·      Language!

·      Logical, analytical processing (the Spock idea)

·      Math

·      Time + order

·      Interpretation of the world

·      Details

·      Local processing

Processing of parts

Kids with autism tend to notice the details of a movie (clothes, etc.) more than non-autistic kids, who remember plot more. This is an example of use of which hemisphere?

Right hemisphere specialties

·      Visuo-spatial skills and imagery

·      Recognizing faces

·      Recognition of expression of emotion

·      Music + humor

·      Gestures + prosody

·      Global processing

Visuo-spatial skills and imagery

RIGHT HEMISPHERE

·      Really good sense of direction

·      Visualizing a map and looking down at it when asked to think of the fastest route somewhere

Recognition of expression of emotion

RIGHT HEMISPHERE

·      Some people can recognize expression / emotion in others, can’t produce it themselves

·      Vice versa

Music + humor

RIGHT HEMISPHERE

·      People lose ability to recognize subtle humor

·      Non-brain damaged people are sometimes tone deaf and have no idea

Gestures + prosody

RIGHT  HEMISPHERE

·     Use + interpret gestures properly

·     Brain damage can cause monotone voice

·  Difficult to understand someone with almost no intonation in voice

·  We use intonation to disambiguate things we hear in speech

 Global processing

RIGHT HEMISPHERE

·     Processing of wholes

·     Integration of parts

Logical, analytical processing

(The Spock idea)

RIGHT HEMISPHERE

(left ear)

·      Music

·      Non-verbal sounds

·      Recognition of simple musical tunes

How would a split brain patient respond if they were asked to…

            name an object felt (but not seen) with the left hand?

CAN’T NAME IT

How would a split brain patient respond if they were asked to…

name an object felt (but not seen) with the right hand?

CAN NAME IT

How would a split brain patient respond if they were asked to…

draw an object seen in the right visual field with the right hand?

How would a split brain patient respond if they were asked to…

draw an object seen in the left visual field with the left hand?

CAN DRAW IT

How would a split brain patient respond if they were asked to…

name a word heard in only their right ear?

CAN NAME IT

How would a split brain patient respond if they were asked to…

name a word heard in only their left ear?

CAN’T NAME IT

How would a split brain patient respond if they were asked to…

            use an object held (but not seen) in their right hand?

CAN USE IT

How would a split brain patient respond if they were asked to…

use an object held (but not seen) in their left hand?

CAN USE IT

How would a split brain patient respond if they were asked to…

name an object shown in the left visual field?

CAN’T NAME IT

How would a split brain patient respond if they were asked to…

name a word shown in the right visual field?

CAN NAME IT

How would a split brain patient respond if they were asked to…

draw what they see with their left hand (and they see “chain” in the left visual field and “saw” in the right visual field presented at the same time)

THEY WILL DRAW A SAW AND DRAW A CHAIN (BUT MAY NOT KNOW WHY THEY DREW THE CHAIN)

How would a split brain patient respond if they were asked to…

draw what they see with their right hand (and they see “chain” in the left visual field and “saw” in the right visual field presented at the same time)

THEY WILL DRAW A SAW

How would a split brain patient respond if they were asked to…

point to what they saw when shown a face made out of fruit in their right visual field? (face or fruit?)

THEY WILL POINT TO FRUIT

How would a split brain patient respond if they were asked to…

point to what they saw when shown a face made out of fruit in their left visual field? (face or fruit?)            

THEY WILL POINT TO FACE

Hemispherectomy

The partial or total removal of a cerebral hemisphere

Used to treat some types of severe seizure disorders, such as Rasmussen's syndrome

·  Children develop normally until 5 – 12 years old

·  Late onset, progressive seizures

·  Unilateral (one-sided)

·  Rarest of seizure disorders

Language is highly lateralized

·      Language is LH dominant in most people

·      True even of lefties (70%; nearly 95% of righties are LH language dominant)

Evidence that language is LH dominant

· Brain lesions in the left hemisphere lead to aphasia

· Neuro-imaging shows us

· Wada test

Brain lesions in the LH lead to aphasia (how do we know?)

Autopsy, surgery, observation

More LH activity during language processing

Wada test

·     Putting one hemisphere “to sleep” (anesthetize)

··  Sodium amytal is injected into a cerebral artery

·     When each side is asleep

··  Identify pictures / words (language)

··  Later asked what items were shown (memory)

··  With a sleeping LH, most people can’t speak or comprehend language

·      Today, cerebral commissurotomy is much rarer. They will sometimes do partial split-brain surgery.

·      Some people (very, very rarely) are born without a corpus callosum.

··     Often misdiagnosed as autism. 

Dr Sperry + Dr Gazzaniga

·      They set up tests so info only went to one hemisphere

·      When your corpus callosum is in tact, hemisphere dominance is still communicated to the other hemisphere.

··     Right visual field goes to and the LH but communicates with the RH.

·      When your corpus callosum is cut, info stays in the dominant hemisphere

··     Right visual field goes to the LH and stays there.

Is the right hemisphere completely stupid?

In everyday life, split-brain patients respond normally to objects in their environment. How is this possible?

Both visual fields, all senses, etc. involved in everyday life. Unintentional (and even intentional) compensation. 

Two words are flashed to a patient:

Key (LVF)

Ring (RVF)

Left hand rests on several objects (key, ring, keyring)

Patient asked to respond by touch and voice.

How will they respond?

They’ll say “ring” but pick out the key.

Unusual split-brain patient

VJ – left-handed patient (1996)

·      She can say words displayed to LH but not to RH (normal)

·      She writes words displayed to the RH, but NOT words displayed to the LH (not normal)

··     LH seems to control speech, while the RH controls writing

··     Are some lefties wired differently?

Sometimes split-brain patients would display “oppositional” behaviors

One hand tries to do the intended task (buttoning a shirt) while the other travels along and undoes all of the progress.

LEFT HEMISPHERE

(right ear)

·      Speech

·      Words

·      Processing language

Right hemisphere

(left ear)

·      Music

·      Non-verbal sounds

·      Recognition of simple musical tunes