Spatial frequency characteristics of receptive fields of neurons in the lateral suprasylvian area of the cat cortex

Two-dimensional spatial frequency characteristics of receptive fields of 46 neurons in the lateral suprasylvian area of the cat cortex were obtained. These receptive fields possessed orientation anisotropy. Peak frequencies lay in the frequency region below 1.5 cycles/deg. The transmission band width was measured during optimal orientation of test gratings in 21 neurons. It averaged 1.47±0.6 octave. In the remaining neurons the lower boundary frequency was shifted into the region of spatial frequencies below the range used. During nonoptimal orientation of test gratings, inhibition of the discharge was observed in 17 neurons. The inhibitory spatial frequency characteristics of six neurons were of the narrow band type, and averaged 1.1±0.6 octave.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 14, No. 6, pp. 608–614, November–December, 1982.     

Receptive fields of neurons in the lateral suprasylvian area of the cat

The structure of receptive fields of single neurons in the lateral suprasylvian area of the cat's cortex was studied. Receptive fields of neurons in this area are larger (up to 2000 deg² or more) than those of the visual projection cortex. A difference was found in the sizes of these fields of the same neuron when measured by presentation of a black object and spot of light. Experimental results showed that most neurons of the area (104 of 148) that are sensitive to visual stimulation respond clearly to flashes of a stationary spot of light. Because of this feature the structure of the receptive fields of the neurons were studied by point by point testing of their whole surface. Intensities of on- and off-components of on-off neurons were found to differ. Only 16% of receptive fields had equal numbers of discharges in on- and off-components of the on-off response. Dominance of one component was observed in 84% of on-off neurons. Receptive fields with several discharge centers are a characteristic feature of neurons in this area. A concentric organization of the receptive fields was found in 11% of neurons.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan, Translated from Neirofiziologiya, Vol. 14, No. 3, pp. 278–283, May–June, 1982.     

纹外皮层PMLS区反馈投射对初级视皮层神经元反应特性的影响

神经系统中存在大量下行投射,与上行输入一起形成复杂的前馈与反馈回路,调控神经信号的传导和处理,但目前对皮层内反馈投射的功能作用认识还比较薄弱.通过微量注射抑制性神经递质γ-氨基丁酸(γ-aminobutyric acid,GABA),使猫纹外皮层后内侧外上雪氏区(area posteromedial lateral suprasylvian,PMLS)局部可逆性失活,使用胞外记录方法,研究初级视皮层17区神经元反应特性的变化.实验结果显示,PMLS区失活后,17区细胞对运动刺激的反应总体减弱,反应的相对稳定性基本不变,最高发放率/自发之比有所下降.与此同时,细胞的方向选择性指数减小,朝向选择性无显著变化.除少数"双向"反应细胞外,绝大部分细胞的最优方向基本不变.进一步分析发现,细胞对各个方向刺激的反应普遍下降,最优方向上的下降程度最大,是导致方向选择性减弱的主要原因.这些结果表明,PMLS区反馈投射可增强初级视皮层的方向选择性,而对朝向选择性影响有限.这一作用特点体现了PMLS区在皮层中偏重处理运动视觉信息的功能.     

Stereopsis and the random element in the organization of the striate cortex.

Receptive field position and orientation disparities are both properties of binocularly discharged striate neurons. Receptive field position desparities have been used as a key element in the neural theory for binocular depth discrimination. Since most striate cells in the cat are binocular, these position disparities require that cells immediately adjacent to one another in the cortex should show a random scatter in their monocular receptive field positions. Superimposed on the progressive topographical representation of the visual field on the striate cortex there is experimental evidence for a localized monocular receptive field position scatter. The suggestion is examined that the binocular position disparities are built up out of the two monocular position scatters. An examination of receptive field orientation disparities and their relation to the random variation in the monocular preferred orientations of immediately adjacent striate neurons also leads to the conclusion that binocular orientation disparities are a consequence of the two monocular scatters. As for receptive field position, the local scatter in preferred orientation is superimposed on a progressive representation of orientation over larger areas of the cortex. The representation in the striate cortex of visual field position and of stimulus orientation is examined in relation to the correlation between the disparities in receptive field position and preferred orientation. The role of orientation disparities in binocular vision is reviewed.     

