Higher Percentage Of Responses Research Articles

Motor cortex modulation of exteroceptive information at bulbar and thalamic lemniscal relays in the cat

We have studied the control of the primary motor cortex on the activity of lemniscal neurons in semi-chronic implanted cats. In each experiment, two to three foci in the primary motor cortex were identified by intracortical microstimulation at low threshold (up to 20 μA) for their capacity to evoke movements of contralateral single limb joints. Neurons belonging to the dorsal column nuclei (main cuneate nucleus and gracile nucleus), or to the ventral posterolateral nucleus, were sampled for their response to stimulation of the peripheral cutaneous fields, as well as the antidromic response to stimulation of the contralateral medial lemniscus and ipsilateral somatosensory cortex, respectively. These neurons were then tested for stimulation of the cortical foci using a current intensity equal to the threshold needed to evoke motor effects, although we reduced the duration of the stimulating trains; thus, we avoided evoking movements which could elicit afferent volleys along the somatosensory paths. It was found that the primary motor cortex was able to modulate the transmission of exteroceptive signals at the level of both dorsal column nuclei and ventral posterolateral nucleus with analogous modalities. In particular: (i) a high percentage of responses, with a prevalence of excitatory effects, was observed when the receptive field of the neurons topographically corresponded to, or was very close to, the joint controlled by a given cortical focus; (ii) in these cases, higher percentages of excitations were observed in tests which concerned the distal segments of limbs than the proximal segments; (iii) the percentage of responses became lower as the neuronal receptive field was located further from the cortical motor target, the pattern being more frequently inhibitory in nature. From a functional point of view, the motor cortex control appears to be organized in a very precise manner. Its excitatory nature might subserve integrative mechanisms by which exteroceptive information arising in a given limb segment would be enhanced by a motor command inducing movements of the same body part. Moreover, a better definition of the afferent input could be obtained by a simultaneous depression of neurons, which send towards the cortex signals from adjacent or more distant cutaneous regions. It can be hypothesized that such an organization of the cortical control could improve the discriminative somatosensory aspects during the execution of explorative movements, besides supplying a sharper cutaneous feedback to the motor cortex.

Aggressive chemotherapy for acute leukemia relapsed after transplantation.

Bone marrow transplantation procedure has emerged as an effective treatment for hematological malignancies. However, recurrence of leukemia is still the major cause of treatment failure. Subsequent treatment in this category of patients, generally considered incurable, has not been yet standardized. At our institution, 13 patients, 7 with acute non lymphoid leukemia (ANLL) and 6 with acute lymphoid leukemia (ALL), were treated at relapse after bone marrow transplantation either autologous or allogeneic (AuBMT 8, ABMT 4) performed in complete remission (CR). The interval between BMT and relapse was less than 9 months in 6 patients (2 ABMT and 4 AuBMT) and more than 9 months in 7 patients. Early relapsed patients showed no response to treatment and died at a median of 5.5 months (range 1-13) after relapse. Late relapse after BMT was characterized by a high percentage of response (5 CR and 1 PR), particularly after intensive chemotherapy and by a longer survival (median 14 months; range 2-36). Chemotherapy after transplantation should be carefully evaluated in patients relapsed after BMT in order to select a population that can achieve long term disease free survival.

The role of R-S ∗ expectancy in discrimination and discrimination reversal learning

Four experiments assessed the role of response-reinforcement (R-S ∗) expectancy as rats either learned a discrimination or a discrimination reversal. Experiment 1 showed that the higher the percentage of reinforcement during nondiscriminative pretraining the more quickly a subsequent discrimination is learned. Experiment 2 demonstrated that the overlearning reversal effect (ORE) can be obtained even though the overtraining phase consists of responses to a single neutral card. In Experiment 3 subjects were again overtrained on a single neutral stimulus under conditions of varying reinforcement. ORE was apparent under reinforcement of a high percentage of responses but was not apparent under reinforcement of a low percentage. Experiment 4 revealed that the fewer errors a subject makes prior to reversal the better its reversal performance is. Results of these studies were discussed in terms of generalized attention theories and the expectancy notions of Bolles ( Psychological Review, 1972, 79(5), 394–409 .

A phase II study of phenesterin (NSC‐104469)

Phenesterin was evaluated in 222 patients with two different dosage regimens, one by daily treatment and the other with an intermittent schedule. Toxicity was moderate with both programs. The largest group of patients treated had breast cancer; they experienced a 10% response rate. Of interest was a higher percentage of responses in ovarian cancer (36%). An expanded study of patients with ovarian cancer would be of interest.

Some determinants of associations to French and English words

The effect of language set and language competence on bilingual word associations was studied. Students at varying levels of competence in French were given preliminary instructions in either French or English, and they then took a wordassociation test, consisting of stimulus words in both languages. More advanced students gave more responses in French. Students instructed in French gave a higher percentage of responses in French, and French stimuli produced more French responses for advanced students. There was a strong tendency to respond with a word from the same form class as the stimulus.

Neurophysiological evidence for a differential organization of the mesencephalic reticular formation

1. I. A systematic exploration of the reticular activating system (RAS) was carried out to study the possibility to elicit selectively either the immediate phasic component or the delayed tonic component of the reticular response to brief stimulation, previously described (Bonvallet and D'Anna 1966). The whole extent of the reticular formation and of the posterior hypothalamus was stimulated point by point with short lasting trains of repetitive pulses in encéphale isolé cats under Flaxedil. All the recorded responses were compared, using EEG desynchronization, inhibition of the pupillo-constrictor tone and inhibition of a polysynaptic cranial reflex as indicators of the duration of reticular activation. The following observations were made. 1. (a) The immediate phasic component was present in all the recorded responses. 2. (b) A delayed tonic component of variable duration was also present in the responses evoked by stimulation of the bulbar and pontine reticular planes. The highest percentage of responses with a very long lasting sustained component was observed in the responses elicited from the dorsal part of the rostro-pontine tegmentum (Fig. 2, plane E). 3. (c) In the responses elicited from the anterior mesencephalon the sustained component was markedly reduced (Fig. 3, planes F and G). This component was completely absent from the responses evoked by stimulating a well defined area located above the anterior pole of the red nucleus. The short lived responses elicited from this localized area were not prolonged following elimination of the bulbar control of reticular activation (Fig. 6). 4. II. The electrical responses evoked by somesthetic and auditory stimuli in the reticular regions differentiated during the stimulation experiments were also compared. 1. (a) The somatic evoked potentials recorded in the rostral pontine tegmentum were more consistent and had shorter latencies than those recorded in the anterior mesencephalon. 2. (b) In the above described localized suprarubral area the somatic evoked potentials either were absent or had a small amplitude and an elevated threshold. 3. III. These results indicate the critical importance of the rostro-pontine reticular activating structures for the production not only of sustained cortical arousal ( cf. Batini et al. 1959a, b) but also for sustained reticular discharges influencing motor and vegetative activities. They also give evidence of a functional differentiation of a small reticular area in the anterior mesencephalon, which appears to be implicated only in the transmission of very short lasting reticular influence.