Signal averaging of visually evoked cortical potentials was done on Wistar strain rats during recovery from nembutal (sodium pentobarbital) anesthesia. Several studies (Dafny, 1978; Gines et al., 1963; Roig et al., 1961) have shown significant differences between recordings from unanesthetized rats and from rats anesthetized with various agents. The purpose of this study was to evaluate changes in the cortical response throughout an eight hour nembutal recovery period in order to determine the feasibility of using a signal averaging technique for classification of anesthetic depth. The results of this study show that the recovery from nembutal anesthesia is characterized by three major changes in the cortical response: the presence or absence of the secondary response component, the appearance of desynchronized cortical firing and a change in the latency of the individual component peaks. Using these neurophysiological signs, the rate of recovery from nembutal anesthesia can be described and quantified. The characterization of these changes will provide future researchers with a tool to evaluate electrophysiologically the usefulness of various treatments at altering the rate of recovery from anesthesia.

The purpose of these experiments was to determine the effects of cholinergic depletion on spontaneous and evoked activity of neurons in the different layers of the posteromedial barrel subfield (PMBSF) of the rat somatosensory cortex. Acetylcholine neurons in nucleus basalis of Meynert (NBM) were selectively lesioned with an immunotoxin (IT), 192 IgG-saporin. Spontaneous activity was significantly lower in layers II-III, Va, and VI in IT-injected animals compared to control animals. Evoked activity was significantly lower in layers II-III, IV, Vb, and VI of IT-injected animals compared to control animals. The largest difference was observed in layer Vb. Thus, cholinergic depletion causes significant changes in the magnitude of spontaneous and evoked activity but these differences are not completely in register with one another.

As neural interfaces continue to progress toward practical applications, there is increased demand for smaller, more efficient and cost effective devices. Event related potentials (ERPs) have recently been demonstrated to be reliable for practical communication in disabled individuals using the P300 Speller paradigm. With the objective of simplifying the processing of ERPs in order to minimize the hardware/computational requirements, and therefore the power consumption (for increased battery life for wireless, etc.), this study examines the effects of the analog-to-digital converter amplitude quantization on the ERP classification accuracy for the P300 Speller.

No description available.

Die Ableitung Vagus-somatosensibel evozierter Potentiale (VSEP) ist eine vielversprechende, kostengünstige und nicht-invasive Methode zur Frühdiagnostik von Alzheimer-Demenz. In der vorliegenden Arbeit wurde die Retest-Reliabilität der VSEP untersucht. Des Weiteren wurden alternative Stimulationsbedingungen (Stimulation in der Cymba conchae und im anterioren äußeren Gehörgang) und alternative Ableitbedingungen (referentielle Ableitungen mit Elektroden an Mastoid, Spina scapulae, Vertebra prominens und Handrücken) getestet und mit der herkömmlichen Methode verglichen. Die Reliabilitätsuntersuchungen wurden an 24 gesunden Probanden im Abstand von sechs Monaten durchgeführt. Die alternativen Stimulations- und Ableitbedingungen wurden an je zehn bis zwölf Probanden angewandt und die Ergebnisse mit denen von Messungen mit der herkömmlichen Methode verglichen. Es zeigte sich eine besonders gute Reliabilität in den Ableitungen T3/O1 und T4/O2. Außerdem liegen Hinweise darauf vor, dass das Alter der Probanden die Reliabilität beeinflusst. Als beste alternative Ableitposition erwies sich das Mastoid. Die Messungen mit alternativen Stimulationspositionen ergaben stark von der herkömmlichen Methode abweichende Ergebnisse, deren Ursache die vorliegende Studie nicht sicher klären kann. / The recording of vagus somatosensory evoked potentials (VSEP) is a promising, cheap and non-invasive method for the early diagnosis of Alzheimer´s disease. The present study examined the retest-reliability of VSEP. Furthermore alternative stimulation sites (stimulation at cymba concha and at the anterior side of the external auditory canal) as well as alternative recording sides (recording electrodes at mastoid, spina scapulae, vertebra prominens and dorsum of the hand) were examined and compared to the standard method. For the reliability tests, VSEP-measures were performed on 24 healthy subjects at intervals of at least six months. For the alternative stimulation and recording sites VSEP measures were carried out on ten to twelve subjects for each site and the results were then compared to the ones of measures with the conventional method. The recording positions T3/O1 and T4/O2 showed the highest reliability. Additionally there is evidence for an affection of reliability by the subjects´ age. Among the alternative recording sites, mastoid showed to be the most appropriate one. The VSEP-measures with alternative stimulation sites revealed highly divergent results compared to the results from standard measures. The present study cannot certainly clarify the reasons for these divergences.

No description available.

