‘What’ and ‘where’ in the human brain

“Both inferior-occipital and temporal cortices constitute part of a hierarchically organized ventral visual stream (Ungerleider & Haxby, 1994) specialized for object recognition/categorization (Sergent, Ohta, & MacDonald , 1992a) and their coactivation during the presentation of auditory verbal…”

“Interestingly, these compensations can be specific for the ‘‘where’’ and ‘‘what’’ pathways (e.g., Ungerleider and Haxby, 1994): in fact, Chen et al. (2006) have recently reported that while early vision deprivation may enhance blind people’s auditory processing along the ‘‘where’’ pathway, this…”

“These regions have been linked with the processing of visual object and form representation (Ungerleider & Haxby, 1994).”

“Subsequent studies using behavioral, electrophysiological or anatomical approaches have confirmed the existence of parallel processing streams in extrastriate visual cortex of human”

“…studies (Dehaene et al., 2004; Vinckier et al., 2007) have provided evidence for a hierarchical organization in the ventral visual pathway (Ungerleider and Haxby, 1994) for the visual word form, leading to the proposal that running posterior to anterior along this pathway, neurons are…”

“…example, posterior areas specialized for spatial vision have a more superior location in parietal cortex in the human than in the monkey, whereas those specialized for object vision have a more inferior location in temporal cortex (for reviews see Ungerleider & Haxby (1994) and Ungerleider (1995)).”

“The parahippocampal cortex itself receives visuospatial information from the parietal cortex (A. D. Milner & Goodale, 1995; Ungerleider & Haxby, 1994; Van Hoesen, 1982).”

“The parahippocampal cortex and the retrosplenial cortex around the parietal occipital sulcus receive visuospatial information from the parietal cortex (Milner and Goodale, 1993; Suzuki and Amaral, 1994a; Ungerleider and Haxby, 1994; Van Hoesen et al., 1981).”

“To date, most proposals regarding parietal function have focused on other functions such as spatial vision, vision-foraction or action understanding (Ungerleider and Haxby, 1994; Milner and Goodale, 1995; Rizzolatti and Matelli, 2003).”

“First, there is evidence that visual processing (Mishkin et al., 1983; Sergent et al., 1992; Ungerleider and Haxby, 1994) and long-term memory (Moscovitch et al., 1995) are divided into dorsal and ventral pathways, corresponding approximately to “what” and “where” information.”

“Ordering these BAs by processing hierarchy (Ungerleider and Haxby, 1994), that is, by the information flow from primary visual cortex to subsequent relays within the ventral visual stream, we generally observe decreased power in LF, and increased power in MF2 and HF bands (Fig.”

“The visual cortex is characterized by rich and complex interconnections between functionally specialized areas (see Van Essen et al., 1993; Ungerleider and Haxby, 1994) so that pathological increases in activity are unlikely to be restricted to a single specialized visual area.”

“In agreement with prior studies (Shapiro et al., 1997; Knierim, 2002), the CA1 place field representation split, as equal numbers of cells rotated with each set of cues, and a large number of cells remapped.”

“…consistent with its critical role in spatial perception and movement in space that has been clearly established from work in human subjects (Mesulam, 1981; Posner et al., 1984) and monkeys (Petrides & Iversen, 1979), as well as from functional neuroimaging studies (Ungerleider & Haxby, 1994).”

“Early on, this pathway was portrayed as the ‘where’ system [ 72 ], designed to convey informa-”

“Performance in chronic lesion patients is of course subject to reorganization and recovery, qualifying the inferences that can be drawn about normal brain function (Ungerleider and Haxby, 1994).”

“…which in the macaque are located within the lunate sulcus and on the prelunate gyrus, bringing them close to the caudal end of the IPL (Kaas, 2006; Ungerleider and Haxby, 1994), whereas in humans these areas are located more caudo-ventrally (ventral visual stream) and caudodorsally (dorsal…”

“Lesions in this area are associated with visuospatial neglect, optic ataxia and difficulties in spatial learning, such as stylus maze learning (Ungerleider and Haxby 1994).”

“…and in addition to the “what” and “where” of functional networks associated with the ventral and dorsal visual pathways (Goodale and Milner 1992; Ungerleider and Haxby 1994), there also exists a central module for sensory “how much,” localized to the insula and extending into the lateral…”

“derived from multiple sources of evidence (Grafton et al. 1992; Ungerleider and Haxby 1994 ).”

“The position invariance of some representations at higher levels of the ventral visual pathway is reminiscent of such a factorisation of states, as it suggests “what” can be represented independently of “where” 75,76 and of “when” 77 .”

“The hierarchy was subsequently refined in order to better accommodate the what/ventral and where/dorsal streams of Ungerleider and Mishkin [8–10].”

“…cortex; dorsal visuospatial pathway; frontal eye fields Visual processing in the cerebral cortex proceeds through multiple visual areas into a dorsal pathway responsible for spatial vision and into a ventral pathway responsible for object vision (for review, see Ungerleider and Haxby, 1994).”

“…permitted the exploration of the extent to which the posterior sensory and polymodal areas that demonstrate clear what/where dissociation in the sensory processing of visual information (Belger et al., 1998; Ungerleider and Haxby, 1994) also demonstrate domain-specific mnemonic properties.”

“The execution of visuospatial tasks (Haxby et al. 1991; Ungerleider and Haxby 1994; Cohen et al. 1996; Goebel et al. 1998; Trojano et al. 2000; Sack, Sperling, et al. 2002) as well as visuospatial imagery (Mellet et al. 1996; Trojano et al. 2000; Sack, Hubl, et al. 2002) leads to increased…”

“1996; Haxby et al. 1991; Ungerleider and Haxby 1994) and Three factors seem most likely to have contributed to the neurophysiological (Goldman-Rakic 1995; Wilson et al. present, positive result.”

“…two anatomically segregated and functionally specialized parallel processing streams (Arnott, Binns, Grady, & Alain, 2004; Goodale & Milner, 1992; Hickok & Poeppel, 2004, 2007; Mishkin, Ungerleider, & Macko, 1983; Rauschecker & Tian, 2000; Ungerleider & Haxby, 1994; Ungerleider & Mishkin, 1982).”

“M. Jeannerod, P. Jacob / Neuropsychologia xxx (2004 matching 385 of seen objects (e.g., Ungerleider & Haxby, 1994).”

“Sensory systems are in fact biologically organized in this fashion in order to perceive identity and location, and to detect movement (Ungerleider & Haxby, 1994; Ungerleider & Mishkin, 1982).”

“…more dorsal regions represent the egocentric and allocentric spatial locations of those objects and are essential for making reaching and grasping movements and for directing attention to objects and/or locations (Goodale & Milner, 1992; Ungerleider & Haxby, 1994; Ungerleider & Mishkin, 1982).”

“…activation patterns in dorsal regions (dorsal occipital cortex (BA 19) plus the inferior parietal lobule (BA 7)) during spatial localization, as have other positron emission tomography and fMRI visual localization studies (Clark et al., 1994; Goodale and Milner, 1992; Ungerleider and Haxby, 1994 ).”

“In an extreme version of this view, the two streams underlie the perception of ‘what’ and ‘where’ concurrently and relatively independently of each other (Ungerleider & Haxby, 1994; Ungerleider & Mishkin, 1982).”

“The dorsal pathway, including parietal cortex, on the other hand, processes information regarding the spatial locations of objects, the spatial relationships among objects, and the guidance of motor movements toward objects [26,33,73,74].”

“[34] report that visual processing in an object detection task in complex visual scenes can be achieved in under 150 ms, which is on the order of the latency of the signal trans mis ion from the retina to inferotemporal cortex (IT), the highest area in the ventral visual stream th ought to have a key role in object re…”

“These regions were located in the visual ventral pathway (Ungerleider and Mishkin 1982; Ungerleider and Haxby 1994 ), although the term pathway is improper here because simultaneous, rather than serial, activation was observed.”

