Effects of neonatal enucleation on receptive-field properties of visual neurons in superior colliculus of the golden hamster

1980 ◽  
Vol 43 (3) ◽  
pp. 595-611 ◽  
Author(s):  
R. W. Rhoades ◽  
L. M. Chalupa

1. Monocular enucleation in infant hamsters results in a marked expansion of the normally very limited ipsilateral retinotectal projection (13). In 34 hamsters subjected to removal of one eye within 12 h of birth, the receptive-field characteristics of superior collicular neurons ipsilateral and contralateral to the remaining eye were investigated quantitatively and compared to those of normal animals. In six additional neonatal enucleates, the density of the expanded retinotectal projection was studied with the autoradiographic method and an attempt was made to relate the anatomical reorganization with the electrophysiological findings, 2. The response characteristics of visual cells in the colliculus contralateral to the remaining eye were not significantly different from those observed in normal animals. In the ipsilateral tectum, however, numerous changes were observed. Visual receptive fields were abnormally large. The incidence of directional selectivity was markedly reduced, as were the magnitudes of the discharges elicited by either flashed or moving stimuli. Fewer cells were activated by small flashed spots and most of the units that were responsive to such stimulation failed to exhibit the surround suppression typical for the majority of tectal neurons in normal hamsters. Most cells in the ipsilateral colliculus responded only to relatively low (less than 50 degrees/s) stimulus velocities and response decrements resulting from repeated stimulation also occurred much more readily for the neurons tested on this side. 3. The results of additional experiments in neonatal enucleates (n = 8), which were also subjected to acute bilateral removal of the visual cortex, demonstrated that such damage resulted in a marked reduction in the incidence of directional selectivity in the colliculus contralateral to the remaining eye but had no effect on the responses of cells innervated by the aberrant ipsilateral pathway. 4. A correlation between the relative density of the ipsilateral retinal projection at different points in the colliculus, as demonstrated by the autroradiography and the nature of the visual responses obtained in different portions of the structure, indicated that receptive-field size was negatively correlated with the density of the aberrant retinotectal projection and that absolute responsivity (number of impulses elicited by an optimal stimulus) was positively correlated with autoradiographic grain density. 5. These findings demonstrate that while the aberrant retinocollicular projection can, along with the other visual inputs to the tectum, result in the organization of normal response properties for a small number of tectal neurons, the majority of the visual cells innervated by this pathway have responses that are appreciably different from normal.

1993 ◽  
Vol 90 (23) ◽  
pp. 11142-11146 ◽  
Author(s):  
S Bisti ◽  
C Trimarchi

Prenatal unilateral enucleation in mammals causes an extensive anatomical reorganization of visual pathways. The remaining eye innervates the entire extent of visual subcortical and cortical areas. Electrophysiological recordings have shown that the retino-geniculate connections are retinotopically organized and geniculate neurones have normal receptive field properties. In area 17 all neurons respond to stimulation of the remaining eye and retinotopy, orientation columns, and direction selectivity are maintained. The only detectable change is a reduction in receptive field size. Are these changes reflected in the visual behavior? We studied visual performance in cats unilaterally enucleated 3 weeks before birth (gestational age at enucleation, 39-42 days). We tested behaviorally the development of visual acuity and, in the adult, the extension of the visual field and the contrast sensitivity. We found no difference between prenatal monocularly enucleated cats and controls in their ability to orient to targets in different positions of the visual field or in their visual acuity (at any age). The major difference between enucleated and control animals was in contrast sensitivity:prenatal enucleated cats present a loss in sensitivity for gratings of low spatial frequency (below 0.5 cycle per degree) as well as a slight increase in sensitivity at middle frequencies. We conclude that prenatal unilateral enucleation causes a selective change in the spatial performance of the remaining eye. We suggest that this change is the result of a reduction in the number of neurones with large receptive fields, possibly due to a severe impairment of the Y system.


2005 ◽  
Vol 93 (6) ◽  
pp. 3537-3547 ◽  
Author(s):  
Chong Weng ◽  
Chun-I Yeh ◽  
Carl R. Stoelzel ◽  
Jose-Manuel Alonso

Each point in visual space is encoded at the level of the thalamus by a group of neighboring cells with overlapping receptive fields. Here we show that the receptive fields of these cells differ in size and response latency but not at random. We have found that in the cat lateral geniculate nucleus (LGN) the receptive field size and response latency of neighboring neurons are significantly correlated: the larger the receptive field, the faster the response to visual stimuli. This correlation is widespread in LGN. It is found in groups of cells belonging to the same type (e.g., Y cells), and of different types (i.e., X and Y), within a specific layer or across different layers. These results indicate that the inputs from the multiple geniculate afferents that converge onto a cortical cell (approximately 30) are likely to arrive in a sequence determined by the receptive field size of the geniculate afferents. Recent studies have shown that the peak of the spatial frequency tuning of a cortical cell shifts toward higher frequencies as the response progresses in time. Our results are consistent with the idea that these shifts in spatial frequency tuning arise from differences in the response time course of the thalamic inputs.


