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Visual and somatosensory integration in the anterior ectosylvian cortex of the cat
No full textWe recorded from single neurons in both banks of the posterior two-thirds of the anterior ectosylvian sulcus. All neurons were tested with visual and tactile stimulations. In each bank of the anterior ectosylvian sulcus the majority of neurons were bimodal, i.e. responded to both visual and tactile stimuli (B cells); the remaining population was strictly unimodal, responding either to visual (V cells) or to somatosensory (T cells) stimulation. Bimodal and unimodal neurons were recorded at all explored cortical sites and were consistently intermixed. Unlike bimodal neurons, unimodal neurons showed an asymmetric localization: the V cells were significantly more numerous in the ventral bank while the T neurons were preferentially found in the dorsal bank of the sulcus. We could not detect an orderly somatotopic or visuotopic representation, nor was it possible to find a systematic spatial correspondence between somatic and visual receptive fields. The functional organization of the anterior ectosylvian cortex is discussed in terms of a hierarchical processing of sensory information
Organization of claustro-cortical projections to the primary somatosensory area of primates.
No full textHas music a specific effect on temporal control of movements? An auditory-motor task of synchronization.
No full textThe timing of action is analyzed by studying a repetitive task in which participants are required to execute simple isochronous repetitive movements (IRMs) avoiding prerequisites for explicit temporal representation. Movements are performed in free condition and accompanying predictable time-based auditory stimuli such as metronome clicks and robustly timed musical excerpts
Circle drawing and tracing dataset for evaluation of fine motor control
No full textWe introduce a motion dataset from healthy human subjects (n = 125) performing two fine motor control tasks on a graphic tablet, namely circle drawing and circle tracing. The article reports the methods and materials used to capture the motion data. The method for data acquisition is the same as the one used to investigate some aspects of fine motor control in healthy subjects in the paper by Cohen et al. (2018) “Precision in drawing and tracing tasks: Different measures for different aspects of fine motor control” (https://doi.org/10.1016/j.humov.2018.08.004) [1]. The dataset shared here contains new raw files of the two-dimensional motion data, as well information on the participants (gender, age, laterality index). These data could be instrumental for assessing other aspects of fine motor control, such as speed-accuracy tradeoff, speed-curvature power law, etc., and/or test machine learning algorithms for e.g., task classification
Interhemispheric influences on area 19 of the cat
No full textAnatomical studies have shown an extensive network of homotopic and heterotopic interhemispheric connections in area 19 of the cat visual cortex (Segraves and Rosenquist 1982a; 1982b). We have investigated their functional organization by recording visual responses in area 19 of cats following a midsagittal section of the optic chiasm. This operation interrupts all crossed optic fibers coming both from the nasal and the temporal retinae; as a result, each hemisphere receives optic fibers only from the lateral hemiretina of the ipsilateral eye which conveys information from the contralateral visual field. Visual information transmitted to the same hemisphere from the contralateral retina and the ipsilateral visual field must be attributed to an indirect, interhemispheric pathway. We found that a rather high proportion of neurons (31.8%) in area 19 of seven split-chiasm cats responded to visual stimuli presented to the contralateral eye. 1 - All neurons receiving this interhemispheric activation were also driven by the ipsilateral eye via an intrahemispheric pathway. 2 - The property of binocularity was significantly related to the visuotopic map in that both receptive fields of each binocular neuron adjoined or were in the immediate vicinity of the vertical meridian. 3 - Due to the small size of receptive fields in area 19, the contribution of the interhemispheric pathway to the representation of the visual field is rather limited and it is certainly less extensive than that predicted by anatomical studies. The representation of the ipsilateral visual field in area 19 of intact cats, as assessed electrophy-siologically, was comparable to that found in split-chiasm cats. Recordings in areas 17-18 of split-chiasm cats showed that the visual field represented through the corpus callosum in these visual areas is certainly not less and probably more, extensive than that found in area 19. The results support the conclusion that the relation to the vertical meridian and the receptive field size can explain the organization of the interhemispheric connections in the visual areas studied so far. © 1985 Springer-Verlag
