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Biomedical subjects

C D Hull

Publications and source records attributed to C D Hull.

At least 55 records · Page 3Linked to original sources
PubMed1983

Effects of neonatal destruction of the medial forebrain bundle in the cat: long-term disturbances in learning ability, response to amphetamine challenge, and reactivity to auditory stimuli.

These experiments ascertain some of the long-term behavioral effects of neonatal medial forebrain bundle (MFB) lesions in the cat. Bilateral electrolytic lesions (N = 27) were made when the animals were 11 to 22 days of age. The long-term behavioral development of cats with these lesions were compared with that of a group of intact littermates (N = 37) and a group of littermates that received lesions that did not encroach upon the MFB. When the animals were 18 to 40 days of age they were tested in a spatial discrimination. Animals with bilateral MFB lesions were capable of learning the discrimination but made more repeated errors than animals in the other groups. This effect was compensated for with additional training. When tested on a visual discrimination at 3 to 4 months of age, kittens with MFB lesions learned the discrimination in a normal manner. When the discrimination cues were reversed, however, they responded more frequently to the previously reinforced cue. The effects of d-amphetamine were assessed when animals were 7 to 12 months of age. Animals with bilateral MFB lesions displayed less frequent and intense head movement stereotypies and more locomotor responses to amphetamine than animals in other groups. The reactivity to a series of auditory stimuli was assessed when the animals were 1 to 2 years of age. Neonatal MFB lesions produced an impaired pattern of habituation of reactivity to auditory stimuli. Cats with these lesions responded normally to the initial presentations of the vocalizations. However, 24 h later they responded to the stimuli more vigorously than animals in the other groups. Taken together the results of this experiment and the previous report indicate that some effects of neonatal MFB damage were qualitatively different from those of lesions inflicted in mature animals and that a complex interaction among a number of factors was probably responsible for these differences.

Acoustic Stimulation↗
PubMed1982

Amphetamine alters evoked responses of nigral neurons in kittens and adult cats.

The effects of i.p. amphetamine administration (5 mg/kg) on the evoked unitary responses of substantia nigra (SN) neurons to electrical stimulation of their afferents were tested in 4 kittens (3-27 days of age) and 4 adult cats. In adults, amphetamine had two major effects: (1) it blocked temporarily (15-30 min) all neuronal responses caudate (Cd) and cortical (Cx) stimulation; neuronal responsiveness recovered by 75 min post-drug; and (2) after 15 min postdrug, Cd and Cx stimulation evoked initial excitatory responses that were almost never found predrug. The latencies of Cd-evoked excitations indicated the existence of a mono- or oligosynaptic excitatory strionigral pathway while latencies of Cx-evoked excitations suggested that corticonigral excitatory influences were mediated multisynaptically. In kittens, amphetamine also produced an initial blockade of Cd- and Cx-evoked responses. However, the sign of initial responses to Cd stimulation was not altered since excitations were found both before and after drug treatment. These results indicated that amphetamine reveals excitatory evoked responses of SN neurons to striatal and striatally-mediated inputs that are masked during the course of normal postnatal development. Drug-related alterations of afferent inputs to SN neurons may underlie amphetamine-induced shifts in spontaneous neuronal activity which have been reported frequently.

Afferent Pathways↗
PubMed1982

Development of spontaneous neuronal activity in the caudate nucleus, globus pallidus-entopeduncular nucleus, and substantia nigra of the cat.

Spontaneous single unit activity was obtained from caudate (Cd), globus pallidus-entopeduncular nucleus (GP-Ento), and substantia nigra (SN) neurons in kittens of 1-60 days of age and adult cats. Five developmental trends were found in the spontaneous firing patterns of these neurons: (1) overall mean interspike intervals (ISIs) decreased with age; (2) the occurrence of neurons with shorter mean ISIs (less than 400 ms) increased with age; (3) the occurrence of neurons with burst activity increased with age; (4) burst activity became more complex with age; and (5) the rate of burst occurrence in neurons with burst activity increased with age. Neurons within each region of the basal ganglia had characteristic patterns of spontaneous activity. Furthermore, the developmental patterns of spontaneous neuronal activity were different in each structure. The spontaneous activity of GP-Ento and SN neurons matured before the spontaneous activity of Cd neurons. Thus, spontaneous firing may mature in the output nuclei of the basal ganglia prior to its maturation in the Cd.

Action Potentials↗
PubMed1982

Postnatal ontogeny of evoked neuronal responses in the substantia nigra of the cat.

