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H V Hirsch

Publications and source records attributed to H V Hirsch.

At least 19 recordsLinked to original sources
PubMed1997

Experience-dependent developmental plasticity in the optic lobe of Drosophila melanogaster.

Early experience can affect nervous system development in both vertebrate and invertebrate animals. We have now demonstrated that visual stimulation modifies the size of the optic lobes in the laboratory fruitfly Drosophila melanogaster. Monocular deprivation (painting over one eye) decreases the aggregate volume of the lamina, medulla, and lobula plate by up to 6%. The laminae of control flies kept in complete darkness showed a more robust volume difference that could be as much as 30%. An electron microscopy study revealed that the changes in the lamina are largely attributable to an increase in the terminals of the photoreceptor cell axons. The volume of the lamina increases during the first 24 hr after emergence, and it grows more in the light than in darkness. When flies are kept in the dark for the first 12 hr of their adult life and are then brought back to light for the next 3.5 days, the lamina is almost as small as in flies raised for 4 d in constant darkness. Twelve hour dark shifts at a later time are less effective. This finding suggests a critical period for lamina development during day 1 of the adult. The lamina depends on visual stimulation to maintain its size during the first 5 d after emergence. Dark-rearing for 1 d or more at any stage during that period decreases its volume to the level of flies raised in constant darkness. A lamina that is once reduced in size seems not to recover.

Animals↗
PubMed1994

The flexible fly: experience-dependent development of complex behaviors in Drosophila melanogaster.

We demonstrate that Drosophila melanogaster provides a rich model system for studying behavioral development. Two additions to the many well-known advantages of this species are exploited here. First, as in mammals and higher vertebrates, early experience affects behavioral development of Drosophila. Second, the affected behaviors are complex and yet readily studied in the laboratory. Thus, Drosophila can be used to study the developmental mechanisms by which organisms can optimize their behavioral repertoires to enhance their chances for survival. Evidence that early experience affects female responsiveness to courting males is reviewed; in each case, experience modifies responses to behavioral targets. Our results demonstrate that developmental plasticity allows adjustment of intrinsically determined responses to visual targets so that they can take into account the actual characteristics of the developing animal's environment. Furthermore, plasticity makes it possible to introduce 'cultural' and 'social' elements into courtship and mate choice in insects. This previously unrecognized role for developmental plasticity in insects has broad theoretical and practical implications.

Animals↗
PubMed1990

Rearing in darkness changes visually-guided choice behavior in Drosophila.

To test whether visual experience can affect development of visual behavior in the fruitfly, Drosophila, we measured the visually-guided choice behavior of groups of flies reared in complete darkness, compared with controls reared in a normal light/dark cycle. We used a simple visual preference test, i.e. choice among four different visual targets each consisting of vertical black lines of a particular width on a white background, using a blind testing procedure so that the individual rearing histories were not known by the tester. Both groups of flies were strongly attracted to the vertical lines; however, generally the dark-reared flies were more attracted to the wider stimulus lines than were the control flies. Control experiments in which normally reared adults were kept for several days in darkness showed that the effects of dark-rearing were not simply due to being in darkness, but depended upon the timing of the deprivation. The results indicate that the development of visual behavior can be affected by visual experience in Drosophila and thus open the possibility of using Drosophila for genetic dissection of mechanisms of visual plasticity.

Animals↗
PubMed1985

The role of visual experience in the development of cat striate cortex.

By the third postnatal week, intrinsic developmental programs have established a framework within the cat visual system; this will be used to guide the course of subsequent experience-dependent development. Key elements in this framework are precociously mature cells in visual cortex area 17. These orientation-selective cells are predominantly first-order neurons, they are concentrated in layers IV and VI of area 17, most of them are activated monocularly, many may receive their direct excitatory input from lateral geniculate nucleus X cells, and the distribution of their preferred orientations is biased toward horizontal and vertical. Between the third and the sixth postnatal week, most of the remaining cells in area 17 develop orientation selectivity; this extension of orientation selectivity is blocked or delayed if kittens are deprived of normal patterned visual stimulation. Furthermore, exposure to a limited range of stimulus orientations can lead to an increase in the proportion of orientation-selective cells, and the range of orientation preferences that the cells acquire is restricted by the range of orientations to which the animal is exposed. This occurs with no apparent change in the physiology or morphology of intrinsically selective area 17 cells. Thus selective exposure may have its effect by influencing the connections between the intrinsically selective cells and higher-order neurons in area 17. Experience-dependent changes in the visual system may function to "fine-tune" sensory processing and thus optimize the system's response to the dominant features of the environment. This experience-dependent process could help the young animal to focus its "attention" on those features of its environment that are critical to its survival.

