The `Parahippocampal Place Area' Responds Selectively to High Spatial Frequencies

Defining the exact mechanisms by which the brain processes visual objects and scenes remains an unresolved challenge. Valuable clues to this process have emerged from the demonstration that clusters of neurons (“modules”) in inferior temporal cortex apparently respond selectively to specific categories of visual stimuli, such as places/scenes. However, the higher-order “category-selective” response could also reflect specific lower-level spatial factors. Here we tested this idea in multiple functional MRI experiments, in humans and macaque monkeys, by systematically manipulating the spatial content of geometrical shapes and natural images. These tests revealed that visual spatial discontinuities (as reflected by an increased response to high spatial frequencies) selectively activate a well-known place-selective region of visual cortex (the “parahippocampal place area”) in humans. In macaques, we demonstrate a homologous cortical area, and show that it also responds selectively to higher spatial frequencies. The parahippocampal place area may use such information for detecting object borders and scene details during spatial perception and navigation.National Institutes of Health (U.S.) (NIH Grant R01 MH6752)National Institutes of Health (U.S.) (grant R01 EY017081)Athinoula A. Martinos Center for Biomedical ImagingNational Center for Research Resources (U.S.)Mind Research Institut

Primary T-cell lymphoma of the thyroid gland with chemokine receptors of Th1 phenotype complicating autoimmune thyroiditis

Lymphoma of the thyroid is almost exclusively derived from B cells of mucosa-associated lymphoid tissue (MALT), and frequently co-exist with autoimmune thyroiditis in which most infiltrating cells are of Th1 cell origin. We present here two rare cases of peripheral T-cell lymphoma (PTCL) based on chronic thyroiditis with the phenotype CD3+, CD4+, CD8−, TCRαβ+. Furthermore, lymphoma cells in both cases were CXCR3+, CCR5+ and ST2(L)−, suggesting a Th1 cell origin. Eight of 11 cases of PTCL of the thyroid in the literature, including our cases, were associated with thyroiditis. Except for one tumor of γδT-cell type, all of the five lymphomas analyzed for CD4 expression were positive for the antigen. Among them, both those examined for chemokine receptors were phenotypically of Th1-cell origin with a background of thyroiditis, suggesting that Th1 activation induced by chronic inflammation could lead to PTCL of themselves as well as MALT-lymphoma of B cells