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Lipreading in patients with schizophrenia.

This study was designed to explore whether schizophrenic patients who are able to maintain their gaze with adequate persistence could competently lip-read. Four lipreading tests, designed to assess recognition of syllables, words, and overlearned sentences, were administered to 15 schizophrenic and 15 normal subjects matched for age, sex, and educational level. The patients proved to be competent lip-readers susceptible to the blend illusion and were inferior only in lipreading of overlearned sentences. The latter difficulty may tentatively be attributed to the inadequacy of the patient's premorbid social network for establishing contextual cues that aid in the recognition of overlearned sentences.

Adult

Changes in alpha rhythm asymmetry during learning of verbal and visuospatial tasks.

Alpha activity in the two cortical hemispheres was examined during learning and overlearning of a verbal and a visuospatial task. Compared to a pretask baseline condition, the amount of alpha activity during the tasks was decreased. An increase in alpha activity was found from learning to overlearning in both tasks. A greater amount of alpha was found in the right hemisphere for both tasks. In addition, no difference in the degree of alpha asymmetry was found between the tasks. This was discussed in light of prior contrary findings. A significant positive correlation was found between change in learning rate and change in alpha asymmetry during the verbal task. An interpretation of this finding was offered in terms of the level of hemispheric activation reflecting the degree of task engagement.

Alpha Rhythm

Visual and auditory event-related potentials elicited by linguistic and non-linguistic incongruities.

To test the hypothesis that violation of overlearned relations between stimuli in a sequence is critical for eliciting the event-related potential (ERP) N400, we recorded scalp ERPs in sequences where interstimulus relations were either overlearned (sentences or famous songs) or not (geometric figures or scale notes): 25% of the sequences ended with an incongruous stimulus. N400 occurred after incongruous words in sentences only. It seems to index the further processing necessary to specify the nature of the mismatch detected between attended and expected stimuli, when complex information is involved. Earlier components also varied as a function of experimental factors.

Adolescent

Letter matching: effects of age, Alzheimer's disease, and major depression.

We compared Alzheimer's disease (AD) patients and Major Depressive Disorder (MDD), Aged normal, and Young normal controls on a letter-matching task designed to measure the time needed to access overlearned linguistic information in long-term memory. Name identity (NI) and physical identity (PI) reaction time and the NI-PI difference were compared for ADs, MDDs, and Aged normals and separately for Aged and Young normal groups. AD subjects had slower NI and PI reaction times and a bigger NI-PI difference than Aged normal and MDD subjects, suggesting that speed of access to overlearned letter-name information in long-term memory is slowed for ADs. There were no reliable differences between Aged normal and MDD subjects. Aged normals had slower NI and PI reaction times and a bigger NI-PI difference than Young normals, suggesting that the highly practiced operations needed to access letter-name information slow with age. A discriminant analysis was used to evaluate the usefulness of the "easy to perform" letter-matching task for diagnostic purposes. Ninety percent of normal and MDD subjects but only 68% of AD subjects were classified correctly.

Adult

Reorganization of activity in the supplementary motor area associated with motor learning and functional recovery.

The supplementary motor area (SMA) of primates has been implicated in the initiation and execution of limb movements. However, when a motor task was extensively overlearned, few SMA neurons, if any, were active before the movement onset. Subsequent lesions of the primary motor cortex gave rise to the appearance of premovement activity changes, indicating usedependent reorganization of the neuronal activity in SMA.

Animals

The effects of word length and visual complexity on verbal reaction times.

Thirty adult subjects learned to associate nonsense names varying in word length with nonsense visual stimuli varying in visual complexity. Simple reaction times (SRTs), visual duration thresholds (VDTs), matching response latencies (MRLs), and naming response latencies (NRLs) were then obtained from these subjects. The data indicate that SRTs, VDTs, and NRLs are significantly related to word length and that VDTs and NRLs are significantly related to visual complexity. There is also a tendency for MRLs to increase with increases in word length, particularly for "no" responses. However, the effects of word length on VDTs, MRLs, and NRLs may be confounded with the number of trials needed to learn the paired associates or with the number of overlearning trials. The data are consistent with an interpretation that motor planning or some form of implicit speech process may be a part of the total time required for the naming response.

