Abstract:
:The firing rate of an abducens motoneuron (AbMN) is linearly related to eye position with slope K, above recruitment threshold theta. Within the AbMN population K increases as theta increases. It is possible that these properties depend on the synaptic drives generated by the major premotor inputs to AbMNs, namely position-vestibular-pause (PVP) cells and eye and head velocity (EHV) cells in the medial vestibular nucleus, and eye-position and burst-position cells in the nucleus prepositus hypoglossi (NPH). Premotor inputs to AbMNs were therefore modelled by a two-layer net, in which the output nodes represented the AbMNs (with fixed intrinsic properties) and the input nodes the three classes of premotor units ( n=20/class). Conjugate eye-position commands were used to generate the firing rates in premotor units found experimentally. The output of the net was compared with observed AbMN firing rates, and the resultant error used to adjust the magnitude and sign of the connection weights between premotor units and AbMNs. To provide additional constraints on permitted weights, the net was also trained under simulated smooth pursuit, cancellation of the vestibular-ocular reflex, and the vestibulo-ocular reflex itself (all at 0.5 Hz). Since the projections of EHV cells have not been clearly characterized, two versions of the model were trained, corresponding to different assumptions about these projections. In both versions, position-related AbMN firing rates were derived mainly from an excitatory drive from PVP cells and an inhibitory drive from NPH cells with the opposite ON direction. Variation in AbMN threshold theta and position sensitivity K depended on the strength of the drive from the NPH: the stronger the drive, the higher both K and theta. This arrangement was observed in six variants of the basic model with different parameter values, and in a simplified form (constant PVP drive and varying NPH drive) was able to generate qualitatively the observed relationship between K and theta even in the absence of input from EHV cells. It appears to be a robust mechanism for producing the experimentally observed variation in position-related firing of AbMNs, even without a contribution from their intrinsic properties, and predicts that local blocking of the inhibitory drive from cells in the NPH should lower both the position threshold and sensitivity of an individual AbMN. The model also indicates that if EHV cells have ipsilateral inhibitory projections, as has been proposed on the basis of their similarity with cells receiving input from the flocculus, then their role in eye-position control would reinforce that of cells in the NPH.
journal_name
Exp Brain Resjournal_title
Experimental brain researchauthors
Hazel TR,Sklavos SG,Dean Pdoi
10.1007/s00221-002-1176-8keywords:
subject
Has Abstractpub_date
2002-09-01 00:00:00pages
184-96issue
2eissn
0014-4819issn
1432-1106journal_volume
146pub_type
杂志文章abstract::Trajectories of goal-directed movements are less curved for movements over a surface (constrained) than for movements in empty space (unconstrained). To study whether this difference arises from feeling the surface slip across the skin or having to control the movements in a third dimension, we manipulated the availab...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-014-4030-x
更新日期:2014-11-01 00:00:00
abstract::Changing direction during walking is a common task humans encounter every day. This destabilizing event requires the central nervous system (CNS) to quickly produce an appropriate response, maintain stability, and propel the body in the intended direction. Previous research has demonstrated that 'individuals with mult...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-014-3873-5
更新日期:2014-06-01 00:00:00
abstract::The integrity of the paramedian pontine reticular formation (PPRF) is necessary for the generation of rapid eye movements. The main saccade-related population is of the burst type with latencies between 0 and 40 ms preceding a saccade, and they can be divided into medium- and long-lead burst neurons. Burst neurons hav...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00237155
更新日期:1983-01-01 00:00:00
abstract::Previous research has shown that the timing of a sensor-motor event is recalibrated after a brief exposure to a delayed feedback of a voluntary action (Stetson et al. 2006). Here, we examined whether it is the sensory or motor event that is shifted in time. We compared lag adaption for action-feedback in visuo-motor p...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-009-2047-3
更新日期:2010-03-01 00:00:00
abstract::This study examined precision-grip force applied to an instrumented test object held aloft while the weight of the object was predictably varied by transporting and placing loads (50, 100, or 200 g) atop the test object. Transport of the loads was performed either by the subject or the experimenter. Grip force was exa...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002210000337
更新日期:2000-06-01 00:00:00
