The anatomical connections of IT cortex also support a role in ob

The anatomical connections of IT cortex also support a role in object recognition and visual memory (Figure 2).

IT cortex lies at the pinnacle of the ventral cortical visual processing stream and its neurons receive convergent projections from many visual areas at lower ranks, thus affording integration of information from a variety of visual submodalities (Desimone et al., 1980 and Ungerleider, 1984). As noted above, IT cortex is also reciprocally connected with MTL structures that are critical for acquisition of declarative memories (Milner, 1972, Mishkin, 1982, Murray et al., 1993 and Squire and Zola-Morgan, 1991). Finally, the visual response properties of IT neurons, which have been explored in much detail over the past 40 years, also exhibit features

SAR405838 that suggest a role in object recognition and visual memory (for review see Gross et al., 1985 and Miyashita, 1993). Most importantly, IT neurons are known to respond selectively to complex objects—often those with some behavioral significance to the GSK2118436 nmr observer, such as faces (Desimone et al., 1984 and Gross et al., 1969). Based on this collective body of evidence, it would seem that IT cortex is unique among visual areas and strongly implicated as a storage site for long-term associative memories. Yet, there are reasons to suspect that associative neuronal plasticity may be a general property of sensory cortices. Evidence for this comes in part from functional brain imaging studies that have found learning-dependent activity changes in early cortical visual areas (e.g., Shulman et al., 1999 and Wheeler et al., 2000). Motivated by these findings, Schlack and Albright (2007) explored the possibility that associative learning

might influence response properties in the middle temporal visual area (area MT), which occupies a relatively early position in the cortical visual processing hierarchy (Ungerleider and Mishkin, 1979). In an experiment that represents a simple analog to the paired-association learning studies of Sakai and Miyashita (1991) and Messinger et al., 2001 and Schlack and almost Albright, 2007 trained monkeys to associate directions of stimulus motion with stationary arrows. Thus, for example, monkeys learned that an upward-pointing arrow was associated with a pattern of dots moving in an upward direction, a downward arrow was associated with downward motion, etc. (Figures 3A and 3B). Moving stimuli were used for this training because it is well known that such stimuli elicit robust responses from the vast majority of neurons in cortical visual area MT (Albright, 1984).

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