1996 ◽  
Vol 75 (6) ◽  
pp. 2441-2450 ◽  
Author(s):  
D. D. Rasmusson

1. Single neurons in the ventroposterior lateral thalamic nucleus were studied in 10 anesthetized raccoons, 4 of which had undergone amputation of the fourth digit 4-5 mo before recording. Neurons with receptive fields on the glabrous skin of a forepaw digit were examined in response to electrical stimulation of the “on-focus” digit that contained the neuron's receptive field and stimulation of an adjacent, “off-focus” digit. 2. In normal raccoons all neurons responded to on-focus stimulation with an excitation at a short latency (mean 13 ms), whereas only 63% of the neurons responded to off-focus digit stimulation. The off-focus responses had a longer latency (mean 27.2 ms) and a higher threshold than the on-focus responses (800 and 452 microA, respectively). Only 3 of 32 neurons tested with off-focus stimulation had both a latency and a threshold within the range of on-focus values. Inhibition following the excitation was seen in the majority of neurons with both types of stimulation. 3. In the raccoons with digit removal, the region of the thalamus that had lost its major peripheral input (the “deafferented” region) was distinguished from the normal third and fifth digit regions on the basis of the sequence of neuronal receptive fields within a penetration and receptive field size as described previously. 4. Almost all of the neurons in the deafferented region (91%) were excited by stimulation of one or both adjacent digits. The average latency for these responses was shorter (15.3 ms) and the threshold was lower than was the case with off-focus stimulation in control animals. These values were not significantly different from the responses to on-focus stimulation in the animals with digit amputation. 5. These results confirm that reorganization of sensory pathways can be observed at the thalamic level. In addition to the changes in the somatotopic map that have been shown previously with the use of mechanical stimuli, the present paper demonstrates an improvement in several quantitative measures of single-unit responses. Many of these changes suggest that this reorganization could be explained by an increased effectiveness of preexisting, weak connections from the off-focus digits; however, the increase in the proportion of neurons responding to stimulation of adjacent digits may indicate that sprouting of new connections also occurs.


1994 ◽  
Vol 11 (4) ◽  
pp. 703-720 ◽  
Author(s):  
Ming Sun ◽  
A. B. Bonds

AbstractThe two-dimensional organization of receptive fields (RFs) of 44 cells in the cat visual cortex and four cells from the cat LGN was measured by stimulation with either dots or bars of light. The light bars were presented in different positions and orientations centered on the RFs. The RFs found were arbitrarily divided into four general types: Punctate, resembling DOG filters (11%); those resembling Gabor filters (9%); elongate (36%); and multipeaked-type (44%). Elongate RFs, usually found in simple cells, could show more than one excitatory band or bifurcation of excitatory regions. Although regions inhibitory to a given stimulus transition (e.g. ON) often coincided with regions excitatory to the opposite transition (e.g. OFF), this was by no means the rule. Measurements were highly repeatable and stable over periods of at least 1 h. A comparison between measurements made with dots and with bars showed reasonable matches in about 40% of the cases. In general, bar-based measurements revealed larger RFs with more structure, especially with respect to inhibitory regions. Inactivation of lower cortical layers (V-VI) by local GABA injection was found to reduce sharpness of detail and to increase both receptive-field size and noise in upper layer cells, suggesting vertically organized RF mechanisms. Across the population, some cells bore close resemblance to theoretically proposed filters, while others had a complexity that was clearly not generalizable, to the extent that they seemed more suited to detection of specific structures. We would speculate that the broadly varying forms of cat cortical receptive fields result from developmental processes akin to those that form ocular-dominance columns, but on a smaller scale.


1975 ◽  
Vol 38 (3) ◽  
pp. 572-586 ◽  
Author(s):  
A. E. Applebaum ◽  
J. E. Beall ◽  
R. D. Foreman ◽  
W. D. Willis