Animals↗
PubMed1983

Removal of the more-experienced eye decreases visual field deficits in cats reared with unequal alternating monocular exposure.

Unequal alternating monocular exposure produces a nasal field deficit for the less-experienced eye, which persists despite prolonged unrestricted binocular exposure. We now report that this deficit decreases after the more experienced eye is removed. Prior to enucleation, the visual field of the less-experienced eye was restricted to the temporal hemifield; 5 months after enucleation of the more-experienced eye, this field extended into the nasal field. Our results are consistent with those in monocularly-deprived cats, and with the occasional recovery of human amblyopes after loss of the fixating eye.

Animals↗
PubMed1983

Effects of visual deprivation upon the geniculocortical W-cell pathway in the cat: area 19 and its afferent input.

We studied the receptive field properties of 206 single units in area 19 of normal cats and 228 single units in area 19 of cats deprived of vision for 9-14 months by monocular lid suture. The ocular dominance of a sample of cells in area 17 of normal cats was studied for comparison. In some of these monocularly deprived animals, we also studied the sizes of relay cells in the parvocellular C laminae of the dorsal lateral geniculate nucleus labeled by electrophoretic injections of horseradish peroxidase into area 19. In area 19 of normal cats, the large majority of cells, regardless of their laminar location and the retinal eccentricity of their receptive fields, were binocular. Most responded equally well to the two eyes. In area 17, (see also Leventhal and Hirsch, '78, '80) but not in area 19, the cells which had the narrowest receptive fields tended to be activated unequally by the two eyes. In area 19 of monocularly deprived cats, virtually all cells (97%), regardless of their laminar location and receptive field eccentricity, responded only to stimulation of the normal eye. Thus, the effects of monocular deprivation upon area 19 are apparently more severe than those reported for area 17. In area 17 significant numbers of neurons in layer 4 can be activated by the deprived eye (Shatz and Stryker, '78). Within the limits of our technique, measurements of relay cells in the parvocellular C laminae labeled by injections into area 19 of deprived cats indicated that cell size in the deprived C laminae was unaffected by the deprivation. In contrast, cells in the deprived A laminae of these cats were severely shrunken. These findings suggest that the types of relay found in the parvocellular C laminae (referred to collectively as W-cells) are not affected by visual deprivation as severely as are the X- and Y-cells in the A laminae. Since laminar location and receptive field width are related to binocularity in area 17 but not in area 19 and the sizes of relay cells in the parvocellular C laminae (see also Hickey, '80) are not seriously affected by monocular deprivation, it is suggested that binocular interactions in area 19 are mainly determined by connections among cortical cells.

Animals↗
PubMed1983

Effects of exposure to lines of one or two orientations on different cell types in striate cortex of cat.

We raised cats using goggles to control early visual exposure (stripe-rearing). Four conditions were used: (a), both eyes exposed to 0 degrees lines, (b), both eyes exposed to 90 degree lines, (c), one eye exposed to 45 degree lines, the other to 135 degree lines, (d), one eye exposed to 0 degree lines, the other to 90 degree lines. At the completion of the rearing, we recorded extracellularly from single cells in striate cortex (area 17) of these animals; circular statistics were used to analyse the distribution of the orientation preferences of neurones recorded. Exposure to either one or two stimulus orientations produced a significant bias in the distribution of the orientation preferences of cells recorded. We found no more non-selective cells in cats exposed to one orientation (15%) than in cats exposed to two orientations (14%). We found about the same mean proportion of binocular cells in cats exposed to one orientation (27%) as in cats exposed to two orientations (24%). Cells were comparable in orientation selectivity in cats exposed to one orientation (mean half-width at half-height = 37 degrees) and in cats exposed to two orientations (mean half-width at half-height = 34 degrees). The effects of the rearing depended upon the receptive field properties of the cells. For cells with narrow receptive fields and low cut-off velocities, the rearing produced no bias in the distribution of the orientation preferences; for all other groups of cells the rearing produced a bias toward the exposed orientation. In addition, the cells with narrow receptive fields and low cut-off velocities were more finely tuned for orientation than the remaining cells. We conclude that there are cell types in the striate cortex of the cat which differ in their susceptibility to the effects of stripe-rearing; these cell types can be discriminated on the basis of their physiological characteristics. We can compare these cell types with morphologically identified cell types that also differ in their susceptibility to the effects of stripe-rearing.

Animals↗
PubMed1983

Physiological effects of unequal alternating monocular exposure.

