Biology subjects

Spampinato, G.

Publications and source records attributed to Spampinato, G..

3 recordsLinked to original sources

bioRxiv2025

The Rod Bipolar Cell Pathway Contributes To Surround Responses In OFFRetinal Ganglion Cells

Sensory neurons can be influenced by stimuli beyond their receptive field center, yet the mechanisms underlying this surround modulation remain poorly understood. In the retina, many OFF ganglion cells exhibit responses to ON stimulation outside their receptive field center. However, disentangling the pathways and cell types contributing to these responses has been challenging with traditional experimental approaches. Here, we combined optogenetics, two-photon holographic stimulation, and multi-electrode array recordings to identify the intermediate retinal cell types involved in this circuit. We found that the pathway formed by rod bipolar cells and AII amacrine cells--one of the primary relays of rod-driven signals under low-light conditions--plays a key role in mediating this surround modulation. Specifically, crossover inhibition exploits the same amacrine cells responsible for surround suppression to disinhibit distant ganglion cells. This suggests that the retina repurposes existing circuits for surround modulation, optimizing resources through multifunctional inhibitory pathways.

neuroscience↗

bioRxiv2022

Differences in non-linearities determine retinal cell types

Classifying neurons in different types is still an open challenge. In the retina, recent works have taken advantage of the ability to record a large number of cells to classify ganglion cells into different types based on functional information. While the first attempts in this direction used the receptive field properties of each cell to classify them, more recent approaches have proposed to cluster ganglion cells directly based on their response to standard stimuli. These two approaches have not been compared directly. Here we recorded the responses of a large number of ganglion cells and compared two methods for classifying them into types, one based on the receptive field properties, and the other one using their responses to standard stimuli. We show that the stimulus-based approach allows separating more types than the receptive field-based method, leading to a better classification. This better granularity is due to the fact that the stimulus-based method takes into account not only the linear part of ganglion cell function, but also non-linearities. A careful characterization of non-linear processing is thus key to allow functional classification of sensory neurons.

neuroscience↗

bioRxiv2018

Taxonomy, ecology and distribution of Juniperus oxycedrus L. group in the Mediterranean Region using morphometric, phytochemical and bioclimatic approaches.

The ecology, taxonomy and distribution of the Juniperus oxycedrus L. group of taxa are studied. From an ecological aspect, this work proposes a new ombroedaphoxeric index to explain the presence of populations of Juniperus in ombrotypes that are not the optimum for these taxa. The controversy among various authors on the taxonomy of the oxycedrus group with regard to J. oxycedrus subsp. badia and J. oxycedrus subsp. lagunae is clarified. The phytochemical differences in essential oils are addressed, and their similarities analysed; greater similarities are observed between oxycedrus and badia (H. Gay) Debeaux, and between navicularis Grand. and macrocarpa (Sm.) Ball. The phytochemical, molecular and distribution differences allow J. macrocarpa and J. navicularis to be maintained as species.

plant biology↗