Responses of cat auditory cortical neurons to tones of different frequencies and electrical stimulation of corresponding regions of the cochlea

Characteristic frequencies of neurons in the cat auditory cortex (area AI) whose receptive fields are located in different parts of the basilar membrane of the cochlea were determined in cats anesthetized with pentobarbital. The higher the characteristic frequency of a neuron in area AI, the nearer its receptive field lies to the base of the cochlea. Receptive fields of neurons with a characteristic frequency higher than 4 kHz lie on the first 10 mm of the basilar membrane. Receptive fields of neurons with a characteristic frequency below 4 kHz lie on the remaining 11–12 mm of the membrane. The effect of electrical stimulation of the center of the receptive field of a neuron corresponds to its response to a tone of characteristic frequency. The more the frequency of the acting tone differs from the characteristic frequency, or the further the point of stimulation from the center of the receptive field of the neuron, the less likely is the neuron to respond with an action potential. Neurons with a low characteristic frequency have wider receptive fields than neurons with a high characteristic frequency. Receptive fields of neurons with close characteristic frequencies on the basilar membrane overlap considerably. It was shown by the method of paired stimulation that excitation evoked in neurons in area AI by the action of a tone of a particular frequency is followed by long-lasting inhibition. This inhibition lasts longest and is most effective if a tone of the characteristic frequency is used.     

Receptive fields of auditory cortical neurons in the cat

Receptive fields of auditory cortical neurons were studied by electrical stimulation of nerve fibers in different parts of the cochlea in cats anesthetized with pentobarbital. The dimensions of the receptive fields were shown to depend on the topographic arrangement of the neuron in the auditory cortex. The more caudad the neuron on the cortical projection of the cochlea in the primary auditory cortex, the more extensive its receptive field. The receptive fields were narrowest in the basal turn of the cochlea and were symmetrical with respect to their center. It is suggested that the region of finest discrimination of acoustic stimuli in cats is located in the basal region of the cochlea, i.e., in that part of its receptor system which has the narrowest receptive field and is represented by significantly more (than the middle and apical regions of the cochlea) nerve cells in the primary auditory cortex [1].A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 13, No. 5, pp. 467–473, September–October, 1981.     

Cooperative nonlinearities in auditory cortical neurons

Cortical receptive fields represent the signal preferences of sensory neurons. Receptive fields are thought to provide a representation of sensory experience from which the cerebral cortex may make interpretations. While it is essential to determine a neuron's receptive field, it remains unclear which features of the acoustic environment are specifically represented by neurons in the primary auditory cortex (AI). We characterized cat AI spectrotemporal receptive fields (STRFs) by finding both the spike-triggered average (STA) and stimulus dimensions that maximized the mutual information between response and stimulus. We derived a nonlinearity relating spiking to stimulus projection onto two maximally informative dimensions (MIDs). The STA was highly correlated with the first MID. Generally, the nonlinearity for the first MID was asymmetric and often monotonic in shape, while the second MID nonlinearity was symmetric and nonmonotonic. The joint nonlinearity for both MIDs revealed that most first and second MIDs were synergistic and thus should be considered conjointly. The difference between the nonlinearities suggests different possible roles for the MIDs in auditory processing.     

Rabbit visual cortical neurons with simple and complex receptive fields

Receptive fields of neurons of the rabbit visual cortex selective for stimulus orientation were investigated. These receptive fields were less well differentiated than those of the analogous neurons of the cat visual cortex (large in size and circular in shape). Two mechanisms of selectivity for stimulus orientation were observed: inhibition between on and off zones of the receptive field (sample type) and oriented lateral inhibition within the same zone of the receptive field (complex type). Lateral inhibition within the same zone of the receptive field also took place in unselective neurons; "complex" selective neurons differed from them in the orientation of this inhibition. A combination of both mechanisms was possible in the receptive field of the same neuron. It is suggested that both simple and complex receptive fields are derivatives of unselective receptive fields and that "complex" neurons are not the basis for a higher level of analysis of visual information than in "simple" neurons.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 10, No. 1, pp. 13–21, January–February, 1978.     

