The effect of different hypertension models on active avoidance learning

This study tested the effects of different hypertension models on active avoidance learning in rats. Three-month-old male Wistar rats were divided randomly into six groups as follows: control (C), sham operated (sham), two kidney-one clip (2K-1C), one kidney-one clip (1K-1C), deoxycorticosterone-salt (DOCA), and N-omega-nitro-L-arginine-methyl ester (L-NAME) groups. Mean arterial blood pressures were significantly higher in four hypertensive groups compared with control and sham groups. The active avoidance training results indicated that hypertension state is associated with learning impairment. Thiobarbituric acid-reactive substances (TBARS) were determined as an indicator of lipid peroxidation in brain and hippocampus. Additionally, brain and hippocampus nitrite levels were studied.     

Word associations in deep dyslexia

Deep dyslexia is an acquired reading disorder resulting in the production of semantic errors during oral reading and an inability to read aloud nonwords. Several researchers have postulated that patients with deep dyslexia have both phonological and semantic access impairments but the data supporting these claims are not convincing. In fact, the hallmark feature of deep dyslexia--the semantic errors--strongly implies that these patients can access semantic information from printed words. We test the integrity of the semantic system in two such patients through auditory and visual word association tasks. The data support the notion that semantics remains intact and that the disorder and associated errors arise through a selection impairment related to failure of inhibitory connections in the phonological lexicon.     

Modulation of tremor amplitude during deep brain stimulation at different frequencies

Rest tremor was quantified in the index finger tip of 16 patients with Parkinson's disease (PD) receiving deep brain stimulation (DBS) of the ventro-intermediate nucleus (Vim) of the thalamus, the subthalamic nucleus (STN), or the internal part of the globus pallidus (GPi) while being off L-dopa for 12h. Clinically, without DBS, tremor amplitude varied from absent to high. Tremor was recorded continuously for about 5 min under three conditions of DBS repeated twice, namely, effective frequency (E), ineffective frequency (I), and no DBS (O). No changes in tremor were observed across conditions in subjects with little or no tremor. However, in subjects with moderate to large amplitude tremor, DBS decreased tremor amplitude to near normal values within a few seconds. Generally, transitions were progressive and occurred with a varying time delay. Occasionally, tremor escaped from control regardless of the stimulation condition considered. In some cases tremor amplitude in one condition appeared to depend on the preceding condition. Finally, the results were reproducible on two consecutive days. We conclude that tremor control with DBS follows specific dynamical rules, which must be compatible with the hypotheses proposed regarding the underlying mechanisms of DBS.     

The time course of attentional focusing in dyslexic and normally reading children

A cue size procedure was used to evaluate the time course of visuo-spatial attention in dyslexic and normally reading children. When a stimulus target is presented inside a large cue vs a small cue the identification time is slower. In the present study two cue-target delays (100 and 500 ms) were used. Results showed a slower time course of attentional focusing in dyslexics vs normal readers. Indeed, dyslexics exhibited no cue size effect at a shorter cue-target delay (100 ms), while it was present at a longer cue-target delay (500 ms). In contrast, a cue size effect was found at both cue-target delays in normally reading children. These results further support the hypothesis of sluggish automatic focusing of visual attention in dyslexics. This impairment could be a consequence of a general magnocellular deficit demonstrated previously in dyslexics.     

Do separate processes identify objects as exemplars versus members of basic-level categories? Evidence from hemispheric specialization

When an object is identified as a specific exemplar, is it analyzed differently than when it is identified at the basic level? On the basis of a previous theory, we predicted that the left hemisphere (LH) is specialized for classifying objects at the basic level and the right hemisphere (RH) is specialized for classifying objects as specific exemplars. To test this prediction, participants were asked to view lateralized pictures of animals, artifacts, and faces of famous people; immediately after each picture was presented, a label was read aloud by the computer, and the participants decided whether the label was correct for that picture. A label could name the object at either the basic level (e.g., bird) or as an exemplar (e.g., robin). As predicted, we found that basic-level labels were matched faster when pictures were presented in the right visual field (and hence encoded initially in the LH), whereas exemplar labels were matched faster when pictures were presented in the left visual field (and hence encoded initially in the RH).     

Impaired processing of prosodic and musical patterns after right hemisphere damage

The distinction between the processing of musical information and segmental speech information (i.e., consonants and vowels) has been much explored. In contrast, the relationship between the processing of music and prosodic speech information (e.g., intonation) has been largely ignored. We report an assessment of prosodic perception for an amateur musician, KB, who became amusic following a right-hemisphere stroke. Relative to matched controls, KB's segmental speech perception was preserved. However, KB was unable to discriminate pitch or rhythm patterns in linguistic or musical stimuli. He was also impaired on prosodic perception tasks (e.g., discriminating statements from questions). Results are discussed in terms of common neural mechanisms that may underlie the processing of some aspects of both music and speech prosody.     

Item recognition memory and the receiver operating characteristic

Four experiments were conducted to investigate the effects of study time, study repetition, semantic and orthographic similarity, and category length on item recognition memory receiver operating characteristics (ROCs). Analyses of ROC shape rejected A. P. Yonelinas's (1994) dual-process model. The normal unequal variance signal-detection model provided a better account of the data, except for a small but consistent excess of high-confidence errors. It was found that z-transformed ROC slope was increased by similarity, category length, and study item repetition, rejecting R. Ratcliff, G. McKoon, and M. Tindall's (1994) "constancy-of-slopes" generalization for these variables, but slope was relatively unaffected by massed study time.     

Recognising facial expression from spatially and temporally modified movements

We examined how the recognition of facial emotion was influenced by manipulation of both spatial and temporal properties of 3-D point-light displays of facial motion. We started with the measurement of 3-D position of multiple locations on the face during posed expressions of anger, happiness, sadness, and surprise, and then manipulated the spatial and temporal properties of the measurements to obtain new versions of the movements. In two experiments, we examined recognition of these original and modified facial expressions: in experiment 1, we manipulated the spatial properties of the facial movement, and in experiment 2 we manipulated the temporal properties. The results of experiment 1 showed that exaggeration of facial expressions relative to a fixed neutral expression resulted in enhanced ratings of the intensity of that emotion. The results of experiment 2 showed that changing the duration of an expression had a small effect on ratings of emotional intensity, with a trend for expressions with shorter durations to have lower ratings of intensity. The results are discussed within the context of theories of encoding as related to caricature and emotion.