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The avian isthmic nuclei are constituted by a group of structures reciprocally connected with the tectum opticum and considered to play a role in the modulation of intratectal processes. Although the two larger isthmic nuclei, the n. isthmi pars parvocellularis (Ipc) and the n. isthmi pars magnocellularis (Imc), have been studied in detail previously, the(More)
One-day-old pigeons (Columba livia) were monocularly deprived by occluding the left or the right eye for 10 days. Up to 3 years later, degree and direction of functional and morphological asymmetries of deprived and control pigeons were analyzed. In control pigeons, the usual right-eye superiority was obtained in a visual discrimination task. In left-eye(More)
The dominance for visual pattern analysis of the left hemisphere in normal pigeons and the concomitant morphological asymmetries in the optic tectum can be attributed to a 'natural' prehatch monocular deprivation of the left eye resulting from an asymmetrical embryonic position within the egg. Using control animals and pigeons which were monocularly(More)
Tetrodotoxin is one of the most potent and oldest known neurotoxins. It acts by blocking the voltage-gated sodium channels in nerve cell membranes, leading to a transient silencing of neural activity. TTX is among the most widely used pharmacological agents for the temporary and selective blocking of neural structures. As such, an exact knowledge of the(More)
The optic tectum of vertebrates is an essential relay station for visuomotor behavior and is characterized by a set of connections that comprises topographically ordered input from the eyes and an output that reaches premotor hindbrain regions. In the avian tectofugal system, different ascending cell classes have recently been identified based on their(More)
The embryonically induced visual lateralization in pigeons can be modified by occlusion of one eye after hatching. Here we show that this deprivation effect could be also attained by short-term blocking of retinal activity with tetrodotoxin (TTX), leading to a dominance of the ipsilateral hemisphere in a visual discrimination task. This lateralization(More)
The nucleus ventrolateralis thalami (VLT) in pigeons receives direct retinal and forebrain projections and has reciprocal connections with the optic tectum. Although VLT is a component of the avian visual system, no study directly examined its connections or its cellular response characteristics. We, therefore, recorded from single units in the pigeon's VLT(More)
A large body of evidence indicates that pigeons use olfactory cues to navigate over unfamiliar areas with a differential contribution of the left and right hemispheres. In particular, the right nostril/olfactory bulb (OB) and left piriform cortex (Cpi) have been demonstrated to be crucially involved in navigation. In this study we analysed behaviour-induced(More)
Pigeons use olfactory cues to navigate over unfamiliar areas, and any impairment of the olfactory system generates remarkable reduction of homing performance. Lesion and deprivation studies suggest a critical involvement of the right nostril and thus, the right olfactory bulb (OB) and the left piriform cortex (CPi) for initial orientation. This functional(More)
A large number of endogenous and exogenous factors have been identified to upregulate and downregulate proliferation, differentiation and/or survival of newborn cells in the adult hippocampus. For studying neuronal mechanisms mediating the impact of those factors, we used a transgenic synRas mouse model expressing constitutively activated Valin12-Harvey Ras(More)