A visual lamina in the medulla oblongata of the frog, Rana pipiens. (15th October 2020)

• Record Type: Journal Article
• Authors: Wallace, Mark T.; Recktenwald, Eric; Dudkin, Elizabeth A.; Gruberg, Edward R.
• Is Part Of: Neuroscience letters. Volume 737(2020)
• Publication Date: 2020-10-15
• Subjects: Reticular formation -- Tectobulbar -- Motor pattern generation -- Multimodal convergence -- Receptive fields -- Sensorimotor transformation; Neurology -- Periodicals; Neurology -- Periodicals; Research -- Periodicals; Neurologie -- Périodiques; Neuroanatomie -- Périodiques; Neuropharmacologie -- Périodiques; Neurophysiologie -- Périodiques; Neurology; Periodicals; Electronic journals; 617.48
• DOI: 10.1016/j.neulet.2020.135280
• Languages: English
• ISSNs: 0304-3940

Abstract

Highlights: There is a visually-driven lamina in the frog medial medulla along its full extent. Visually responsive areas in the midbrain and thalamus project to this lamina. The upstream projections to the lamina are not segregated but extensively overlap. Purely visual units are located mostly in the rostral part of the lamina. Bimodal units (visual and somatosensory) are mostly in the caudal part. Abstract: We have discovered a lamina of visually responsive units in the medulla oblongata of the frog. It spans the entire medial aspect of the rostrocaudal length of the medulla and extends dorsoventrally from the cell-dense dorsal zone into the cell-sparse ventral zone. Most visual units within this lamina have large receptive fields, with the majority extending bilaterally in the frontal visual field. Most of these neurons are binocular, have no apparent directional preference, respond equally well to stimuli of a variety of shapes and sizes, and exhibit strong habituation. More medial locations in the visual lamina represent ipsilateral visual space while more lateral locations within the lamina represent contralateral visual space. Many units in the caudal aspect of the visual lamina are bimodal, responding to both visual and somatosensory stimuli. HRP tracing reveals inputs to the lamina from many primary and secondary visual areas in the midbrain and diencephalon. There is no area-by-area segregation of the projections to the visual lamina. For example, most parts of the tectum project across the visual lamina. The only spatial order in the visual lamina is that at more medial sites there tends to be more input from contralateral tectum; and at more lateral sites there tends to be more input from ipsilateral tectum. There is bilateral input to the visual lamina from tectum, tegmentum, posterior nucleus of the thalamus, posterior tuberculum, and ventromedial thalamic nucleus. There is ipsilateral input to the visual lamina from torus semicircularis, pretectum, nucleus of Bellonci, and ventrolateral thalamic nucleus. There is contralateral input to the visual lamina from basal optic complex. Collectively, these results show the presence of visual influences in regions of the medulla that likely represent an important step in sensorimotor transformation.