Hemispheric Specialisation

Hemispheric Specialisation

Earliest Research –

First observed through stroke victims or other injuries to only one hemisphere...

Work by Sperry and Gazzaniga

Roger Sperry and Michael Gazzaniga

What we already know...

AOS: 1 - Outcome: 1

Key Knowledge from Study Design

Role of the brain in mental processes and behaviour

• the influence of different approaches over time to understanding the role of the brain, including the brain vs

heart debate, mind-body problem, phrenology, first brain experiments and neuroimaging techniques

• the basic structure and function of the central and peripheral nervous systems as communication systems between the body’s internal cells and organs and the external world

• the role of the neuron (dendrites, axon, myelin and axon terminals) as the primary functional unit of the nervous system, including the role of glial cells in supporting neuronal function

• the basic structure and function of the hindbrain (cerebellum, medulla), midbrain (reticular formation) and forebrain (hypothalamus, thalamus, cerebrum)

• the role of the cerebral cortex in the processing of complex sensory information, the initiation of voluntary movements, language, symbolic thinking and the regulation of emotion, including localisation of functio

Think....

What do we know about

the lobes of the brain?

Frontal?

Parietal?

Occipital?

Temporal?

some cool stuff ...

Findings

If objects were flashed to the left side of the screen, and therefore processed by the right hemisphere the patient was unable to name the object, but could show that they understood what the object was by pointing to it or drawing it with their left hand

If the object was flashed on the right side of the screen, and therefore processed by the left hemisphere, the patient could name the object.

The role of the two hemispheres...

split brain studies

mr. split brainy

1. Studying people with intact brains

2. studying people with split brains

3. studying people with brain damage

roger sperry

http://www.nobelprize.org/educational/medicine/split-brain/splitbrainexp.html

What is a split brain?

Split-brain op: where the corpus callosum is cut to treat severe cases of epilepsy. This did not lead to any obvious physical side-effects. It was also believed at first that their was no psychological effects either.

Roger Sperry (1974): first studies to clearly & scientifically indicate that the left hemisphere is responsible for verbal & analytical tasks and that the right brain is responsible for spatial & non-verbal tasks

split brain research

Roger Sperry was an intersting fella...

Here is a few interesting experiments he ran before his split brain studies

Sperry set up an experiment involving flashing items on either the left or right side of a screen

Items flashed to the left side of the screen are processed by the right hemisphere

Items flashed to the right side of the screen are processed by the left hemisphere

what is happening?

Roger Sperry

...

Fish

So What'd he do?

Pop out the eyeballs....

Once the rat recovered from surgery, Sperry placed it on an electrical grille where, if it stepped on a certain spot, it got a shock. The result was black comedy. If the rat shocked its back left leg, it's brain felt the sting of pain in the right leg... (thanks to the switched nerves)

The rat jerked the right leg up and began limping. Unfortunately, this put more weight on the left leg, which is where the wounf actually was. Worse, as soon as the rat wandered near that electrified spot ain, it's left leg got another shock. Which because of the switched nerves make it seem like theright leg was hurting even worse.

Sperry was able to suggest that the rats neurons never learned better, like Paul Weiss had predicted, and months and months passed and the rats never learned to lift the foot that was shocked..

Fish and their eyes...

In 1941 he started a series of experiemtns on rats to test whether any neuron could do the job of any other neuron... (Paul Weiss' theory)

He opened up the rats two back legs, finding the nerves that carried pain signals to the brain, and switching them, so that the left pain nerve was now located in the right leg and vice versa...

Was a keen sportsman when he was young and set a state javelin record in high school and was awesome at basketball, baseball and track.

He spend his undergraduate hours in seventeenth century poetry but psych intrigued him, and he went on to get a master's degree in psychology and then a doctorate in zoology.

Sperry would pop out the eye balls of fish, sever the optic nerves, rotate the eyballs 180 degrees in the socket, then sew them back in.

When the fish's eye regenerated, because the eyeballs had been rotated, the nevers rewired themselves backwards - forcing the fish to see the world upside down.

Wriggle a worm below its jaw, and it snapped upward... the fish never unlearned this behaviour