Humans

Recognition of inverted photographs of faces by children and adults.

Inverted black-white photographs of the faces of highly familiar peers (classmates, fraternity brothers, etc.) were presented to 350 Ss ranging from 3 to 20 years of age. In an untimed test session, S tried to identify the person in the inverted photograph. Success in this task was positively correlated with age up to approximately 14 years, but performance deteriorated after this age; college-age Ss and preschool Ss' performances were approximately equal. This finding contrasts with the current view that the effects of disorientation on perception becomes less potent with age. A cognitive explanation is offered for the early rise in the performance curve; the subsequent reduction in level of performance is attributed to rigidity of the perceptual mechanism as a function of overlearning of a mono-oriented configuration.

Adolescent

Neuropsychologic impairment in astrocytoma survivors.

Thirteen patients selected for long-term survival with primary astrocytic tumor (who failed to return to premorbid educational or vocational levels) were examined by neuropsychologic tests of specific and generalized higher cortical functions. In the absence of tumor regrowth or other neurologic disorders, each demonstrated difficulty in problem solving or coping with novel situations when previously acquired abilities, overlearned material, and psychometric intelligence appeared consistent with their premorbid level. The diffuse difficulties were unrelated to tumor type or location, and were not explicable by existing focal deficits, psychotic or depressive thought disorders, metabolic difficulties, or hydrocephalus. These examinations explained in part why these patients failed to resume active social lives or premorbid employment. The diffuse cortical dysfunction was most notable on the Category Test, Trails B, and Localization component of the Tactual Performance Test.

Adolescent

Stimulus function in simultaneous discrimination.

In discrimination learning, the negativity of the stimulus correlated with nonreinforcement (S-) declines after 100 training trials while the stimulus correlated with reinforcement (S+) is paradoxically more positive with lesser amounts of discrimination training. Training subjects on two simultaneous discrimination tasks revealed a within-subjects overlearning reversal effect, where a more-frequently presented discrimination problem was better learned in reversal than was a discrimination problem presented less frequently during training.

Animals

Thalamic astasia: inability to stand after unilateral thalamic lesions.

Inability to stand in the absence of motor weakness or marked sensory loss is usually considered to reflect midline cerebellar disease. However, the 15 patients reported here had astasia related to unilateral thalamic lesions, documented by autopsy and computed tomography in 2 patients and by computed tomography in 13. The lesions, including infarction (6), hemorrhage (7), and tumor (2), involved primarily the superoposterolateral portion of the thalamus, but spared the rubral region. Alert, with normal or near-normal strength on isometric muscle testing and a variable degree of sensory loss, the patients could not stand and 7 of them could not sit up unassisted. They fell backwards or toward the side contralateral to the lesion. They appeared to have a deficit of overlearned motor activity of an axial and postural nature. In the vascular cases, the deficit improved in a few days or weeks. However, these patients had a tendency to sustain falls during the rehabilitation period.

Aged

Increased susceptibility to memory intrusions and the Stroop interference effect during acute marijuana intoxication.

The marijuana-induced acute memory impairment was assessed in a double-blind, crossover experiment. Twelve males smoked NIDA-supplied cigarettes containing 1.2% delta-9-tetrahydrocannabinol (THC) or cannabinoid-exhausted marijuana (placebo) in counterbalanced order on 2 days 1-3 weeks apart. Practice, pre- and postsmoking test sessions were conducted with the Paced Auditory Serial Addition Test, Stroop Color and Word Test, and alternate forms of the Randt Memory Battery and the Controlled Oral Word Association Test. A significantly greater number of short story omissions and intrusions occurred in delayed free recall after marijuana. Immediate and sustained attention, controlled retrieval from semantic memory, and speed of reading and naming colors were not affected. The Stroop interference effect was significantly greater following marijuana. Subjects appeared to experience parallel difficulties in inhibiting associations to the new material and inhibiting the overlearned response of reading in a new learning task. Marijuana may compromise associative control, presumably a cognitive process inherent in memory function.

Adult