Abstract:Selective interhemispheric circuits account for a cardinal bias in spontaneous activity within early visual areas, NeuroImage, http://dx.doi.org/10. 1016/j.neuroimage.2016.09.048 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that d… Show more
“…Secondly, it is line with a dominance of cardinal contours that was previously observed in cortical structures and mirrored in the response strength of V1 neurons (cats: Pettigrew et al, 1968 ; Frégnac and Imbert, 1978 ; Orban et al, 1981 ; Leventhal and Schall, 1983 ; monkeys: Mansfield and Ronner, 1978 ; Blakemore et al, 1981 ), the number of neurons (Li et al, 2003 ), the cortical column size (Chapman and Bonhoeffer, 1998 ; Coppola et al, 1998 ; Dragoi et al, 2001 ; Wang et al, 2003 ; Yacoub et al, 2008 ), as well as in the maps of ongoing activity (Kenet et al, 2003 ). Our present finding confirms our previous studies supporting that the interhemispheric network exhibits a cardinal bias in its ongoing (Altavini et al, 2017 ) and stimulus-driven actions (Schmidt et al, 2010 ). Here, we extend this action to the construction of RFs in the area receiving callosal input.…”
Section: Discussionsupporting
confidence: 93%
“…As already observed with spike rates and cortical maps (Schmidt et al, 2010 ; Altavini et al, 2017 ), contralateral thermal deactivation dominantly affected the RFs of neurons preferring cardinally, especially horizontally oriented contours. A closer look revealed cooling induced direction-selective changes among neurons preferring directions crossing the VM.…”
Section: Discussionsupporting
confidence: 73%
“…Previously, we had observed that orientation and direction selectivity of these neurons play a role in the strength of the modulatory influence, i.e., that CC act in an orientation- and direction-selective manner (Peiker et al, 2013 ). As neurons preferring cardinal contours have been shown previously to be more susceptible to visual callosal input (Schmidt et al, 2011 ; Altavini et al, 2017 ) we split all RFs under investigation into three categories according to the orientation preference of the neurons (vertical, horizontal, oblique ± 22.5 degrees; Figure 7 ). We observe that when stimulated ipsilaterally , RFs of neurons preferring either horizontal or vertical (i.e., cardinal ), but not to oblique contours shrink significantly during CC deactivation (n cardinal = 37, Wilcoxon signed rank, p = 0.0002; n oblique = 39, p = 0.06).…”
Section: Resultsmentioning
confidence: 99%
“…Most of the studies describing profound RF changes in the absence of callosal input used irreversible sections of the chiasm and/or the corpus callosum. More recent studies of callosal function using reversible deactivation suggested that CC serve to scale responses in a mainly multiplicative manner (Wunderle et al, 2013 ) acting both directly, changing the receiving neurons' sensitivity to specific features (Schmidt et al, 2010 ; Altavini et al, 2017 ), and indirectly, by unspecifically modulating the gain of the receiving neuron (Wunderle et al, 2015 ). From this type of interaction, CC would be expected to only moderately influence RF size.…”
One leading hypothesis on the nature of visual callosal connections (CC) is that they replicate features of intrahemispheric lateral connections. However, CC act also in the central part of the binocular visual field. In agreement, early experiments in cats indicated that they provide the ipsilateral eye part of binocular receptive fields (RFs) at the vertical midline (Berlucchi and Rizzolatti, 1968), and play a key role in stereoscopic function. But until today callosal inputs to receptive fields activated by one or both eyes were never compared simultaneously, because callosal function has been often studied by cutting or lesioning either corpus callosum or optic chiasm not allowing such a comparison. To investigate the functional contribution of CC in the intact cat visual system we recorded both monocular and binocular neuronal spiking responses and receptive fields in the 17/18 transition zone during reversible deactivation of the contralateral hemisphere. Unexpectedly from many of the previous reports, we observe no change in ocular dominance during CC deactivation. Throughout the transition zone, a majority of RFs shrink, but several also increase in size. RFs are significantly more affected for ipsi- as opposed to contralateral stimulation, but changes are also observed with binocular stimulation. Noteworthy, RF shrinkages are tiny and not correlated to the profound decreases of monocular and binocular firing rates. They depend more on orientation and direction preference than on eccentricity or ocular dominance of the receiving neuron's RF. Our findings confirm that in binocularly viewing mammals, binocular RFs near the midline are constructed via the direct geniculo-cortical pathway. They also support the idea that input from the two eyes complement each other through CC: Rather than linking parts of RFs separated by the vertical meridian, CC convey a modulatory influence, reflecting the feature selectivity of lateral circuits, with a strong cardinal bias.
