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Thalamocortical processing in vision

Published online by Cambridge University Press:  20 June 2017

REECE MAZADE
Affiliation:
Department of Biological and Visual Sciences, State University of New York, College of Optometry, New York, New York 10036
JOSE MANUEL ALONSO*
Affiliation:
Department of Biological and Visual Sciences, State University of New York, College of Optometry, New York, New York 10036
*
*Address correspondence to: Jose-Manuel Alonso, State University of New York, College of Optometry, Department of Biological and Visual Sciences, 33 West, 42nd street, 17th floor New York, NY 10036. E-mail: jalonso@sunyopt.edu
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Abstract

Visual information reaches the cerebral cortex through a major thalamocortical pathway that connects the lateral geniculate nucleus (LGN) of the thalamus with the primary visual area of the cortex (area V1). In humans, ∼3.4 million afferents from the LGN are distributed within a V1 surface of ∼2400 mm2, an afferent number that is reduced by half in the macaque and by more than two orders of magnitude in the mouse. Thalamocortical afferents are sorted in visual cortex based on the spatial position of their receptive fields to form a map of visual space. The visual resolution within this map is strongly correlated with total number of thalamic afferents that V1 receives and the area available to sort them. The ∼20,000 afferents of the mouse are only sorted by spatial position because they have to cover a large visual field (∼300 deg) within just 4 mm2 of V1 area. By contrast, the ∼500,000 afferents of the cat are also sorted by eye input and light/dark polarity because they cover a smaller visual field (∼200 deg) within a much larger V1 area (∼400 mm2), a sorting principle that is likely to apply also to macaques and humans. The increased precision of thalamic sorting allows building multiple copies of the V1 visual map for left/right eyes and light/dark polarities, which become interlaced to keep neurons representing the same visual point close together. In turn, this interlaced arrangement makes cortical neurons with different preferences for stimulus orientation to rotate around single cortical points forming a pinwheel pattern that allows more efficient processing of objects and visual textures.

Information

Type
Review Article
Copyright
Copyright © Cambridge University Press 2017 
Figure 0

Fig. 1. Thalamocortical visual function in different animals: primates, carnivores, scandentia, lagomorphs, and rodents. Top. The number of LGN cells is correlated to the size of area V1 (left) and cortical visual acuity (right). Bottom. Cortical visual acuity is also correlated to the size of area V1 (left, expected from correlations shown at the top), and the horizontal extent of the binocular field (shown as a percentage of the total horizontal extent of the visual field). Size of area V1 refers to only one hemisphere. See Table 1 for references.

Figure 1

Table 1. Comparison of visual systems across different animals: primates, carnivores, scandentia, lagomorphs, and rodents. Columns 1–9 are taken from references cited below. Column 10 is calculated as column 8 times column 9; column 11 is calculated as column 10 divided by column 7; column 12 is calculated as column 6 times one million divided by column 8. Columns are numbered from left to right, from [1] for body weight to [12] for LGN-axon density in V1. All areas and volumes refer only to one hemisphere. Human: (Howland et al., 2004) for [1], [2]; (Curcio & Allen, 1990) for [3], [4], [5]; (Selemon & Begovic, 2007) for [6]; (Andrews et al., 1997) for [7], [8], [10]. Macaque: (Howland et al., 2004) for [1]; (Perry & Cowey, 1985) for [2]; (Kong et al., 2010) for [3]; (Kim et al., 1996) for [4]; (Perry & Cowey, 1985) for [5]; (Connolly & Van Essen, 1984) for [6]; (Malpeli & Baker, 1975) for [7]; (Adams et al., 2007) for [8]; (Hubel & Wiesel, 1968) for [9]. Cat: (Howland et al., 2004) for [1], [2]; (Hughes, 1975) for [3], [5]; (Hughes & Wassle, 1976) for [4]; (Williams et al., 1993) for [5], [6], [7]; (Tusa et al., 1978) for [8]; (Hubel & Wiesel, 1962) for [9]. Tree Shrew: (Howland et al., 2004) for [1], [2]; (Engelmann & Peichl, 1996) for [3]; (Drenhaus et al., 1997) for [4]; (Petry et al., 1984) for [5]; (Conway & Schiller, 1983) for [6], [7]; (Sesma et al., 1984) for [8]; (Muly & Fitzpatrick, 1992) for [9]. Ferret: (Howland et al., 2004) for [1], [2]; (Henderson, 1985) for [3], [4]; (Vitek et al., 1985) for [5]; (Gautschi & Clarke, 2007) for [6]; (Zahs & Stryker, 1985) for [7]; (Law et al., 1988) for [8], [9]. Rabbit: (Howland et al., 2004) for [1], [2]; (Oyster et al., 1981) for [3], [4], [5]; (Najdzion et al., 2009) for [6], [7]; (Hughes, 1971) for [8], [9]. Mouse: (Howland et al., 2004) for [1], [2]; (Drager and Olsen, 1981) for [3]; (Williams et al., 1996) for [4]; (Jeon et al., 1998) for [5]; (Seecharan et al., 2003) for [6], [7]; (Garrett et al., 2014) for [8]; (Antonini et al., 1999) for [9]. RGC: retinal ganglion cells

