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PubMed1998

Alterations in information transmission in ensembles of primary muscle spindle afferents after muscle fatigue in heteronymous muscle.

This study showed that fatigue of the ipsilateral medial gastrocnemius muscle caused a clear-cut reduction in the ability of ensembles of primary muscle spindle afferents from the lateral gastrocnemius muscle to discriminate between muscle stretches of varying amplitude. The results were probably caused by reflex-mediated effects from chemosensitive group III and IV afferents onto the gamma-motoneurons projecting to lateral gastrocnemius muscle spindles. The experiments were conducted on seven cats anaesthetized with alpha-chloralose and a total of 41 primary muscle spindle afferents from the lateral gastrocnemius were registered. Afferents were simultaneously recorded in ensembles of three to 10 afferents. A method based on principal component analysis and algorithms for quantification of stimulus discrimination in ensembles of muscle afferents was used prior to, immediately following and five or more minutes after muscle fatigue had been induced to the ipsilateral medial gastrocnemius muscle. It is well established that the primary muscle spindle afferents play an important role in proprioception and kinaesthesia. Therefore the decrease in the accuracy of the information transmitted by ensembles of primary muscle spindle afferents caused by fatigue in an ipsilateral muscle implies concomitant effects on proprioception and kinaesthesia.

Animals↗

PubMed1999

A linear canal-otolith interaction model to describe the human vestibulo-ocular reflex.

A control systems model of the vestibulo-ocular reflex (VOR) originally derived for yaw rotation about an eccentric axis (Crane et al. 1997) was applied to data collected during ambulation and dynamic posturography. The model incorporates a linear summation of an otolith response due to head translation scaled by target distance, adding to a semi-circular canal response that depends only on angular head rotation. The results of the model were compared with human experimental data by supplying head angular velocity as determined by magnetic search coil recording as the input for the canal branch of the model and supplying linear acceleration as determined by flux gate magnetometer measurements of otolith position. The model was fit to data by determining otolith weighting that enabled the model to best fit the data. We fit to the model experimental data from normal subjects who were: standing quietly, walking, running, or making active sinusoidal head movements. We also fit data obtained during dynamic posturography tasks of: standing on a platform sliding in a horizontal plane at 0.2 Hz, standing directly on a platform tilting at 0.1 Hz, and standing on the tilting platform buffered by a 5-cm thick foam rubber cushion. Each task was done with the subject attending a target approximately 500, 100, or 50 cm distant, both in light and darkness. The model accurately predicted the observed VOR response during each test. Greater otolith weighting was required for near targets for nearly all activities, consistent with weights for the otolith component found in previous studies employing imposed rotations. The only exceptions were for vertical axis motion during standing, sliding, and tilting when the platform was buffered with foam rubber. In the horizontal axis, the model always fit near target data better with a higher otolith component. Otolith weights were similar with the target visible and in darkness. The model predicts eye movement during both passive whole-body rotation and free head movement in space implying that the VOR is controlled by a similar mechanism during both situations. Factors such as vision, proprioception, and efference copy that are available during head free motion but not during whole-body rotation are probably not important to gaze stabilization during ambulation and postural stabilizing movement. The linearity of the canal-otolith interaction was tested by re-analysis of the whole body rotation data on which the model is based (Crane et al. 1997). Normalized otolith-mediated gain enhancement was determined for each axis of rotation. This analysis uncovered minor non-linearities in the canal-otolith interaction at frequencies above 1.6 Hz and when the axis of rotation was posterior to the head.

Adult↗

PubMed1994

Role of proprioceptors in the mylohyoid muscle.

Afferent discharges of the mylohyoid muscle branch during respiration were studied electrophysiologically in the rat. Afferent discharges from the mylohyoid muscle branch of the mylohyoid nerve were found to be synchronized with respiration. Stretching of the mylohyoid muscle elicited afferent discharges of the mylohyoid muscle branch, suggesting that lengthening of the mylohyoid muscle caused electrical activity in the proprioceptors. When the central cut end of the mylohyoid muscle branch was stimulated electrically, reflex discharges were recorded from the EMG lead at the sternohyoid muscle where it is innervated by the cervical nerve. The latency between the electrical stimulation and the action potential in the sternohyoid muscle was 3-4 ms. Therefore, the mylohyoid muscle branch may transmit information to the sternohyoid muscle regarding the stretching actions of the mylohyoid muscle resulting from movements of the hyoid bone.

