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Subjects suffering from extreme peripheral deafferentation can recruit vision to perform a significant range of basic physical actions with limbs they can't proprioceptively feel. Self-ascriptions of deafferented action – just as deafferented action itself – fundamentally depend, therefore, on visual information of limb position and movement. But what's the significance of this result for the concept of self patently at work in these self-ascriptions? In this paper, I argue that these cases show that bodily awareness grounding employment of the self-concept in self-ascriptions of action can be fundamentally third-personal and concern a body that is not presented as one's own, but as an object among others. [ABSTRACT FROM AUTHOR]

Background: Two commonly prevalent neurolinguistic constructs that have been clinically challenging are neologisms and perseveration. Both are integral parts of the language deficit that are seen in the spontaneous verbal output of patients with paragrammatism and neologistic jargon types of anomia. Both can appear in modality-specific domains and usually co-occur, adumbrating verbal output impairments. These are also known to occur in selected phases of the restitution, usually in the acute and sub-acute periods, generally disappearing with recovery. Both constructs have been extensively investigated but largely as isolated phenomena. We show here that neologisms can occur in oral reading and that perseveration can be a major factor in the genesis of neologism. Aims: To date, most patients observed to have neologistic jargon aphasia also exhibited anomia and impaired auditory comprehension. Traditionally, neologisms have been studied in spontaneous verbal output, or at confrontation naming or repetition contexts. This study focuses on oral reading of a patient with aphasia who produced neologisms, but who nevertheless demonstrated good comprehension for the spoken language. There was no neologism present in her spontaneous verbal output. Methods & Procedures: The patient studied was a 76-year-old woman post removal of temporal lobe mass with subsequent haemorrhagic CVA. Neurolinguistic data were obtained from a standardised assessment and five treatment sessions in a 2-month period. Transcription and analysis of the patient's oral reading revealed a profound disassociation in grapheme-to-phoneme conversion resulting in the production of neologisms in single-word reading, which was further contaminated by perseveration. Outcomes and Results: An analysis of the neologisms in reading aloud revealed that not just one process had contributed to their production; rather there were multiple mechanisms that were noted to be operational in the genesis of neologisms. Conclusions: Neologisms can occur independently of impaired auditory comprehension; they can also extend beyond spontaneous verbal output and there are many linguistic processes that contribute to the genesis of neologism, with recurrent perseveration serving a crucial productive role in constructing the surrogate words that “mask” the deep retrieval blocks of words. [ABSTRACT FROM AUTHOR]

Background: A right handed man with trauma to the head was admitted with headache and seizures. A severe right sided weakness was noted after a blunt trauma to the right side of his head. Methods and results: MRI of brain revealed a right-sided subdural hematoma and a normal left hemisphere and downstream motor pathways. Bimanual simultaneous drawing and manual reaction times indicated that the patient was right hemispheric in laterality of his major hemisphere. Conclusion: The right sided weakness in this patient was due to temporary transcallosal disconnection (diaschisis) of the minor hemisphere (left, in this case) from the excitatory signals arising from those structures of his major hemisphere devoted to movements occurring on nondominant side, transmitted via the corpus callosum to his left hemisphere. This case draws attention to disparity between neural and behavioral handedness (laterality of major hemisphere versus that of the preferred hand). Drawing longer lines by the left hand in simultaneous bimanual tasks and a slower simple reaction time to central visual stimuli by the ostensible dominant hand permitted lateralization of the major hemisphere to the right. Thus, the neurally nondominant side (right) lagged behind the dominant (left) by an interval equal to interhemispheric transfer time. [ABSTRACT FROM AUTHOR]

To examine the contribution of whisker inputs to the initial emergence and subsequent refinement of the rodent whisking pattern we combined surgical treatments producing varying degrees of postnatal whisker deafferentation with observations and video analysis of whisking across the first month of life. Whisking emerges during the second postnatal week, preceding eye opening by a few days. In contrast to the absence of deafferentation effects in adults, whisker deafferentation in pups, if carried out between the second and third postnatal week, delays (but does not prevent) the emergence of whisker movements and disrupts the development of normal whisking kinematics and coordination. The extent of the delay varies directly with the reduction in whisker input. When regeneration of the nerve is prevented by a cyanoacrylate block emergence of the normal pattern may be delayed indefinitely. Moreover, section of the whisker motor nerve contralateral to the deafferented side, substantially potentiates the effects of the initial deafferentation. These results confirm and extend an earlier description of the development of whisking in normal rat pups (Welker, Behaviour 12:223–244, 1964), fix the time of its initial emergence more precisely at P (postnatal day) 11–13, and suggest a critical role for trigeminal afference in the development of the normal whisking pattern. They are discussed in relation to the development of pattern generating mechanisms in the rodent whisker system. [ABSTRACT FROM AUTHOR]