A technique is described for recording from axons belonging to the spinothalamic tract of the monkey. The axons arose from cell bodies located within the spinal cord since the latency of orthodromic activation by afferents within the dorsal funiculus was short. The axons were antidromically activated from the ipsilateral diencephalon. The spectrum of conduction velocities indicates that the recordings favored large-diamter axons. However, all of the classes of spinothalamic tract units described from soma-dendritic recordings were represented in the sample. When the locations of the axons in the ventrolateral white matter were mapped, there was virtually complete overlap in the distributions of hair-activated, low-, and high-threshold spinothalamic tract axons, suggesting that the "lateral spinothalamic tract" conveys tactile, as well as pain and temperature, information. The only segregated population of axons were those belonging to units activated by receptors in deep tissues, including muscle. These were in a band along the ventral surface of the cord. The stimulus points for antidromically activating spinothalamic cells of axons were in the known diencephalic course of the spinothalamic tract, including the ventral posterior lateral nucleus. Stimulus point locations were similar for high-threshold and other categories of units. Receptive-field sizes were smaller for high-threshold spinothalamic cells or axons than for hair-activated or low-threshold units. Receptive-field size was correlated with position on the hindlimb. The smallest fields belonged to cells in lamina I, with progressively larger sizes for cells in laminae IV and V. Receptive-field shape was evaluated by the length/width ratio, which was smallest for high-threshold units and progressively larger for low-threshold and hair-activated units. The receptive-field positions of spinothalamic tract axons were related to the locations of the axons. There was a rough somatotopic representation in the tract, with the most caudal dermatomes represented dorsolaterally, and the most rostral ventromedially.


1991 ◽  
Vol 66 (3) ◽  
pp. 777-793 ◽  
Author(s):  
J. W. McClurkin ◽  
T. J. Gawne ◽  
B. J. Richmond ◽  
L. M. Optican ◽  
D. L. Robinson

1. Using behaving monkeys, we studied the visual responses of single neurons in the parvocellular layers of the lateral geniculate nucleus (LGN) to a set of two-dimensional black and white patterns. We found that monkeys could be trained to make sufficiently reliable and stable fixations to enable us to plot and characterize the receptive fields of individual neurons. A qualitative examination of rasters and a statistical analysis of the data revealed that the responses of neurons were related to the stimuli. 2. The data from 5 of the 13 "X-like" neurons in our sample indicated the presence of antagonistic center and surround mechanisms and linear summation of luminance within center and surround mechanisms. We attribute the lack of evidence for surround antagonism in the eight neurons that failed to exhibit center-surround antagonism either to a mismatch between the size of the pixels in the stimuli and the size of the receptive field or to the lack of a surround mechanism (i.e., the type II neurons of Wiesel and Hubel). 3. The data from five other neurons confirm and extend previous reports indicating that the surround regions of X-like neurons can have nonlinearities. The responses of these neurons were not modulated when a contrast-reversing, bipartite stimulus was centered on the receptive field, which suggests a linear summation within the center and surround mechanisms. However, it was frequently the case for these neurons that stimuli of identical pattern but opposite contrast elicited responses of similar polarity, which indicates nonlinear behavior. 4. We found a wide variety of temporal patterns in the responses of individual LGN neurons, which included differences in the magnitude, width, and number of peaks of the initial on-transient and in the magnitude of the later sustained component. These different temporal patterns were repeatable and clearly different for different visual patterns. These results suggest that visual information may be carried in the shape as well as in the amplitude of the response waveform.


2000 ◽  
Vol 17 (2) ◽  
pp. 263-271 ◽  
Author(s):  
HIROYUKI UCHIYAMA ◽  
TAKAHIDE KANAYA ◽  
SHOICHI SONOHATA

One type of retinal ganglion cells prefers object motion in a particular direction. Neuronal mechanisms for the computation of motion direction are still unknown. We quantitatively mapped excitatory and inhibitory regions of receptive fields for directionally selective retinal ganglion cells in the Japanese quail, and found that the inhibitory regions are displaced about 1–3 deg toward the side where the null sweep starts, relative to the excitatory regions. Directional selectivity thus results from delayed transient suppression exerted by the nonconcentrically arranged inhibitory regions, and not by local directional inhibition as hypothesized by Barlow and Levick (1965).


1987 ◽  
Vol 57 (4) ◽  
pp. 977-1001 ◽  
Author(s):  
H. A. Swadlow ◽  
T. G. Weyand

