Physiol. Res. 49: 369-378, 2000

Discharge Properties of Neurons in Subdivisions of the Medial Geniculate Body of the Guinea Pig

E. Kvašòák, J. Popeláø, J. Syka

Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic

Received August 5, 1999
Accepted January 25, 2000


Summary
The activity of 194 neurons was recorded in three subdivisions of the medial geniculate body (74 neurons in the ventral, 62 in the medial and 44 neurons in the dorsal subdivision, i.e. vMGB, mMGB and dMGB) of guinea pigs anesthetized with ketamine-xylazine. The discharge properties of neurons were evaluated by means of peristimulus time histograms (PSTHs), interval histograms (INTHs) and auto-correlograms (ACGs). In the whole MGB, the most frequent PSTH responses to pure tone stimuli were onset (43 %) or chopper (32 %). The onset responses were mostly present in the vMGB, whereas chopper responses dominated in the dMGB. In the whole MGB Poisson-like and bimodal INTHs were found in 46 % and 40 % of neurons, respectively. The mMGB revealed fewer bimodal and more symmetrical types of INTH. In the whole MGB, 60 % of units were found to have ACGs typical for short bursts (<100 ms), 23 % for long bursts (>100 ms) and 15 % of units fired without bursts. Neurons in the vMGB were characterized by short bursting, whereas those in the mMGB and dMGB expressed more activity in the long bursts. The results demonstrate that the type of information processing in the vMGB, which belongs to the ”primary” auditory system, is different from that in two other subdivisions of the MGB.


Key words
Discharge pattern · Single neuron activity · Medial geniculate body · Subdivisions · Guinea pig

Reprint requests
Mgr. Eugen Kvašòák, Institute of Experimental Medicine, Academy of Science of the Czech Republic, Vídeòská 1083, 142 20 Prague 4, Czech Republic.


© 2000 by the Institute of Physiology, Czech Academy of Sciences