Koç University School of Medicine Neurophysiology Laboratory

(What If Lab: WI-LAB)

Gap in the literature in neuromuscular physiology: Since it is difficult to study the functions of the neuromuscular system in human subjects, most of our knowledge comes from studies on experimental animals. However, since the animals are usually anaesthetized or decerebrated in these experiments, and since such reduction processes are known to alter the synaptic interactions, it is not possible to directly apply these findings to human subjects. Therefore, details of the synaptic interactions between sensory or cortical afferents and motoneurons, the process of feed-back from the peripheral receptors to the motoneurons, the pathways used in these processes, and conditions where such synaptic interactions are modulated are still unknown in human subjects. Because of the fact that we do not yet understand the functions of the neuromuscular system in human subjects, we cannot develop knowledge based methods for diagnosing and treating neuromuscular dysfunctions. The main aim of this project therefore is to investigate some of the functions of the human neuromuscular system.

Current projects in the lab aim to:
1. Discover the EMG interference in EEG;
2. Discover the functions of the Renshaw circuitry in human motor control;
3. Discover the physiology of the vibration induced reflex responses;
4. Investigate the cortically evoked silent period using frequency analysis;
5. Study the ALS effect on motor neurons of humans and experimental animals.

Methods and Design: To achieve the above-mentioned goals, we stimulate either the peripheral receptors using mechanical or electrical means or the motor cortex using transcranial magnetic stimulator. The response of skeletal muscles to such stimuli are recorded using surface and intramuscular electromyography electrodes to estimate the properties of the neuronal circuitries, number of synapses and the properties of the synaptic potentials.

Significance: With these studies, we are aiming to investigate the connections between peripheral receptors / motor cortex and motoneurons in human volunteers using our error-free new method of frequency analysis. With the new method, we aim to find out which of the ‘previously-establish’ pathways are genuine and which are erroneous. Using the new method, we are also likely to discover previously unknown neuronal pathways that could not have been illustrated using the classical methods. Furthermore, we will also find out whether or not synapses in neuronal pathways are modulated during movement. This study will also set the norm for future human reflex studies and change some of the current beliefs on the reflex connections. Since reflexes are used to probe the human neuromuscular system and to estimate synaptic potentials, this information will be used to form the wiring diagram of the human nervous system. Therefore, these studies will establish the correct circuitries and will help understand the operation of the neuromuscular system so that this information can be utilized in clinical neurology to develop knowledge based methods for diagnosis and treatment of neuromuscular dysfunctions. This knowledge can also be used to develop feedback controlled artificial limbs for spinal injury patients.