Cerebellar stimulation in man : I.S. Cooper (Ed.) (Raven, New York, 1978, 222 p., U.S. $ 22.50)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23369/1/0000313.pd

Functional imaging with positron emission tomography in multiple system atrophy

Although the current guidelines for the clinical diagnosis of multiple system atrophy (MSA) do not require structural or functional brain imaging, investigations utilizing positron emission tomography (PET) have been helpful diagnostically in differentiating between MSA and primary autonomic failure; idiopathic Parkinson’s disease; and sporadic olivopontocerebellar atrophy. These investigations have demonstrated different patterns of cerebral glucose utilization and of nigrostriatal projection abnormalities among these disorders and between the cerebellar and parkinsonian forms of MSA. Most of the studies have focused upon patients with well-established disease and none have examined the utility of PET imaging in early stage patients with follow-up of clinical course and autopsy verification to ensure accuracy of diagnosis and to determine the sensitivity and specificity of PET techniques for diagnosis. Recent PET studies have revealed denervation of myocardial post-ganglionic sympathetic neurons in some MSA patients, indicating that this disorder can affect the peripheral autonomic as well as the central nervous system. Investigations utilizing ligands to quantify central nervous system dopaminergic and cholinergic terminals have begun to provide insight into the neurochemical disorders that may underlie two of the sleep disturbances common in MSA, rapid eye movement sleep behavior disorder and obstructive sleep apnea.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41651/1/702_2005_Article_351.pd

Parasagittal zonation of GABA-B receptors in molecular layer of rat cerebellum

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27682/1/0000065.pd

The temporal structure of spike trains in the primate basal ganglia: afferent regulation of bursting demonstrated with precentral cerebral cortical ablation

We studied the temporal pattern of discharge of single units in the basal ganglia of awake primates sitting quietly. Bursting was studied with a procedure that identified individual bursts in a spike train, quantifying burst intensity (surprise), bursts per 1000 spikes, spikes per burst and burst length. Autocorrelation techniques were used to assess the dependencies of spike trains on the temporal order of intervals. Straital units had a greater tendency to burst (79% of units) than pallidal units (50%). The caudate nucleus and putamen had nearly identical burst properties on all measures. In the pallidum, bursting was more prevalent in the external segment and bursts were more intense and more frequent than in the internal segment. The autocorrelation analysis revealed that the temporal structure of the spike train was more dependent on the order of intervals in the striatum than in the pallidum. Bursting units had an increased probability of discharge after each spike and the relative refractory period was shorter in bursting units than units without bursts. Very few units exhibited cyclic discharge properties. Ablations of areas 4 and 6 in the precentral cortex demonstrated that striatal bursting was under afferent control. The putamen, which receives more cortical afferents from areas 4 and 6 than the caudate nucleus, had fewer and less intense bursts after the afferents were lesioned. Bursts intensity did not change in the pallidum after the lesion. The findings indicate that bursting properties contribute to discharge variability in the basal ganglia and suggest that information transfer in the striatum may utilize bursts. In contrast, rate coding may be a more important mechanism for units in the pallidum.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29420/1/0000496.pd

Lesions of the Precentral Gyrus in Nonhuman Primates: A Pre-Medline Bibliography

Many contemporary investigators are unaware of the important papers involving lesions of the primate primary motor cortex published prior to those revealed by a computer search of the literature (i.e., papers published prior to about 1966). In order to increase awareness of these reports, we present here an annotated bibliography of these papers beginning with that of Ferrier and Yeo (1884). We provide evidence that these papers can provide valuable information on the function of the primate motor cortex and on recovery of behavior after brain lesions, and are also useful for sharpening the questions posed by more refined modern studies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44566/1/10764_2004_Article_454345.pd

GABAA, GABAB, and benzodiazepine binding sites in the cerebellar cortex of the red-eared turtle (Pseudemys scripta)

We used receptor autoradiography to ascertain the distribution of GABAA and GABAB binding sites in the cerebellar cortex of the red-eared turtle (Pseudemys scripta). GABAA binding sites were found in both molecular and granule cell layers with highest levels in the granule cell layer. GABAB binding sites were found at highest level in the molecular layer. Benzodiazepine binding sites were found in approximately equal abundance in both layers. Little binding of any ligand was seen in the Purkinje cell layer. Our results are similar to those found in mammals and other non-mammalian vertebrates and indicate that the organization of inhibitory pathways of the cerebellar cortex has been conserved in the course of vertebrate evolution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29731/1/0000067.pd

