Neuronal tuning and population representations of shape and category in human visual cortex.

Object recognition and categorization are essential cognitive processes which engage considerable neural resources in the human ventral visual stream. However, the tuning properties of human ventral stream neurons for object shape and category are virtually unknown. We performed large-scale recordings of spiking activity in human Lateral Occipital Complex in response to stimuli in which the shape dimension was dissociated from the category dimension. Consistent with studies in nonhuman primates, the neuronal representations were primarily shape-based, although we also observed category-like encoding for images of animals. Surprisingly, linear decoders could reliably classify stimulus category even in data sets that were entirely shape-based. In addition, many recording sites showed an interaction between shape and category tuning. These results represent a detailed study on shape and category coding at the neuronal level in the human ventral visual stream, furnishing essential evidence that reconciles human imaging and macaque single-cell studies.

Active and Passive Cycling Decrease Subthalamic ß Oscillations in Parkinson's Disease.

BACKGROUND: Preserved cycling capabilities in patients with Parkinson's disease, especially in those with freezing of gait are still poorly understood. Previous research with invasive local field potential recordings in the subthalamic nucleus has shown that cycling causes a stronger suppression of ß oscillations compared to walking, which facilitates motor continuation. METHODS: We recorded local field potentials from 12 patients with Parkinson's disease (six without freezing of gait, six with freezing of gait) who were bilaterally implanted with deep brain stimulation electrodes in the subthalamic nucleus. We investigated ß (13-30 Hz) and high γ (60-100 Hz) power during both active and passive cycling with different cadences and compared patients with and without freezing of gait. The passive cycling experiment, where a motor provided a fixed cadence, allowed us to study the effect of isolated sensory inputs without physical exercise. RESULTS: We found similarly strong suppression of pathological ß activity for both active and passive cycling. In contrast, there was stronger high γ band activity for active cycling. Notably, the effects of active and passive cycling were all independent of cadence. Finally, ß suppression was stronger for patients with freezing of gait, especially during passive cycling. CONCLUSIONS: Our results provide evidence for a link between proprioceptive input during cycling and ß suppression. These findings support the role of continuous external sensory input and proprioceptive feedback during rhythmic passive cycling movements and suggest that systematic passive mobilization might hold therapeutic potential. © 2023 International Parkinson and Movement Disorder Society.

Low-dose every-second-day LHRH treatment following bilateral orchidopexy in children with bilateral cryptorchidism may improve their fertility outcome.

INTRODUCTION/BACKGROUND: Currently the standard treatment for bilateral cryptorchidism is bilateral surgical orchidopexy. Whether a hormonal treatment should be routinely administered postoperatively to increase fertility is debatable. Low-dose postoperative luteinizing hormone releasing hormone (LHRH) can increase spermatogonial numbers, but the effect of native LHRH (Kryptocur®) on adult fertility is unclear. OBJECTIVE: To determine if low-dose every-second-day postoperative LHRH administration in children with bilateral cryptorchidism improves fertility in adulthood and if Nistal testicular histological grading could guide the decision to administer LHRH. STUDY DESIGN METHODS: All patients, actually at least 16yr of age, that underwent a bilateral orchidolysis and orchidopexy for bilateral cryptorchidism (surgery between 1997 and 2018) were contacted and offered a clinical exam, hormone levels, sperm analysis, and a scrotal ultrasound. At the original surgery, testicular biopsy was performed (if 60% of the tubuli contain >1 spermatogonia, this is normal = Nistal-1, if 30-60% filled = Nistal-2, if <30% = Nistal-3 and if Sertoli only = Nistal-4) and if in at least one testis impaired. A low dose native LHRH treatment was offered to the patients, as this treatment is known to increase the number of spermatogonia in a short term. Kryptocur® (LHRH, Gonadorelin, Hoechst®) was prescribed and dosed at 200 µg (one spray in one nostril) every other day for 6-8 months. RESULTS AND LIMITATIONS: Forty-two men were eligible for this study. 20/42 accepted the invitation for a clinical and hormonal evaluation. 16/20 men accepted the invitation for an additional sperm analysis. Fourteen of 20 men received low-dose LHRH postoperatively in a nonrandomized manner. Three men had Nistal grade 1, eight grade 2, seven grade 3, and two had grade 4. Inhibin B levels were higher in men with Nistal 1 and 2 compared with Nistal 3 and 4 P ≤ 0.037). Severe oligospermia/azoospermia (<1 × 106/ejaculate) was observed in 33% of the treated group vs 67% of the untreated group (P ≤ 0.036.) DISCUSSION AND CONCLUSIONS: Low-dose every-second-day postoperative LHRH treatment improves fertility outcome in bilateral cryptorchidism. Histological analysis of prepubertal testes according to Nistal grading cannot be used as a predictive diagnostic test for LHRH treatment.

Computed tomography based assessment of programmable shunt valve settings.

Introduction: Programmable shunt valve settings can sometimes be difficult to assess using classic read-out tools, warranting a skull X-ray. Research question: Can we use available head computed tomography (CT) scans to determine the valve settings, in order to obviate the need for additional skull X-rays? Material and methods: The valve setting of two different programmable shunts (Codman Certas Plus® and Sophysa Polaris®) were assessed by two blinded observers in 24 patients using 65 head CT scans (slice thickness ≤2 â€‹mm). Using multi-planar reconstruction (MPR) tools, images were resliced according to the direction of the valve, allowing a direct readout of the valve settings. We validated our CT based method against 32 available skull X-rays. Results: For all CT scans it was possible to assess the valve setting. No interobserver variability was found and there was a 100 â€‹% concordance between the CT based method and skull X-rays. Discussion: CT based assessment of programmable shunt valve settings is feasible and reliable. It may obviate the need for additional skull x-rays when a head CT scan is available. Conclusions: This technique can reduce radiation exposure and can be applied to historical CT imaging with unknown valve settings.