Inhibitory components in the neuronal response of the lateral suprasylvian cortical area in the cat

Inhibitory components in the response evoked by presentation of mobile visual stimuli in neurons belonging to the lateral suprasylvian area of the cerebral cortex were investigated in cats. It was demonstrated by comparing poststimulus histograms of neuronal response to movement in two opposite directions that the location of discharge centers within the receptive fields changed in relation to movement direction. No spatial area giving rise to the inhibitory component of response could be found in any of the neurons with monotone stationary structure of their receptive fields. Findings from experiments involving techniques of stimulating a test area of the receptive field separately indicated that inhibitory components of response in neurons of the lateral suprasylvian area with monotone organization of the receptive field could represent inhibitory after-response following the neuronal excitation produced by the visual stimulus traveling across this field.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 299–308, May–June, 1987.     

Connections between the parietal cortex with the lateral suprasylvian gyrus (Clare-Bishop area) and auditory cortex in cats

Projections between areas 5 and 7 and the lateral suprasylvian gyrus (Clare-Bishop area) were investigated using anterograde degeneration techniques. This showed a topographic organization of projections from areas 5 and 7 to the lateral suprasylvian gyrus. Area 5 association fibers terminate mainly in the anterior portion of the lateral suprasylvian gyrus; this corresponds to the intermediate zone and anterior section of the posterior suprasylvian region. Area 7 efferents are located more caudally, terminating in the posterior section of the intermediate zone and in the posterior region, excluding the outer posterior limits. Fields 5 and 7 give rise to single efferent fibers terminating in the auditory cortex. Fibers from area 5 terminate in the medial ectosylvian and medial, sylvian gyri, i.e., in zones Al and AII or areas 22 and 50. A projection from area 7 terminates at the superior border of the medial ectosylvian gyrus, corresponding to the upper limit of zone A1 or areas 22 and 50.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 22, No. 6, pp. 739–745, November–December, 1990.     

Connections of thalamic nucleus lateralis posterior with suprasylvian cortex in cats

Cats were immobilized with D-tubocurarine. Responses of 231 neurons of the thalamic nucleus lateralis posterior to cortical stimulation in areas 5b and 21 of the suprasylvian gyrus were studied. Responses of 34 neurons were antidromic, indicating the existence of a direct projection of this nucleus to the cortical areas studied. This projection was most extensive in area 5b. The long latencies (up to 60 msec) of the antidromic responses of some neurons indicate that axons of certain neurons of thalamic nucleus lateralis posterior conduct excitation very slowly (0.3 m/sec). Orthodromic responses with latencies of 2–3 msec to cortical stimulation point to the presence of direct pathways from cortex to nucleus. The flow of afferent impulses into the nucleus from area 5b is stronger than from area 21. Convergence of impulses from these areas was observed on 44% of neurons of the nucleus. Cortical stimulation of areas 5b and 21 evoked postsynaptic inhibition in most neurons of the nucleus. It is concluded that two-way direct connections exist between nucleus lateralis posterior of the thalamus and the suprasylvian cortex.     

Inhibition of axoplasmic transport in the developing visual system of the rat: IV. Quantitative Golgi, electron microscopic, and histochemical analyses of the maturation of the visual cortex

Intraocularly injected colchicine suppresses axonal transport within the developing rat's optic nerve throughout the critical period of visual system development. This results in a stunting of retinofugal terminals and relay neurons in the lateral geniculate nucleus. The present study focuses upon the effects of this unique form of developmental deprivation on the maturation of the visual cortex. Colchicine, in concentrations of from 10(-5) to 10(-2) M, was injected into the eyes of albino rats at birth or at 5, 10, or 15 days of age. Litters were killed at 5 to 50 days after this single injection, and the brains were processed for Nissl, rapid Golgi, histochemical, or electron microscopic analysis. The following results were obtained: Planimetry of coronal sections of the striate cortex revealed a reduction in the thickness of the cortex and in the ratio of neuropil area to neuronal soma area contralateral to the injected eye which was confined principally to layer IV, lower layer III, and upper layer V. This effect was inversely related to postnatal age at injection and directly proportional to colchicine concentration. A rapid Golgi analysis of 51 pairs of layer V pyramidal neurons in control and experimental cortex demonstrated a reduction in the number and size of spines along the portion of the apical dendrite passing through lower layer III and IV following colchicine administration at birth or 5 or 10 days of age but no significant change in the branching pattern of the entire dendritic arbor. Electron microscopy revealed a reduction in the number of small, asymmetric synaptic complexes with the result that the average size of remaining profiles was increased in layers III and IV. Histochemical analysis of cortical succinic dehydrogenase and cytochrome oxidase revealed a distinct band of intense enzyme activity in lower layers III and IV in normal cortex at 20-30 days of age. This band was significantly reduced in intensity after neonatal injection of colchicine as shown by densitometric measurements and comparison of experimental and control cortex. It is concluded that the geniculocortical projection, while not affected directly by colchicine administration, is altered by the secondary effects of axonal transport suppression, leading to an alteration in the establishment of cortical synaptic patterns and arborizations of their postsynaptic neurons whose dendrites are located in those layers recipient to this projection.     

