摘要:

AbstractThe regions of the gill neural plexus responsible for habituation of the withdrawal reflex were studied using surgical and electrophysiological techniques. Waterdrops were applied to the gill pinnule, and testing for habituation was carried out in each preparation before and after ganglionectomy of the large ganglion in the gill and pinnule isolation. Three parameters of habituation, response decrement, spontaneous recovery, and dishabituation, were used to evaluate the function of the ganglion and the plexus in the pinnule in habituation of the reflex. Disruption of response decrement, of spontaneous recovery, and of dishabituation were caused by either isolating the stimulated pinnule from the gill ganglion by severing the branchial nerve, or by extirpating the gill ganglion. We conclude that: (a) the gill ganglion is necessary for the withdrawal reflex to exhibit the three parameters which characterize hibituation; and (b) the plexus in the pinnule mediates the withdrawal reflex. Extracellular recordings from the pinnule showed that sensory adaptation cannot be contributing to habituation of the reflex since the apparent sensory activity evoked by waterdrops in the pinnule was unaltered by repeated stimulation. In gill ganglion neurons, biphasic potentials were evoked by waterdrops and consisted of an initial depolarization followed by a longer lasting hyperpolarization whose duration was increased with repeated stimulation. In three spontaneously active neurons the rate of activity decreased with repeated stimulation. It is felt that the decreased rate is brought about by potentiation of the hyperpolarization. The rate of spike activity is considered to control the reflex amplitude since the increased rate with intracellular stimulation, in one neuron, resulted in an increased amplitude and since the absence of spontaneous discharge, after ganglionectomy, resulted in a reduced amplitude. A neural network mediating habituation of the withdrawal reflex is proposed.

ISSN:0022-3034    

DOI:10.1002/neu.480050303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractOptomotor memory in crustaceans was studied by recording the activity of optomotor neurons. Animals were placed in a stationary striped drum, which was subsequently turned in the dark to a new position. Upon reillumination the eye movements of the animals follow the apparent movement of the stripes. It can be inferred that the position of the stripes after movement is compared with the remembered position of the stripes before movement.The size and sign of the memory response of the optomotor neurons are functions of the apparent movement. Changes as small as 0.1° can be detected. Memory starts forming almost immediately upon exposure of a position and develops as a function of viewing time. While a new memory is forming, the old one, though declining, is still present for 30 sec. In the dark a memory declines gradually, lasting for more than 8 min. In certain circumstances the set point of memory is adjusted for the effects of eye movements.The possibilities that memory involves a peripheral afterimage or stabilization of a particular part of the eye upon a particular feature of the surroundings are considered

ISSN:0022-3034    

DOI:10.1002/neu.480050304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe efflux of45Ca2+and3H‐GABA from cat cerebral cortex has been measuredin vivoby a superfusion technique. Under control conditions, the efflux of both these isotopes is sensitive to increments in the calcium concentration of the superfusion medium but insensitive to the addition of 25 mMGABA. After 40 min of contact with medium containing 25 mMglutamate, however, neither45Ca2+nor3H‐GABA efflux is affected by added Ca2+but3H‐GABA efflux becomes considerably enhanced by 25 mMGABA. The mean membrane potentials at this time were found to be less than controls. Depolarization generally continued past this time, recovery beginning 150 min after superfusion with glutamate. Peaks in45Ca2+efflux were also correlated with seizure activity which was sometimes elicited by topical glutamate. It is suggested that the transport systems for Ca2+and GABA may be sensitive to states of neural activity, such as spreading depre

ISSN:0022-3034    

DOI:10.1002/neu.480050305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe patterns of protein metabolism of identified cholinergic (R2, L10, and L11) and neurosecretory (R3–13, R14, and Bag cells) cells were analyzed with the use of SDS‐polyacrylamide gel electrophoresis and isoelectric focusing. L11was unique amongst the three cholinergic neurons in its relatively high rate of incorporation of labeled leucine into proteins at 12,000 daltons. All the neurosecretory cells incorporated relatively large quantities of3H‐leucine into small proteins (<12,000 daltons), which were concentrated in putative neurosecretory granule fractions of these cells. R3–13and R14synthesized a distinct basic protein which appeared specifically in the branchial nerve which contains the axons of these cells. The combination of these two analytical electrophoretic techniques allowed for the characterization of protein specificity in single nerv

ISSN:0022-3034    

DOI:10.1002/neu.480050306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractWhen stimulated with rapidly approaching targets, the crayfish defense reflex exhibited habituation, spontaneous recovery, dishabituation, and stimulus generalization. The rate of habituation increased with stimulus repetition rate over a narrow range of stimulus rates. At the highest repetition rate examined, 20 min, the rate of habituation diminished. After 150 trials at 20 min, responsiveness to subsequent stimuli at lower repetition rates was enhanced. Dishabituation was elicited with mechanical prods to the dorsal thoracic carapace or a 1‐min session of 20\min stimulation. After completion of habituation a 5° shift in the axis of a 10° target resulted in substantial response recovery. Evidence for weak interocular generalization of habituation was also obtained. These results suggest both retinal‐dependent and retinal‐independent sites of habituation. Picrotoxin (2.4 mg\kg body weight) reversed a previously established response habituation and delayed the onset of rehabituation to repetitive stimuli. The effects of picrotoxin suggest the participation an inhibitory mechanism in defense reflex habi

ISSN:0022-3034    

DOI:10.1002/neu.480050307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480050302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY