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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 88 (1992), S. 517-530 
    ISSN: 1432-1106
    Keywords: Basal ganglia ; Globus pallidus ; Neostriatum ; Movement Neuronal activity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single-unit extracellular neuronal recordings were obtained from the globus pallidus (GP) and the neostriatum (NS) of rats while they performed a learned head movement in response to an auditory cue. In both GP and NS, units that altered their discharge rate in association with head movements and with the cues that triggered these head movements were prevalent. Frequently, the responses were directionally-specific (i.e., the magnitude or direction of change in firing rate of these neurons was substantially different for trials in which head movements were made to the left vs. the right). For some units, firing rates were altered only in response to the movement cue or only in association with head movements. However, the majority of neurons exhibited responses with both cue-related and movement-related components. Neuronal responses to the auditory cue usually were context-dependent, in that they did not occur if the same stimulus was presented when the animal was not performing the task. At least a small proportion of GP and NS neurons also appeared to exhibit context-dependent movement-related activity, in that responses occasionally were observed that were associated either with sensory-triggered head movements or with spontaneous head movements, but not with both. These data are consistent with previous suggestions that the activity of basal ganglia neurons during movement performance is highly dependent on the conditions associated with movement initiation. The data also indicate that the response characteristics of both GP and NS neurons in the rat are generally similar to those that have been described for basal ganglia neurons in primates and cats during sensory triggered movement tasks. However, the proportion of task-related neurons that exhibited responses with both movement-related and cue-related components was greater than has generally been reported in studies of cats and primates, suggesting that neurons with these response properties may be more predominant in the rat basal ganglia.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 51 (1983), S. 227-235 
    ISSN: 1432-1106
    Keywords: Long-lasting neostriatal inhibition ; Neostriatal spiny neuron ; Basal ganglia ; Disfacilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Excitatory postsynaptic potentials evoked in rat neostriatal spiny projections neurons were followed by a long (100–300 ms) period of membrane hyperpolarization, followed in turn by a late depolarization. Concomitant with these changes in membrane potential were inhibition and subsequent excitation of spontaneous firing and excitatory activity evoked from substantia nigra and cerebral peduncle, but not from cortical stimulating sites. Thalamic-evoked excitatory activity was sometimes sensitive and sometimes insensitive to this inhibition, which has previously been believed to result from intrinsic inhibitory synaptic activity among neostriatal neurons. In intracellular recordings from neostriatal neurons in urethane anesthetized rats this longlasting inhibitory response (1) exhibited alterations with intracellularly applied steady currents comparable to those of the EPSP, (2) failed to respond to intracellular injection of chloride ions, (3) was associated with either a decrease or no detectable change in the input conductance of the neurons, and (4) was abolished after lesions that interrupted polysynaptic pathways to neostriatum through intracortical and intrathalamic synaptic circuits. These findings indicate that the long lasting inhibitory portion of the responses of neostriatal neurons arises from a phasic inhibition of tonically active corticostriatal and thalamostriatal neurons and a concurrent decrease in the excitability of polysynaptic pathways converging on neostriatal neurons.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 51 (1983), S. 217-226 
    ISSN: 1432-1106
    Keywords: Thalamostriatal pathway ; Neostriatum ; Basal ganglia ; Neostriatal spiny neuron ; Thalamostriatal EPSPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stimulation of thalamic intralaminar nuclei or structures along the intrathalamic trajectory of thalamostriatal axons evoked complex EPSPs and subsequent hyperpolarizations in rat neostriatal spiny neurons identified by intracellular injection of horseradish peroxidase and/or antidromic activation from substantia nigra. In intact urethane-anesthetized rats, the initial EPSP portion of the response consisted of several components and lasted up to 75 ms. Short (1–10 ms) latency components exhibiting latency variations suggestive of a polysynaptic origin were often observed, and sometimes were the earliest components of the response. However, individual components of the excitatory response could not be clearly distinguished in most neurons and the earliest excitatory component usually appeared to be monosynaptic. After large acute aspiration lesions of ipsilateral cerebral cortex, the early polysynaptic EPSP components of thalamic-evoked EPSPs were absent or greatly attenuated. This suggested that most or all of the short latency polysynaptic EPSP components arose via a thalamo-cortico-striatal route. A short latency (1.6–4.0 ms) monosynaptic EPSP and a second excitatory component with a longer and more variable latency (8–28 ms) remained intact after acute decortication. These were not dependent upon intact corticothalamic or corticostriatal axons, since they were both still present in experiments performed as long as 4 days following ipsilateral hemidecortication. The longer latency excitatory response was shown to be polysynaptic by its latency variation with changes in stimulus intensity and frequency. This component of the response was abolished after acute thalamic hemitransections separating thalamostriatal neurons from their axons. In these experiments, stimulation of thalamostriatal axons rostral to the transection continued to evoke monosynaptic EPSPs in neostriatal spiny neurons. These EPSPs ranged from 1.8 to 3.0 ms in latency, had peak amplitudes up to 11 mV and were 20–37 ms in duration.
    Type of Medium: Electronic Resource
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