Stuttering acquired from subcortical pathologies and its alleviation from thalamic perturbation

Acquired stuttering subsequent to subcortical pathology of mesothalamus was observed in four neurosurgical subjects. The patients suffered from chronic pain, seizures, and somatosensory disorders. They also exhibited unpredictable and uncontrollable speech, spasmodic blocks which were devoid of accessory features, and adaptation effect. Therapeutic mesothalamic stimulation, used as a treatment of last resort to relieve the pain and associated symptoms, also had an ameliorating effect on the stuttering. Spontaneously occurring focal abnormal EEG discharges were anatomically delineated and used as a guide for therapeutic stimulation electrode placement. Attentuation of the abnormal discharges was followed by alleviation of symptoms. This investigation examines the clinical characteristics of stuttering in four neurosurgical patients and suggests an electropathologic basis for their mesothalamic-generated speech dysfluencies. The cooccurrence of pain, seizures, somatosensory disorders, and stuttering, and their concurrent amelioration, suggests that both chronic pain and stuttering may be implicated by similar or related reticular electropathologic generators, couched in overlapping reticular networks extending from the brain stem to the thalamus, and that the acquired stuttering may be recruited as one component of a larger syndrome complex.     

The effect of thalamic stimulation in processing of verbal stimuli in dichotic listening tasks: a case study

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct anatomic connection with the left dominant hemisphere. The role played by extralinguistic factors, such as attention and functional tuning of the associated cortical structures, has not been carefully examined. This investigation was undertaken to evaluate the effects of the left thalamic electric stimulation on the processing (recognition and recall) of dichotically presented CVC verbal stimuli in a patient being treated for chronic pain. We report the positive effects of electric stimulation (confirmed by increased subcortical metabolic activity using SPECT, a brain imaging technique) on the processing of dichotically presented verbal stimuli.     

Performance as a function of resultant achievement motivation (perceived ability) and perceived difficulty

Subjects worked on a task which was described as either easy or difficult. When the task was thought to be difficult, Ss high in resultant achievement motivation performed better than those low in resultant achievement motivation. However, when the task was perceived as easy, the high motive group performed worse than the low group. These results confirm a prediction from Kukla's attributional theory of performance, in which resultant achievement motivation is conceived as a measure of perceived ability. They are not, however, deriveable from Spence's theory of the effects on performance of objective task difficulty, nor from Weiner's hypothesis concerning the motivational effects of success and failure. On the other hand, Kukla's theory provides an explanation for both the data usually cited in support of Spence's position and those taken to confirm Weiner's hypothesis. The relationship between the present results and Atkinson's theory of achievement motivation, which also hypothesizes an effect of perceived difficulty on performance, is discussed.     

Metacognition in argument generation: the misperceived relationship between emotional investment and argument quality

Overestimation of one’s ability to argue their position on socio-political issues may partially underlie the current climate of political extremism in the U.S. Yet very little is known about what factors influence overestimation in argumentation of socio-political issues. Across three experiments, emotional investment substantially increased participants’ overestimation. Potential confounding factors like topic complexity and familiarity were ruled out as alternative explanations (Experiments 1–3). Belief-based cues were established as a mechanism underlying the relationship between emotional investment and overestimation in a measurement-of-mediation (Experiment 2) and manipulation-of-mediator (Experiment 3) design. Representing a new bias blind spot, participants believed emotional investment helps them argue better than it helps others (Experiments 2 and 3); where in reality emotional investment harmed or had no effect on argument quality. These studies highlight misguided beliefs about emotional investment as a factor underlying metacognitive miscalibration in the context of socio-political issues.     

Dissociating the effects of attention and contingency awareness on evaluative conditioning effects in the visual paradigm

Two experiments are described that investigate the effects of attention in moderating evaluative conditioning (EC) effects in a picture-picture paradigm in which previously discovered experimental artifacts (e.g., Field & Davey, 1999 ) were overcome by counterbalancing conditioned stimuli (CSs) and unconditioned stimuli (USs) across participants. Conditioned responses for individuals who had attention enhanced were compared against a control group and groups for whom attention was impeded using a distracter task. In a second experiment the effects of attention were dissociated from those of contingency awareness by using backward-masked US presentations. The results of these experiments indicate that although associative EC effects may not be disrupted by a lack of contingency awareness, attention is an important factor in establishing conditioning. These results shed some light onto the possible boundary conditions that could explain past inconsistencies in obtaining EC effects in the visual paradigm.     

Right-hemispheric language evidence from cortical stimulation

While the left-hemispheric dominance for language in most right-handers is unquestionable, clinical observations suggest that the right, nondominant hemisphere has a considerable capacity for language. Under certain neuroanatomical conditions, the right-hemispheric capacity becomes functional and, thus, measurable. This study focuses on evoked language responses during electrical stimulation of the right hemisphere in three left-dominant patients undergoing temporal lobe resections for medically intractable seizures.