abstract::The present study examined, in the superior colliculus (SC) of anaesthetised cats, the functional connectivity between superficial-layer neurones (SLNs) and tectoreticular neurones (TRNs: collicular output cells). TRNs were antidromically identified by electrical stimulation of the predorsal bundle. The auto- and cros...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002219900263
更新日期:2000-03-01 00:00:00
abstract::Studies on grasp control underlying manual dexterity in people with Parkinson disease (PD) suggest that anticipatory grasp control is mainly unaffected during discrete tasks using simple two-digit grasp. Nevertheless, impaired hand function during daily activities is one of the most disabling symptoms of PD. As many d...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-010-2179-5
更新日期:2010-05-01 00:00:00
abstract::In earlier studies the tetrahydroisoquinoline derivative N-methyl-norsalsolinol (2-MDTIQ) was discovered in lumbar cerebrospinal fluid and brain of patients with Parkinson's disease. To establish whether 2-MDTIQ is toxic to the dopaminergic system, 2-MDTIQ or 6-hydroxydopamine (6-OHDA) were stereotactically injected i...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00227181
更新日期:1996-11-01 00:00:00
abstract::In order to find out whether human vergence eye movements are influenced by simultaneous hand tracking movements, vergence was studied when sinusoidal (expressed in vergence angles) target movements were tracked. The target motion was externally generated and the target actually moved in depth. Tracking was done by th...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00234117
更新日期:1993-01-01 00:00:00
abstract::The aim of this study was to analyse the functional impairments caused by chronic median nerve compression at the wrist on hand sensation and manual skill. Hand function was assessed in 11 patients (8 women and 3 men) with severe carpal tunnel syndrome (CTS) and compared with that of an age- and sex-matched control gr...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002210050817
更新日期:1999-09-01 00:00:00
abstract::Antispastic effects of the noradrenaline and dopamine precursor l-3,4-dihydroxyphelanine (L-dopa) were investigated in 11 subjects in which exaggerated stretch reflexes developed after spinal cord injuries. The effects were evaluated from changes in the electromyographic (EMG) response of the quadriceps muscle during ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00227307
更新日期:1996-09-01 00:00:00
abstract::Visual receptive field properties of neurons in the region of the thalamic internal medullary lamina were studied in alert cats while they fixated in various directions. In slightly more than 50% of the cells, the responsiveness of the cells was found to depend on the location of the stimulus with respect to the head-...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00237535
更新日期:1980-01-01 00:00:00
abstract::We examined the coordination of multi-digit grasping forces as they developed during object grasping and lifting. Ten subjects with Parkinson's disease (PD; OFF and ON medication) and ten healthy age-matched control subjects lifted a manipulandum that measured normal forces at each digit and the manipulandum's positio...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-007-1129-3
更新日期:2008-02-01 00:00:00
abstract::In a recent study (Whitwell et al. in Exp Brain Res 185:111-119, 2008), we showed that the visuomotor system is "cognitively impenetrable" to the extent that explicit predictive knowledge of the availability of visual feedback on an upcoming trial fails to optimize grasping. The results suggested that the effects of t...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-009-1737-1
更新日期:2009-04-01 00:00:00
abstract::Past studies of the kinematics of human prehension have shown that varying object size affects the maximum opening of the hand, while varying object distance affects the kinematic profile of the reaching limb. These data contributed to the formulation of a theory that the reaching and grasping components of human preh...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00231054
更新日期:1991-01-01 00:00:00
abstract::Within-arm somatotopy was identified in multiple motor areas of six normal human subjects who performed a visuomotor tracking task during positron emission tomography (PET) measurement of relative cerebral blood flow (relCBF). A randomly moving target, presented on a computer monitor, was continuously followed with th...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00229666
更新日期:1993-01-01 00:00:00
abstract::3,4-Methylene-dioxy-N-methylamphetamine (MDMA, 'ecstasy') has a broad spectrum of molecular targets in the brain, among them receptors and transporters of the serotonergic (5-hydroxytryptamine, 5-HT) and noradrenergic systems. Its action on the serotonergic system modulates motor systems in rodents and humans. Althoug...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-014-4095-6
更新日期:2015-01-01 00:00:00
abstract::Single unit recording from trained rhesus monkeys demonstrate that the activity of the prelunate cortex is enhanced when a visual stimulus becomes a target of saccadic eye movement. As a rule, the enhancement is spatially selective: it does not occur if the animal makes an eye movement away from, rather than towards t...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00237333