Afferent Pathways↗

PubMed2003

Nitrous oxide suppresses tonic and phasic nociceptive behaviors but not formalin-induced c-Fos expression in the rat spinal cord dorsal horn.

BACKGROUND: The aim of this study was to investigate the anesthetic and analgesic effects of subanesthetic concentration of nitrous oxide and to compare these effects with halothane and fentanyl. METHODS: The antinociceptive effects were assessed in male Sprague-Dawley rats by behavioral responses to phasic and tonic nociceptive stimulations and biochemical index of pain, formalin-induced Fos-like immunoreactivity (Fos-LI), in spinal cord dorsal horn. Neurological functions (proprioception, mental status and motor function) were monitored to determine whether or not behavioral responses were impaired by anesthetic action of the treatment. Four groups of rats treated with: (1) saline, (2) 75% nitrous oxide (0.5 MAC), (3) 0.5% halothane (0.5 MAC) and (4) fentanyl 100 micrograms/kg were subject either to graded intensity of CO2 laser stimulation (phasic pain) or s.c. injection of 50 microliters 2.5% formalin (tonic pain) in two separate studies. All rats in the tonic pain study were killed for immunohistochemistry at 60 min after formalin injection. Maximal counts of Fos-LI labelled neurons in rat spinal cord dorsal horn were compared according to the laminar distribution. RESULTS: We found that all rats exhibited normal righting reflexes regardless of whatever treatment. Nitrous oxide and halothane greatly impaired mental status and motor function, indicating that both agents could induce a modest degree of sedation and paresis at subanesthetic concentrations. Fentanyl increased the threshold level to noxious thermal stimulation, and reduced the formalin-induced licking/biting behaviors and the number of Fos-LI labelled neurons which are predominantly found in the neck of the dorsal horn. Nitrous oxide and halothane increased the thermal nociceptive threshold, suppressed licking/biting behavior in both early and late phases of the formalin test. Unlike fentanyl, nitrous oxide and halothane failed to suppress c-fos expression. The extent and pattern of nitrous oxide-induced antinociception was identical to halothane, which is known to have little or no analgesic effect. The lack of attenuated biochemical response to tonic pain stimulation may suggest that nitrous oxide fails to suppress spinal sensitization despite its potent inhibition on behavioral hyperalgesia. CONCLUSIONS: These findings suggest that, at the spinal level, subanesthetic concentration of nitrous oxide greatly attenuates nociceptive behaviors mainly due to a non-selective suppression of behavioral responses that are commonly associated with inhalation anesthetic drugs.

Anesthetics, Inhalation↗

PubMed1985

Activity of spindle afferents from cat anterior thigh muscles. III. Effects of external stimuli.

Chronically implanted electrodes were used to record the activity of identified single muscle spindle afferents in awake cats during responses to various types of manual and electrical stimulation. During vigorous cyclical responses such as shaking and scratching, spindle afferents generally maintained at least some activity during both lengthening and shortening of the parent muscle, indicating that the programs for these movements include both extra- and intrafusal recruitment. During noncyclical responses such as ipsilateral limb withdrawal and crossed-extension, spindle activity was modest and poorly correlated with extrafusal activity. Weak cutaneous nerve shocks during walking elicited complex excitatory and inhibitory phase-dependent reflexes in the various muscles studied but caused relatively little change in spindle afferent activity, indicating a lack of correlation between alpha and gamma motoneuron activity. A primary and a secondary afferent from sartorius muscle were recorded simultaneously during walking cycles that were perturbed by electrically induced twitches of the antagonist hamstring muscles; both demonstrated highly sensitive, short latency responses to the resulting skeletal motion, consistent with their previously suggested roles in detecting small brief mechanical perturbations. The degree to which fusimotor responses were correlated with extrafusal responses to somatosensory perturbations was highly dependent on the specific nature of the stimulus and the response. Fusimotor reprogramming of the spindle sensitivity appears to be a feature of cyclical movements that are presumably under proprioceptive control, whereas brief perturbations within the context of a particular motor program may be ignored by the fusimotor system.

Afferent Pathways↗

PubMed2006

Organization of dye-coupled cerebellar granule cells labeled from afferent vestibular and dorsal root fibers in the frog Rana esculenta.

