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  • 1
    Electronic Resource
    Electronic Resource
    Post-crucial Period Effects of Auditory Experience and Deprivation on the Guinea-pig Superior Collicular Map of Auditory Space (1992)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 4 (1992), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The auditory space map in the superior colliculus of the guinea-pig requires for its normal emergence at 32 days after birth (DAB) bimodal, auditory and visual experience during a 4-day crucial period (26–30 DAB) (Withington-Wray et al., Neurosci. Lett., 116, 280–286, 1990d). The need for auditory experience has been proposed to be linked to the rapid changes in the cues for auditory localization brought about by head growth. Head growth is particularly rapid during the first postnatal month but continues more slowly until ∼70 DAB. This suggests that sensory experience may be required beyond the initial crucial period to accommodate later growth. In this paper the role of auditory experience beyond the crucial period has been investigated. Deprivation of ordinary auditory experience was effected by placement of the animals in an environment in which continuous omnidirectional noise obscured the cues of sound direction. Animals deprived of auditory experience during the crucial period and then allowed normal experience showed limited ability to construct an auditory space map and the resulting map was less accurate than that found in normally reared animals. Auditory deprivation following normal experience during the crucial period caused a profound degradation, of both spatial tuning and topography, of auditory multi-unit receptive fields in the superior colliculus. The spatial tuning and topography of auditory fields from older animals (100 DAB) deprived of ordinary auditory cues for a 4-week period were normal. Thus, in the guinea-pig, susceptibility of the superior collicular space map to deprivation of auditory cues is limited by the age of the animal. The timing of the cessation of vulnerability may, in part, be due to the stabilization of directional cues affected by head growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1992.tb00158.x
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  • 2
    Electronic Resource
    Electronic Resource
    The Maturation of the Superior Collicular Map of Auditory Space in the Guinea Pig is Disrupted by Developmental Visual Deprivation (1990)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 2 (1990), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the normal guinea pig a map of auditory space appears, in the deeper layers of the superior colliculus, at 32 days after birth (DAB). The animal is unable to construct this collicular map of auditory space in the absence of developmental visual experience. Auditory receptive fields of animals dark-reared from birth are typically large, occupying most of the contralateral hemifield. There is no topographic relationship between the collicular location of the recording electrode and the spatial position from which auditory stimuli elicit a maximal response. The fields of dark-reared animals resemble, in their tuning parameters, the spatially undifferentiated fields typical of young postnatal normal guinea pigs. To investigate the time-course during which visual experience is required for map emergence, animals received normal visual experience until either 18 or 26 DAB and were then dark-reared until the terminal mapping experiment. Maps developed in neither group. Animals provided with a normal visual environment until 30 DAB, and then placed in the dark did, however, construct topographically organized spatial maps with discrete spatial receptive fields. Maps also failed to emerge in animals receiving normal visual experience both before and after a 4-day period of visual deprivation between 26 and 30 DAB. We conclude that this 4-day period, or part of it, constitutes a ‘crucial’ period during which visual experience is required for the normal elaboration of the collicular map of auditory space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1990.tb00458.x
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  • 3
    Electronic Resource
    Electronic Resource
    The Maturation of the Superior Collicular Map of Auditory Space in the Guinea Pig is Disrupted by Developmental Auditory Deprivation (1990)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 2 (1990), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Guinea pigs, reared from birth in an environment of omnidirectional white noise, fail to develop a map of auditory space in the deeper layers of the superior colliculus. Collicular responses from such noise-reared animals reveal large auditory spatial receptive fields. The representation of auditory space in the colliculus shows no topographic order. Exposing developing animals to the noise environment only for restricted time periods showed that animals reared normally up to 26 days after birth (DAB) and then placed in the noise chamber could not construct spatial maps, whereas animals reared normally to 30 DAB and then