更新日期:1981-01-01 00:00:00
abstract::Intracellular recordings from thalamic neurons receiving cerebellar inputs were performed under urethane anesthesia in the rat. A total of 64 neurons were recorded intracellularly with micropipettes filled with 4% biocytin solution (dissolved in 0.5 M K-acetate), and cerebellar-induced EPSPs (CN-EPSPs), the membrane r...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00231841
更新日期:1991-01-01 00:00:00
abstract::The cerebellum is recognised to bilaterally modulate sensorimotor function and has recently been shown to play a role in swallowing. Unilateral cerebellar repetitive trans-cranial magnetic stimulation (rTMS) excites corticobulbar motor pathways to the pharynx but the effects of bilateral versus unilateral cerebellar r...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-020-05787-x
更新日期:2020-08-01 00:00:00
abstract::The aim of this work was to study the neurochemical effects in the brain of GABA-transaminase inhibition by systemic administration of gabaculine (100 mg/kg, i.a.) in the rat. In order to investigate neurotransmitter and related amino-acid compartmentation and metabolism, we have developed an original tool: the coupli...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002210050802
更新日期:1999-08-01 00:00:00
abstract::Single cell activity was recorded in area 18 during optokinetic nystagmus (OKN) in awake cats. The search coil technique was used to record the horizontal and vertical eye movements. Cells showing direction specific responses to a moving large area random dot pattern (70%) were tested with different velocities in the ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00231138
更新日期:1984-01-01 00:00:00
abstract::We investigated the effects of intracerebroventricular (i.c.v.) pertussis toxin upon the sensitivity of supraoptic oxytocin neurones to intravenous morphine (1-5000 micrograms/kg) in urethane-anaesthetized rats. The maximal inhibitory capacity of morphine was diminished by prior administration of pertussis toxin. Some...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00230292
更新日期:1993-01-01 00:00:00
abstract::Ageing affects many visual functions. Here, we investigated the effects of ageing on vernier acuity and backward masking using the shine-through paradigm. We divided healthy older adults (>60 years) into two groups depending on whether vernier duration was comparable to younger adults (Older Adults 1) or not (Older Ad...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-015-4314-9
更新日期:2015-08-01 00:00:00
abstract::The objective of this study was to define cortical and subcortical structures activated during both active and passive movements of the ankle, which have a fundamental role in the physiology of locomotion, to improve our understanding of brain sensorimotor integration. Sixteen healthy subjects, all right-foot dominant...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-005-2335-5
更新日期:2005-09-01 00:00:00
abstract::In order to determine whether neurones in the parvicellular reticular formation are in direct synaptic contact with motoneurones innervating facial muscles, a combined retrograde and anterograde transport study was carried out in the rat. Animals received injections of the retrograde tracer cholera toxin B conjugated ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00227336
更新日期:1994-01-01 00:00:00
abstract::Saccadic latencies measured in response to a step-wise displacement of the target may be substantially reduced if a gap separates the offset of the initial fixation point and the onset of the peripheral target. According to Fischer and Ramsperger (1984) this paradigm provokes a bimodal latency distribution which consi...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00229892
更新日期:1992-01-01 00:00:00
abstract::Reaching movements made to targets during exposure to passive constant velocity rotation show significant endpoint errors. By contrast, reaching movements made during voluntary rotation of the torso are accurate. In both cases, as a consequence of the simultaneous motion of the arm and the torso, Coriolis forces are g...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-008-1321-0
更新日期:2008-06-01 00:00:00
abstract::A recent study (Rossi et al. 2001) implied the absence of figure-ground based contextual modulation in macaque V1, in contrast to the study on which it was modelled (Zipser et al. 1996). We suggest that Rossi et al. may have underestimated the extent of modulation by considering only positive and not also negative mod...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-004-1847-8
更新日期:2004-05-01 00:00:00
abstract::Scientific interest has increased the influence of temperature in neurodegenerative and psychiatric disorders, and according to the monoamine hypothesis, depression is a neurochemical disorder arising from hypofunctioning of brain monoamine systems. Here, in vivo flow-oxymetry is applied to verify relationships betwee...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-013-3443-2
更新日期:2013-10-01 00:00:00