Application of neurobiotin to the nerves of individual labyrinthine organs and dorsal root fibers of limb-innervating segments of the frog resulted in labeling of granule cells in the cerebellum showing a significant overlap with a partial segregation in the related areas of termination. In different parts of the cerebellum, various combinations of different canal and otolith organ-related granule cells have been discerned. The difference in the extension of territories of vertical canals vs. horizontal canals may reflect their different involvement in the vestibuloocular and vestibulospinal reflex. Dye-coupled cells related to the lagenar and saccular neurons were localized in more rostral parts of the cerebellum, whereas cells of the utricle were represented only in its caudal half. This separation is supportive of the dual function of the lagena and the saccule. The territories of granule cells related to the cervical and lumbar segments of the spinal cord were almost completely separated along the rostrocaudal axis of cerebellum, whereas their territories were almost entirely overlapping in the mediolateral and ventrodorsal directions. The partial overlap of labyrinthine organ-related and dorsal root fiber-related granule cells are suggestive of a convergence of sensory modalities involved in the sense of balance. We propose that the afferent input of vestibular and proprioceptive fibers mediated by gap junctions to the cerebellar granule cells subserve one of the possible morphological correlates of a very rapid modification of the motor activity in the vestibulocerebellospinal neuronal circuit.

Afferent Pathways↗

PubMedDate not supplied

[Cruciate ligament injuries with knee joint effusion--why can the Lachman sign not be elicited?].

In acute anterior cruciate ligament (ACL) lesions with effusion of the knee joint it is often difficult to realize a positive Lachman sign. It was suggested that the tension of the joint capsule may reduce tibial displacement although the ACL is completely disrupted. In 10 cadaver knee joints the ACL was dissected and the capsule was closed again. By a canula the knee joints were filled with isotonic saline solution in steps of 20 ml up to 100 ml. Before and after dissection of the ACL and during filling the joint we measured the anterior tibial displacement by use of the MEDmetric KT 1000 arthrometer. In a second series we examined 5 patients with acute effusion of the knee joint before and after puncture of the effusion. We detected the electromyographic activity of the quadriceps muscle end and the hamstrings during the KT 1000 test and patellar reflex. In the cadaver tests we found no reduction of the anterior tibial translation while filling the joint with saline solution. The electromyographic examinations showed a reflectory action in the quadriceps muscle and in the hamstrings when the Lachman test was performed. In the quadriceps muscle the electromyographic amplitude was reduced after puncture; the hamstrings showed a drastically reduced amplitude and duration of the signal. When patellar reflex was performed we recorded an electromyographic action in both muscle groups, too. Puncture could only reduce the signals of the hamstrings. Our results suggest that the reduction of the anterior drawer and the Lachman test in acute effusion is caused not mechanically by the tension of the capsule but by a reflectory muscle action of the hamstrings.

Anterior Cruciate Ligament↗

PubMed1999

AAEM case report 4: Guillain-Barré syndrome. American Association of Electrodiagnostic Medicine.

A 57-year-old woman developed rapidly progressive, symmetric, extremity weakness, facial diplegia, ophthalmoplegia, respiratory insufficiency, and sensory ataxia over a 3-week period. Electrodiagnostic studies were performed on days 6, 13, and 50 following the onset of weakness. Motor nerve conduction abnormalities were the predominant findings. Prolonged motor distal latencies, prolonged or absent F waves, and partial motor conduction blocks were present and form the diagnostic features of an acquired, demyelinating polyneuropathy. Abnormalities in sensory nerve conductions and blink reflexes were also present. Guillain-Barré syndrome was diagnosed prompting the initiation of therapeutic plasma exchange. The patient's clinical status continued to worsen over the next 10 days before stabilizing. Considerable improvement in extremity strength, ocular motility, and respiratory function occurred in the subsequent weeks. Well-planned and well-executed electrodiagnostic studies generate key adjunctive data to the clinical diagnosis of Guillain-Barré syndrome.

Action Potentials↗

PubMedDate not supplied

The nervous structures of anterior cruciate ligament of human knee, healthy and lesioned, studied with confocal scanning laser microscopy.