1. In order to investigate the effects of an imbalance in stimulation to the eyes without the confounding influence of continuous deprivation of one eye, we reared cats with unequal alternating monocular exposure (AME) and, for comparison, cats with equal AME. We recorded extracellularly from single cells in area 17 of visual cortex. 2. For unequal AME cats, a majority of the cells that were visually responsive were dominated by the eye that had received more patterned visual experience. The percentage of cells dominated by the more experienced eye was greater with a large imbalance in stimulation to the two eyes (AME 8/1, 77%) than with a small imbalance (AME 8/4, 62%). 3. For both equal AME cats and unequal AME cats, we obtained evidence for differences in cells activated by the contralateral and by the ipsilateral afferents. a) In equal AME cats receiving only 1 h of exposure per day, we obtained a greater dominance by the contralateral eye (60%) than in equal AME cats receiving 8 h of exposure per day (42%). b) Although a large imbalance in stimulation (AME 8/1) resulted in a shift in ocular dominance in both cortical hemispheres, a moderate imbalance (AME 8/4) resulted in a smaller shift, which was apparent only in the hemisphere ipsilateral to the less-experienced eye. 4. The percentage of cortical cells responsive to each eye was uniform throughout the depth of cortex. Thus, for the unequal AME cats, cells activated by the less-experienced eye were no more frequent in layer IV of visual cortex than in the infragranular and supragranular layers. 5. Although almost all cells recorded from AME cats had relatively normal receptive-field properties, three receptive-field properties of cells in unequal AME cats showed an effect of the rearing. In each case cells dominated by the less-experienced eye and recorded in the cortical hemisphere ipsilateral to it showed the largest changes. These cells a) were more poorly tuned, b) had lower cutoff velocities, and c) had smaller receptive fields. 6. It is suggested that cortical cells that putatively receive Y-cell afferents from the dorsal lateral geniculate nucleus (LGNd) are more affected by an imbalance in stimulation than are cortical cells that putatively receive X-cell afferents. Thus, the decrease in mean receptive-field area and cutoff velocity for the cells dominated by the less-experienced eye is suggested to be due to a greater shift in ocular dominance by the cortical cells receiving Y-cell afferents from the LGNd. 7. The interaction between binocular competition and deprivation of pattern vision may contribute to differences between monocularly deprived cats and unequal AME cats.

Animals↗
PubMed1983

Binocular exposure causes suppression of the less experienced eye in cats previously reared with unequal alternating monocular exposure.

In unequal alternating monocular exposure (unequal AME), each eye receives normal patterned visual input but on alternate days and for unequal periods. It has been shown previously that this imbalance in stimulation produces a deficit in the nasal visual field of the less experienced eye (LEE). The effect of subsequent binocular exposure on these visual deficits has now been examined. No evidence of recovery was found. Instead, visual fields remained the same or became smaller. In cats reared with little or no imbalance (8 hr/day vs 7 hr/day or 1 hr/day vs 1 hr), subsequent binocular exposure had no effect on visual fields. In cats reared with a moderate or large imbalance (8 hr/day vs 4 hr/day or 8 hr/day vs 1 hr/day), subsequent binocular exposure led to a suppression of the LEE: when tested binocularly, these cats rarely responded to targets presented in the monocular field of the LEE. The deficits became progressively more severe throughout the period of binocular exposure, until eventually they could be observed even when the LEE was tested monocularly. Most of these cats were clearly esotropic but not all esotropic cats showed suppression. The degree of suppression was correlated with the degree of the imbalance imposed during unequal AME. Our results suggest that when the eyes are misaligned, binocular exposure does not permit recovery of visual function in a disadvantaged eye, but may exacerbate the existing imbalance.

Age Factors↗
PubMed1982

Exposure to lines of only one orientation modifies dendritic morphology of cells in the visual cortex of the cat.

To determine whether selective exposure to lines of one orientation modifies the shape of the dendritic fields of cells in visual cortex, we examined the dendritic morphology of neurons in area 17 of five normally reared cats, five cats reared viewing only vertical lines, and three cats reared viewing only horizontal lines. Kittens were placed with their mothers into a totally dark room before their eyes had opened. Beginning at 4 weeks of age, the kittens were brought out for daily periods of exposure wearing masks that limited the vision of each eye to a field of three vertical lines or three horizontal lines. After a minimum of 170 hours of exposure, the animals were killed and blocks of visual cortex were impregnated by the Golgi-Kopsch procedure and cut tangential to the pial surface. Complete neurons from layers III and IV were drawn with the aid of a camera lucida, and the orientations of the dendritic fields wer analyzed using Sholl diagrams. In normal cats, the distributions of the orientations of dendritic fields were uniform, whereas in strip-reared cats, the distributions for the layer III pyramidal cells were shifted. The direction of this shift varied with the experience of the cat: In cats reared viewing only vertical lines, the dendritic fields were oriented orthogonal to the representation of the vertical meridian, and in cats reared viewing only horizontal lines, the fields were oriented parallel to the representation of the vertical meridian. In contrast, the distribution of dentritic orientations for the stellate cells was not affected by stripe-rearing. These results demonstrate a morphological effect of early visual experience that is specific to the particular stimulus presented during rearing and suggest that (1) cortical cells differ in the degree to which they can be modified by such experience, and (2) the dendritic morphology of cortical neurons is related to their preferred orientations.

