Learning to read involves the acquisition of letter-sound relationships (i.e., decoding skills) and the ability to visually recognize words (i.e., orthographic knowledge). Although decoding skills are clearly human-unique, given they are seated in language, recent research and theory suggest that orthographic processing may derive from the exaptation or recycling of visual circuits that evolved to recognize everyday objects and shapes in our natural environment. An open question is whether orthographic processing is limited to visual circuits that are similar to our own or a product of plasticity common to many vertebrate visual systems. Here we show that pigeons, organisms that separated from humans more than 300 million y ago, process words orthographically. Specifically, we demonstrate that pigeons trained to discriminate words from nonwords picked up on the orthographic properties that define words and used this knowledge to identify words they had never seen before. In addition, the pigeons were sensitive to the bigram frequencies of words (i.e., the common co-occurrence of certain letter pairs), the edit distance between nonwords and words, and the internal structure of words. Our findings demonstrate that visual systems organizationally distinct from the primate visual system can also be exapted or recycled to process the visual word form.O n the surface, the human brain seems to have evolved for reading (1). Across individuals and cultures (2), reading activates an identical area in the left lateral occipitotemporal sulcus known as the visual word form area (VWFA) (3). This activation occurs no matter the case or font of the script (4), it increases in the transition from being illiterate to literate (5), and it increases with improvements in reading fluency (6). However, the presence of a VWFA is difficult to assimilate with the fact that writing was invented merely ∼5,400 y ago, and only became widespread very recently in human history, making it impossible that an area of the human brain evolved specifically for reading (7). Without the time to evolve, how can we explain the presence of the VWFA? One intriguing possibility is that the VWFA is the product of neuronal recycling, with its neurons learning to code visual stimuli (i.e., words) that greatly differ from the visual objects it initially evolved to code (8, 9).Anatomically, the VWFA lies just downstream of the ventral visual (i.e., what) pathway, a hierarchy of areas critical to visual object and face recognition in human and nonhuman primates. Dehaene et al. (10) argue that this hierarchy of areas can be tuned to the visual word form, with areas lower in the hierarchy simply encoding letter identities, and areas in the upper echelons of the hierarchy, specifically the VWFA, tuned to the co-occurrence of letter pairs (i.e., bigrams) and letter strings. At the present time, there are no neurophysiological studies that have investigated whether neurons in the nonhuman primate temporal lobe can learn to code anything beyond individual alphabetic ...

Low-frequency electric fields propagating in ex vivo biological tissues have been observed by using double-correlation optical coherence tomography (OCT). An adaptive Wiener filtering approach has been used to remove background noise, and a Fourier domain correlation algorithm has been applied to the sequence of OCT images. The results present the first direct observation (to our knowledge) of the scope of the electric field influencing biological tissues with OCT. The results show that variation in voltage and frequency of the applied electric field relates exponentially to the magnitude of its influence on biological tissue. The magnitude of influence is about twice more for fresh tissue samples in comparison to nonfresh ones. The obtained results suggest that OCT can be used for observation and quantitative evaluation of the electrokinetic changes in biological tissues under different physiological conditions, functional electrical stimulation, and food quality control.

Brownian systems often surmount energy barriers by absorbing and emitting heat to and from their local environment. Usually, the temperature gradients created by this heat exchange are assumed to dissipate instantaneously. Here we relax this assumption to consider the case where Brownian dynamics on a time-independent potential can lead to self-induced temperature gradients. In the same way that externally imposed temperature gradients can cause directed motion, these self-induced gradients affect the dynamics of the Brownian system. The result is a coupling between the local environment and the Brownian subsystem. We explore the resulting dynamics and thermodynamics of these coupled systems and develop a robust method for numerical simulation. In particular, by focusing on one-dimensional situations, we show that self-induced temperature gradients reduce barrier-crossing rates. We also consider a heat engine and a heat pump based on temperature gradients induced by a Brownian system in a nonequilibrium potential.

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