal representation of the position of body in space. These findings suggest that: 1) the modulation of TB activity induced by rotation of the ipsilateral wrist may at least partially depend upon the simultaneous changes in P-cell activity and 2) the interaction of vestibular and somatosensory wrist signals at P-cell level may represent the substrate of the plastic changes that affect the VSR when animal tilt and wrist rotation are driven together. A preliminary report of these data has been presented [ Responses of cerebellar Purkinje cells to forepaw rotation in decerebrate cat. Pflügers Arch 440:R31].