Spatial summation processes in the receptive fields of visually driven neurons of the cat's cortical area 21a

The spatial summation in receptive fields (RF) of single neurons in cat's extrastriate area 21a was investigated as a basic neurophysiological substrate for central integration processing of visual information. The results showed that the majority of investigated neurons changed their response patterns with gradual increase of applied stimulus size. In approximately 82% of cases the suppression of neuron discharges was observed when the length of the moving strip exceeded that of the RF. In some neurons the increased size of the moving stimulus leads to the changes in the RF substructure. Receptive fields of neurons recorded at the same microelectrode penetration depth showed a great variety of RF superpositions distributed in a spatially asymmetric manner. As a result, every single RF consists of multiple sub-regions within the RF, differing from each other by the number of superimposed RF-s (density factor). We suggest that such complex spatial organization of the RF provides the neurophysiological basis for central integration processing of the visual information.     

A model of striate response properties based on geniculate anisotropies

The orientation biases seen in the responses of cells in the retina and dLGN are dependent on the spatial frequency of the stimulus, being appreciable only at higher spatial frequencies. An inhibitory mechanism that suppresses the responses to low spatial frequencies would leave a striate cell receiving a biased geniculate input with an orientation sensitivity at the higher spatial frequencies. Such an inhibition could in fact come from one or a small group of LGN cells (through cortical interneurones), since their response extends to spatial frequencies much lower than for cortical cells at the same eccentricity. According to this scheme, a number of other striate response characteristics, e.g., their length and spatial frequency response functions, can also be explained.     

A linear model for symmetric receptive fields: implications for classification tests with flashed and moving images

The purpose of this study was to explore the effects of spatial and temporal properties on the expected responses of visual neurons that have linear receptive fields (RFs), particularly those having a mirror symmetric distribution of spatial subregions. Receptive fields that are symmetric in at least one spatial dimension occur in neurons of the retina, the lateral geniculate nucleus (LGN), and the visual cortex of mammals. Responses to flashing bars, moving bars, and moving edges were studied for different configurations of an analog RF model in which spatial and temporal aspects were varied independently. Responses of the model at intermediate stimulus speeds were found to agree with responses in the literature for X and Y units of the LGN and often for simple units of the visual cortex. In particular, having separated regions of response to light and dark edges, an identifying property of simple cells, was found to be a linear consequence of RF regions responding inversely to stimuli of opposite polarity. Model differences from responses of cortical complex units show that a linear model cannot mimic their responses, and imply that complex units employ major nonlinearities in coding image polarity (light vs dark), which signifies a nonlinearity in coding intensity. Because sudden flux changes inherent in flashing bars test mainly temporal RF properties, and slowly moving edges test mainly spatial properties, these two tests form a useful minimal set with which to describe and classify RFs. The usefulness of this set derives both from its sensitivity to spatial and temporal variables, and from the correlation between the linearity of a cell's processing of stimulus intensity and its RF classification.     

Responses and properties of receptive fields of neurons in the visual projection zone of the pigeon hyperstriatum

Unit responses in the hyperstriatal region of the pigeon forebrain to the action of various visual stimuli were investigated. Particular attention was paid to the discovery of retinotopic projection in the Wulst region. It was shown that as the electrode was advanced in the caudal direction in the zone of visual projection of the hyperstriatum the receptive fields of the neurons recorded shifted in the opposite direction in the visual field. The receptive fields of neurons of the ventral and dorsal hyperstriatum lie higher in the visual field and are larger in diameter than those of neurons of the accessory hyperstriatum. Unit responses in the visual projection zone of the Wulst depend on the intensity of illumination, size, and speed and direction of movement of the test objects across the receptive field. The functional role of the retino-thalamo-telencephalic system in visual interpretation in birds is discussed and it is suggested that the Wulst region is comparable with the striatal and also with the frontal regions of the mammalian cortex.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 8, No. 3, pp. 230–236, May–June, 1976.     

