Experience-dependent Modulation of Category-related Cortical Activity

Abstract

Naming pictures of objects from different categories (e.g. animals or tools) evokes maximal responses in different brain regions. However, these 'category-specific' regions typically respond to other object categories as well. Here we used stimulus familiarity to further investigate category representation. Naming pictures of animals and tools elicited category-related activity in a number of previously identified regions. This activity was reduced for familiar relative to novel stimuli. Reduced activation occurred in all object responsive areas in the ventral occipito-temporal cortex, regardless of which category initially produced the maximal response. This suggests that object representations in the ventral occipito-temporal cortex are not limited to a discrete area, but rather are widespread and overlapping. In other regions (e.g. the lateral temporal and left premotor cortices), experience-dependent reductions were category specific. Together, these findings suggest that category-related activations reflect the retrieval of information about category-specific features and attributes.

Learning Acts on Distinct Processes for Visual Form Perception in the Human Brain

“…Our work advances our understanding of the processes that mediate adaptive shape recognition beyond previous studies in the following main respects. First, previous functional imaging studies have implicated occipitotemporal and frontoparietal circuits in shape learning (Dolan et al, 1997;Gauthier et al, 1999;Grill-Spector et al, 2000;Chao et al, 2002;Kourtzi et al, 2005;Op de Beeck et al, 2006). However, the indirect, slow hemodynamic response of fMRI limits our understanding of the spatiotemporal brain dynamics that mediate visual form learning.…”

“…Some studies argue that learning alters early sensory processing (Adini et al, 2002;Teich and Qian, 2003), while others propose that learning alters later decision-related processes (Dosher and Lu, 1999;Li et al, 2004;Law and Gold, 2008;Jacobs, 2009). Previous fMRI studies have implicated both occipitotemporal and frontoparietal circuits in shape learning (Dolan et al, 1997;Gauthier et al, 1999;Grill-Spector et al, 2000;Chao et al, 2002;Kourtzi et al, 2005;Op de Beeck et al, 2006). However, little is known about how learning shapes interactions between these circuits and mediates perceptual improvements in the discrimination of global forms (Scott et al, 2006(Scott et al, , 2008Rossion et al, 2007).…”

Meta‐analyses of object naming: Effect of baseline

“…Several previous objectnaming studies were excluded from the meta-analyses. The exclusion criteria were: no non-object baseline [Chao et al, 1999[Chao et al, , 2002Chao and Martin, 2000]; results were only reported in regions of interest rather than for the whole brain [Grabowski et al, 1998;Grafton et al, 1997;Heim et al, 2002;Kan and Thompson-Schill, 2004]; the task was action rather than object naming [Damasio et al, 2001]; and the task was scene identification rather than object naming [Renvall et al, 2003]. …”

“…Previous studies have compared object-naming activation to reading [Bookheimer et al, 1995;Moore and Price, 1999b], color naming [Price et al, 1996], verbal fluency [Etard et al, 2000], semantic categorization [Tyler et al, 2004], or a range of baselines [Murtha et al, 1999]. Other studies have investigated how the activation pattern changes for overt and covert naming [Zelkowicz et al, 1998], for object category [Chao et al, 1999[Chao et al, , 2002Chao and Martin, 2000;Damasio et al, 1996;Grabowski et al, 1998;Kawashima et al, 2001;Martin et al, 1996;Moore and Price, 1999a;Smith et al, 2001], by scanning modality [Votaw et al, 1999], across languages [Vingerhoets et al, 2003], with name agreement [Kan and Thompson-Schill, 2004], with gender of subjects [Grabowski et al, 2003], and during object learning [van Turennout et al, 2000[van Turennout et al, , 2003. To our knowledge, no previous study has segregated the objectnaming system into its perceptual, semantic, and phonological components.…”

A task-dependent causal role for low-level visual processes in spoken word comprehension.

“…Initial univariate fMRI studies on object recognition localized selective activation in response to pictures of animate versus inanimate items to distinct portions of fusiform gyrus and lateral occipital cortex (Chao, Haxby, & Martin, 1999;Chao, Weisberg, & Martin, 2002; for review see Martin, 2007). More recently, several fMRI studies using multivariate pattern analysis (MVPA) reported successful decoding of conceptual categories based on picture stimuli from ventral temporal areas (Haxby et al, 2001;Shinkareva et al, 2008).…”