Single unit extracellular responses evoked by striatal, cortical, and somatosensory stimulation were recorded in substantia nigra (SN) neurons of kittens (1-70 days of postnatal age) and adult cats. Neuronal responses to stimulation of each site were obtained throughout postnatal development. However, 4 major developmental shifts in the response of neurons were found: (1) the responsiveness of neurons to orthodromic activation increased with age; (2) the signs of the initial responses of neurons to orthodromic activation increased with age; (2) the signs of the initial responses of neurons to caudate and cortical stimulation changed with age (excitatory and inhibitory responses in kittens vs almost entirely inhibitory responses in adults); (3) the the response latencies of neurons decreased with age; (4) nigral neurons that were activated antidromically by stimulation of nigrostriatal axons showed age-related decreases in refractory periods and increases in conduction velocities.

Age Factors↗
PubMed1982

Effects of caudate nuclear or frontal cortical ablation in neonatal kittens or adult cats on the spontaneous firing of forebrain neurons.

In this paper we have determined the long-lasting consequences of caudate and frontal cortical lesions on spontaneous neuronal firing. Lesions were made both in neonatal and adult cats. All recordings were made in adults. Qualitatively, the effects of the caudate ablations were similar whether they had been carried out in kittens or in adult cats. Caudate lesions produced long-lasting (greater than or equal to 1 year) decreases in the spontaneous firing of cortical neurons. These changes were more pronounced when made in neonates than in adults. The distributions of mean interspike intervals were also altered by these caudate lesions in the pallidum and in the ventral lateral nucleus of the thalamus. Again these effects were more marked if the animals were lesioned as neonates than as adults. Frontal cortical lesions inflicted upon adult cats produced more widespread changes in spontaneous firing rates than similar lesions made in neonates. In both groups frontal lesions slowed spontaneous firing and changed the distributions of mean interspike intervals of caudate neurons. These effects were long-lasting (greater than or equal to 1 year in neonatally-ablated animals). Cortical lesions made in adult cats markedly altered thalamic and pallidal spontaneous activity. Similar lesions made in neonates produced relatively small changes in thalamic and pallidal activity.

Action Potentials↗
PubMed1981

Quantitative developmental studies of feline neostriatal spiny neurons.

This research documents aspects of the quantitative development of the 'medium' spiny neuron in the kitten from 2 to 143 days of age. Using material derived from 244 Golgi-impregnated neurons in 15 kittens and with computer assistance the changes in somatic, dendritic and spine development were quantified. Although mean somatic diameter increased only slightly from 2--3 to 8--10 days of age, the proportion of neurons with large diameters increased significantly during the developmental period. In addition, the radius of the dendritic field of caudate spiny neurons increased significantly over the age period examined. An unexpected finding was that the number of dendrites per neuron decreased with age, probably due to a decrease in the proportion of neurons with 6 or more dendrites in animals 90--143 days of age. Growth of dendritic segments occurred throughout the age period studied. This growth was apparently caused by lengthening of all dendritic segments and this resulting increase was proportional to the initial length of the individual branches. Number of branches per dendrite and frequency of dendritic branches with different orders remained constant across age indicating that the basic dendritic branching pattern is probably set for the cat before birth. With maturation the density of spines on distal dendritic branches increased while on proximal dendritic branches spine density decreased. The time course of these quantitative changes was related to alterations in synaptogenesis and physiological changes in caudate neurons.

Aging↗
PubMed1980

Iontophoretically applied dopamine depolarizes and hyperpolarizes the membrane of cat caudate neurons.

Dopamine (DA) was applied iontophoretically on intracellularly recorded cat caudate neurons. Ejected approximately 100 micrometers away from the cell soma, it caused slow depolarizations of the membrane while the ongoing firing rate was reduced. This last effect was not due to sodium inactivation. Cortically evoked EPSP-IPSP sequences were inhibited during the depolarizations. The latency of cortically evoked action potentials was consistently increased during DA-ejections. These effects were blocked by fluphenazine, relatively selective blocker of the DA-sensitive adenylate cyclase. Nevertheless, there are serious doubts as to the specificity of these actions of DA as a number of other substances like naloxone, nicotine, acetylcholine or glutamate-diethylester occasionally had very similar effects on membrane potential, firing rate and cortically evoked EPSP-IPSP sequences. If DA was applied nearer to the soma, approximately 50 micrometers away, 70% of the recorded neurons continued to display the slow depolarizations above described, while 30% of the cells now reacted by a hyperpolarization accompanied also by a reduced firing rate. If DA was applied for prolonged periods on such cells, the initial hyperpolarization was followed by the slow depolarization. The observation that during the slow depolarization there is a decrease in firing rate and amplitude of the cortically evoked IPSP is explained by the assumption that the region of the axon hillock is hyperpolarized by DA, and that the slow depolarization is a phenomenon restricted to the distant recording site and possibly to the dendritic region. None of the 74 responsive neurons displayed an increased firing fate when DA was ejected either continuously, i.e. for more than 5 sec, or in short pulses of 50--500 msec.

Animals↗
PubMed1980

The spontaneous firing patterns of forebrain neurons. V. Time course of changes in caudate unit activity following dopamine-depleting lesions.

The effects of unilateral medial forebrain bundle ("MFB") lesions on the spontaneous firing patterns of caudate neurons on both sides of the brain in cats were studied 3 days, 7 days and more than 2 weeks postlesion. Our results indicate that: (1) the spontaneous firing of neurons in the caudate nucleus ipsilateral to the lesion slows significantly by 3 days postlesion and returns to control values by 7 days postlesion, (2) the spontaneous activity of contralateral caudate neurons slows progressively with postlesion time and (3) these changes in neural activity are not correlated with changes in dopamine concentrations in the caudate nucleus.

Animals↗
PubMed1980

Development of motor activity in kittens.

Developmental alterations in motor activity were quantified for the 1st 7 postnatal months in the kitten. Motor activity measured with a stabilimeter was low and constant for the 1st 9 postnatal days, increased markedly until Day 14, and remained stable until Day 21. Locomotor activity measured in an open field decreased slightly during the 1st 3 weeks, increased markedly during the next 2 weeks, and then remained relatively constant until the 9th week. Activity increased again during the 3rd and 4th month and then declined until 7 months of age. We suggest that the marked increase in motor activity during the 2nd week reflects development of visual and auditory systems whereas the increase in locomotor activity during the 4th and 5th weeks represents maturation of neural systems concerned with motor control. The underlying causes of the final activity changes probably represent the maturation of many neural systems and concomitant development of adult behavior in the cat.

Age Factors↗
PubMed1979

Intracellular analysis of the development of responses of caudate neurons to stimulation of cortex, thalamus and substantia nigra in the kitten.

Intracellular recordings were made from caudate neurons in anesthetized kittens of 2-72 days of age. In adult cats, results of intracellular recordings indicate that caudate neurons respond most frequently to stimulation of their major afferents from cortex, thalamus and substantia nigra with a sequence of excitation followed by inhibition (EPSP-IPSP sequence). The results of the present study show that the prominent IPSP of this sequence is not well developed in young kittens and does not reach adult values in terms of frequency of occurrence until beyond 40 days of age. Amplitude and duration of the IPSP evoked by cortical stimulation also did not reach adult values until beyond 40 days of age. In contrast, EPSPs can be evoked in the youngest kittens by stimulation of afferents to the caudate. These findings suggest that the caudate nucleus may alter its role during development. In early postnatal periods it functions as a simple relay system transmitting incoming information to its outputs in a relatively unaltered fashion. Later in development it becomes a system capable of complex modulation and filtering of neural information.

Aging↗
PubMed1979

Projections to the neostriatum from the cat precruciate cortex. Anatomy and physiology.

The projections to the striatum from two cytoarchitectonically and functionally distinct subdivisions of the cat precruciate motor cortex were studied using anatomical and electrophysiological techniques. Our results indicate that the medial precruciate cortex (stimulation of which leads to movements of the axial and proximal musculature) has a widespread projection to the lateral half of the caudate nucleus. The lateral precruciate cortex (stimulation of which leads to movements of the distal musculature) has a localized projection within the caudate nucleus adjacent to the internal capsule. Both medial and lateral precruciate areas project to the putamen. These results are discussed in relation to recent studies suggesting that the basal ganglia are involved in the enabling and sequencing of movements.

Afferent Pathways↗
PubMed1979

The spontaneous firing patterns of forebrain neurons. IV. Effects of bilateral and unilateral frontal cortical ablations on firing of caudate, globus pallidus and thalamic neurons.

To assess the effects of partial deafferentation of the neostriatum on spontaneous neuronal activity in the basal ganglia and related thalamic nuclei, ablations of frontal cortex were carried out in adult cats. Postoperative measures of interspike intervals of single neurons in the caudate nucleus, globus pallidus and ventral anterior-ventral lateral complex of the thalamus revealed a slowing of neuronal firing in these structures as compared with non-lesioned controls. The fact that deafferentation by cortical damage produces changes in neuronal firing in target neurons of the striatum (globus pallidus) and in thalamic neurons at least two synapses removed from the striatum is noteworthy. The possible extent to which these results might have been influenced by reduction of cortical inputs to or denervation of the thalamus is discussed.

Afferent Pathways↗
PubMed1978

Preparation for movement in the cat. I. Unit activity in the cerebral cortex.

Single unit activity was recorded from the 'motor' cortex of cats during performance of a forelimb flexion movement. Two classes of cortical neurons were defined with respect to the onset of electrographic activity associated with this movement. 'Early' unit, first showing changes in firing rates more than 0.5 sec prior to the movement, were found almost exclusively in the medial precruciate cortex. The lateral cortex appears to be made up almost uniformly of 'late' unit, that is, neurons whose activities are more closely related with the actual movement. The medial cortex, on the other hand, contains both 'early' and 'late' units and thus may have the additional function of participating in the neural system which is the substrate for response set.

Animals↗