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K Turlejski

Publications and source records attributed to K Turlejski.

9 recordsLinked to original sources
PubMed1989

The inhibitory components in the responses of the lateral suprasylvian area neurons to moving stimuli in cats.

The inhibitory components in the neuronal responses of the cat's lateral suprasylvian area (LSA) to moving bright and dark stimuli were investigated. The LSA neurons could be divided into two groups. Neurons of the first group (33%) do not reveal spatial displacement of the inhibitory zones and show displacement of the discharge centers in the receptive field only for one polarity of contrast of moving stimuli, either brighter or darker than the background. The second group (67%) contained the neurons which showed a spatial displacement of the inhibitory components and discharge centers in the receptive field for either polarity of contrasts of the moving stimuli. Tested with stationary flashing stimuli, the majority of neurons in both groups had overlapping ON-OFF discharge regions within their receptive fields. The results obtained with moving stimuli of different speeds and with the masking method suggest the rebound origin of the inhibitory responses in LSA neurons.

Animals↗
PubMed1989

Properties of the visually driven neurons of cat's hippocampal regions CA 1 and CA 3.

Neurons in areas CA 1 and 3 of cat's dorsal hippocampus were studied. Fifteen percent of the investigated cells were influenced by visual stimuli. Eighty five such neurons were investigated. The organization of their receptive fields was tested with stationary and moving visual stimuli. Twenty eight percent of neurons had small receptive fields (10-20 deg square). Forty one neurons responded to stationary flashing spots. They were ON-OFF, ON and OFF types with phasic (66%) and tonic (34%) characteristics. Seventy five responded to dark and bright stimuli moving across their receptive fields. Twenty five neurons were direction-sensitive and 21 responded better to the dark moving stimuli than to the bright ones. No significant differences in the response properties of neurons in the CA 1 and CA 3 fields were observed.

Action Potentials↗
PubMed1987

On the numbers of neurons in fields CA1 and CA3 of the hippocampus of Sprague-Dawley and Wistar rats.

In a previous study it was found that there are significant differences in the numbers of granule cells in the dentate gyrus of adult Sprague-Dawley and Wistar rats and also that the continued postnatal addition of new cells to the dentate gyrus has quite different consequences in the two strains. We have now extended these observations to the two major cytoarchitectonic fields of the hippocampus (the regio superior or field CA1; and the regio inferior or field CA3). The mean number of pyramidal neurons in field CA1 of 1-month-old Sprague-Dawley rats is 420,000 (+/- 60,000 S.E.), while Wistar rats at the same age have 320,000 (+/- 20,000). The numbers of neurons in field CA3 in the two strains are: 330,000 (+/- 30,000) and 210,000 (+/- 20,000), respectively. Whether these strain differences reflect specific differences in the neural organization of the hippocampal formation in the two strains, or are related to more general differences in total body weight or brain weight, is unknown. Since during the first two days postnatally we estimate that there are between 358,000 and 491,000 cells in field CA1 of Sprague-Dawley rats, it would seem that there is no significant naturally-occurring neuronal death in this hippocampal field. This may be due to the extensive collateral projections of the hippocampal pyramidal neurons.

Animals↗
PubMed1985

Decrease in the number of synapses formed by subcortical inputs to the striate cortex of binocularly deprived cats.

The density of synapses was determined from electronmicrographs taken from area 17 of cats binocularly deprived of pattern vision for 6 months and in normally reared litter mates. In each cat the optic radiation was transected on one side 4 days before sacrifice and the density of synapses of subcortical origin was estimated by comparing the density of normal synapses remaining on the lesioned side with the density of synapses on the unlesioned side. In normal animals 36% of the synapses were formed by subcortical afferents, but in the binocularly deprived animals this figure was reduced to only 17%. A decrease found in the total synaptic density in the deprived visual cortex was not statistically significant. Thus, binocular deprivation seems to selectively diminish the subcortical contribution to the synaptic density in the visual cortex.

Animals↗
PubMed1984

Crosscorrelation analysis of intracolumnar neuronal connectivity in area 17 of binocularly deprived cats.

Eight cats were binocularly deprived of pattern vision by rearing in masks from the time of eye opening. Twenty five groups of 3 neurons and 28 neuronal pairs were studied in visual orientation columns of their striate cortices. The crosscorrelograms of neuronal discharges were analyzed and the inference of underlying interneuronal connectivity was made. The results were compared with the normal cats data obtained earlier in an identical experiment. Total number of existing interactions was only slightly reduced: from 95010 of analyzed pairs in normal cats to 90 percent in deprived animals. The most pronounced effect of visual deprivation was the reduction of the percentage of neuronal pairs that shared the same source of input from 61 to 34 percent. The proportion of direct excitatory connections was not affected, while an increase in the number of inhibitory correlations was found.

Animals↗
PubMed1983

Responses of area 17 neurons in cats binocularly deprived by rearing in hoods.

Responses of single units of area 17 were recorded in cats binocularly deprived by rearing in hoods. Neurons were recorded in pairs or in three-neuron groups with multichannel microelectrodes. Of 131 units recorded 22 percent were not visually excitable. The rest were predominantly monocularly driven. Response strength defined as the PST peak-to-background ratio was lower than 10 in 90 percent of cells. The orientation selectivity defined as the ratio of response strengths for the preferred and null stimulus orientations was lower than 5 in 79 percent of neurons. Directional selectivity was detected in 22 percent of units. The aim of this paper is to show that, considering the electrophysiological effects in cortica1 area 17, rearing in hoods can be used instead of eyelid suturing. This paper describes the standard parameters of units that were subsequently used for the analysis of interneuronal connectivity in visually deprived cortex (10).

Adaptation, Physiological↗
PubMed1975

Clare-Bishop area in the cat: location and retinotopical projection.

Visual responses of single units in the cortex of the middle suprasylvian sulcus were evaluated in the pretrigeminal cat. Electrode penetrations which passed through the Clare-Bishop area were in 94 percent of the cases within the stereotaxic coordinates A2 and A8. Within the Clare-Bishop area 40 percent of the units were responsive to the visual stimuli employed whereas adjacent to it only 10-20 percent responded. Correlation between receptive field size and eccentricity was poor or absent. Most receptive field centers lay within the lower contralateral quadrant. Because of the large size of the receptive fields, their scatter and individual variability, it was not possible to depict a precise scheme of retinotopical projection.

Animals↗
PubMed1975

Visual responses of neurons in the Clare-Bishop area of the cat.

Single unit responses in the Clare-Bishop area of the pretrigeminal cat were analyzed using stationary and moving visual stimuli. Of the units responding, 80 percent could be influenced by a 0.5 s diffuse flash, most displaying inhibition or excitation to both "on" and "off". In most units responses to stationary shapes were not very specific. Responses to moving stimuli were strong and directional preference was usually present. For the majority of cells the optimal speed of movement was in the range from 100 to 800 deg/s, and some cells preserved their direction preferences when the speed was over 1,500 deg/s. The direction preference could be reversed depending on the speed of movement, location in the receptive field or the shape of stimulus.

Animals↗