Kyoto University · Neuroscience
Professor Tadashi Isa's research lab specializes in the neural circuitry underlying sensorimotor integration, with a primary focus on the superior colliculus and corticospinal pathways in rodents and primates. The lab employs whole-cell patch-clamp recordings in brain slice preparations to dissect microcircuits involved in gaze control and motor coordination, particularly the role of disynaptic and polysynaptic connections. A central theme is understanding how propriospinal neurons mediate recovery of fine motor functions, such as precision grip, after corticospinal tract injury. The lab also investigates the functional properties of glutamatergic receptors, especially AMPA receptors, in developing and mature neurons.
Figures are computed from collected data and may differ slightly.
Intrinsic circuit of the superior colliculus (SC), in particular the pathway from the optic tract (OT) to neurons in the intermediate layer (SGI), was investigated by whole-cell patch-clamp recording in slice preparations obtained from 17- to 24-d-old rats. Stimulation of the OT induced monosynaptic EPSPs in neurons in the superficial gray layer (SGS) and the optic layer (SO), and disynaptic or polysynaptic EPSPs in a majority of SGI neurons. Stimulation of the SGS induced monosynaptic or oligos
The superior colliculus plays an important role in the translation of sensory signals that encode the location of objects in space into motor signals that encode vectors of the shifts in gaze direction called saccades. Since the late 1990s, our two laboratories have been applying whole cell patch-clamp techniques to in vitro slice preparations of rodent superior colliculus to analyze the structure and function of its circuitry at the cellular level. This review describes the results of these exp
Recent studies from our group have demonstrated the existence of a disynaptic excitatory cortico-motoneuronal (CM) pathway in macaque monkeys via propriospinal neurons in the midcervical segments. Results from behavioral studies with lesion of the direct pathway suggest that the indirect CM pathway can mediate the command for dexterous finger movements.
Candidate propriospinal neurons (PNs) that mediate disynaptic pyramidal excitation to forelimb motoneurons were studied in the C3-C4 segments in anesthetized macaque monkeys (n = 10). A total of 177 neurons were recorded (145 extracellularly, 48 intracellularly, and 16 both) in laminae VI-VII. Among these, 86 neurons (73 extracellularly, 14 intracellularly and 1 both) were antidromically activated from the forelimb motor nucleus or from the ventrolateral funiculus just lateral to the motor nucle
The direct cortico-motoneuronal connection is believed to be essential for the control of dexterous hand movements, such as precision grip in primates. It was reported, however, that even after lesion of the corticospinal tract (CST) at the C4-C5 segment, precision grip largely recovered within 1-3 mo, suggesting that the recovery depends on transmission through intercalated neurons rostral to the lesion, such as the propriospinal neurons (PNs) in the midcervical segments. To obtain direct evide
1. Current-voltage (I-V) relationships and Ca2+ permeability of receptor channels activated by bath application of kainate, a non-desensitizing agonist of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, were examined in various types of neurones in hippocampal slices of 5- to 13-day-old rats by using the tight-seal patch clamp recording technique. 2. Three types of responses were observed: type I response with outwardly rectifying I-V relationship, type II response wit
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