The thalamo-caudate versus thalamo-cortical projections as studied in the cat with fluorescent retrograde double labeling
No full textThe distribution of thalamic cells projecting to the head of the caudate and their interrelations with thalamo-cortical cells were studied in the cat with different combinations of fluorescent tracers. Injections in the head of the caudate were combined with the injections in the pericruciate, proreal, suprasylvian, anterior cingulate, occipital and ectosylvian cortices. The following results were obtained: (i) Injections in the head of the caudate resulted in retrograde labeling of thalamic cells medially and laterally to the anteromedial (AM) nucleus, and in the medioventral part of the ventral anterior (VA) nucleus. Further, labeled cells were distributed throughout the anterior intralaminar central medial (CeM), paracentral (Pc) and central lateral (CL) nuclei, and the posterior intralaminar center median-parafascicular complex (CM-Pf). Labeled cells were mainly grouped in the mediodorsal parts of the anterior intralaminar nuclei; they were also found in the more dorsal part of the mediodorsal (MD) nu cleus, ventral to the thalamic paraventricular (Pv) nucleus and to the habenular complex. (ii) Thalamo-cortical and thalamo-caudate cells overlapped in the medial part of the VA; in the anterior intralaminar nuclei they were either intermingled or were distributed in separate clusters or longitudinal bands. The two cell populations also overlapped in the posterior intralaminar complex. The greatest overlap occurred with the thalamic cell population projecting to the pericruciate cortex. (iii) Thalamic cells bifurcating to the head of the caudate and to the pericruciate cortex were found lateral to the AM, within the VA, and throughout the anterior intralaminar nuclei, especially in the CeM and in the posterior part of the CL; a few branched cells were also found in the CM. Thalamic cells bifurcating to caudate and anterior suprasylvian cortex were also found in the VA. Very few cells (scattered in the anterior thalamus lateral to the AM, as well as in the CeM, Pc and CL) were found to bifurcate to the head of the caudate and the other cortical fields here examined
Acetylcholine, GABA and neuronal networks: a working hypothesis for compensations in the dystrophic brain.
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Voronoi-based spatial analysis reveals selective interneuron changes in the cortex of FALS mice
No full textThe neurodegenerative disease amyotrophic lateral sclerosis affects lower motoneurons and corticospinal cells. Mice expressing human mutant superoxide dismutase (SOD)1 provide widely investigated models of the familial form of disease, but information on cortical changes in these mice is still limited. We here analyzed the spatial organization of interneurons characterized by parvalbumin immunoreactivity in the motor, somatosensory, and visual cortical areas of SOD1(G93A) mice. Cell number and sociological spatial behavior were assessed by digital charts of cell location in cortical samples, cell counts, and generation of two-dimensional Voronoi diagrams. In end-stage SOD1-mutant mice, an increase of parvalbumin-containing cortical interneurons was found in the motor and somatosensory areas (about 35% and 20%, respectively) with respect to wild-type littermates. Changes in cell spatial distribution, as documented by Voronoi-derived coefficients of variation, indicated increased tendency of parvalbumin cells to aggregate into clusters in the same areas of the SOD1-mutant cortex. Counts and coefficients of variation of parvalbumin cells in the visual cortex gave instead similar results in SOD1-mutant and wild-type mice. Analyses of motor and somatosensory areas in presymptomatic SOD1-mutant mice provided findings very similar to those obtained at end-stage, indicating early changes of interneurons in these cortical areas during the pathology. Altogether the data reveal in the SOD1-mutant mouse cortex an altered architectonic pattern of interneurons, which selectively affects areas involved in motor control. The findings, which can be interpreted as pathogenic factors or early disease-related adaptations, point to changes in the cortical regulation and modulation of the motor circuit during motoneuron disease
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