Signalled free-operant avoidance of shock by pigeons pecking a key

Two pigeons were trained to peck a key under a free-operant avoidance schedule. Then, changes in key color signalled the beginning (safe period) and the end (warning period) of the response-shock interval, with a response required to change the key color. Finally, a change in key color signalled the warning period and either a response or a shock reinstated the safe stimulus. During signalled avoidance, response rate was higher during the warning stimulus than during the safe stimulus. More responding tended to occur in the warning stimulus when it was terminated by either a response or a shock than by only a response. In either procedure, response latency during the warning stimulus was a function of the duration of the warning stimulus. In general, response and shock rate were higher during unsignalled than during signalled avoidance. When the warning stimulus was brief, the results were similar to those of unsignalled avoidance. These results confirm previous findings with pigeons, are in general agreement with data provided by other species in studies of signalled avoidance, and thereby indicate the transituationality of the key-pecking operant.     

The role of anionic, imidic and amidic forms in structure-activity relationships. Conjugation and bacteriostatic activity in sulphonamides.

The electronic structures of anionic, imidic and amidic forms of sulphonamides were investigated and compared by means of I.R., Raman and U.V. spectroscopy. Indices reflecting the electronic situation of the common moiety p-H2N-C6H4-SO2 was a whole, although not necessarily related, physically, to any event taking place in the biological processes, were found to correlate with the in vitro bacteriostatic activity of the specific individual forms. The influence of N1-substituents both on the SO2 electronic features and on the coupling between the para amino group and the phenyl ring was discussed. It resulted that the most active chemical species, in this class of compounds, are characterized, electronically, by the most electron-rich common moiety and, in particular, by the most negative oxygens in the SO2 group and the most available (less engaged) lone-pair in the rho-amino group. These conclusions give a new settlement both to the problem of resonance and to the relation between resonance effects and bacteriostatic activity in this class of compounds.     

Conditioning of striatal dopamine metabolism with methadone,morphine or bulbocapnine as an unconditioned stimulus

Psychotropic drugs such as methadone, morphine and bulbocapnine produce increments in dopamine metabolism as an unconditioned reflex. When a buzzer noise is used as a conditioned stimulus (CS) with these drugs as unconditioned stimuli, the buzzer CS acquires the properties of the drugs in increasing dopamine metabolism. These results suggest that the brain, like other visceral organs, can be conditioned in terms of neurotransmitter release or metabolism.     

Acquired aphasia in children and the ontogenesis of hemispheric functional specialization.

We have described a series of 26 cases of cortical lesions in children from $\text{3}\text{1}\text{2}$ to 15 years of age (17 left-sided, six right-sided, three bilateral), in which 19 had varying degrees of language disturbance. We have attempted to establish the nature and evolution of these aphasic disorders, and have compared our observations to those previously published. Our analysis appears to indicate a relative hemispheric equipotentiality which permits the transfer of language representation to the opposite hemisphere in the case of a unilateral lesions in childhood. This conclusion, however, has at least the appearance of being in conflict with other reported findings, viz., those deriving from psychometric testing of subjects with unilateral perinatal lesions; and those concerning studies of fetal and newborn brains which suggest a very early, if not innate, hemispheric specialization.The fact of this discrepancy has lead us to reconsider the concept of a critical period as defined by Lenneberg. In this respect, we have also discussed the possibility of a partial transfer of language representation, of an intrahemispheric reorganization by intact “uncommitted” areas (P. Goldman), and finally, the need for an adequate stimulus during a given period in order for a preformed area to become functional.