“In the non-human primate neuroanatomy, object recognition involves the flow of visual information through the ventral pathway, originating in primary visual cortex (V1), continuing through extrastriate areas (V2,V4), and terminating in inferotemporal (IT) cortex (Hubel and Wiesel, 1962; Van Essen et al., 1992; Ungerle…”

“One celebrated example is the segregation of the brain into ventral (‘what’) and dorsal (‘where’) streams [74] that may reflect the statistical independence between ‘what’ and ‘where’.”

“Perhaps the most celebrated example of transcribing statistical independencies into neuroanatomy is the segregation of dorsal and ventral visual processing streams of the brain [2,35,36].”

“Cortical region PG, well recognized as a key region in the so-called visual where pathway (Felleman and Van Essen, 1991; Ungerleider and Haxby, 1994) of the macaque visual system, was found to display a relatively high macroscale degree, but a (relative to the fitted linear relationship) small dendritic tree (Fig.”

“1 B, TP7, TP8, T5, and T6 electrodes) were selected on the basis of an a priori hypothesis because previous studies showed the importance of the lateral occipital area and the ventral “what” pathway for object recognition (Tanaka, 1993; Ungerleider and Haxby, 1994; Malach et al., 1995).”

“This view is in line with the well-known integration of the dPCC in the dorsal visual stream—the " where " system for spatial processing (Ungerleider and Haxby, 1994; Ungerleider and Mishkin, 1982; Vogt et al., 2006), in contrast to vPCC's relation to the ventral " what " system (cf. above).”

“This concept is inspired by earlier studies that postulated distinct hierarchies for processing different visual features, such as color or motion, in extrastriate visual cortex (Ungerleider and Haxby, 1994).”

“Connections from visual cortex to the dorsal (‘where’) and ventral (‘what’) streams (Figure 1) can be thought of as carrying evidence in favour of spatial configurations or stimulus identities, respectively [12].”

“…serial order information in the visual and verbal STM conditions; the activation we observed in right superior parietal and superior occipital areas is indeed consistently reported in studies involving spatial processing (e.g., Baker et al., 1996; Hautzel et al., 2002; Ungerleider & Haxby, 1994).”

“…to the functional specializations of each area, a number of complex receptive field characteristics have been described in higher levels that appear to be absent or less prevalent at lower levels (Felleman and Van Essen 1991; Ungerleider and Haxby 1994; Van Essen and Gallant 1994; see Discussion).”

“Direct visual input from V1 has been shown to spread dorsally to the parietal lobe (Ungerleider and Mishkin 1982; Goodale and Milner 1992; Ungerleider and Haxby 1994), which was implemented in our model space as an endogenous connection between V1 and the SMG. Figure 2.”

“These regions, in sighted individuals, are often associated with the analysis of object features and object identification (Ungerleider and Mishkin, 1982; Ungerleider and Haxby, 1994).”

“…in the AL field, which the authors interpreted as evidence for a ‘what’ (object identification) versus ‘where’ (spatial localization) functional segregation between anterior and posterior fields, as in primate visual cortex (Ungerleider & Haxby 1994; Kaas & Hackett 1999; Rauschecker & Tian 2000).”

“These regions form part of the ventral 10 visual processing stream responsible for the recognition of objects (Ungerleider and Mishkin, 1982; Ungerleider and Haxby, 1994), letters and words (Petersen et al., 1990; Posner and Abdullaev, 1999; Cohen et al., 2002; Gaillard et al., 2006).”

“Parallel “what” and “where” pathways exist in all the major sensory modalities (Ungerleider and Haxby, 1994; Ahveninen et al., 2006).”

“These cortical fields form a part of functional processing streams, beginning in V1, that extend either dorsally or ventrally in the brain, where they are involved in visuomotor control and object recognition, respectivel”