Figure 2

Table 2. Cortical mapping of visual space in different animals: primates, carnivores, scandentia, lagomorphs, and rodents. Columns 1–2, 5, 9–10 are taken from references cited below. Column 3 is calculated as column 2 divided by column 1 times 100; column 4 is calculated as column 8 from Table 1 divided by column 1 in this table; column 6 is calculated as column 4 times column 5; column 7 is calculated as column 1 divided by column 5; column 8 is calculated as column 2 divided by column 5. Columns are numbered from left to right as in Table 1. Macaque: (Adams et al., 2007) for [1], [2]; (Levitt et al., 2001) for [5]; (De Valois et al., 1982) for [9]; (Hubel & Wiesel, 1968) for [10]. Cat: (Sherman, 1974) for [1], [2]; (Cai et al., 1997) for [5]; (Movshon et al., 1978) for [9]; (Hubel & Wiesel, 1962) for [10]. Tree shrew: (Kaas et al., 1972) for [1], [2]; (Holdefer & Norton, 1995) for [5]; (Johnson et al., 2010) for [9]; (Humphrey & Norton, 1980) for [10]. Ferret: (Law et al., 1988) for [1], [2]; (Zahs & Stryker, 1985) for [5]; (Baker et al., 1998) for [9]; (Law et al., 1988) for [10]. Rabbit: (Hughes, 1971) for [1], [2]; (Bezdudnaya et al., 2006) for [5]; (Zhuang et al., 2013) for [9]; (Murphy & Berman, 1979) for [10]. Mouse: (Scholl et al., 2013) for [1]; (Heesy, 2004) for [2]; (Tang et al., 2016) for [5]; (Niell & Stryker, 2008) for [9]; (Drager, 1975) for [10]. RF: receptive field

Figure 3

Fig. 2. Thalamocortical networks underlying the organization of visual cortical maps. (a) Number of non-overlapping LGN receptive fields needed to tile a horizontal line across the visual field (shown on top left corner of each rectangle, taken from column 7 in Table 2). Only 1/10 of the horizontal visual field is represented for illustration purposes. (b) Number of nonoverlapping LGN-axon-patches needed to tile a horizontal line through area V1 (shown on top left corner of each rectangle, taken from column 3 in Table 3). Green and orange colors represent two different afferents. (c) The largest spacing between two LGN-axon-patches covering one LGN receptive field in visual cortex (shown on top left corner of each rectangle, taken from column 5 in Table 3). For simplicity, axon patches are represented as squares. (d) Cortical optimal visual acuity across 11 different species (values obtained from the references cited below). Colored circles indicate pinwheel orientation maps in visual cortex. Mouse: (Niell & Stryker, 2008). Rat, Gray squirrel, Bush baby, Owl monkey: (Heimel et al., 2005). Rabbit: (Zhuang et al., 2013). Ferret: (Baker et al., 1998). Tree shrew: (Johnson et al., 2010). Marmoset: (Forte et al., 2005). Cat: (Movshon et al., 1978). Macaque: (De Valois et al., 1982). VF: visual field. RF: receptive field.

Figure 4

Table 3. Comparison of LGN axon-patch density across different animals: primates, carnivores, scandentia, and rodents. Column 1 is taken from references cited below. Column 2 is calculated as the square root of column 1 times 1000; column 3 is calculated as column 8 in Table 1 divided by column 1 in this table; column 4 is calculated as column 6 in Table 1 times column 1 in this table times one million and divided by column 8 in Table 1; column 5 is calculated as the square root of the ratio between column 6 of Table 2 and column 1 of this table. Columns are numbered from left to right as in Table 1. Macaque: (Blasdel & Lund, 1983) for [1]. Cat (area 17): (Humphrey et al., 1985a) for [1]. Tree shrew: (Raczkowski & Fitzpatrick, 1990) for [1]. Mouse: (Antonini et al., 1999) for [1]. RF: receptive field

Figure 5

Fig. 3. Changes in orientation preference and receptive field position along a horizontal track of cat visual cortex. From top to bottom, the rows show OFF receptive fields mapped with dark stimuli (in blue), ON receptive fields mapped with light stimuli (in red), the ON–OFF receptive field difference (diff.), and the orientation/direction preference measured with moving bars (circles show the orientation preference predicted from the receptive field maps). From left to right, the columns show cortical measurements separated by 0.1 mm from 0 to 1.2 mm distance. The column on the right shows the receptive field average along the entire horizontal track (top three receptive fields) and the central positions of ON (red circles) and OFF receptive fields (blue circles). The position of these ON and OFF cortical receptive fields is determined by the receptive field population of ON and OFF thalamic afferents. Reproduced from Kremkow et al. (2016).

Figure 6

Fig. 4. Pinwheel pattern of the cortical map for stimulus orientation. Colors illustrate the different orientations represented on the cortical surface (cat area 17, 2 × 2 mm). A square of 0.5 × 0.5 mm is shown centered on a cortical pinwheel.

Figure 7

Table 4. Cortical spacing for ocular dominance and orientation pinwheels in area V1 of primates, carnivores, scandentia, and rodents. Column 2 is calculated as the square root of 1/pinwheel density. References for the column on the left [1] and on the right [2] are provided below. Human: (Adams et al., 2007) for [1]; (Yacoub et al., 2008) for [2]. Macaque: (Adams et al., 2007) for [1]; (Obermayer & Blasdel, 1993) for [2]. Cat area 17: (Lowel, 1994) for [1]; (Bonhoeffer et al., 1995) for [2]. Cat area 18: (Lowel, 1994) for [1]; (Bonhoeffer & Grinvald, 1993) for [2]. Owl monkey: (Takahata et al., 2014) for [1]; (Xu et al., 2004) for [2]. Bush baby: (Xu et al., 2005) for [1], [2]. Marmoset: (Roe et al., 2005) for [1]; (Liu & Pettigrew, 2003) for [2]. Squirrel monkey: (Adams & Horton, 2003) for [1]; (Obermayer & Blasdel, 1997) for [2]. Ferret: (Law et al., 1988) for [1]; (Rao et al., 1997) for [2]