Neuropsychologia
-
Clinical Trial
Networks of domain-specific and general regions involved in episodic memory for spatial location and object identity.
Positron emission tomography (PET) was used to investigate human episodic memory for spatial location and object identity. We measured regional cerebral bloodflow (rCBF) while subjects engaged in perceptual matching of the location or the identity of line drawings of objects. Perceptual matching also involved incidental encoding of the presented information. ⋯ Evidence of domain-specificity was also found in the prefrontal cortex and the left hippocampus, but the effect interacted with encoding and retrieval. Domain-general structures included bilateral superior temporal cortex regions, which were preferentially activated during encoding, and portions of bilateral middle and inferior frontal gyri, which were preferentially activated during retrieval. Together, our data suggest that encoding and retrieval in episodic memory depend on the interplay between domain-specific structures, most of which are involved in memory as well as perception, and domain-general structures, some of which operate more at encoding and others more at retrieval.
-
A patient developed the severe amnesic syndrome 8 years after temporal lobe surgery for epilepsy. He underwent left temporal lobectomy (6 cm, 43.5 g; hippocampal sclerosis) aged 19, and remained seizure free for 8 years until a convulsion followed a head injury. He became severely amnesic after a fourth convulsion 16 months later. ⋯ Autopsy showed: previous left temporal lobectomy with absence of left amygdala and hippocampus, atrophy of fornix and mamillary body; neuronal loss in the right hippocampus, severe in CA1 and CA4; intact right amygdala and parahippocampal gyrus; recent diffuse damage associated with cause of death. A convulsion can cause severe hippocampal damage in adult life. Hippocampal zones CA1 and/or CA4 are critical for maintaining memory and the amygdala and parahippocampal gyrus cortex alone cannot support acquisition of new memories.
-
Case Reports
Untroubled musical judgement of a performing organist during early epileptic seizure of the right temporal lobe.
The case of a professional musician with a right temporal lobe epilepsy is presented. Whilst playing an organ concert (John Stanley's Voluntary VIII, Op. 5), he suffered a complex partial seizure. The recorded concert performance (with the seizure) was analysed and compared with other available exercise records and with the composition. ⋯ With increasing duration of the seizure discharge, the dissociation of both hands from the score increased but the right hand compensated for the errors of the left hand in a musically meaningful way, i.e. with the aim to compensate for the seizure-induced errors of the left hand. The case illustrates untroubled musical judgement during epileptic activity in the right temporal lobe at the beginning of the seizure. Whereas the temporal formation of the performance was markedly impaired, the ability of improvisation-in the sense of a 'perfect musical solution' to errors of the left hand-remained intact.
-
Training and instructions in the use of mental imagery can lead to improved retention in patients with memory impairment as the result of brain injury or disease. The amount of improvement varies inversely with the severity of memory impairment, but it largely unrelated to either the aetiology or the locus of brain damage. ⋯ However, brain-damaged patients may need explicit prompting if they are to use imagery mnemonics successfully and often fail to maintain their use on similar learning materials or to generalise their use to new learning situations. As a result, imagery mnemonics will typically be of little practical value in enabling memory-impaired individuals to respond to the cognitive challenges of everyday life.
-
Clinical Trial
Motor imagery of a lateralized sequential task is asymmetrically slowed in hemi-Parkinson's patients.
We examined seven right-handed, asymmetrical (right side affected) Parkinson's disease patients and seven age-matched controls in a manual finger sequencing test using left and right hands in vision, no vision, and motor imagery conditions. All patients displayed motor asymmetry, favoring the left hand. ⋯ Additionally, impairment in mental hand rotation correlated significantly with the imagery asymmetry. These data support two related hypotheses: (a) Motor sequence imagery and execution share common neural structures. (b) The frontostriatal system is among these shared structures.