Animals↗
PubMed1982

Chronic intraventricular administration of lysergic acid diethylamide (LSD) affects the sensitivity of cortical cells to monocular deprivation.

In kittens, but not in adult cats, depriving one eye of pattern vision by suturing the lids shut (monocular deprivation or MD) for one week reduces the proportion of binocular units in the visual cortex. A sensitivity of cortical units in adult cats to MD can be produced by infusing exogenous monoamines into the visual cortex. Since LSD interacts with monoamines, we have examined the effects of chronic administration of LSD on the sensitivity to MD for cortical cells in adult cats. Cats were assigned randomly to one of four conditions: MD/LSD, MD/No-LSD, No-MD/LSD, No-MD/No-LSD. An osmotic minipump delivered either LSD or the vehicle solution alone during a one-week period of MD. The animals showed no obvious anomalies during the administration of the drug. After one week the response properties of single units in area 17 of the visual cortex were studied without knowledge of the contents of the individual minipumps. With the exception of ocular dominance, the response properties of units recorded in all animals did not differ from normal. In the control animals (MD/No-LSD, No-MD/LSD, No-MD/No-LSD) the average proportion of binocular cells was 78%; similar to that observed for normal adult cats. However, in the experimental animals, which received LSD during the period of MD, only 52% of the cells were binocular. Our results suggest that chronic intraventricular administration of LSD affects either directly or indirectly the sensitivity of cortical neurons to MD.

Animals↗
PubMed1982

Divergent strabismus following neonatal callosal section is due to a failure of convergence.

Eye alignment was measured in neonatal callosum-sectioned cats that were 1-3 years old. Alignment was measured from photographs of the cat's corneal reflex when alert, anesthetized and paralyzed, and by plotting to optic disc separation during paralysis. The callosal alignment was equally divergent when alert and paralyzed and was identical to the control alignment under paralysis. Therefore, the alert callosal divergence results from a failure to converge the eyes.

Animals↗
PubMed1982

Visual field deficits in cats reared with unequal alternating monocular exposure.

Thirty-four kittens reared by allowing each eye patterned visual input, but on alternate days and for unequal periods of time (unequal alternating monocular exposure (AME)), were tested for their ability to orient to targets at different positions in visual space. In all unequal AME cats, the visual field of the more experienced eye (MEE) was normal, while that of the less experienced eye (LEE) was restricted. In contrast, in 14 cats reared with equal AME, the fields of both eyes were equal and of normal size. The field deficits observed in the unequal AME cats must therefore be due to the imbalance in stimulation and thus result from a competitive interaction between the afferents from the MEE and the LEE. The field deficits observed in the unequal AME cats differed from those observed in two monocularly deprived (MD) cats. Neither of the MD cats ever responded to targets presented in the region of normal binocular overlap when tested with the deprived eye (DE). The unequal AME cats all showed a nasal field loss in the LEE, but responded normally to targets throughout the temporal portion of the binocular visual field. When the imbalance in stimulation was large (8 to 1) or moderate (8 to 4), there was an abrupt drop in responsiveness (from 100% to zero) as the position of the target was changed from temporal to nasal. When the imbalance was slight (8 to 7), the drop in responsiveness was more gradual and occurred within the nasal field. Our results demonstrate that (1) the paradigm of unequal AME is a useful one for studying binocular competition quantitatively, (2) even the slightest imbalance in stimulation of the two eyes can affect the outcome of the competitive interaction, and (3) the pathways serving binocular vision are not uniformly affected by binocular competition: the ipsilateral pathway is more sensitive than the contralateral pathway.

Animals↗
PubMed1980

Unequal alternating monocular deprivation causes asymmetric visual fields in cats.

Kittens were reared so that each eye received normal patterned vision on alternate days. If the eyes received equal periods of stimulation, the visual fields were normal. If one eye received much more experience than the other, the field of the less experienced eye was restricted to the temporal hemifield. This change, which differs from that observed when one or both eyes are deprived continuously of patterned input, suggests that an imbalance in the duration of stimulation can influence the outcome of the normal competitive interaction between pathways from the two eyes and can cause a selective suppression of a portion of the input from the less experienced eye. This suppression may involve the ipsilateral retino-geniculo-cortical pathways or it may involve the entire cortical pathway from the less experienced eye, leaving the colliculus to control responses to visual targets.

Animals↗