OBJECTIVE: To investigate the effect of a 12-week exercise-based physical therapy on movement-evoked pain (MEP) in knee osteoarthritis (OA) and assess the relations between baseline psychological factors and treatment responses based on MEP. BACKGROUND: Pain during movement (i.e., MEP) is one of the most common complaints amongst people with knee OA, which induces greater functional challenges during daily activities. Although the worsening of pain during exercise appears to hinder activity-based treatment adherence, the assessments of MEP tend to be overlooked in the pain management in knee OA. METHODS: The data analyzed in this study was from the parent study, Wearable Sensors in Knee Osteoarthritis (WESENS-OA) study, a longitudinal, single-arm clinical trial of a 12-week exercise intervention in people with symptomatic knee OA. In the WESENS-OA (n = 60), participants self-reported pain intensity during the nominated activity as well as psychological symptoms (Center for Epidemiologic Studies Depression Scale), cognitive pattern (Pain Catastrophizing Scale), and central sensitization (Central Sensitization Inventory). Pain intensity during functional tasks and strength testing were collected during the laboratory visits. Three characteristics of MEP outcomes were assessed: (1) pain during the nominated activity, (2) functional MEP, and (3) exercise MEP. The participants reported the pain intensity during the nominated activity that is most troublesome due to their knee pain weekly using the 11-point numerical rating scale (NRS, range: 0-10). Pain intensity during or immediately after functional tasks (i.e., 6-minute walking, chair stand, climbing the staircase, range: 0-10) and strength testing (i.e., maximal voluntary isometric contractions of knee extensors and flexors, isokinetic knee flexion-extension at 60°/s and 120°/s each, range: 0-10) were evaluated to measure functional MEP or exercise MEP, respectively. MEP index score (i.e., maximum pain corrected for baseline pain) was reported as the outcome. Mixed model repeated measures (MMRM) analysis was utilized to evaluate the effect of an exercise intervention on the change in movement-evoked pain from baseline to 12 weeks, and least square means with the standard error were reported simultaneously. Each participant’s treatment response was determined by comparing the change in MEP from baseline to Week 12. A participant with a difference of ≥ 2 points in NRS for pain-nominated activity was classified as a responder, and for functional MEP and exercise MEP, treatment responder classification was done based on the hierarchical agglomerative clustering analysis. After dichotomizing participants, using binomial regression, the relative risk (RR) was reported to explore the predictive ability of CSI, CES-D, and PCS on treatment response based on MEP. RESULTS: For pain during nominated activity, the mean difference (MD) from baseline to Week 6 was -1.72 with 95% CI (-2.35 to -1.08; P <0.0001), and the difference at Week 12 was -2.41 with 95% CI (-2.92 to -1.89; P <0.0001). For functional MEP, MD with 95% CI at Week 6 was -0.34 (-0.52 to -0.16; P = 0.0003), and at Week 12 was -0.44 (-0.58 to -0.31; P<0.0001). Unlike the other MEP measures, for exercise MEP, MD was measured at one timepoint, at Week 12, which was -0.58 with 95% CI (-0.88 to -0.27; P = 0.003). Our secondary analysis did not provide evidence that baseline measures of CSI, CES-D, and PCS were associated with the treatment response based on the change in MEP measures after the exercise intervention. CONCLUSION: In conclusion, our study strongly supports the effect of exercise on reduction in three measures of MEP—pain during nominated activity, functional MEP, and exercise MEP. Our hypothesis to confirm the predictive ability of psychological factors on treatment response based on MEP was not reached, with insufficient evidence to substantiate such a notion. However, our findings hold strength to pioneer discovering the underlying mechanism of understudied MEP in knee OA. / 2026-02-28T00:00:00Z

No description available.

No description available.

<p> Alterations in neural tissues associated with environmental variables have been studied for many years. Anatomical changes in the neocortex of rats in response to exposure to complex environments were observed and replicated in a number of studies both within and across species. These changes are not dependent on the age of the animal or on the duration of exposure, and have been demonstrated in structures outside of the cortex. Due to the undisputed involvement of both the neocortex and the hippocampus in learning and memory, researchers applied a widely used model system of a synaptic mechanism for learning, long-term potentiation (LTP), to the environmental enrichment paradigm and demonstrated significant enhancements in hippocampal field potentials in enriched rats. The present study examines whether the neocortex also showed evidence of plasticity in synaptic transmission. No effects for environmental enrichment were observed on the maximum amplitude of neocortical field responses evoked from the corpus callosum. To assess the plasticity of the chronic preparation used in the study, the animals were exposed to trains of pulses previously shown to induce electrical LTP in the cortex, but revealed only a slight, although significant, depression of the evoked response amplitude. An alteration in the stimulation parameters did not result in an enhanced response. Cortical depth measures suggested that the enriched environment was indeed sufficient to produce plastic changes in anatomy, if not in the efficacy of synaptic transmission. The importance of these findings in the neocortex leads us to question the validity of the LTP model of learning and memory.</p> / Thesis / Master of Science (MSc)