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Abstract Working memory (WM) is a critical cognitive function allowing recent information to be temporarily held in mind to inform future action. This process depends on coordination between prefrontal cortex (PFC) subregions and other connected brain areas. However, few studies have examined the degree of functional specialization between these subregions throughout WM using electrophysiological recordings in freely-moving mice. Here we record single-units in three neighboring mouse medial PFC (mPFC) subregions—supplementary motor area (MOs), dorsomedial PFC (dmPFC), and ventromedial (vmPFC)—during a freely-behaving non-match-to-position WM task. The MOs is most active around task phase transitions, when it transiently represents the starting sample location. Dorsomedial PFC contains a stable population code, including persistent sample-location-specific firing during the delay period. Ventromedial PFC responds most strongly to reward-related information during choices. Our results reveal subregionally segregated WM computation in mPFC and motivate more precise consideration of the dynamic neural activity required for WM.

How the visual system adapts to stimuli along multiple feature axes during natural viewing is poorly understood. Here, the authors show significant enhancement of stimulus coding of image features in visual cortex after rapid exposure to an orthogonal feature.

Authors develop an integrated wireless system to examine brain states in freely-moving monkeys. They show that neural population activity in prefrontal cortex covaries with natural behavioral dynamics. Active behavior is associated with elevated arousal and increases in spiking activity while reducing low-frequency synchrony within cortical populations.

Focuses on environmental taxes in China. Overview on the country's environmental problems; Advantages of an emissions tax for the country; Provisions imposed under the country's proposed pollution levy system. INSET: The economics of emissions taxes..

Presents a response by Milton Russell to letters to the editor about his article "Environmental Protection for the 1990s -- and Beyond," in the September 1987 issue.