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Biomedical subjects

F S Lo

Publications and source records attributed to F S Lo.

45 records · Page 3Linked to original sources
PubMed1983

Both fast and slow relay cells in lateral geniculate nucleus of rabbits receive recurrent inhibition.

Intracellular recordings from slow relay cells in the rabbit lateral geniculate nucleus demonstrated that the slow cells, just like the fast ones, receive a monosynaptic EPSP and a trisynaptic IPSP from the optic nerve. The IPSP is most likely mediated by interneurones activated by recurrent collaterals of the relay cell axon. In slow relay cells, both the EPSP and the IPSP from the optic nerve are brought about via the same group of slowly-conducting fibers. No mutual inhibition between the fast and the slow conducting system was observed in the rabbit lateral geniculate nucleus.

Animals↗
PubMed1982

Projection of brain stem neurons to the perigeniculate nucleus and the lateral geniculate nucleus in the cat.

Small horseradish peroxidase injections in the perigeniculate nucleus (PGN) or the lateral geniculate nucleus (LGN) gave retrograde labeling of many cells in the pontomesencephalic reticular formation (RF), the nuclei raphe dorsalis and centralis linearis, locus coeruleus, nucleus of the optic tract and nucleus parabigeminalis. Antidromic stimulation was used to identify neurons in the RF projecting to the PGN-LGN complex. Threshold mapping through the PGN and the LGN shows separate projection from the reticular formation to the PGN and the LGN.

Animals↗
PubMed1982

Functional distinction of perigeniculate and thalamic reticular neurons in the cat.

Two types of neurons can be recognized in the region above the lateral geniculate nucleus. One cell type is found in the caudal part of the reticular nucleus of thalamus; these cells are accordingly called reticular neurons. The other cell type is located in the perigeniculate nucleus immediately above lamina A of the lateral geniculate nucleus and in the intermediate zone between the perigeniculate nucleus and the reticular nucleus. These cells are referred to as perigeniculate neurons. Electrical stimulation of the optic tract and the visual cortex typically evokes a short burst of spikes in the perigeniculate neurons, and the excitation has a shorter latency from the cortex (range 1.2-2.5 ms) than from the optic tract (range 1.5-3.1 ms). The perigeniculate neurons are also activated by adequate visual stimuli. In contrast, the reticular neurons are unresponsive to visual stimuli and electrical stimulation of the optic tract but they may respond with a burst of spikes to cortex stimulation with rather long latency (range 2.7-5.5 ms). It is concluded that only perigeniculate neurons qualify as interneurons in the recurrent inhibitory pathway to principal cells in the lateral geniculate nucleus.

Animals↗
PubMed1981

Synaptic organization of the lateral geniculate nucleus of the rabbit: lack of feed-forward inhibition.

The synaptic organization in the lateral geniculate nucleus of the albino rabbit was studied with an intracellular recording technique. A disynaptic IPSP from the cortex and a trisynaptic IPSP from the optic nerve could be recorded from both fast and slow relay cells. These IPSPs are most likely mediated by a common recurrent inhibitory pathway. No evidence for a feed-forward inhibitory pathway to the relay cells was obtained.

Animals↗
PubMedDate not supplied

Inhibition of nociceptive discharges of parafascicular neurons by direct electrical stimulation of nucleus centrum medianum.

Pain evoked unit discharges in the parafascicular nucleus could be inhibited by direct electrical stimulation of the centromedian nucleus of thalamus, with residual inhibitory effect lasting for several minutes after cessation of stimulation. The optimal frequency of stimulation for production of the inhibitory effect was found to be 4--8 pulses per second. The duration of inhibition following each stimulating pulse lasted for 100--170 msec. Analysis of oscillographic records shows that there exists before the onset of the inhibition of parafascicular discharges a latent period of 10--20 msec which far exceeds the time required for impulse conduction between the two closely related structures, suggesting that a long tortuous neuronal circuit is involved in elaboration and transmission of the inhibitory effect.

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