A vector calculus for neural computation in the cerebellum.

When a neuron modulates its firing rate during a movement, we tend to assume that it is contributing to control of that movement. However, null space theory makes the counter-intuitive prediction that neurons often generate spikes not to cause behavior, but to prevent the effects that other neurons would have on behavior. What is missing is a direct way to test this theory in the brain.

Rejuvenating silicon probes for acute neurophysiology.

Neurophysiological recording with a new probe often yields better signal quality than with a used probe. Why does the signal quality degrade after only a few experiments? Here, we considered silicon probes in which the contacts are densely packed, and each contact is coated with a conductive polymer that increases its surface area. We tested 12 Cambridge Neurotech silicon probes during 61 recording sessions from the brain of three marmosets.

The olivary input to the cerebellum dissociates sensory events from movement plans.

Neurons in the inferior olive are thought to anatomically organize the Purkinje cells (P-cells) of the cerebellum into computational modules, but what is computed by each module? Here, we designed a saccade task in marmosets that dissociated sensory events from motor events and then recorded the complex and simple spikes of hundreds of P-cells. We found that when a visual target was presented at a random location, the olive reported the direction of that sensory event to one group of P-cells, but not to a second group. However, just before movement onset, it reported the direction of the planned movement to both groups, even if that movement was not toward the target.

Effort cost of harvest affects decisions and movement vigor of marmosets during foraging.

Our decisions are guided by how we perceive the value of an option, but this evaluation also affects how we move to acquire that option. Why should economic variables such as reward and effort alter the vigor of our movements? In theory, both the option that we choose and the vigor with which we move contribute to a measure of fitness in which the objective is to maximize rewards minus efforts, divided by time. To explore this idea, we engaged marmosets in a foraging task in which on each trial they decided whether to work by making saccades to visual targets, thus accumulating food, or to harvest by licking what they had earned.

Complex spikes perturb movements and reveal the sensorimotor map of Purkinje cells.

Computations that are performed by the cerebellar cortex are transmitted via simple spikes of Purkinje cells (P-cells) to downstream structures, but because P-cells are many synapses away from muscles, we do not know the relationship between modulation of simple spikes and control of behavior. Here, we recorded the spiking activities of hundreds of P-cells in the oculomotor vermis of marmosets during saccadic eye movements and found that following the presentation of a visual stimulus, the olivary input to a P-cell coarsely described the direction and amplitude of the visual stimulus as well as the upcoming movement. Occasionally, the complex spike occurred just before saccade onset, suppressing the P-cell's simple spikes and disrupting its output during that saccade.

Complex spikes perturb movements, revealing the sensorimotor map of Purkinje cells.

The cerebellar cortex performs computations that are critical for control of our actions, and then transmits that information via simple spikes of Purkinje cells (P-cells) to downstream structures. However, because P-cells are many synapses away from muscles, we do not know how their output affects behavior. Furthermore, we do not know the level of abstraction, i.

Effort cost of harvest affects decisions and movement vigor of marmosets during foraging.

Unlabelled: Our decisions are guided by how we perceive the value of an option, but this evaluation also affects how we move to acquire that option. Why should economic variables such as reward and effort alter the vigor of our movements? In theory, both the option that we choose and the vigor with which we move contribute to a measure of fitness in which the objective is to maximize rewards minus efforts, divided by time. To explore this idea, we engaged marmosets in a foraging task in which on each trial they decided whether to work by making saccades to visual targets, thus accumulating food, or to harvest by licking what they had earned.

Stimulus presentation can enhance spiking irregularity across subcortical and cortical regions.

Stimulus presentation is believed to quench neural response variability as measured by fano-factor (FF). However, the relative contributions of within-trial spike irregularity and trial-to-trial rate variability to FF fluctuations have remained elusive. Here, we introduce a principled approach for accurate estimation of spiking irregularity and rate variability in time for doubly stochastic point processes.

Synchronous spiking of cerebellar Purkinje cells during control of movements.

SignificanceThe information that one region of the brain transmits to another is usually viewed through the lens of firing rates. However, if the output neurons could vary the timing of their spikes, then, through synchronization, they would spotlight information that may be critical for control of behavior. Here we report that, in the cerebellum, Purkinje cell populations that share a preference for error convey, to the nucleus, when to decelerate the movement, by reducing their firing rates and temporally synchronizing the remaining spikes.

A high gain multiband offset MIMO antenna based on a planar log-periodic array for Ku/K-band applications.

An offset quad-element, two-port, high-gain, and multiband multiple-input multiple-output (MIMO) planar antenna based on a log-periodic dipole array (LPDA) for Ku/K-band wireless communications is proposed, in this paper. A single element antenna has been designed starting from Carrel's theory and then optimized with a 50-Ω microstrip feed-line with two orthogonal branches that results mainly in a broadside radiation pattern and improves diversity parameters. For experimental confirmation, the designed structure is printed on an RT-5880 substrate with a thickness of 1.

P-sort: an open-source software for cerebellar neurophysiology.

Analysis of electrophysiological data from Purkinje cells (P-cells) of the cerebellum presents unique challenges to spike sorting. Complex spikes have waveforms that vary significantly from one event to the next, raising the problem of misidentification. Even when complex spikes are detected correctly, the simple spikes may belong to a different P-cell, raising the danger of misattribution.

Brain Networks Sensitive to Object Novelty, Value, and Their Combination.

Novel and valuable objects are motivationally attractive for animals including primates. However, little is known about how novelty and value processing is organized across the brain. We used fMRI in macaques to map brain responses to visual fractal patterns varying in either novelty or value dimensions and compared the results with the structure of functionally connected brain networks determined at rest.

Hips with synovial chondromatosis may display the features of femoroacetabular impingement.

Background: Both synovial chondromatosis and femoroacetabular impingement present with hip pain and may lead to hip osteoarthritis. We present a small case series and describe the clinical presentation, investigation, and treatment of patients with synovial chondromatosis who also had cam-type femoroacetabular impingement involving the same hip.

Methods: Five patients (four men and one woman with a mean age of thirty-four years [range, thirty to thirty-seven years]) with unilateral synovial chondromatosis of the hip presented with clinical and radiographic features of ipsilateral cam-type femoroacetabular impingement.