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Biomedical subjects

C Galletti

Publications and source records attributed to C Galletti.

At least 55 records · Page 3Linked to original sources
PubMed1981

Contralateral tectal projections from single areas of the visual cortex in the cat.

1. The projections from cat cortical visuals areas to the contralateral superior colliculus (SC) were studied by the autoradiographical tracing method. Microinjections of L- [5-3H] proline were carried out in cortical visual areas 17, 18, 19 and the lateral suprasylvian visual area (LS) in different cats. Only one cortical area was injected in each animal. Survival times of 30 hours or 8 days were allowed. 2. Areas 17, 18, 19 and LS send projections to laminae, I, II and III of the frontal pole of the contralateral SC. Areas 19 and LS project also the contralateral pretectal nuclei, mainly to the posterior pretectal nucleus. 3. Cortical fibres reaching the contralateral SC pass through the brachium of the ipsilateral SC. They run along the caudal part of this structure, cross the midline and then run along the caudal part of the contralateral SC; finally, they turn anterolaterally and reach the rostal part of SC. This pathway is the tectal semidecussation (5). Cortical fibres from LS (in particular from PLLS; 15) reach the contralateral SC also via the commissure of SC. 4. Our data support the suggestion (3) that the frontal poles of SC, in the cat, may subserve straight-ahead attention and orientation to visual stimuli.

Animals↗
PubMed1980

Autoradiographic evidence for projections from cortical visual areas 17, 18, 19 and the Clare-Bishop area to the ipsilateral claustrum in the cat.

Projections from different visual areas of the cerebral cortex to the ipsilateral claustrum have been investigated in the cat by intracortical injections of [3H]proline. As a consequence of axonal flow an accumulation of radioactive material within a dorso-caudal region of the ipsilateral claustrum was found. The proline-transporting terminal arborizations of projections from areas 17, 18, 19 and the Clare-Bishop area overlap in the same claustral region. No point-to-point relation was observed between any one visual area and its claustral projection. Differences in the terminal distribution pattern were detectable according to the visual areas of origin.

Animals↗
PubMed1980

Projections from the visual cortex to the contralateral claustrum of the cat revealed by an anterograde axonal transport method.

Contralateral projections from visual areas 17, 18, 19 and the Clare-Bishop area of the cerebral cortex to the claustrum have been investigated in the cat using intracortical injections of [3H]proline. Radioactive material was found in a dorsocaudal region of the contralateral claustrum. This region was homotopic with respect to that found for the ipsilateral projection from visual cortex. The contralateral connection is assumed to be a monosynaptic pathway. The pattern by which the corticofugal fibres terminate in the claustrum is quite similar to the one described for the opposite hemisphere [6].

Animals↗
PubMed1980

Autoradiographic evidence of visual cortical projections to the frontal cortex in the cat.

In II adult cats, areas 17, 18, 19 as well as the lateral suprasylvian area were separately injected with L-[5-3H] proline and their efferent projections to the frontal cortex were autoradiographically searched. Only area 19 and lateral suprasylvian area showed such projections; terminal sites were localized in the ventral and dorsal banks of the cruciate sulcus and in the adjacent mesial surface of the brain. The possibility that these labeled regions may correspond to the monkey's frontal eye field is discussed.

Animals↗
PubMed1979

Stimulus-response function at several levels of background luminance, in the cat visual areas 17 and 18.

Stimulus-response curves of simple cells of the visual cortex were obtained by using 500-msec stationary stimuli. Background influence on single unit responses was studied. The contrast sensitivity of simple cells increases as a function of background luminance. The resolution power of these cortical cells for detecting differences in stimulus contrast decreases at background levels above 0.09 cd/m2.

Animals↗
PubMed1979

Acid-base equilibrium during acute long-lasting experiments in artificially ventilated cats.

Experiments were carried out to study blood acid-base equilibrium in the cat during experiments with artificial ventilation. Blood acid-base equilibrium was examined in the arterial and venous blood by analyzing pH, carbon dioxide and oxygen partial pressure, and plasma bicarbonates. Artificial ventilation was regulated on the basis of this analysis; CO2 concentration in expired air was monitored throughout the experiment. An attempt was made to verify if artificial ventilation could be regulated indirectly only on the basis of CO2 concentration in expired air. The most appropriate acid-base equilibrium was maintained when CO2 concentration in expired air was kept within the range of 3.9-4.1%.

Acid-Base Equilibrium↗
PubMed1977

Maintained activity of single neurons in the cat visual cortex at different levels of retinal adaptation.

The influence of ambient illumination on the maintained electrical activity of single neurons of the cat visual cortex was studied by using the closed chamber technique for extracellular recordings. Several levels of light background within the scotopic-mesopic range were explored. Phasic and tonic changes in firing rate were observed following a background change. The former were irregular and unpredictable variations lasting up to 15-20 min. The latter, which usually followed the phasic changes, showed the constant characteristic of being in direct relation to luminance variations for neurons isolated in the striate area and in inverse relation for units recorded from the two non-striate areas of the visual cortex; in all cases, they lasted until a new luminous level was set. Changes in firing rate were not dependent upon either the neuron receptive field organization or the EEG pattern, simultaneously recorded. The background-locked firing rate variations recorded at the visual cortex seem to be the result of a particular cortical distribution of afferent fibers carrying luminance information. Applications to vision research are also suggested.

Action Potentials↗