because the premotor cortex itself is heterogenous and different subregions have different connectivity. Generally the premotor cortex has strong afferent (input) and efferent (output) connectivity to the primary motor cortex, the supplementary motor area, the superior and inferior parietal cortex, and prefrontal cortex. Subcortically it projects to the spinal cord, the striatum, and the motor thalamus among other structures. In the study of neurolinguistics, the ventral premotor cortex has been implicated in motor vocabularies in both speech and manual gestures. A mental syllabary — a repository of gestural scores for the most highly used syllables in a language — has been linked to the ventral premotor cortex in a large-scale meta-analysis of functional imaging studies. A recent prospective fMRI study that was designed to distinguish phonemic and syllable representations in motor codes provided further evidence for this view by demonstrating adaptation effects in the ventral premotor cortex to repeating syllables. The premotor cortex is now generally divided into four sections. First it is divided into an upper (or dorsal) premotor cortex and a lower (or ventral) premotor cortex. Each of these is further divided into a region more toward the front of the brain (rostral premotor cortex) and a region more toward the back (caudal premotor cortex). A set of acronyms are commonly used: PMDr (premotor dorsal, rostral), PMDc (premotor dorsal, caudal), PMVr (premotor ventral, rostral), PMVc (premotor ventral, caudal). Some researchers, especially those who study the ventral premotor areas, use a different terminology. Field 7 or F7 denotes PMDr; F2 = PMDc; F5=PMVr; F4=PMVc. These subdivisions of premotor cortex were originally described and remain primarily studied in the monkey brain. Exactly how they may correspond to areas of the human brain, or whether the organization in the human brain is somewhat different, is not yet clear. PMDc (F2) PMDc is often studied with respect to its role in guiding reaching. Neurons in PMDc are active during reaching. When monkeys are trained to reach from a central location to a set of target locations, neurons in PMDc are active during the preparation for the reach and also during the reach itself. They are broadly tuned, responding best to one direction of reach and less well to different directions. Electrical stimulation of the PMDc on a behavioral time scale was reported to evoke a complex movement of the shoulder, arm, and hand that resembles reaching with the hand opened in preparation