Biomedical subjects

P L Randall

Publications and source records attributed to P L Randall.

4 recordsLinked to original sources

PubMed1998

Schizophrenia as a consequence of brain evolution.

Connectionist integration of central nervous system function may have proceeded by a process of biological trial and error throughout brain evolution. As existing structures enlarged, and as new elements of brain function were added, misconnectionist variants could arise. This might account for a number of developmental syndromes in the human brain including schizophrenia. Ultimately, these would derive from aspects of hominid brain evolution and its vertebrate ancestry.

Animals↗

PubMed1983

Schizophrenia, abnormal connection, and brain evolution.

Abnormalities of functional connection between specialized areas in the human brain may underlie the symptoms which constitute the schizophrenia syndrome. Callosal and intrahemispheric fibres may be equally involved. The clinical emergence of symptoms in the later stages of brain maturation may be dependent on myelination of these fibre groups, both of which have extended myelination cycles. Ontogenetically earlier variants of the same mechanism could theoretically result in dyslexia and the syndromes of Kanner and Gilles de la Tourette. As new and unique extensions of specialized function emerge within the evolving brain, biological trial and error of connection both within and between them may produce individuals possessing phylogenetically advanced abilities, or equally, others possessing a wide range of abnormalities including those which comprise the schizophrenia syndrome. A dormant phenotypic potential for schizophrenia may exist in individuals who never develop symptoms during the course of a lifetime though some of these may become clinically apparent under the influence of various precipitating factors. It is concluded that abnormal functional connection and its normal and "supernormal" counterparts may be natural, essential, and inevitable consequences of brain evolution, and that this may have been so throughout the history of vertebrate brain evolution.

Agenesis of Corpus Callosum↗

PubMed1981

An alternative mechanism of actions for neuroleptic and antidepressant drugs.

It has earlier been proposed by the author that the aetiology of schizophrenic symptomatology may be due to the presence of abnormally connected interhemispheric fibres which link specialised functions in the brains of schizophrenics that are not connected in normal subjects, and that the neuroleptic drugs may produce their action through a local anaesthetic-like effect in suppression of conduction in these fibres. This line of thought has been extended here to consider the possible mechanism of action of the neuroleptic drugs in more detail, as well as that of the tricyclic antidepressant drugs which are derivatives of the phenothiazine group. Pharmacological similarities with the local anaesthetics both structurally and functionally have been considered, as well as the effects that these drug groups may have in common with the lithium salts. It has been suggested that these drugs all produce their primary effect on cell membranes, though not necessarily at the synapse, that the time course of their clinical effect may correlate with their incorporation into various cell membranes within the CNS, and that they may thus bring about a fundamental alteration in cell membrane microstructure. The possible role of electroconvulsive therapy has also been considered. The corollary of this argument is that the affective disorders may be genetically determined diseases of cell membrane microstructure.

Anesthetics, Local↗

PubMed1980

A neuroanatomical theory on the aetiology of schizophrenia.

This theory proposes that schizophrenic symptoms are due to the presence of myelinated interhemispheric nerve fibres which link functional areas in the brains of schizophrenics which are not connected in normal subjects. The role these fibres would have in the production of schizophrenic symptoms is examined in the context of recent neuroanatomical and neurophysiological findings in schizophrenics. The functional emergence of these fibres is examined phylogenetically in conjunction with central nervous system myelination. Genetic biochemical and therapeutic implications are considered.

Brain↗