Rapid reorganization of adult rat motor cortex somatic representation patterns after motor nerve injury.

The potential for peripheral nerve injury to reorganize motor cortical representations was investigated in adult rats. Maps reflecting functional connections between the motor cortex and somatic musculature were generated with intracortical electrical stimulation techniques. Comparison of cortical somatotopic maps obtained in normal rats with maps generated from rats with a facial nerve lesion indicated that the forelimb and eye/eyelid representations expanded into the normal vibrissa area. Repeated testing from an electrode placed chronically in the motor cortex showed a shift from vibrissa to forelimb within hours after facial nerve transection. These comparatively quick changes in motor cortex representation pattern suggest that synaptic relations between motor cortex and somatic musculature are continually reshaped in adult mammals.     

The effect of pre-admission education on domiciliary recovery following laparoscopic cholecystectomy.

OBJECTIVES: The objectives of this randomised controlled study were to determine if pre-admission patient education affects post-operative pain levels, domiciliary self-care capacity and patient recall following a laparoscopic cholecystectomy (LC). Participants were randomised to receive the standard preadmission program (SP) or an individualised, education intervention (El). DESIGN: A pre-operative questionnaire was administered in the pre-admission clinic to determine participants' knowledge of LC and post-operative management. Telephone follow-up and post-operative questionnaire were conducted approximately 14 days post discharge. SETTING: Preadmission clinic of a Sydney, Australia, tertiary referral hospital. SAMPLE: Ninety-three elective LC patients. RESULTS: EI participants experienced lower pain levels and had significantly greater recall of provided information. However, no significant differences were found between the control and intervention groups for domiciliary self-care. CONCLUSION: Pre-admission education intervention helps reduce post-operative pain levels following LC and significantly increases patients' knowledge of self-care and complication management.     

High-resolution myocardial perfusion mapping in small animals in vivo by spin-labeling gradient-echo imaging.

An ECG and respiration-gated spin-labeling gradient-echo imaging technique is proposed for the quantitative and completely noninvasive measurement and mapping of myocardial perfusion in small animals in vivo. In contrast to snapshot FLASH imaging, the spatial resolution of the perfusion maps is not limited by the heart rate. A significant improvement in image quality is achieved by synchronizing the inversion pulse to the respiration movements of the animals, thereby allowing for spontaneous respiration. High-resolution myocardial perfusion maps (in-plane resolution=234 x 468 microm2) demonstrating the quality of the perfusion measurement were obtained at 4.7 T in a group of seven freely breathing Wistar-Kyoto rats under isoflurane anesthesia. The mean perfusion value (group average +/- SD) was 5.5 +/- 0.7 ml g(-1)min(-1). In four animals, myocardial perfusion was mapped and measured under cardiac dobutamine stress. Perfusion increased to 11.1 +/- 1.9 ml g(-1)min(-1). The proposed method is particularly useful for the study of small rodents at high fields.     

Organization of adult motor cortex representation patterns following neonatal forelimb nerve injury in rats

Somatotopic representation patterns in the motor cortex (MI) of rats that had a unilateral forelimb amputation on the first postnatal day were examined after 2-4 months of survival. Intracortical electrical stimulation and recording techniques were used to map the somatic representation in MI and in the somatic sensory cortex (SI). In normal rats, vibrissa, forelimb, and hindlimb areas comprise the bulk of the MI representation. Stimulation within the forelimb area elicits elbow, wrist, or digit movements at the lowest current intensities. The proximal limb representation appears to be contained within the distal forelimb area, since shoulder movements are nearly always evoked by stimulating at higher current intensities at some distal forelimb sites. In agreement with previous studies, the distal forelimb representation overlapped the adjacent part of the granular SI cortex. Following removal of the forelimb at birth, 3 novel features of MI organization were observed. First, the areas from which stimulation evoked movements of the vibrissa or the shoulder musculature were larger than normal. Stimulation thresholds were lower than those required for comparable movements in normal rats throughout these areas, suggesting that nerve section had not simply unmasked a high-threshold representation. Second, vibrissa movements were more commonly paired with movements of the proximal forelimb muscles at the same site. Third, stimulation in the adjacent granular SI cortex failed to evoke shoulder or trunk movements, although receptive-field mapping in this region showed that cells were responsive to cutaneous stimulation of the trunk and shoulder region. These results indicate that several organizational features develop differently in MI following perinatal nerve injury: certain remaining muscle groups have enlarged cortical representations, there is a strengthening of some normally weak connections from MI to the proximal musculature, and muscles are grouped in unusual combinations. These data demonstrate that the formation of MI representation patterns is strongly influenced by nerve injury during the perinatal period.