Birth of olfactory neurons: Lifelong neurogenesis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24850/1/0000277.pd

A comment on the "glissade"

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33915/1/0000180.pd

Automated retinotectology

The retinotectal projection has been the principal battleground, since the 1930s, for the experimental investigation of the factors determining specific neural connections. Since the late 1950s, the electrophysiological determination of the retinotectal map has been the dominant experimental method. Many of the conclusions derived with this method have been questioned (by other investigators using the same method), and some of these disputes remain unresolved even today. Recently, David Northmore and his associates have developed two automated methods for assessing retinotectal function which are described below. In different ways, these methods correct some of the deficiencies of the old method.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25889/1/0000452.pd

The time course of saccadic eye movements in goldfish

Spontaneous saccadic eye movements (2-25[deg]) made by goldfish have an initial brief acceleration, followed by a more prolonged deceleration, and occasionally a terminal phase during which the velocity reverses sign following overshoot of the final position. Overshoots by the individual eyes are independent events. The duration and the maximum velocity increase monotonically with the size of the saccade. Goldfish saccades have greater durations and slightly smaller maximum velocities than mammalian saccades of similar size.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22121/1/0000548.pd

Growth-related changes in the size of receptive field centers of retinal ganglion cells in goldfish

Intraocular recordings were made from the retinal ganglion cells of small ( 140 mm) intact paralyzed, submerged goldfish to determine how the size of their receptive field centers is influenced by the 2.5-fold increase in retinal magnification factor which accompanies growth. The angular subtense of the centers was only slightly smaller in large than in small fish, corresponding to a greater than 2-fold increase in the center diameter as measured in micrometers on the retinal surface. This statistically significant increase suggests that the number of centers which overlap a given point on the retina remains approximately constant during growth. Other implications of this result are also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24584/1/0000867.pd

Local control of retinomotor activity in the fish retina

Small circular spots of light were focussed on otherwise unilluminated retinas of paralyzed fish. Cichlasoma biocellatum. The retinas were subsequently examined histologically, and a small circular region was found within which the cones and pigmented retinal epithelium were photomechanically light adapted; rods could not be resolved. The same result was obtained with the optic nerve cut. The region was circular and about the same size as the adapting spot. There existed a transition zone between light- and dark-adapted regions within which the photomechanical state was intermediate. These results exclude the hypothesis that light-induced retinomotor phenomena are systemically controlled, and favor local control. An analysis of the transition zone favors the view that photomechanical light adaptation of a given cell may be caused by light caught by that cell or its neighbors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22770/1/0000325.pd

Electroretinographically-determined scotopic spectral sensitivities of some marine fish

The b-wave threshold spectral sensitivity was determined in three species of marine fish. In all cases, the action spectrum of the dark adapted animal peaked at 510-520 nm and fit Dartnall's template curve for the extinction spectrum of a vitamin A1-based visual pigment. High frequency flicker of the stimulus on a white background revealed a long-wavelengthsensitive photopic mechanism, establishing that these were duplex retinas. We conclude that in these teleosts, the dark adapted b-wave is a reliable indicator of rod function, in marked distinction to the case with goldfish and carp.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33877/1/0000138.pd

Wavelength discrimination by the goldfish near absolute visual threshold

Goldfish were classically conditioned to discriminate between 532 nm and 636 nm lights while light adapted, and then tested for their ability to continue the discrimination as the intensities were reduced. In all tests, the two stimuli were balanced for effectiveness at absolute threshold. We find that goldfish can discriminate between these wavelengths about 1 log unit above absolute threshold. In contrast, fish who were trained to discriminate between 532 nm and 441 nm stopped discriminating 2-3 log units above absolute threshold. There are two conclusions from these results. First, some aspect of the neural signals generated by the rod and red cone mechanisms must be different, despite electrophysiological evidence that suggests they are the same. Second, the goldfish has color vision near rod threshold.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22777/1/0000332.pd

Behavioral confirmation of the "silent period" during adaptation to bright lights

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22774/1/0000329.pd

Growth of the adult goldfish eye--I: Optics

We have measured the optical and retinal fields of goldfish eyes; the animals ranged from 6 to 20 cm in body length. Both fields are spherically symmetric, invariant with the size of the eye, and equal (retinal FIELD = 185.3[deg] +/- 4.1[deg], optical FIELD = 183.6[deg] +/- 2.7[deg], means +/- S.D.). They are tilted with respect to one another by a few (< 10) degrees. We have also measured the retinal magnification factor, the number of [mu]m per degree on the retinal surface. It is 20.5 x lens diameter, where lens diameter is expressed in mm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23062/1/0000634.pd