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K Shibuki

Publications and source records attributed to K Shibuki.

45 records · Page 3Linked to original sources
PubMed1984

Supraoptic neurosecretory cells: synaptic inputs from the nucleus accumbens in the rat.

Synaptic inputs from the nucleus accumbens (ACB) to neurosecretory cells of the supraoptic nucleus (SON) were studied in the rat. One hundred and twenty SON neurones responded antidromically to pituitary stalk stimulation and were identified as neurosecretory cells. Sixty-three of these cells were identified as vasopressin-secreting cells and 45 as oxytocin-secreting cells by their spontaneous firing patterns. About one half of the vasopressin-cells and two thirds of the oxytocin-cells were responsive to stimulation of the basal forebrain including the ACB. More vasopressin-cells were excited than were inhibited, and oxytocin-cells were mainly inhibited. Depth profile of effective stimulation sites in the basal forebrain revealed that ACB stimulation selectively produced the responses. Most of those SON neurones responsive to ACB stimulation also responded to septal stimulation. A positive correlation was observed between responses to ACB and septal stimulation in each unit. After septal lesion, the number of SON neurones which were responsive to ACB stimulation was significantly decreased. In two rats, a single SON unit was tested for ACB stimulation both before and after septal lesion, and the previously observed synaptic inputs were not seen after the lesion. Fifty septal neurones projecting to the area including the SON were antidromically identified after SON stimulation. About one half of these neurones were excited by ACB stimulation. These results demonstrate the existence of a neural pathway from the ACB to the SON and suggest that the pathway is mediated by septal neurones.

Afferent Pathways↗
PubMed1984

Noxious inputs to supraoptic neurosecretory cells in the rat.

The effects of noxious stimuli were studied on discharge activity of the neurosecretory cells identified in the supraoptic nucleus by antidromic excitation after pituitary stimulation, in anaesthetized rats. Tail pinching excited 24% and inhibited spontaneous discharge of 6% of the 91 cells tested. Noxious heat stimuli (44-63 degrees C) applied to the hindlimb paw produced a transient excitation in 26% of the 23 cells tested. Electric stimulation of either the sciatic or cutaneous nerve with 20-Hz pulses for 1 s, at an intensity 5 times stronger than the threshold for evoking the changes in respiratory movements and blood pressure similar to those after tail pinching or noxious heat stimuli, excited about 30% of the cells tested. The excitation produced by these noxious stimuli preceded, on some occasions, the respiratory movement and blood pressure decrease which occurred concomitantly. Peristimulus time histograms of spontaneous discharges constructed during stimulation of either nerve at 1 Hz, revealed the presence of excitatory synaptic inputs in about 35% of the neurosecretory cells tested. These data indicate the existence of direct neural pathways which mediate excitatory synaptic inputs originating from nociceptors to supraoptic neurosecretory cells. Since 9 of the 22 cells which were excited by tail pinching exhibited a "phasic" pattern of spontaneous discharge which is known to characterize certain vasopressin-secreting neurones in rats, it is suggested that these excited cells were, at least in part, vasopressinergic.

Animals↗
PubMed1984

Conditioned heart rate response: testing under anaesthesia in rats.

Classically conditioned heart rate response was studied in anaesthetized rats. Rats were conditioned with photic stimuli followed by electric tail shocks in a conscious state and tested under anaesthesia for conditioned heart rate change. Testing photic stimuli evoked a transient bradycardia in about one-third of testing trials. Magnitude of the bradycardia was significantly greater in conditioned rats than that in untrained or control rats trained with electric tail shocks followed by photic stimuli. The difference was found to be mainly due to the difference in amplitude of individual bradycardia response rather than that in frequency of occurrence of the response. Testing stimuli also evoked a slight and sustained tachycardia, but magnitude of the tachycardia in conditioned rats did not differ significantly from that in control or untrained rats. These results suggest that effects of classical conditioning on autonomic functions can be detected and studied under anaesthesia.

Anesthesia↗
PubMed1984

Integration of retinal and motor signals of eye movements in striate cortex cells of the alert cat.

Responses of saccade-depressed (SD) and saccade-excited (SE) cells in the striate cortex to eye movements of alert cats under presentation of a visual pattern were studied under reinforcement of the eye movements with rewards of water. These responses were compared to those on passive displacement of the visual pattern reproducing the movements of the retinal image occurring during eye movements while eye movements were suppressed by withdrawal of reinforcement. Passive displacement of the visual pattern produced in the SD cells depression closely resembled the depression occurring during eye movements under presentation of the visual pattern, in time course as well as in amplitude. Both the saccade depression and the depression due to passive movement of the visual pattern were nonselective to the direction of eye movements. Saccade excitation of the SE cells frequently contained two components occurring at 20 and 80 ms after the onsets of eye movements. Passive displacement of the visual pattern produced in the SE cells excitation comparable with the early component of the saccade excitation. These findings suggest that saccade depression in the SD cells and the early component of the saccade excitation in the SE cells are related to retinal reafference of eye movement. During presentation of visual patterns, saccade excitation in the SE cells was closely related to parameters of eye movements, such as direction, amplitude, duration, and velocity. The correlations were completely lost or strongly reduced in darkness. Lines of evidence were provided that the saccade excitation of the SE cells in darkness or the later component of the saccade excitation under presentation of a visual pattern represents efference copy signals of eye movement transferred to the striate cortex through the Clare-Bishop (CB) cortex. Excitation comparable with saccade excitation in darkness occurred in synchrony with activities of the oculomotor nuclei even after retrobulbar paralysis of eye movement, indicating that the excitation is related to efference copy signals rather than proprioceptive reafference of eye movement.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Eye movement-related activities in cells of the lateral suprasylvian cortex of the cat.

Investigation of eye movement-related activities and photic responsiveness using behaving cats demonstrated distinctive representations of eye movement signals in different areas of the lateral suprasylvian cortex: visual reafference in the medial bank of the middle suprasylvian sulcus and non-visual signals (proprioceptive reafference or efference copy) in the lateral bank.

Animals↗
PubMed1982

Amygdalar inputs to ADH-secreting supraoptic neurones in rats.

Effects of amygdala stimulation on the discharge activity of antidromically identified supra-optic neurosecretory neurones were studied in male rats anaesthetized with urethane. Stimulation of the medial and the basal amygdala produced excitation or inhibition of discharge activity both in phasically firing ("phasic") and in continuously firing ("continuous") neurones. More "phasic" neurones were excited than were inhibited after medial amygdala stimulation. On the other hand, fewer "continuous" neurones were excited by stimulation of the either amygdala area than were inhibited. This difference of responsiveness between "phasic" and "continuous" neurones is statistically significant. Synaptic inputs to supraoptic neurosecretory neurones after amygdala stimulation were also observed in rats with a lesion of the stria terminalis. Supraoptic nucleus stimulation activated antidromically 14 of the 336 amygdala neurones tested. Since "phasic" neurones have been identified as ADH-secreting neurones, it is concluded that ADH-secreting neurones in the rat supraoptic nucleus receive predominantly excitatory synaptic inputs from the medial amygdala and these amygdalar synaptic inputs are mediated by pathways which are at least in part monosynaptic and are not included in the stria terminalis.

Amygdala↗