Tectal mosaic: Organization of the descending tectal projections in comparison to the ascending tectofugal pathway in the pigeon

2004 ◽  
Vol 472 (4) ◽  
pp. 395-410 ◽  
Author(s):  
Burkhard Hellmann ◽  
Onur Güntürkün ◽  
Martina Manns
Keyword(s):  
Tectofugal Pathway

Hyperstriatum ventrale in pigeons: Effects of lesions on color-discrimination and color-reversal learning

1997 ◽  
Vol 14 (6) ◽  
pp. 1029-1041 ◽  
Author(s):  
Lin M. Chaves ◽  
William Hodos
Keyword(s):  
Reversal Learning ◽  
Visual Information ◽  
Original Learning ◽  
Color Discrimination ◽  
Visual Pathway ◽  
Visual Input ◽  
Impaired Performance ◽  
Nucleus Rotundus ◽  
Tectofugal Pathway ◽  
Hyperstriatum Ventrale

AbstractPrevious lesion studies of color-reversal learning in pigeons show that an impairment results when (1) the tectofugal visual pathway is damaged at either the thalamic level (nucleus rotundus) or the telencephalic level (ectostriatum), or (2) the thalamofugal visual pathway is damaged at the telencephalic level (the visual Wulst). An impairment does not result, however, when the thalamic source of thalamofugal input (n. opticus principalis thalami or OPT) to the visual Wulst is damaged. These results suggest that the visual Wulst plays a role in color-reversal learning as a consequence of visual information routed from the tectofugal pathway via other visual areas in the telencephalon. One such area is the hyperstriatum ventrale (HV). In the present study, after ablation of the medial and lateral regions of HV, pigeons were trained postoperatively to discriminate between two colors presented simultaneously. After reaching criterion, the pigeons were required to perform a series of discrimination reversals in which the positive and negative stimuli were interchanged. Lesions of medial HV resulted in impaired performance of a color-discrimination task (i.e. original learning), but did not affect discrimination reversal. An impairment in color-reversal learning resulted from combined damage to lateral HV and the fronto-thalamic tract (FT), which carries ascending visual input from OPT to the visual Wulst. No deficits were observed when either lateral HV or FT were damaged alone. These findings suggest that both the thalamofugal and tectofugal pathways provide the visual Wulst with visual input relevant to color-reversal learning.

scholarly journals Neurons in the pigeon visual network discriminate between faces, scrambled faces, and sine grating images

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
William Clark ◽  
Matthew Chilcott ◽  
Amir Azizi ◽  
Roland Pusch ◽  
Kate Perry ◽  
...  
Keyword(s):  
Hierarchical Organization ◽  
Critical Function ◽  
Linear Discriminant ◽  
Object Categories ◽  
Electrophysiological Recordings ◽  
Early Visual Cortex ◽  
Primate System ◽  
Avian Visual System ◽  
Tectofugal Pathway ◽  
Visual Network

AbstractDiscriminating between object categories (e.g., conspecifics, food, potential predators) is a critical function of the primate and bird visual systems. We examined whether a similar hierarchical organization in the ventral stream that operates for processing faces in monkeys also exists in the avian visual system. We performed electrophysiological recordings from the pigeon Wulst of the thalamofugal pathway, in addition to the entopallium (ENTO) and mesopallium ventrolaterale (MVL) of the tectofugal pathway, while pigeons viewed images of faces, scrambled controls, and sine gratings. A greater proportion of MVL neurons fired to the stimuli, and linear discriminant analysis revealed that the population response of MVL neurons distinguished between the stimuli with greater capacity than ENTO and Wulst neurons. While MVL neurons displayed the greatest response selectivity, in contrast to the primate system no neurons were strongly face-selective and some responded best to the scrambled images. These findings suggest that MVL is primarily involved in processing the local features of images, much like the early visual cortex.

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