Los experimentos de Lashley con ratas, y las observaciones de Head sobre pacientes humanos, han sido reintcrpretados de forma gradual. De hecho, se ha llegado a conclusiones similares a partir de estudios sobre conductas diferentes del lenguaje. Las lesiones del hemisferio derecho no producen estos defectos. Las consecuencias de estas lesiones irritativas son exactamente opuestas a las de las lesiones destructivas como consecuencia de un ictus o un traumatismo.

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In addition, the dominant hemisphere sometimes comments on the performance of the nondominant hemisphere, frequently exhibiting a false sense of confidence regarding problems in which it cannot know the solution, since the prijcipios was projected exclusively to the nondominant hemisphere.

However, a presynaptic cell does not neuociencia touch or communicate anatomically with the postsynaptic cell since the two cells are separated by a space, the synaptic cleft. This pattern of connection, in which one neuron activates many target cells, is called neuronal divergence; it is especially common in the input stages of the nervous system.

We now have obtained the first molecular structure of an ion channel, providing us with a threedimensional understanding of the ion channel pore. Most receptor potentials are depolarizing excitatory. Toward that end, we have completely redesigned the illustrations in the book to provide accurate, yet vividly graphic, diagrams that allow the reader to understand the fundamental concepts of neural science.

Specific brain regions are not concerned with faculties of the mind, but with elementary processing operations. The French neurologist Pierre Paul Broca was much influenced by Gall and by the idea that functions could be localized. Third, Gall proposed that the center for each mental function grew with dric, much as a muscle bulks up with exercise. These processes include the specification of cell fate, cell migration, axon growth, target recognition, and synapse formation.

We shall learn more about myelination in Chapter 4 and about action potentials in Chapter 9. An essay concerning humane understanding.

Posner and his colleagues concluded that the brain pathways and sensory codes used to see words are different from those used to hear words.

In the sensory systems receptor neurons at the input stage usually branch out and make multiple, divergent connections with neurons that represent the second stage of processing. Several areas defined by Brodmann have been found to control specific brain functions. As Adrian put it insummarizing his work on sensory fibers: But he could not speak grammatically or create complete sentences, nor could he express ideas in writing.

There is no evidence that glia are directly involved in electrical signaling. Similarly, areas of the brain concerned with movement contain an orderly arrangement of neural connections representing the musculature and specific movements.

The cytoarchitecture of the cerebral cortex of Ateles: Figure B The four lobes of the cerebral cortex. Thus, the signals that convey information about vision are identical to those that carry information about odors. In this task, she was aided by our colleague Jane Dodd, who as art editor supervised the program both scientifically and artistically.

Most other reflexes, including most spinal reflexes, use polysynaptic circuits that include one or more sets of interneurons. Aphasia patients not only manifest cognitive defects in language, but also have trouble with the affective aspects of language, such as intonation or prosody.

A modern form of this hypothesis was advanced by the Polish psychologist Jerzy Konorski in Thus, by the beginning of the twentieth century there was compelling biological evidence for many discrete areas in the cortex, some with specialized roles in behavior.

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