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Biomedical subjects

F Crick

Publications and source records attributed to F Crick.

At least 19 recordsLinked to original sources
PubMed1995

Are we aware of neural activity in primary visual cortex?

It is usually assumed that people are visually aware of at least some of the neuronal activity in the primary visual area, V1, of the neocortex. But the neuroanatomy of the macaque monkey suggests that, although primates may be aware of neural activity in other visual cortical areas, they are not directly aware of that in area V1. There is some psychophysical evidence in humans that supports this hypothesis.

Animals↗
PubMed1993

Looking backwards: a birthday card for the double helix.

This 'birthday' paper outlines very briefly the history of the discovery of the DNA double helix, the way it was received and how it was confirmed. The paper also discusses why, at that time, we foresaw so little of the rapid progress produced by the techniques of recombinant DNA. The key feature of the nucleic acids--discovered by Jim Watson--is their ability to form specific base pairs.

DNA↗
PubMed1993

Backwardness of human neuroanatomy.

To interpret the activity of living human brains, their neuroanatomy must be known in detail. New techniques to do this are urgently needed, since most of the methods now used on monkeys cannot be used on humans.

Animals↗
PubMed1989

The recent excitement about neural networks.

The remarkable properties of some recent computer algorithms for neural networks seemed to promise a fresh approach to understanding the computational properties of the brain. Unfortunately most of these neural nets are unrealistic in important respects.

Algorithms↗
PubMed1989

Neural edelmanism.

The recent book Neural Darwinism (ND) by Gerald Edelman, claims to put forward 'a radically new view of the function of the brain and nervous system'. Its main focus is on the understanding of the biological basis of perception. This new view is based on what Edelman calls 'The Theory of Neuronal Group Selection', the subtitle of his book. In spite of Edelman's lengthy and spirited account of this new theory, most readers appear to have had some difficulty in grasping his ideas and many have complained that the book is not easy to read. It has been particularly difficult to relate Edelman's ideas to those already current and well-known, especially as Edelman himself says rather little on this topic. In this critique I aim to set out Edelman's central ideas, as they appear to me, in a clearer and more digestible form. I examine both his general exposition of these ideas and the simulations he has presented to support them, giving page references so that the concerned reader can check my statements against the text. I have considered also Edelman's original papers, upon which the book is based, but I have not considered more recent papers which deal with matters (such as Darwin III) that are not covered in the book.

Animals↗
PubMed1984

Function of the thalamic reticular complex: the searchlight hypothesis.

It is suggested that in the brain the internal attentional searchlight, proposed by Treisman and others, is controlled by the reticular complex of the thalamus (including the closely related perigeniculate nucleus) and that the expression of the searchlight is the production of rapid bursts of firing in a subset of thalamic neurons. It is also suggested that the conjunctions produced by the attentional searchlight are mediated by rapidly modifiable synapses--here called Malsburg synapses--and especially by rapid bursts acting on them. The activation of Malsburg synapses is envisaged as producing transient cell assemblies, including "vertical" ones that temporarily unite neurons at different levels in the neural hierarchy.

Animals↗
PubMed1982

Long axons within the striate cortex: their distribution, orientation, and patterns of connection.

Rockland and Lung [Rockland, K. S. & Lung, J. S. (1982) Science 215, 1532-1534] have recently observed that an injection of horseradish peroxidase into the striate cortex of the tree shrew produces a patchy distribution of label adjacent to the injection site. They proposed that this pattern might be due to populations of neurons with long-range cortico-cortical connections that are interspersed with populations having no such connections. We suggest here an alternative explanation. We can account for the pattern by supposing that the label is carrier by a system of oriented axons. We suppose that these axons link cells with similar orientation preferences and make their connections within a narrow strip of cortex whose direction is related to the orientation of the cells in question. We suggest that such connections could be involved in generating complex receptive fields from simple ones. Other possibilities are that they are used to generate very elongated receptive fields, inhibitory flanks, or end-stopping. We suggest a number of experimental tests of these ideas.

Animals↗
PubMed1982

DNA today.

Explore the source record for details and available documents.

Base Sequence↗
PubMed1979

Split genes and RNA splicing.

A number of genes in higher organisms and in their viruses appear to be split. That is, they have "nonsense" stretches of DNA interspersed within the sense DNA. The cell produces a full RNA transcript of this DNA, nonsense and all, and then appears to splice out the nonsense sequences before sending the RNA to the cytoplasm. In this article what is known about these intervening sequences and about the processing of the RNA is outlined. Also discussed is their possible use and how they might have arisen in evolution.

Animals↗