Acute improvement of sensory functions in the contralateral hand during experimental, tourniquet-induced anaesthesia has been described. Tourniquet compression over an extended time period, however, may be painful – which may influence the result. To study the effects of deafferentation of the upper extremity with the pain factor eliminated, we investigated 100 patients with anaesthetised axillary plexus for perception of touch and tactile discrimination in the contralateral (unanaesthetised) hand. Anaesthesia induced a rapid, significant, improvement in tactile discrimination in the contralateral hand, compared with before anaesthesia, measured as two-point discrimination ( p =0.0001), and perception of touch, measured with Semmes-Weinstein monofilament ( p =0.0005). The improvement lasted as long as the arm was anaesthetised. Understanding the mechanisms of brain plasticity, including interhemispheric plasticity, is essential for designing appropriate strategies for upregulation and downregulation of cortical reorganisational changes to promote sensory relearning after nerve injury. [ABSTRACT FROM AUTHOR]

The rat's ability to vary its whisking "strategies" to meet the functional demands of a discriminative task suggests that whisking may be characterized as a "voluntary" behavior--an operant--and like other operants, should be modifiable by appropriate manipulations of response-reinforcer contingencies. To test this hypothesis we have used high-resolution, optoelectronic "real-time" recording procedures to monitor the movements of individual whiskers and reinforce specific movement parameters (amplitude, frequency). In one operant paradigm ( N = 9) whisks with protractions above a specified amplitude were reinforced (Variable Interval 30 s) in the presence of a tone, but extinguished (EXT) in its absence. In a second paradigm ( N = 3), rats were reinforced on two different VI schedules (VI-20s/VI-120s) signaled, respectively, by the presence or absence of the tone. Selective reinforcement of whisking movements maintained the behavior over many weeks of testing and brought it under stimulus and schedule control. Subjects in the first paradigm learned to increase responding in the presence of the tone and inhibit responding in its absence. In the second paradigm, subjects whisked at significantly different rates in the two stimulus conditions. Bilateral deafferentation of the whisker pad did not impair conditioned whisking or disrupt discrimination behavior. Our results confirm the hypothesis that rodent whisking has many of the properties of an operant response. The ability to bring whisking movement parameters under operant control should facilitate electrophysiological and lesion/behavioral studies of this widely used "model" sensorimotor system. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) has been implicated in the processes by which animals recover from peripheral vestibular damage (''vestibular compensation''). However, there is little systematic data available on the effects of NO inhibition on the vestibular compensation process. In the present study we administered the nitric oxide synthase (NOS) inhibitor N[sup G]-nitro-L-arginine methyl ester (L-NAME) using a subcutaneous osmotic minipump and examined its effects on the compensation of spontaneous nystagmus (SN), yaw head tilt (YHT) and roll head tilt (RHT) in guinea pigs. Following unilateral labyrinthectomy (UL), treatment with 5, 10, 50 or 100 mM L-NAME had no effect on the expression of any of these symptoms or their rate of compensation. By contrast, pre-UL treatment with 100 mM L-NAME resulted in a decrease in SN frequency at 10 h post-UL and an increase in its rate of compensation. Lower concentrations had no effect on SN. Pre-UL treatment with L-NAME had no significant effect on YHT or RHT at any particular time point. Analysis of NOS activity demonstrated that the highest concentration of L-NAME inhibited NOS activity in the contralateral vestibular nucleus complex, bilateral cerebellum and bilateral cortices. These results suggest that L-NAME may have different effects on vestibular compensation in guinea pigs compared to other species, such as the rat and frog. [ABSTRACT FROM AUTHOR]

Previous experiments from this laboratory have indicated that transection of the infraorbital nerve (ION, the trigeminal \[V] branch that supplies the mystacial vibrissae follicles) at birth and in adulthood has markedly different effects on galanin immunoreactivity in the V brainstem complex. Adult nerve transection increases galanin immunoreactivity in the superficial layers of V subnucleus caudalis (SpC) only, while neonatal nerve transection results in increased galanin expression in vibrissae-related primary afferents throughout the V brainstem complex. The present study describes the distribution of binding sites for this peptide in the mature and developing V ganglion and brainstem complex and determines the effects of neonatal and adult ION damage and the associated changes in galanin levels upon their distribution and density. Galanin binding sites are densely distributed in all V brainstem subnuclei and are particularly dense in V subnucleus interpolaris and the superficial layers of SpC. They are present at birth (P-0) and their distribution is similar to that in adult animals. Transection of the ION in adulthood and examination of brainstem 7 days later indicated marked reductions in the density of galanin binding sites in the V brainstem complex. With the exception of the superficial laminae of SpC, the same reduction in density remained apparent in rats that survived 45 days after nerve cuts. Transection of the ION on P-0 resulted in no change in the density of galanin binding sites in the brainstem after either 7 or 60 days survival. These results indicate that densely distributed galanin binding sites are present in the V brainstem complex of both neonatal and adult rats, that they are located in regions not innervated by galanin-positive axons, and that their density is not significantly influenced by large lesion-induced changes in the primary afferent content of their natural ligand. [ABSTRACT FROM AUTHOR]