Our results indicated that all parts of V4 are connected with occipital areas V2 (visual area 2), V3 (visual area 3), and V3A (visual complex V3, part A), superior temporal areas V4t (V4 transition zone), MT (medial temporal area), and FST (fundus of the superior temporal sulcus [ STS] area), inferior temporal areas TEO (cytoarchitectonic area TEO in posterior inferior temporal cortex) and TE (cytoarchitectonic area TE in anterior temporal cortex), and the frontal eye field (FEF). 
Bilateral damage to area TEO caused no disruption of performance on any of the abovediscriminations.
The organization of backward projections from the anterior part of the inferotemporal cortex (area TE) to the posterior part of the inferotemporal cortex (area TEO) was studied in the macaque monkey by using the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L). The objectives of the study were to investigate this backward projection and to compare it with 1) the backward projections that have been described previously in the early sensory areas and 2) the forward projection from area TEO to area TE. After a single iontophoretic injection of PHA-L into area TE in three monkeys, a dense distribution of labeled terminals was observed in area TEO and in the ventral bank of the superior temporal sulcus (area PITd) that adjoined area TEO. The forward projections from area TEO to area TE also were studied for comparison by reanalyzing two previous cases (Saleem et al. These projections (from area TEO to area TE) were more focal than the terminations that occurred in area TEO after injections into area TE.
Fewer retrogradely labeled cells were observed in the cortex along the dorsal bank of the superior temporal sulcus, in the parahippocampal cortex, and in area TEO.
Of these 80 neurons, 50 (63%) were recorded in area TEO and 30 (38%) in area TE. These results suggest that area TEO rather than area TE is involved in detecting and processing particular visual shapes..
Pyramidal cells were intracellularly injected with Lucifer Yellow in cortical slices cut tangential to the cortical layers, allowing quantitative comparisons of dendritic field morphology, spine density and cell body size between the blobs and interblobs of the primary visual area (V1), the interstripe compartments of the second visual area (V2), the fourth visual area (V4) and cytoarchitectonic area TEO.
area TEO, which is a major afferent source to area TE, had axonal patches with spacing similar to those in area TE but with smaller sizes (0.4 +/- 0.1 mm). The results show that intrinsic horizontal axons both in area TE and in area TEO arborize in a patchy manner, as has been reported for several other cortical areas.
Thus, in the intraparietal sulcus, area TEO is connected with areas LIPd, LIPv, and V3A, and with the as yet undefined region between LIPv and V3A, whereas the connections of TE are predominantly with LIPd, and to a lesser extent with LIPv. By contrast, the connections of area TEO are limited to areas 8, 45, and 12.
No pontine projections arose from the prelunate convexity ventral to the caudal tip of the Sylvian fissure (ventral part of area V4d and area V4v), area TEO, the inferior temporal gyrus, or the lateral ventral temporal region.
The organization of connections from area TEO to TE was studied by the use of the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L).
In macaque monkeys, lesions involving the posterior portion of the inferior temporal cortex, cytoarchitectonic area TEO, produce a severe impairment in visual pattern discrimination. Because the inputs and outputs of area TEO have not yet been fully described, we injected a variety of retrograde and anterograde tracers into 11 physiologically identified sites within TEO of seven rhesus monkeys and analyzed the areal and laminar distribution of its cortical connections.
Comparison of the subcortical connections of subdivisions of IT cortex in squirrel monkeys and what is presently known of the subcortical connections of subdivisions of IT cortex in macaque monkeys supports the previous suggestion that ITC of squirrel monkeys may be comparable to area TEO of macaques, ITI may be comparable to posterior area TE, and ITR may be comparable to anterior area TE (Weller & Steele, 1992)..
The temporal injections included area TE on the lateral surface of the hemisphere and adjacent portions of area TEO.
Comparison of subdivisions of inferior temporal cortex defined in the present study in squirrel monkeys and those reported in other primates suggests that ITC of squirrel monkeys may correspond to area TEO of macaque monkeys..