Basal ganglia glucose utilization after recent precentral ablation in the monkey

In the macaque monkey, unilateral ablation of areas 4 and 6 of Brodmann result initially in a signficant decrease of glucose metabolic activity in the ipsilateral caudate nucleus, putamen, globus pallidus, substantia nigra, and subthalamic nucleus. The contralateral hemisphere shows nonsignificant but consistently decreased activity in the caudate nucleus, putamen, and globus pallidus. Cerebral blood flow is decreased in the same pattern as the glucose metabolic activity. The change in glucose metabolic activity result from loss of neurons known to project directly from the cerebral cortex to the basal ganglia and also from indirect effect(diaschisis) in basal ganglia structures that do not receive connections from the cerebral cortex.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50310/1/410170503_ftp.pd

A signal generator for testing extracellular recording amplifiers and probes

A portable signal generator that simulates the amplitude and frequency of neuronal signals for testing extracellular recording amplifiers is described. The signal generator is easy to construct and it is extremely useful in tracing signal processing stages in neurophysiological equipment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27130/1/0000123.pd

Primate basal ganglia activity in a precued reaching task: preparation for movement

Single cell activity was recorded from the primate putamen, caudate nucleus, and globus pallidus during a precued reaching movement task. Two monkeys were trained to touch one of several target knobs mounted in front of them after an LED was lighted on the correct target. A precue was presented prior to this target “go cue” by a randomly varied delay interval, giving the animals partial or complete advance information about the target for the movement task. The purpose of this design was to examine neuronal activity in the major structures of the basal ganglia during the preparation phase of limb movements when varying amounts of advance information were provided to the animals. The reaction times were shortest with complete precues, intermediate with partial precues, and longest with precues containing no information, demonstrating that the animals used precue information to prepare partly or completely for the reaching movement before the target go cue was given. Changes in activity were seen in the basal ganglia during the preparatory period in 30% of neurons in putamen, 31% in caudate nucleus, and 27% in globus pallidus. Preparatory changes were stronger and more closely linked to the time of movement initiation in putamen than in caudate nucleus. Although the amount of information contained in the precues had no significant effect on preparatory activity preceding the target go cue, a directional selectivity during this period was observed for a subset of neurons with preparatory changes (15% in putamen, 11% in caudate nucleus, 14% in globus pallidus) when the precue contained information about the upcoming direction of movement. A smaller subset of neurons showed selectivity for the preparation of movement amplitude. A larger number of preparatory changes showed selectivity for the direction or amplitude of movement following the target go cue than in the delay period before the cue. The intensity of preparatory changes in activity in many cases depended on the length of the delay interval preceding the target go cue. Even following the target go cue, the intensity of the preparatory changes in activity continued to be significantly influenced by the length of the preceding delay interval for 11% of changes in putamen, 8% in caudate nucleus, and 18% in globus pallidus. This finding suggests that preparatory activity in the basal ganglia takes part in a process termed motor readiness. Behaviorally, this process was seen as a shortening of reaction time regardless of precue information for trials in which the delay interval was long and the animals showed an increased readiness to move. Preparatory activity in putamen following the target go cue was most intense in trials with a short delay interval, in which motor readiness had not achieved its maximum level prior to the go cue. The results of this study indicate that the basal ganglia are involved in multiple aspects of preparatory processing for limb movement. Preparatory processing is therefore unlikely to be divided anatomically along the functional lines examined in this study. In the basal ganglia, preparatory processing reflects both preparation for target selection and control of timing the onset of movement (motor readiness). These characteristics can be integrated in a functional scheme in which the basal ganglia are predominantly responsible for the automated execution of well-trained behavior.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46566/1/221_2004_Article_BF00229653.pd

A microdrive positioning adapter for chronic single unit recording

A new micropositioner design for use in chronic, transdural single unit recording studies is presented. The adapter is used to position an electrode microdrive assembly to any desired location within a surgically implanted recording chamber. The adapter uses a radial positioning technique that requires few moving parts. In comparison with the X-Y slide manipulator it replaces, it is more durable, it provides access to a larger brain area, and it attaches more securely. In addition, provision can be made to mount a second microdrive, permitting two electrodes to be manipulated independently.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27594/1/0000638.pd