The presence of nervous structures with proprioceptive function in the human knee ligaments is by now well known. Therefore a lesion of the anterior cruciate ligament (ACL), beyond a loss of mechanical stability, causes the interruption of proprioceptive signals. In the present study, the Authors verified the presence of nervous structures in lesioned ligaments, using bioptic samples taken from the distal portion of residual stumps of ACL, during surgical intervention of the ACL reconstruction. Their examination with conventional light microscopy, after silver impregnations and/or PGP 9.5 immunofluorescence, revealed that not all the nervous structures of injured ACL are completely lost after the trauma, but that some of them can maintain their morphology even many months far from the offending event. However most of them undergoes more or less marked alterations, as demonstrated the confocal laser scanning microscopy. The orthopaedic surgeons have to pay attention to the reconstruction of injured cruciate ligaments, even far from the injury, with different techniques which success may also depend on the number of lost proprioreceptors, interrupted reflex circuits or non re-educated propriocetive signals.

Adult↗

PubMed1994

Evidence for corticospinal excitation of presumed propriospinal neurones in man.

1. The possibility that stimulation of the motor cortex facilitates transmission in the pathway mediating non-monosynaptic ('propriospinal') excitation from low-threshold afferents to upper limb motoneurones was investigated. 2. Convergence between peripheral afferent volleys (from the ulnar or musculo-cutaneous nerve) and corticospinal volleys (evoked by magnetic stimulation of the motor cortex) was investigated using the spatial facilitation technique. Thus the effects of these volleys on the flexor carpi radialis H reflex were compared when applied separately and together. When cortical stimulation was optimal for the muscle from which the conditioning volley originated the facilitation of the reflex on combined stimulation was significantly larger than the algebraic sum of the effects of separate stimuli. 3. The extra facilitation on combined stimulation had all the characteristics of 'propriospinal' excitation (low threshold, long central delay, brief duration and depression when the afferent input was increased), and it is suggested that this reflects corticospinal excitation of 'propriospinal' neurones. 4. When varying the time interval between cortical and test stimulations, it was shown that extra facilitation on combined stimulation began 1 ms later than the onset of the control reflex facilitation. Assuming that the latter onset reflects the arrival of the monosynaptic corticospinal volley at the motoneurone pool, this 1 ms delay suggests a disynaptic pathway for the cortical excitation of motoneurones through 'propriospinal' neurones. 5. As at the onset of voluntary movement, the pattern of the cortical excitation of 'propriospinal' neurones was quite specific: extra facilitation of the reflex on combined stimulation only occurred when the cortical volley was preferentially directed to motoneurones supplying the muscle from which the afferents used for the peripheral volley originated. 6. It is concluded that corticospinal axons activate human 'propriospinal' neurones and thereby produce disynaptic excitation of the motoneurone pool. Given temporal summation with the monosynaptic excitation, this 'propriospinally mediated' disynaptic excitation might make a significant contribution to the evoked EMG potential.

Adult↗

PubMed1993

Cerebellar ataxia and muscle spindle sensitivity.

1. The cerebellum has long been known to participate in movement control. One of the enduring theories of cerebellar function is that it "tunes" and coordinates sensorimotor traffic in other parts of the CNS. In particular, it has been implicated in the control of the sensitivity of muscle spindle stretch receptors through the fusimotor system. 2. The stretch sensitivity of spindle primary endings can be varied approximately over a 10-fold range by fusimotor efferent action. For many years it has been believed that cerebellar dysfunction is associated with reduced drive to the fusimotor system and that this in turn causes hypotonia by reducing the reflex excitation of alpha-motoneurons by spindle afferents. 3. The data on which this hypothesis is based were obtained in anesthetized or decerebrate animals. Little direct information is available on animals or humans performing voluntary movements and exhibiting ataxia or other cerebellar symptoms. 4. We tested the hypothesis by recording from nine muscle spindle afferents in behaving cats before and during reversible inactivation of cerebellar interpositus and dentate nuclei. In normal cats fusimotor action varies with motor task, greatly altering spindle stretch sensitivity. We investigated whether this same range of task-related sensitivity manifested itself during ataxia. 5. We found that the full range of spindle sensitivity was still present during ataxia. We therefore conclude that the cerebellar nuclei studied are not primarily responsible for fusimotor control, nor is the ataxia primarily caused by disordered proprioceptive sensitivity.

Afferent Pathways↗

PubMed2006

Postural reactions to soleus muscle vibration in Parkinson's disease: scaling deteriorates as disease progresses.

