Work Locomotion
I worked with Prof. M.L. Shik, Tel Aviv University, on the neurophysiology of hindbrain neurons during transition from rest to evoked locomotion in newt and salamander. The locomotion was elicited by electrical microstimulation of mesencephalic, or midbrain, "locomotor region" (MLR) first described by Shik et al. (1966). Using weak near-threshold current pulses of low amplitude and frequency, the latency of locomotion could be extended up to 15 seconds (so called state transition). MLR neurons project to hindbrain. Here monosynaptically excited neurons initiate the processing that leads to the proper amount and composition of the neuronal population, which in turn activates the spinal locomotor automatism. How many successive synaptic translations occur in the hindbrain after each input volley from the MLR in order to achieve this task? Experiments on salamanders allow to estimate the "functional depth" of the "locomotor" hindbrain. We recorded the extracellular activity of single hindbrain neurons during the extended latency period. The analysis of neuronal firing patterns and their relation to stimuli and the subsequent locomotor behavior revealed some interesting findings about how the hindbrain neurons are recruited and how their activity is translated to downstream stages.
References:
Kagan I., Shik M.L. (2003) How the mesencephalic "locomotor region"
recruits hindbrain neurons.
Progress in Brain Research
143: 219-228
[preprint]
Bar-Gad I., Kagan I., Shik M.L. (1999) Behavior of hindbrain neurons during the
transition from rest to evoked locomotion in a newt.
Progress in Brain Research
123: 285-294
[abstract]
Shik M.L. (1997) Recognizing propriospinal and reticulospinal systems of initiation of stepping. Motor Control 1: 310 - 313
Shik M.L. (1997) Locomotor patterns elicited by electrical stimulation of the brain stem in the mudpuppy. Motor Control 1: 354 - 368
Shik M.L., Severin F.V. & Orlovsky G.N. (1966). Biophysics 11, 756-765
Presentation of Prof. M.L. Shik at the International Symposium on
"Higher Nervous Control of Posture and Locomotion: parallel and centralized control mechanisms"
(March 18-March 22, 2001)
How the mesencephalic "locomotor region" recruits hindbrain neurons? [presentation]