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H J Gabriel

Publications and source records attributed to H J Gabriel.

28 records · Page 2Linked to original sources
PubMed1980

Response variations of neurons in the lateral geniculate body of the freely moving rat.

The influence of the motivational state on the discharge rate and flash evoked activity of 57 single units of the dorsal lateral geniculate body (LGB) was investigated using extracellular microelectrodes. Flashes were presented either alone (control group) or followed by water reinforcement (trained group). With decreasing thirst motivation the background activity of most of the cells of both groups changed. This change consisted mainly in a decrease of the discharge rate. After satiation two thirds of the cells exhibited response variations to light stimuli. In trained thirsty animals in 10 out of 19 cells these changes were of very high degree, as the usual response pattern consisting in a sequence of excitatory and inhibitory phases was lost. Under such conditions the light acted as a conditioned stimulus in the thirsty animal. Nonvisual stimuli preceding the flashes and evoking inhibiton of the reflex behavior in trained rats produced small response modulations in about two thirds of the cells of either animal group. The assumption is made that the motivational state of the animal or environmental stimuli not belonging to the original conditioned stimulus - unconditioned stimulus (CS-US) paradigm are less effective in producing response changes of cells to physically equal stimuli than the biological relevance of the stimulus.

Animals↗
PubMed1977

[Responses of single cells of the rat lateral geniculate body to light stimuli differing in wavelength and intensity].

Single unit responses of the rat's lateral geniculate body to red and green stimuli of light emission diods and to daylight spectrum flashes were recorded. The primary response consisted either in an increase or in a decrease of the discharging rate. Each unit was responsive to all light stimuli either with excitation or inhibition, i.e. the direction of the change in the discharging rate was always the same for one cell. When applying the stimuli in the above mentioned sequence we found a shortening of the latency period and a shorter duration of the primary response, more afterdischarges, and a more marked postexcitatory inhibition.

Animals↗
PubMed1976

[Effect of a conditioned emotional state on the discharging behavior of single neurons of the rat dorsal lateral geniculate body].

1. The spike activity of 155 cells of the dorsal geniculate body of rats was recorded under the influence of flash and the combination of flash with a tone. For test animals the tone has an emotional relevance (ERT), because they had been trained to learn a conditioned emotional reaction with the tone as conditioned stimulus. Controls had been sham trained, i.e. the tone was never reinforced and therefore without emotional relevance (EIT). 2. In the controls there was no difference in the quantity of facilitatory and inhibitory responses to the tone, whereas under ERT there were more often facilitations than inhibitions. 3. The tone changed the reaction to flash. This variation depends on the emotional relevance of the acoustic stimulus. The ERT evoked a stronger increase in the number of excitations than the EIT. The number of inhibitions decreased equally under both conditions. Also, the ERT changed the strength of the flash response more often than the EIT did. An increasing trend of excitation was found especially in primary positive cells, an increasing trend of inhibition especially in primary negative ones. The time course of responses shows these differences to occur in the primary positive cells essentially later than 200 mse cafter the stimulus, in the primary negative cells, however, within this interval.

Acoustic Stimulation↗
PubMed1975

[Plastic response changes in neurons from lateral geniculate body in rats submitted to conditional reflectory stimulation].

In alert curarized rats the influence of an electric stimulation of the tail skin on the flash-evoked activity of single units of the dorsal part of the lateral geniculate body (CGLd) was investigated. The light flashes were applied 400 msec prior to the electric shocks. 50% of the units showed a change of the response pattern to flash. In the majority of cases the response shifts consisted in a facilitation, which developed gradually and persisted in most of the units examined, even when the electrical stimulus was no longer given in combination with the light. The results are discussed taking into consideration the possibility of an altered emotional or motivational status of the animal, which could play a role in the development of plasticity at the unitary level.

Action Potentials↗