A spatial property of the retino-cortical mapping

Striate cortex topography derives from a stretching of retinal space along the optic axis. At the retina, relative distances are preserved in a mapping of retinal space onto a spherical surface in the environment. At the cortex, relative distances along visual meridia in the cortical map are preserved in a mapping of striate cortex onto an environmental conic surface whose base is in the plane of the eye. This eco-cortical relationship can be considered a reference frame through which spatial relationships at the cortex might provide information about the environment. The present analysis provides an explanation of changes in cortical magnification with visual eccentricity in the primate and a detailed three-dimensional model of striate topography for the macaque monkey. In man, a conic environmental surface is shown to be uniformly resolvable along meridia in the visual field. Finally, the implications of this analysis of the structural properties of the retino-striate pathway and visual resolution are considered in relation to depth and distance perception.     

Topical organization of somatic projections in the fur seal cerebral cortex

To map somatic projections in the cerebral cortex of the fur sealCallorhinus ursinus multiple spike activity of cortical neurons evoked by tactile stimulation of different parts of the body surface was recorded in acute experiments. The region of somatic representation is bounded rostrally by the postcruciate and coronal sulci, caudally by the anterior suprasylvian sulcus, and dorsomedially by the ansate sulcus. The somatotopic map is oriented so that the projection of the head faces ventrolaterally, and that of the caudal part of the trunk faces dorsomedially; the projection region of the forelimb is buried in the coronal sulcus. The projection area of the head occupies the greatest area, and in it, the greatest area is occupied by the region of the superior labial vibrissae.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 17, No. 3, pp. 344–351, May–June, 1985.     

Single-cell responses in the ectostriatum of the zebra finch

The responses of single cells to computer-generated spots, bars, gratings, and motion-in-depth stimuli were studied in the ectostriatum and the adjacent neostriatum of the zebra finch, Taeniopygia guttata. No differences in neuronal properties could be detected between ectostriatum and neostriatum. The receptive fields of ectostriatal neurons are large, often extending over the entire visual field of the contralateral eye, and have oddly defined borders. The centers of the receptive fields, located in the foveal region, generally yielded better responses than the periphery, and exhibited different subdivisions. Neurons responded selectively to moving bars, preferring those moving parallel to their longest axis. An SDO (sensitivity, direction, orientation) analysis of responses to sinusoidal gratings showed that all orientations were equally represented by ectostriatal neurons, while there was a slight preference for forward and upward movements. The neurons also showed preferences for gratings of a particular spatial frequency, and responded vigorously to stimuli moving towards the eye (looming). Our results indicate that the ectostriatum is involved in both detecting displacement of the surround and in stimulus identification. By comparison with results obtained in the extrastriate cortex of mammals, it is concluded that the homology of the ectostriatum with the extrastriate cortex of mammals, which was proposed on the basis of hodological findings, is supported by our study.Abbreviations Di index of directionality - HW HH half-width at half-height - PLLS posterolateral lateral suprasylvian cortex - PMLS posterior medial lateral suprasylvian area - PSTH poststimulus time histogram - SDO sensitivity, direction, orientation     

Functional structure of the intermediate and ventral hippocampo–prefrontal pathway in the prefrontal convergent system

The hippocampo–prefrontal pathway is a unique projection that connects distant ends of the cerebral cortex. The direct hippocampo–prefrontal projection arises from the ventral to intermediate third of the hippocampus, but not from the dorsal third. It forms a funnel-shaped structure that collects information from the large hippocampal area and projects it to the prefrontal cortex. The anatomical regional differentiation of the projection has not been described. The hippocampal region is differentiated into structural and behavioural roles. For example, it has been shown that the ventral, but not the dorsal, hippocampus reciprocally connects with the amygdala and influences emotional behaviours. These data imply that hippocampal variation along the dorso–ventral axis is contained within the hippocampo–prefrontal pathway. Here, we present electrophysiological studies that demonstrate regional differences in short- but not long-term plasticity in the intermediate/posterior-dorsal and ventral routes of the hippocampo–prefrontal pathway. Furthermore, behavioural studies revealed that each route appears to play a different role in working memory. These results suggest that hippocampal regional information is processed through different routes, with the integration of individual regulatory functions in the prefrontal convergent system.