Previous research has shown that Parkinson's disease (PD) patients, especially those with postural instability, respond hyperactively to visual, vestibular, and neck proprioceptive sensory manipulation. To determine if this impairment of the sensory information scaling holds true for the lower leg proprioceptive system, we studied postural responses to mechanical vibration (which affects the muscle spindle Ia afferents) applied to the soleus muscles of PD subjects and healthy controls. Early-stage and advanced-stage PD patients as well as age-matched control subjects participated. Each group comprised 11 subjects. Nine pulses of 3-s long vibration were applied randomly to both soleus muscles while subjects kept their eyes closed. Postural responses to these stimuli were measured by static posturography. The effect of dopaminergic medication was established by testing patients in both ON and OFF treatment phases. There was no intergroup difference in the pattern or latencies of responses. However, the amplitudes were significantly larger in advanced PD patients; controls did not differ from early-stage PD patients. Dopaminergic medication had no significant effect on any of the measures. The scaling of postural reactions triggered by lower leg proprioception is disturbed in advanced PD. Neither afferent proprioceptive deficits nor inaccurate timing is involved. This study gives further evidence for the generalized impairment of the scaling of postural responses evoked whenever there is a sudden change of sensory conditions, as occurs with the progression of PD. Such impairment could play a significant role in the pathophysiology of postural instability and falls in PD patients.

Accidental Falls↗

PubMed1984

A progressive neurological syndrome associated with an isolated vitamin E deficiency.

Several authors have recently reported a neurological disorder associated with chronic vitamin E deficiency in man. Except in one patient, this deficiency has always been secondary to an underlying disease resulting in lipid malabsorption. We report a second case of such a neurological syndrome in a patient in whom vitamin E deficiency was an isolated finding. The clinical picture in our patient was characterized by a diffuse muscle weakness most prominent distally and in the lower limbs, generalized areflexia, a decrease in proprioception and vibration sense and slight limb and gait ataxia. His condition improved on alpha tocopherol therapy so that it is very likely that vitamin E deficiency is responsible for his neurological deficit. Since in our patient as well as in several other reported cases this condition has been treatable, it is important that this syndrome be recognized in children presenting a suggestive clinical picture even if they do not have lipid malabsorption.

Ataxia↗

PubMed1990

[Correlation of the evoked vestibulo-postural reaction and spontaneous body sway while standing].

The stability of upright posture was studied by the method of stabilometry in 16 healthy subjects. The efficacy of involving visual, vestibular and proprioceptive afferentation in maintaining posture was examined in four test situations. A direct correlation of stabilometric parameters was established at posture on soft surface and at galvanic stimulation of the vestibular analyzer. The recorded data indicate an indirect correlation between the sensitivity of the vestibular sensor and the sensitivity of that part of the central nervous system which processes vestibular information. The observed relationship results presumably from the action of central compensatory mechanisms in the function of the vestibulo-postural circuit.

Adult↗

PubMed2006

The long-term neurocompatibility of human fibrin sealant and equine collagen as biomatrices in experimental spinal cord injury.

INTRODUCTION: While fibrin sealant (FS) and equine collagen (EC) have been used as scaffold materials in experimental spinal cord injury (SCI), questions concerning neurocompatibility still remain. In this study, we assessed potential adverse effects, as well as functional and histological impact of FS and EC in subtotal hemisection of the thoracic spinal cord (SC) in rats. METHODS: 124 male rats were randomly assigned to four main groups (n=31): Sham (SH), Lesion only (L), fibrin sealant (GFS) and equine collagen group (GEC). SH animals received laminectomy only; all other animals underwent subtotal lateral hemisection at T9. Treatment consisted of application of FS or EC into the lesion gap in GFS and GEC, which was left empty in L. GFS, GEC, L and SH were each further divided into 4 subgroups: One subgroup, consisting of 10 rats was subjected to behavioural and reflex testing before surgery and followed up on days 1,7, 14, 21, 28 post op and then sacrificed. Haemalaun or cresyl violet (CV) was used to identify neutrophils in parasagittal cord sections which were obtained on day 1 (n=7). Sections stained for quantification of microglia/macrophages using ED-1 on day 3 (n=7), day 7 (n=7) and day 28 (n=7 out of 10). Additionally, neural filament (NF) staining was chosen to detect axonal regeneration and the length of ingrowth into FS and EC, Luxol blue for myelination, Von Willebrand factor for vascularisation, and glial fibrillary acidic protein (GFAP) staining for detection of astrocytes in glial scars on day 28. RESULTS: No adverse effects were observed in the treatment groups. Compared to L, GFS and GEC performed significantly better in the Basso, Beattie, Bresnahan (BBB) score and hopping responses. Proprioceptive placing was markedly improved in FS and EC compared to L. Axonal regrowth was found in GFS and GEC--the regrowth in the GFS was accompanied by myelination and vascularisation. Glial scarring occurred in all groups. Discussion Both biomatrices improved functional recovery compared to L and no adverse effects were perceived.

