Damage to the dorsomedial thalamic nucleus, central lateral intralaminar thalamic nucleus, and midline thalamic nuclei on the right-side impair executive function and attention under conditions of high demand but not low demand.

This study reports a patient, OG, with a unilateral right-sided thalamic lesion. High resolution 3T magnetic resonance imaging revealed damage to the parvicellular and magnocellular subdivisions of the dorsomedial thalamus (DMT), the central lateral intralaminar nucleus (also known as the paralamellar DMT), the paraventricular and the central medial midline thalamic nuclei. According to the neuropsychological literature, the DMT, the midline and intralaminar thalamic nuclei influence a wide array of cognitive functions by virtue of their modulatory influences on executive function and attention, and this is particularly indicated under conditions of low arousal or high cognitive demand. We explored this prediction in OG, and compared his performance on a range of low and high demand versions of tests that tapped executive function and attention to a group of 6 age- and IQ-matched controls. OG, without exception, significantly under performed on the high-demand attention and executive function tasks, but performed normally on the low-demand versions. These findings extend and refine current understanding of the effects of thalamic lesion on attention and executive function.

Stimulus timing by people with Parkinson's disease.

Previous literature suggests that Parkinson's disease is marked by deficits in timed behaviour. However, the majority of studies of central timing mechanisms in patients with Parkinson's disease have used timing tasks with a motor component. Since the motor abnormalities are a defining feature of the condition, the status of timing in Parkinson's disease remains uncertain. Data are reported from patients with mild to moderate Parkinson's disease (both on and off medication) and age- and IQ-matched controls on a range of stimulus timing tasks without counting. Tasks used were temporal generalization, bisection, threshold determination, verbal estimation, and a memory for duration task. Performance of patients was generally "normal" on all tasks, but significant differences from performance of controls were found on the memory for duration task. Among the "normal" effects noted were arithmetic mean bisection, asymmetric temporal generalization gradients, and subjective shortening on the memory for duration task. The results suggest (a) that some previous reports of timing "deficits" in Parkinson's patients were possibly due to the use of tasks requiring a timed manual response and (b) small differences between patients and controls may be found on tasks where two stimuli are presented on each trial, whether patients are on medication or off it.

A cognitive neuropsychological and psychophysiological investigation of a patient who exhibited an acute exacerbated behavioural response during innocuous somatosensory stimulation and movement.

We report findings from a cognitive neuropsychological and psychophysiological investigation of a patient who displayed an exacerbated acute emotional expression during movement, innocuous, and aversive somatosensory stimulation. The condition developed in the context of non-specific white matter ischaemia along with abnormalities in the cortical white matter of the left anterior parietal lobe, and subcortical white matter of the left Sylvian cortex. Cognitive neuropsychological assessment revealed a pronounced deficiency in executive function, relative to IQ, memory, attention, language and visual processing. Compared to a normal control group, the patient [EQ] displayed a significantly elevated skin conductance level during both innocuous and aversive somatosensory stimulation. His pain tolerance was also significantly reduced. Despite this, EQ remained able to accurately describe the form of stimulation taking place, and to rate the levels of pain intensity and pain affect. These results suggest that EQ's exaggerated behavioural response and reduced pain tolerance to somatosensory stimulation may be linked to cognitive changes, possibly related to increased apprehension and fear, rather than altered pain intensity or pain affect per se.

Recognition memory abnormalities in asymptomatic biological parents of a patient with schizophrenia.

BACKGROUND: Recognition memory dysfunction has been frequently reported in schizophrenic populations, and has been linked with the development of delusions and thought disorder. A range of neuropsychological abnormalities have also been documented in the biological asymptomatic relatives of patients with schizophrenia; however, recognition memory has not been one of them. AIM: This study was carried out in order to investigate: (i) verbal and facial recognition memory in terms of accuracy and false alarm rates; and (ii) contributions from the episodic and semantic memory systems to recognition memory, in the biological asymptomatic parents of a reported schizophrenic patient and a set of male and female psychotic controls. RESULTS: Gender differences failed to emerge between the psychotic controls on any of the recognition measures (discrimination accuracy, response bias, hit and false alarm rates, 'remember' and 'know' recognition memory decisions). However, there was evidence of recognition dysfunction in the female relative, and to a lesser extent, in the male. Both parent's recognition memory performance profiles were marked by a pathologically elevated false alarm rate, and an increased dependence 'remember' judgements, i.e. input from the episodic memory system, to drive recognition memory decisions. CONCLUSIONS: These findings are discussed in the context of models of episodic and semantic memory impairment in schizophrenia.

Contribution of the left dorsomedial thalamus to recognition memory: a neuropsychological case study.

This study reports a patient with a unilateral left thalamic lesion which was centred on the dorsomedial thalamic nucleus. Cognitive neuropsychological assessment revealed a severe impairment in verbal memory and symptoms of executive dysfunction, in the presence of relatively intact visual and facial recognition, working memory, praxis, language and IQ. Verbal and visual recognition memory were investigated using the remember-know paradigm. The results indicated a profound impairment in recollection-driven verbal recognition memory. These results are discussed in the context of the role of the dorsomedial thalamic nucleus in recognition memory, and functional models of memory.