Early Ideas about Brain and Behavior

Mind, Brain and Behavior Neuroscientists want to unify the science of

the mind with the science of the brain. Actions of the brain underlie all behavior. What we call mind is a range of functions carried

out by the brain. Neural science explains behavior in terms of

brain activities. Where does psychology fit?

Where Does Mind Reside? Which part of the body is the seat of the soul,

the repository of memory? Aristotle (384-322 B.C.) said the heart. Hippocrates (460-379 B.C.) said the brain. Galen (130-200 A.D.) agreed with

Hippocrates: Cerebrum vs cerebellum Ventricles do the work

19th Century Views By the 1800’s, the nervous system had been

completely dissected and gross anatomy described. Injury to the brain disrupts functioning. Brain communicates with the body via nerves. The brain has parts that probably perform different

functions. The brain follows laws of nature and operates like a

machine.

Understanding by Analogy Metaphors have always been drawn from

discoveries in the physical world: fluid mechanics, windmills, man as machine.

Modern analogies: Mind as switchboard Mind as computer

Discarded Theories Fluid in ventricles, flow of humors

Galen Body as machine explained by mechanics

Nerves as hollow tubes full of gas or fluid Descartes

Nerves as “wires” Galvani, du Bois-Reymond, Muller, Helmholtz

The Discovery of the Neuron Golgi developed a silver staining method that

revealed the cell body and projections of the neuron.

Ramon y Cajal used the technique to show that neurons do not quite touch. Neurons are a network of separate (discrete) cells

that communicate. Galvani showed that the signaling is electric.

Golgi Stain

Nissl Stain

Localization vs Distribution Are specific functions carried out in specific

regions of the brain? Are functions an emergent property of brain

activity as a whole? Today’s neuroscience still debates this.

The answers appear somewhere between the two extremes.

Two Alternative Views Cellular connectionism:

Individual neurons are the signaling elements of the nervous system, arranged in functional groups

Supported by empirical observations of Ramon y Cajal, Wernicke, Jackson, Sherrington.

The aggregate field view: All regions of the brain participate in all mental

functions. Mind is NOT completely biological

The Localization Debate Gall – the brain consists of 35+ organs

corresponding to mental faculties. Observable through bumps on the head. Phrenology – anatomical basis for personology

Flourens – “…all perceptions, all volitions occupy the same seat…” Aggregate field view A reaction against strict materialism (mind not

completely biological).

The Discovery of Localization Imaging techniques that show the brain in

action confirm that certain functions are carried out in specific areas of the brain.

This was difficult to see early on because of parallel processing Each function is subserved by more than one

neural pathway. When one pathway is damaged, others may

compensate, making localization harder to see.

Support for the Field View Lashley found that the greater the lesions, the

greater the impairment in functioning. No matter where lesions were made, learning was

impaired. Mass action -- brain mass, not specific regions

was most important to functioning. Maze learning involves multiple functions, so

it is unsuitable for studying localization.

The Current View Functions consist of multiple processes that

occur in specific areas of the brain. Imaging studies reveal the different processes,

called elementary operations. Processing is both serial and parallel.

Even the simplest mental activity requires coordination of processes in multiple areas of the brain. Such processing appears introspectively seamless.