Einheit von Park und Architektur : der Park am IG Hochhaus

Cerebellar granule cells, which constitute half the brain's neurons, supply Purkinje cells with contextual information necessary for motor learning, but how they encode this information is unknown. Here we show, using two-photon microscopy to track neural activity over multiple days of cerebellum-dependent eyeblink conditioning in mice, that granule cell populations acquire a dense representation of the anticipatory eyelid movement. Initially, granule cells responded to neutral visual and somatosensory stimuli as well as periorbital airpuffs used for training. As learning progressed, two-thirds of monitored granule cells acquired a conditional response whose timing matched or preceded the learned eyelid movements. Granule cell activity covaried trial by trial to form a redundant code. Many granule cells were also active during movements of nearby body structures. Thus, a predictive signal about the upcoming movement is widely available at the input stage of the cerebellar cortex, a

Size, Shape, and Appearance of the Normal Female Pituitary Gland 263

One hundred seven women 18-65 years old were studied who were referred for suspected central nervous system disease not related to the pituitary gland or hypothalamus. High-resolution, direct, coronal, contrast-enhanced computed tomography (CT) was used to examine the size, shape, and density of the normal pituitary gland . There were three major conclusions: (1) the height of the normal gland can be as much as 9 mm; (2) the superior margin of the gland may bulge in normal patients; and (3) both large size and convex contour appear to be associated with younger age. It was also found that serum prolactin levels do not appear to correlate with the CT appearances. Both low-and high-density areas were seen within the gland, and may be due to either tumors, cysts, infarcts, or metastases. Noise artifacts inherent in high-detail , thinsection, soft-tissue scanning may be a limiting factor in defining reproducible patterns in different parts of the normal pituitary gland. Computed tomography (CT) has facilitated the radiologic recognition of pituitary gland enlargement. Direct coronal scans in which the interface between the gland and the suprasellar cistern can be seen clearly are preferable to axial scans with sagittal reconstruction because of the loss of spatial resolution inherent in reformatted images. The configuration of the superior surface of the gland , its height, the integrity of the sellar floor, and the position of the infundibulum are all important factors to be considered in diagnosing pituitary tumors. Many authors have described the appearances of both the normal and abnormal glands Subjects and Methods One hundred seven women 18-65 years old referred for suspected central nervous system disease not related to the pituitary gland or the hypothalamus consented to have direct coronal scans of the sella following their standard scans, under guidelines establi shed by the institution's Human Investigation Review Committee. The studies were not consecutive since about 20% of the women contacted refused the additional scan s. The scans were obtained after the intravenous injection of 300 ml of Renografin 30 by drip infusion over 5-10 min . One hundred two of the women also had blood drawn immediately before contrast infusion for the measurement of prolactin and alpha-subunit level s. Th e scans we re obtained on the Somatom 2 Siemens scanner operated at 46 mA , 10 sec , and 120 kV with 2 mm collimation . The pixel size was 0.5 mm 2 . Scanograms, although available , were not obtained , since, after an initial scan approximately through the center of the sella turcica, appropriate pOSitional correction s could easily be made. The scans ex tende

Taking Aim at the Cognitive Side of Learning in Sensorimotor Adaptation Tasks

Sensorimotor adaptation tasks have been used to characterize processes responsible for calibrating the mapping between desired outcomes and motor commands. Research has focused on how this form of error-based learning occurs in an implicit and automatic manner. However, recent work has revealed the operation of multiple learning processes, even in this simple form of learning. This review focuses on the contribution of cognitive strategies and heuristics to sensorimotor learning, and how these processes enable humans to rapidly explore and evaluate novel solutions to enable flexible, goal-oriented behavior. This new work points to limitations in current computational models, and how these must be updated to describe the conjoint impact of multiple processes in sensorimotor learning

Adult birdsong is actively maintained by error correction

Humans learn to speak by a process of vocal imitation that requires the availability of auditory feedback. Similarly, young birds rely on auditory feedback when learning to imitate the songs of adult birds, providing one of the few examples of nonhuman vocal learning. However, whereas humans continue to use auditory feedback to correct vocal errors in adulthood, the mechanisms underlying the stability of adult birdsong are unknown. Here we show that like human speech, adult birdsong is maintained by error correction. We perturbed the pitch (fundamental frequency) of auditory feedback in adult Bengalese finches using custom-designed headphones. Birds compensated for the imposed auditory error by adjusting the pitch of song. When the perturbation was removed, pitch returned to baseline. These results show that adult birds correct vocal errors by comparing auditory feedback to a sensory target and suggest that lifelong error correction is a general principle of learned vocal behavior. Song learning in many species of birds, like language learning in humans, is based on a process of imitation 1, 2. Learning begins when a young bird is exposed to the song of an adult “tutor”. Subsequently, the young bird refines his initially disordered vocalizations int