“…Secondly, it is line with a dominance of cardinal contours that was previously observed in cortical structures and mirrored in the response strength of V1 neurons (cats: Pettigrew et al, 1968 ; Frégnac and Imbert, 1978 ; Orban et al, 1981 ; Leventhal and Schall, 1983 ; monkeys: Mansfield and Ronner, 1978 ; Blakemore et al, 1981 ), the number of neurons (Li et al, 2003 ), the cortical column size (Chapman and Bonhoeffer, 1998 ; Coppola et al, 1998 ; Dragoi et al, 2001 ; Wang et al, 2003 ; Yacoub et al, 2008 ), as well as in the maps of ongoing activity (Kenet et al, 2003 ). Our present finding confirms our previous studies supporting that the interhemispheric network exhibits a cardinal bias in its ongoing (Altavini et al, 2017 ) and stimulus-driven actions (Schmidt et al, 2010 ). Here, we extend this action to the construction of RFs in the area receiving callosal input.…”
Section: Discussionsupporting
confidence: 93%
“…As already observed with spike rates and cortical maps (Schmidt et al, 2010 ; Altavini et al, 2017 ), contralateral thermal deactivation dominantly affected the RFs of neurons preferring cardinally, especially horizontally oriented contours. A closer look revealed cooling induced direction-selective changes among neurons preferring directions crossing the VM.…”
Section: Discussionsupporting
confidence: 73%
“…Previously, we had observed that orientation and direction selectivity of these neurons play a role in the strength of the modulatory influence, i.e., that CC act in an orientation- and direction-selective manner (Peiker et al, 2013 ). As neurons preferring cardinal contours have been shown previously to be more susceptible to visual callosal input (Schmidt et al, 2011 ; Altavini et al, 2017 ) we split all RFs under investigation into three categories according to the orientation preference of the neurons (vertical, horizontal, oblique ± 22.5 degrees; Figure 7 ). We observe that when stimulated ipsilaterally , RFs of neurons preferring either horizontal or vertical (i.e., cardinal ), but not to oblique contours shrink significantly during CC deactivation (n cardinal = 37, Wilcoxon signed rank, p = 0.0002; n oblique = 39, p = 0.06).…”
Section: Resultsmentioning
confidence: 99%
“…Most of the studies describing profound RF changes in the absence of callosal input used irreversible sections of the chiasm and/or the corpus callosum. More recent studies of callosal function using reversible deactivation suggested that CC serve to scale responses in a mainly multiplicative manner (Wunderle et al, 2013 ) acting both directly, changing the receiving neurons' sensitivity to specific features (Schmidt et al, 2010 ; Altavini et al, 2017 ), and indirectly, by unspecifically modulating the gain of the receiving neuron (Wunderle et al, 2015 ). From this type of interaction, CC would be expected to only moderately influence RF size.…”
One leading hypothesis on the nature of visual callosal connections (CC) is that they replicate features of intrahemispheric lateral connections. However, CC act also in the central part of the binocular visual field. In agreement, early experiments in cats indicated that they provide the ipsilateral eye part of binocular receptive fields (RFs) at the vertical midline (Berlucchi and Rizzolatti, 1968), and play a key role in stereoscopic function. But until today callosal inputs to receptive fields activated by one or both eyes were never compared simultaneously, because callosal function has been often studied by cutting or lesioning either corpus callosum or optic chiasm not allowing such a comparison. To investigate the functional contribution of CC in the intact cat visual system we recorded both monocular and binocular neuronal spiking responses and receptive fields in the 17/18 transition zone during reversible deactivation of the contralateral hemisphere. Unexpectedly from many of the previous reports, we observe no change in ocular dominance during CC deactivation. Throughout the transition zone, a majority of RFs shrink, but several also increase in size. RFs are significantly more affected for ipsi- as opposed to contralateral stimulation, but changes are also observed with binocular stimulation. Noteworthy, RF shrinkages are tiny and not correlated to the profound decreases of monocular and binocular firing rates. They depend more on orientation and direction preference than on eccentricity or ocular dominance of the receiving neuron's RF. Our findings confirm that in binocularly viewing mammals, binocular RFs near the midline are constructed via the direct geniculo-cortical pathway. They also support the idea that input from the two eyes complement each other through CC: Rather than linking parts of RFs separated by the vertical meridian, CC convey a modulatory influence, reflecting the feature selectivity of lateral circuits, with a strong cardinal bias.
“…Significantly, ongoing orientation maps preferring cardinal orientations were impacted by the absence of CC input ( Fig. 7 ; Altavini et al, 2017 ). Fig.…”
Highlights
The functional characterization of callosal connections is informed by anatomical data.
Callosal connections play a conditional driving role depending on the brain state and behavioral demands.
Callosal connections play a modulatory function, in addition to a driving role.
The corpus callosum participates in learning and interhemispheric transfer of sensorimotor habits.
The corpus callosum contributes to language processing and cognitive functions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
