W Zmyslowski

Unrestrained walking in cats with medial pontine reticular lesions

The early postoperative effects of lesions, aimed to destroy the caudal pole of the nucleus reticularis pontis oralis (NRPO) and the rostral pole of the nucleus reticularis pontis caudalis (NRPC), were tested in freely moving cats, walking at moderate speed (0.4-1.0 m/s). In cats in which these structures were partly or completely destroyed, the main effect of lesions was an impairment of fore-hindlimb coordination, as shown by a change in the relationships between the lateral and diagonal time shift durations and the step cycle duration. In the second week after the surgery the values of the slopes of linear regressions relating these variables were markedly changed as compared to the preoperative data. The results suggest that the NRPO and NRPC are involved in maintaining the proper forehindlimb coordination during unrestrained locomotion in cats.

Changes in forelimb-hindlimb coordination after partial spinal lesions of different extent in the rat.

Forelimb-hindlimb coordination in adult rats moving freely along 2m long runway was investigated using the method of footprint recording. Rats were divided into 3 groups with different extent of spinal lesions (T(9)). Before surgery rats moved with a mean locomotor speed of 73±20 to 96±18cms(-1), stride lengths of 17.5±2.0 to 21.2±2.0cm, and trot like coordination. Early after surgery the locomotor speed and the stride lengths were decreased. The forelimb steps were shorter than hindlimb steps, which led to the occurrence of unpaired forelimb steps. Unpaired steps occurred when the hind paw print lay more than half the hindlimb stride length in front of the ipsilateral paw. The number of unpaired steps was negatively correlated with the difference between the fore- and hindlimb step lengths. The recovery of locomotor speed, stride length, and step sequence patterns took up to 3.5 months depending on the extent of lesion. In the last testings the coordination was characterized by increased distances between ipsilateral footprints leading to a change from an almost synchronized trot to a lesion-dependent walk. This change was accompanied by a switch from the use of both patterns A and C to the most frequent use of the Aa pattern that is better adapted to maintain the body balance. All locomotor changes depended on the extent of the injury of lateral and ventral funiculi. These results demonstrate that footprint analysis can be used for the evaluation of forelimb-hindlimb coordination after spinal lesion in rats.

Recovery of overground locomotion following partial spinal lesions of different extent in the rat

In six rats with incomplete low thoracic spinal cord lesions of different extent, basic gait indices such as locomotor speed, step cycle duration, soleus (Sol) muscle activity duration, the interval between the onsets of Sol and tibialis anterior (TA) muscle activities and interlimb coordination were investigated by EMG analysis of the Sol and TA muscles recorded using chronic electrodes. The operated animals were divided into two subgroups: (1) those with a smaller lesion involving the dorsal quadrants of the spinal cord and, to a variable extent, the ventrolateral funiculi, and (2) those with an extensive lesion sparing only parts of the ventral funiculi. The locomotion of all rats was tested once a week for the first 5 weeks postsurgery and then once or twice a month, up to 3.5 months. The surgical lesions affected all analyzed gait indices: the locomotor speed decreased, while all other indices increased compared to recordings made preoperatively. In both subgroups the major improvement in locomotion occurred within the first 5 weeks following surgery and the rats reached a plateau in their recovery at around 2 months postoperatively. The late effects of injury depended on the severity of the spinal lesion: in the subgroup of rats with a smaller lesion, the postoperative changes in the different indices amounted to approximately 20%, while in the subgroup with extensive lesions this was increased by 20-50%, with changes in various indices being strongly correlated with the extent of the injury in individual animals. These postoperative changes were partly due to alterations in the relationships between the analyzed variables.

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method The aim of this study was to estimate spectral properties and propagation of the EEG signals registered during sevoflurane anaesthesia between individual EEG recording channels. The intensities of activity flows were calculated for delta, theta, alpha and beta waves using the Directed Transfer Function integration procedure. It was found that delta waves played the dominant role in the EEG signal propagation during anesthesia and it was suggested that theta and alpha waves propagation could be related to the processes participating in the wakefulness control. Data obtained with DTF method were compared with data received from the analysis of cerebral blood flow with the use of PET in other laboratory. This study showed that analysis of the EEG signal propagation is useful for better understanding and thus safer induction of anaesthesia procedure.

Some Problems Concerning the Sensitivity of Neuronal Structures for Changes of Parameters of Their Elements

Abstract The problems concerning the reliability of structures composed of neuron like elements will be discussed in this report. The measure of the net sensitivity for changes of parameters of its elements and then the dependance of sensitivity on the structure of net will be given. Some methods of sensitivity decreasing will be given in the second part of the report. The discussed methods consist in appropriate choosing of pattern of connections and such structure organization so it can detect the elements which parameters changed and generate the corrective signals.