Animals↗

PubMed1993

The influence of arthrogenous muscle inhibition on quadriceps rehabilitation of patients with early, unilateral osteoarthritic knees.

Reflex arthrogenous muscle inhibition (AMI) may cause muscle atrophy or impede effective rehabilitation of affected muscle groups. To investigate this, bilateral quadriceps AMI, isometric and isokinetic muscle strength were measured in 10 patients with unilateral osteoarthritic knees, before and after a course of routine physiotherapy. Before rehabilitation, quadriceps of all the diseased legs were inhibited (P < 0.05) and 40% weaker (P < 0.02) than the non-diseased legs. Following rehabilitation, AMI decreased (P < 0.01) in the diseased leg and strength increased at all test velocities (P < 0.05-0.005); however, strength deficits compared with the non-diseased leg remained. Subjective improvements in functional ability and confidence in the diseased leg were reported. Though AMI may be partially responsible for unilateral muscle weakness, it does not preclude strength gain in affected muscles. Possible physiological mechanisms which evoke AMI may also adversely affect muscle proprioception, implicating AMI as a possible cause of initiation or progression of degenerative joint disease.

Adult↗

PubMed2003

Contribution of the vestibular apparatus to postural control when rising from a chair.

OBJECTIVE: The everyday act of rising from a chair is known to require the combined angular control of a number of the body's joints, especially those within the pitch plane. Precisely how this control is exerted, however, remains controversial. The aim of this study was to obtain a better understanding of the contribution made by the vestibular apparatus to postural control of the body and head when an individual rises from a chair. MATERIAL AND METHODS: A total of 24 healthy controls and 38 patients with varying degrees of vestibular dysfunction were examined. Electromagnetic motion sensors were used to analyze the angular control of the head and body as subjects rose from a chair with their eyes open or closed. RESULTS: We found that unilateral vestibular dysfunction caused fixation of the head with respect to the body, resulting in a loss of spatial stability of the head which was not compensated for by visual input. Visual input did appear to compensate for bilateral vestibular loss, enabling patients with bilateral vestibular apparatus impairment or central disorders to fix the position of their head in space. CONCLUSION: The act of rising from a chair is normally controlled by vestibular and proprioceptive input; the head is aligned according to the gravitational reference so as to obtain stable visual information. In patients with unilateral vestibular hypofunction, posture is still controlled by these two inputs, although the ability to align the head is diminished. In patients with bilateral vestibular hypofunction or a central disorder, head alignment is maintained using visual input, although it may not be the sole or predominant stabilizing force.

Adult↗

PubMed1995

[Autotopagnosia ameliorated by looking at the image reflected in a mirror].

A 52-year-old right-handed man presented progressive dystonia and apraxia of his right hand of five years' duration. He also suffered from parkinsonian features such as rigidity or impaired postural reflexes. Serial investigation of brain MRI revealed progressive cerebral atrophy, which started in the left parietal lobe, and subsequently extended to both hemispheres. He was clinically diagnosed as corticobasal degeneration. He could not point at any part of his own body in response to verbal or visual commands. On the other hand, he could point at every part of the examiner's body or of the illustrated body image. Deep sensations and linguistic functions were not involved. This cognitive impairment was regarded as autotopagnosia. In contrast with inability to recognize any part of the own body in response to the commands, he could name every part of his body as soon as the examiner touched there. Moreover, his symptoms of autotopagnosia were ameliorated by looking at himself in a mirror; he could point at any part of his own body. Disconnection between primary proprioceptive sensory area and the center of body schema was thought to be the mechanism of autotopagnosia in this patient, because the impairment improved with the aid of visual or tactile informations. We speculated the lesion was the left parietal lobe.

Agnosia↗