placed in the noise chamber until the terminal mapping experiment could construct topographically organized spatial maps with local receptive fields. Limiting the noise exposure to the period between 26 and 30 DAB was sufficient to prevent spatial map formation. The failure to form a map of auditory space did not reflect environmental damage to the cochlea or the functional organization of the primary auditory pathway. The response thresholds of cochlear microphonics and of auditory responses in both the inferior and superior colliculus were normal in noise-reared animals. Similarly normal were the tonotopic organization and frequency tuning characteristics of inferior collicular neurons. The rearing environment thus appears to exert a selective effect upon the maturation of the superior collicular map of auditory space. We attribute this effect to the masking, by the omnidirectional broad-band noise, of discrete localized auditory stimuli. Cues deriving from these latter stimuli would appear to be necessary for the elaboration of the map of auditory space. This auditory experience operates during a 4 day crucial developmental period from 26 to 30 DAB. This is the same developmental time window as that during which visual experience is required for the construction of the map.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1990.tb00459.x
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  • 4
    Electronic Resource
    Electronic Resource
    Visual experience alters the molecular profile of NMDA-receptor-mediated sensory transmission (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 11 (1999), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: N-methyl-d-aspartate (NMDA) receptors (NMDArs) may facilitate experience-dependent changes in the visual system. Early sensory experience has an influence over the production of the molecular components from which NMDArs are assembled, and thereby alters the properties of functional receptors. Using the antagonists d-2-amino-5-phosphonovalerate (AP5) and 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonate (CPP), which have some selectivity for different variants of the NMDAr, we demonstrate that visual deprivation (by dark rearing) has functional consequences for NMDArs in the superior colliculus. An increase in the sensitivity of visual responses to AP5 in dark-reared rats indicated that NMDArs were more important for visual transmission in these individuals. We also observed a relative change in the efficacy of the antagonists against the visual responses of normal versus dark-reared rats. AP5 reduced the visual responses of both groups, but CPP was ineffective against visual responses after dark rearing. In the same neurons, CPP blocked NMDA induced activity indicating that molecular adaptations of NMDArs are specific to those synapses mediating visual activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.1999.00544.x
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  • 5
    Electronic Resource
    Electronic Resource
    Excitatory Amino Acid Receptors Participate in Synaptic Transmission of Visual Responses in the Superficial Layers of the Cat Superior Colliculus (1994)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 6 (1994), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The contribution of NMDA and non-NMDA receptors to visual synaptic transmission in the superficial layers of the superior colliculus of the cat has been studied using extracellular recording and iontophoretic techniques. Neuronal responses to natural visual stimulation and the ejection of NMDA and AMPA were observed in the absence and presence of the antagonists CNQX, CPP and AP5. CNQX routinely reduced the responses to visual stimulation at ejection currents which selectively blocked the responses to AMPA but not those to NMDA. Agonist selective ejection currents of CPP and AP5 also reduced visual responses of most SC neurons, but there was a substantial majority whose visual responses were resistant to these antagonists. Neurons with CPP/AP5 resistant visual responses were more commonly found 750–1000 μm from the dorsal surface of the SC. The data indicate that, while non-NMDA receptors are heavily involved in visual synaptic transmission in the superficial SC, the involvement of NMDA receptors varies with recording depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1994.tb00257.x