The middle temporal gyrus, foveal prestriate cortex, and area TEO, a transitional area between temporal and occipital visual areas, were all free from retrogradely labeled cells.
The patterns of label observed after injections in inferotemporal gyrus indicate that area TEO and the ventral part of area V4 receive a major input from the ventral part of the lateral pulvinar (PuLv) while area TE has strong connections with the caudal pole of the medial pulvinar (PuM) and only minor connections with PuLv.
When inferior temporal area TE is removed bilaterally in infant monkeys, the normally transient projection from area TEO to the lateral basal nucleus of the amygdala is maintained, and the normally limited projection from area TEO to the dorsal part of the lateral nucleus of the amygdala expands to invade the terminal space in the lateral nucleus that is normally occupied by terminals from area TE. The maintenance and sprouting of these projections from area TEO could play a role in the permanent preservation of visual memory ability in monkeys that have received bilateral removal of area TE in infancy..
We identified a new visual area, roughly corresponding to cytoarchitectonic area TEO, located between the ventral portion of V4 and area TE.
In adult monkeys, inferior temporal-limbic connections included projections from area TEO to the dorsal portion of the lateral nucleus of the amygdala and from area TE to the lateral and lateral basal nuclei; inputs to both areas TEO and TE included those from the lateral, lateral basal, and medial basal nuclei of the amygdala and to area TE from the accessory basal nucleus. In infant monkeys, we found, in addition to these adultlike connections, a projection from area TEO to the lateral basal nucleus of the amygdala. Inferior temporal cortical connections in adult monkeys included projections from area TEO to area TE and, in turn, from area TE to area TG and perirhinal area 36, as well as from area TE back to area TEO; inputs to both areas TEO and TE included those from area TG, perirhinal areas 35 and 36, and parahippocampal areas TF and TH. All of these adultlike connections were also observed in infant monkeys, but, in addition, the infants showed projections from area TE to perirhinal area 35 as well as to parahippocampal areas TF and TH, and from area TEO to area TF.
The activity of 252 neurons in the inferotemporal visual area TEO, the superior temporal auditory area (AA), and the superior temporal polysensory area (STP) during the performance of a visual spot-fixation task and two variations, blink and tone tests, was examined in two behaving monkeys.
Area LIPv was found to have reciprocal cortico-cortical connections with many extrastriate visual areas, including the parieto-occipital visual area PO; areas V3, V3A, and V4: the middle temporal area (MT); the middle superior temporal area (MST); dorsal prelunate area (DP); and area TEO (the occipital division of the intratemporal cortex).
However, the amygdala is concerned with vision in the following ways: It receives neutral visual information highly processed in the visual cortex, invests the information with emotional and motivational significance through interactions with the cortical and subcortical systems of emotion and motivation, and then it returns the information coded to the visual areas to be re-processed; to be consciously perceived in area TEO, and to be meaningfully cognized, recognized and memorized in areas TE and TEG.
In the temporal cortex, the central field representation of MST as well as FST has connections with visual area TEO and cytoarchitectonic area TF.
No hippocampal label was found following injections in dorsal area TE and area TEO.
The dorsal wall of the STs receives fibers mainly from the inferior parietal lobule (area 7) and superior temporal gyrus (area 22), whereas the ventral wall and floor part of the STs receive fibers from the posterior inferotemporal gyrus (area TEO) and prestriate cortex (areas 18 and 19).
By contrast, little or no loss followed lesions of either the posterior part of inferior temporal cortex (area TEO) or the fusiform-hippocampal gyrus and hippocampus (FHH).
Marked impairment was found only in pattern discrimination retention and only in the monkeys with lesions of area TEO. It was concluded that the posterior limit of the inferotemporal visual learning area is at the ascending limb of the inferior occipital sulcus, and that the posterior subdivision thus comprises the single anatomical area TEO and does not extend into areas OA and OB..
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