Observations on the relationship between verbal explicit and implicit memory and neuronal density in the left and right hippocampus in temporal lobectomy patients.

The relationship between neuronal density and verbal memory in left and right hippocampal subfields was investigated in patients who underwent surgery for alleviation of temporal lobe epilepsy. The surgery consisted of unilateral partial removal of the hippocampus along with the anterior temporal lobe and amygdala. Study 1 looked at post-surgical explicit versus implicit verbal memory for lists of words while Study 2 looked at pre- and post-surgical explicit memory for word pairs. Left subfield CA1 appeared to be the most consistently involved in explicit and implicit memory. The results of the two studies confirm presence of hemispheric asymmetry in verbal memory. The notion that hippocampal control of memory is most apparent in post-surgical performance is discussed

The case for a relationship between human memory, hippocampus and corpus callosum

Unilateral brain damage which includes the hippocampus leads to memory impairments consistent with hemispheric specialization on the same side. Damage to the corpus callosum, the major connecting pathway between the left and right hemispheres, also leads to memory impairments. This suggests both hemispheric specialization on the hippocampal level and a critical role for the corpus callosum in memory functions. A complete hippocampal formation is present on either side of the brain but traditionally only one is studied. However, a comparison between the neuronal populations in the hippocampus on both sides revealed asymmetry in connectivity among hippocampal subfields. The profile of memory impairments of commissurotomy (‘split-brain’) patients is described. The results are discussed in terms of a relationship between hippocampus and corpus callosum in humans. As hemispheric specialization evolved, inter-hippocampal connections became less important and the corpus callosum became prominent in memory functions

Regional differentiation of neuron morphology in human left and right hippocampus: Comparing normal to schizophrenia

Regional differentiation based on size, form, and orientation angle of the soma of individual neurons in human post-mortem hippocampus was determined through correlations between pairs of hippocampal subfields in each side separately. The neurons were previously measured on a computer. In the normal cases, a left-right asymmetrical pattern of regional differentiation based on soma size emerged, while for form and orientation angle, the patterns appeared symmetrical. In schizophrenia, regional soma size, form, and orientation variability were expressed largely symmetrically. Regional correlations based on neuronal density revealed an asymmetrical hemispheric pattern in the normal cases versus a nearly symmetrical pattern in schizophrenia. Taken together, the inter-regional correlations favor a hippocampal landscape that deviates in each side from connectivity based on the canonical trisynaptic hippocampal circuitry. It is proposed that during morphogenesis, rudimentary inter-regional networks are formed through specific interactions between regional neurons; these networks are present in the adult hippocampus and may be vulnerable in brain diseases

Regularity on abelian varieties I

We introduce the notion of Mukai regularity (M-regularity) for coherent sheaves on abelian varieties. The definition is based on the Fourier-Mukai transform, and in a special case depending on the choice of a polarization it parallels and strenghtens the usual Castelnuovo-Mumford regularity. Mukai regularity has a large number of applications, ranging from basic properties of linear series on abelian varieties and defining equations for their subvarieties, to higher dimensional type statements and to a study of special classes of vector bundles. Some of these applications are explained here, while others make the subject of upcoming papers.Comment: 18 pages; final version, with substantial changes in the order of presentation in Section 2, and other minor expository changes, as suggested by the refere

Management of epilepsy

Figures for the incidence of epilepsy in Malta are not available. The overall figure for epilepsy given by the Royal College of General Practitioners (Reid 1960) is 4.82 per 1,000 population. As there is no reason to expect and difference in the incidence in these Islands, one can expect that there are at least 1,500 epileptics in Malta. This would mean that all general practitioners would, at some time, come across a patient with epilepsy.peer-reviewe