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in electrophysiological activity in the accessory olfactory bulb and medial amygdala associated with mate recognition in mice (2005)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 21 (2005), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The ability of female mice to recognize their mate's pheromonal identity is critical for the maintenance of their pregnancy and is hypothesized to involve increases in the inhibitory control of mitral/tufted projection neurons in the accessory olfactory bulb. Local field potential recordings from this region of freely behaving female mice showed oscillating neural activity over a wide range of frequencies, which was affected by chemosensory input and prior experience. Mating caused lasting increases in the baseline neural activity in the accessory olfactory bulb, with large increases in the amplitude of local field potential oscillations across a range of frequencies. Exposure to the mate's urinary cues remained effective in increasing the power of these oscillations following mating, but urinary cues from an unfamiliar male were ineffective. A differential response to the familiar and unfamiliar chemosignals was also observed at the level of the amygdala following mating. Individual neurons in the medial amygdala responded more strongly to urine from an unfamiliar male than from the mating male. These findings are consistent with the selective enhancement of inhibition of the familiar pheromonal signal at the level of the accessory olfactory bulb, which is proposed to underlie recognition of the mating male.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2005.04090.x
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  • 7
    Electronic Resource
    Electronic Resource
    Novel mode of nitric oxide neurotransmission mediated via S-nitroso-cysteinyl-glycine (2000)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: S-nitroso-cysteinyl-glycine, a novel nitric oxide-adduct thiol compound, can be detected in the brain (2.3 ± 0.6 pmol/mg protein), and released following stimulation of sensory afferents to the rat ventrobasal thalamus in vivo (resting conditions 17 n m; stimulation: 186 n m). Iontophoretic application of CysNOGly (20–80 nA) onto thalamic neurons in vivo resulted in enhancements of excitatory responses to either NMDA or AMPA (182 ± 13.6% and 244 ± 27.8% of control values, n = 15). CysNOGly enhanced responses to stimulation of vibrissal afferents to 132 ± 2.2% (n = 7) of control values. In contrast, the dipeptide CysGly reduced responses of ventrobasal neurons to NMDA and AMPA (54 ± 8.4% and 55 ± 10.8% of control, n = 5). CysNOGly was also a potent activator of soluble guanylate cyclase in vitro. Moreover, we found that NMDA elevated CysNOGly levels in vitro and this stimulatory effect was reduced by inhibitors of the neuronal NO synthase and of the γ-glutamyl transpeptidase, suggesting that production of NO and CysGly is a prelude to CysNOGly synthesis. These findings suggest that the nitrosothiol CysNOGly plays a role in synaptic transmission in the ventrobasal thalamus. We propose a novel synaptic buffering mechanism where S-nitroso-cysteinyl-glycine serves to restrict the locus of action of nitric oxide and so increase its local availability for target delivery. This could lead to a change in neuronal responses favouring sensory transmission similar to that seen in wakefulness or arousal in order to locally enhance transmission of persistent sensory stimuli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2000.00285.x
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  • 8
    Electronic Resource
    Electronic Resource
    Developmental changes in NMDA receptor-mediated visual activity in the rat superior colliculus, and the effect of dark rearing (1998)
    Springer
    Experimental brain research 120 (1998), S. 335-344 
    Details
    ISSN: 1432-1106
    Keywords: Key words Plasticity ; Glutamate ; AP5 ; Visual Deprivation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  N-methyl-D-aspartate (NMDA) receptor-mediated activity is considered important for experience-dependent plasticity in the developing visual system. We investigated the influence of age and experience on the role of NMDA receptors in the visual transmission in the superficial grey layer of the superior colliculus (SGS) of the superior colliculus, where, in the adult, NMDA receptors mediate a substantial part of the visual response. In normally reared (postnatal day 14, P14, to adult) rats, visual responses were challenged with NMDA receptor-selective iontophoretic applications of the antagonist D-2-amino-5-phosphonovalerate (AP5). After eye opening (at P14), there was a significant increase in the number of neurones whose visual responses were reduced during AP5 ejection, which peaked at P22 (85%; n = 21), and then declined to adult levels (66%; n = 47) at P25. The mean reduction of the response (from control levels) by AP5 was similar at all ages (approximately 40%). Dark rearing had striking effects on the role of NMDA receptors in visual transmission, especially when comparisons were made between age-matched subjects greater than P25. In these subjects, AP5 ejection reduced the visual responses of all neurones studied. In addition, AP5 ejection caused a significantly larger reduction of visual responses in dark-reared rats (mean reduction 62 ± 4; n = 29) compared with age-matched controls (mean reduction 44 ± 8; n = 23). The D,L-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) reduced the visual responses of every neurone studied and there were no age- or experience-dependent effects. We conclude that NMDA receptors, but not AMPA receptors, assume greater importance for visual transmission in the SGS of dark-reared rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050407
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