Single unit activity in monkey caudate nucleus during operant bar pressing feeding behavior

Unit activity and changes during bar press feeding behavior after presentation of food or non-food were analyzed in 198 neurons in the head of the caudate nucleus of monkey. Eight neurons responded uniquely at the sight of food. The degree of the food-specific responses differed depending on the nature of the food and the hunger-satiation state. On the other hand, 17 neurons responded more or less to the sight of food and during bar pressing for food. These two types of neuron seem to be important to bar pressing feeding behavior, which consists of recognition of food and a bar press task to obtain food.     

Single unit activity in frontal cortex and caudate nucleus of young and old rats

Spontaneous neuronal activity was recorded extracellularly from isolated single units in frontal neocortex and caudate nucleus of young and aged F344 rats anesthetized with urethane. Average firing rates, mean interspike intervals (ISI)±standard deviations, and ISI frequency histograms were computed and analyzed by microprocessor. For frontal cortex cells (N=226), there was a nonsignificant trend toward slower average discharge rates in the old group. However, a significantly longer mean ISI and proportionally more very slow firing cells (<I Hz) were observed in old rats. A laminar analysis of frontal cortex unit activity in young animals showed average discharge rates to be distributed somewhat evenly throughout the cortical mantle with the exception of the zone 1200–1400 μ beneath brain surface. This depth corresponds approximately to layer V where a 50% increase in mean firing rate in young animals was observed. In aged animals, this increased cell firing in layer V was absent, while mean discharge rates in other laminae remained essentially the same in the young and old rat groups. Caudate nucleus cells (n=70) showed a significant shift towards fewer fast discharging cells in old rats, with the average firing rate diminished by one-third. Although more brain regions need to be examined in a similar fashion, the consistency of the present results with those previously reported for the brainstem and cerebellum suggests that slower firing rates and longer ISIs are likely to be wide-spread throughout the brains of aged rats.     

Skilled forelimb movements and unit activity in motor cortex and caudate nucleus in rats

Adult hooded rats were trained to reach for small food pellets into a narrow plexiglass tube and movement of the preferred forelimb was photoelectrically detected. Unit activity was sampled from the motor cortex and caudate nucleus of unrestrained animals with capillary microelectrodes inserted into the brain with a miniature microdrive fixed to a chronically implanted guiding tube. Distribution of isolated spikes during 512 ms before and after the onset of reaching was compiled with a computer. The most striking reaction in the peri-reach histograms was a phasic activity increase starting 64 ms before to 32 ms after the forelimb extension and lasting about 100 ms, which was observed in about 20% neurons (n = 45) in the contralateral motor cortex. This reaction was clearly distinct from tonic excitatory and inhibitory responses starting 200-0 ms before reaching and lasting for several hundred ms. In the contralateral caudate nucleus (n = 62) excitatory and inhibitory responses occurred earlier and were often confined to the pre-extension period. Inhibitory reactions were prevalent in the ipsilateral cortex (n = 52) and caudate (n = 57).It is concluded that the phasic responses in the contralateral motor cortex participate in the actual reaching, whereas the tonic reactions in the contralateral cortex and caudate reflect the auxiliary support mechanisms. Predominantly inhibitory reactions in the ipsilateral hemisphere indicate reduced activity of the centres of the non-preferred forepaw.     

Effect of inactivation of sensomotor cortical function by cold on unit activity in the head of the caudate nucleus

Neuroscience and Behavioral Physiology -     

Neural activity in the caudate nucleus of monkeys during spatial sequencing

Single cell activity was recorded from the monkey caudate nucleus. The animal had to execute motor and oculomotor sequences based on memorised information. In each trial, the monkey had to remember the order of illumination of three fixed spatial targets. After a delay, the animal had to press the targets in the same sequence. The task-related cells were activated by onset of the targets and on execution of saccades or arm movements. In a majority of cells, activation did not depend only on the retinal position of the stimuli or on the spatial parameters of gaze and arm movements, but was contingent on the particular sequence in which the targets were illuminated or the movements were performed.     

Central and peripheral modulation of spontaneous neuronal activity in the caudate nucleus

The modulatory action of the caudate on the neural activity of the contralateral nucleus was studied in locally anesthetized, paralysed and artificially ventilated cats. This type of preparation was necessary because of a complete suppression of spontaneous spike activity after subanesthetic doses of general anesthesia. Two types of caudate action potential were characterized according to their waveform: biphasic and triphasic spikes, with a predominance of the former. These waveforms appeared to be independent of recording distance; however, their responses were similar to both central and peripheral stimuli. Caudate stimulation modified the spontaneous activity of the majority of the single units recorded within the opposite nucleus. This effect was mainly inhibitory and keeps up certain somatotopic distribution in the rostrocaudal extent of the nucleus. Kainic lesion of the site of stimulation suppressed the responses in the contralateral caudate nucleus, whereas the responses to substantia nigra and precruciate cortex remained unaltered. On the other hand, stimulation of the precruciate cortex opposite to the recording sites always excited the caudate neurons. The responses evoked by stimulation of ipsilateral substantia nigra and of contralateral sciatic nerve followed a similar pattern to those elicited by caudate stimuli. These results suggest a mostly inhibitory effect of the caudate on neuronal activity within the opposite nucleus, which is reinforced by the action of central and peripheral somatosensory inputs.     

Cell activity in monkey caudate nucleus preceding saccadic eye movements

Summary Using a special tetrazolium salt technique, a striking correlation was observed between Na⁺ concentration of the incubation medium and the formation of formazan catalyzed by glutamate dehydrogenase (GDH) in glutaniatergic neuropil areas of the hippocampal formation, cerebellum, and other brain regions. Na⁺ concentrations of 130–150 mmol/l caused maximal formazan production. The GDH catalyzed sodium-dependent increase in formazan production is suggested to be a consequence of the sodium dependence of glutamate uptake in glutaniatergic brain structures supplying the enzyme with substrate.     

Cholinergic mechanisms in the caudate nucleus

1. Acetylcholine (ACh), and a number of cholinomimetic and cholinolytic agents, have been applied to single neurones of the caudate nucleus, and the effects compared with those produced by stimulation of nucleus ventralis anterior thalami (VA).2. Neurones responding by excitation following ACh and VA stimulation, and others depressed by both ACh and VA stimulation have been observed. The two types of cell are located in different regions of the nucleus.3. Both types of ACh effect, and the responses to VA stimulation, are prevented by atropine.4. Taken with the earlier observation that the release of ACh from the caudate can be enhanced by VA stimulation, it has been suggested that the present results indicate a final cholinergic link in the pathway from VA to caudate.     

Patterns of unit responses to visual stimuli in the cat caudate nucleus under chloralose anesthesia.

After injection of horseradish peroxidase (HRP) into the right cardiac branches of the vagus nerve in the cat, the majority of HRP-labeled neurons were located ipsilaterally in the reticular formation ventrolateral to the nucleus ambiguus. Additionally, HRP-labeled neurons were also observed within the nucleus ambiguus (Am) and the dorsal motor nucleus of the vagus nerve (DM).     

Sensory afferents to the caudate nucleus

In awake immobilized cats, stimulation of nonspecific thalamic nuclei (NCM, DM) elicits evoked potentials in the head of the caudate nucleus (CN). The evoked potentials (EP) in the ventral part of CN are opposite in sign to those recorded in the dorsal region of CN. The points of polarity reversal are grouped in the lower third of CN. Peripheral sensory stimuli (somatic and visual) evoked potentials with a 20 msec latency. These evoked potentials change their polarity in the same region as the thalamic evoked responses. Visual and somatic responding areas overlap widely. The advantage of bipolar recordings for better localization is discussed.     

Analysis of unit activity in the posterolateral thalamic associative nucleus

Unit activity of the posterolateral thalamic nucleus (PLN) in response to heteromodal afferent stimuli (visual, acoustic, somatic) was investigated in cats anesthetized with chloralose. Most spontaneously active cells responded to all stimuli, alone or in combination, by a clear biphasic complex consisting of excitatory and inhibitory periods in different orders; other neurons responded differently to the stimuli: either with an initial spike discharge or an increase and, sometimes, decrease in the frequency of spontaneous activity. Units discharging only at the time of application of the stimuli possessed marked model specificity and the property of integrating heteromodal effects, as reflected in a significant decrease in latency and a change in the discharge pattern in response to combined stimulation.     

The cognitive functions of the caudate nucleus

The basal ganglia as a whole are broadly responsible for sensorimotor coordination, including response selection and initiation. However, it has become increasingly clear that regions of the basal ganglia are functionally delineated along corticostriatal lines, and that a modular conception of the respective functions of various nuclei is useful. Here we examine the specific role of the caudate nucleus, and in particular, how this differs from that of the putamen. This review considers converging evidence from multiple domains including anatomical studies of corticostriatal circuitry, neuroimaging studies of healthy volunteers, patient studies of performance deficits on a variety of cognitive tests, and animal studies of behavioural control. We conclude that the caudate nucleus contributes to behaviour through the excitation of correct action schemas and the selection of appropriate sub-goals based on an evaluation of action-outcomes; both processes fundamental to successful goal-directed action. This is in contrast to the putamen, which appears to subserve cognitive functions more limited to stimulus-response, or habit, learning. This modular conception of the striatum is consistent with hierarchical models of cortico-striatal function through which adaptive behaviour towards significant goals can be identified (motivation; ventral striatum), planned (cognition; caudate) and implemented (sensorimotor coordination; putamen) effectively.     

Changes in neurons of the caudate nucleus in experimental alcoholism

Reversible changes in caudate neurons and their dendrites in line with the components of compensatory reaction in oligodendrocytes are observed in rats during the first 3 weeks of a 12-month alcoholization period. After 2–4 months of alcoholization (the development of dependency), degenerative changes occur in caudate neurons and their dendrites system were evident. By the end of the 12-month period of alcohol intoxication, intensified deafferentation of the dendritic system was observed, suggesting functional insufficiency of the caudate nucleus. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 7, pp. 66–69, July, 1997