The intrinsic stability of the rabbit eye was exploited to enable receptive-field analysis of antidromically identified corticotectal (CT) neurons (n = 101) and corticogeniculate (CG) neurons (n = 124) in visual area I of awake rabbits. Eye position was monitored to within 1/5 degrees. We also studied the receptive-field properties of neurons synaptically activated via electrical stimulation of the dorsal lateral geniculate nucleus (LGNd). Whereas most CT neurons had either complex (59%) or motion/uniform (15%) receptive fields, we also found CT neurons with simple (9%) and concentric (4%) receptive fields. Most complex CT cells were broadly tuned to both stimulus orientation and velocity, but only 41% of these cells were directionally selective. We could elicit no visual responses from 6% of CT cells, and these cells had significantly lower conduction velocities than visually responsive CT cells. The median spontaneous firing rates for all classes of CT neurons were 4-8 spikes/s. CG neurons had primarily simple (60%) and concentric (9%) receptive fields, and none of these cells had complex receptive fields. CG simple cells were more narrowly tuned to both stimulus orientation and velocity than were complex CT cells, and most (85%) were directionally selective. Axonal conduction velocities of CG neurons (mean = 1.2 m/s) were much lower than those of CT neurons (mean = 6.4 m/s), and CG neurons that were visually unresponsive (23%) had lower axonal conduction velocities than did visually responsive CG neurons. Some visually unresponsive CG neurons (14%) responded with saccadic eye movements. The median spontaneous firing rates for all classes of CG neurons were less than 1 spike/s. All neurons synaptically activated via LGNd stimulation at latencies of less than 2.0 ms had receptive fields that were not orientation selective (89% motion/uniform, 11% concentric), whereas most cells with orientation-selective receptive fields had considerably longer synaptic latencies. Most short-latency motion/uniform neurons responded to electrical stimulation of the LGNd (and visual area II) with a high-frequency burst (500-900 Hz) of three or more spikes. Action potentials of these neurons were of short duration, thresholds of synaptic activation were low, and spontaneous firing rates were the highest seen in rabbit visual cortex. These properties are similar to those reported for interneurons in several regions in mammalian central nervous system. Nonvisual sensory stimuli that resulted in electroencephalographic arousal (hippocampal theta activity) had a profound effect on the visual responses of many visual cortical neurons.(ABSTRACT TRUNCATED AT 400 WORDS)


2003 ◽  
Vol 90 (4) ◽  
pp. 2660-2675 ◽  
Author(s):  
Jennifer F. Linden ◽  
Robert C. Liu ◽  
Maneesh Sahani ◽  
Christoph E. Schreiner ◽  
Michael M. Merzenich

The mouse is a promising model system for auditory cortex research because of the powerful genetic tools available for manipulating its neural circuitry. Previous studies have identified two tonotopic auditory areas in the mouse—primary auditory cortex (AI) and anterior auditory field (AAF)— but auditory receptive fields in these areas have not yet been described. To establish a foundation for investigating auditory cortical circuitry and plasticity in the mouse, we characterized receptive-field structure in AI and AAF of anesthetized mice using spectrally complex and temporally dynamic stimuli as well as simple tonal stimuli. Spectrotemporal receptive fields (STRFs) were derived from extracellularly recorded responses to complex stimuli, and frequency-intensity tuning curves were constructed from responses to simple tonal stimuli. Both analyses revealed temporal differences between AI and AAF responses: peak latencies and receptive-field durations for STRFs and first-spike latencies for responses to tone bursts were significantly longer in AI than in AAF. Spectral properties of AI and AAF receptive fields were more similar, although STRF bandwidths were slightly broader in AI than in AAF. Finally, in both AI and AAF, a substantial minority of STRFs were spectrotemporally inseparable. The spectrotemporal interaction typically appeared in the form of clearly disjoint excitatory and inhibitory subfields or an obvious spectrotemporal slant in the STRF. These data provide the first detailed description of auditory receptive fields in the mouse and suggest that although neurons in areas AI and AAF share many response characteristics, area AAF may be specialized for faster temporal processing.


1997 ◽  
Vol 14 (6) ◽  
pp. 1153-1165 ◽  
Author(s):  
Stewart A. Bloomfield ◽  
Daiyan Xin

AbstractRecent studies have shown that amacrine and ganglion cells in the mammalian retina are extensively coupled as revealed by the intercellular movement of the biotinylated tracers biocytin and Neurobiotin. These demonstrations of tracer coupling suggest that electrical networks formed by proximal neurons (i.e. amacrine and ganglion cells) may underlie the lateral propagation of signals across the inner retina. We studied this question by comparing the receptive-field size, dendritic-field size, and extent of tracer coupling of amacrine and ganglion cells in the dark-adapted, supervised, isolated retina eyecup of the rabbit. Our results indicate that while the center-receptive fields of proximal neurons are approximately 15% larger than their corresponding dendritic diameters, this slight difference can be explained by factors other than electrical coupling such as tissue shrinkage associated with histological processing. However, the extent of tracer coupling of amacrine and ganglion cells was, on average, about twice the size of the corresponding receptive fields. Thus, the receptive field of an individual proximal neuron matched far more closely to its dendritic diameter than to the size of the tracer-coupled network of cells to which it belonged. The exception to this rule was the AII amacrine cells for which center-receptive fields were 2–3 times the size of their dendritic diameters but matched closely to the size of the tracer-coupled arrays. Thus, with the exception of AII cells, our data indicate that tracer coupling between proximal neurons is not associated with an enlargement of their receptive fields. Our results, then, provide no evidence for electrical coupling or, at least, indicate that extensive lateral spread of visual signals does not occur in the proximal mammalian retina.


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