Language and Cognition

Purves et al., Chapters 26 & 27

General
Consider how much communication enhances the human experience.
Also think about how your thought patterns are guided (perhaps constrained) by language.

aphasia is loss of language ability
studies of brain damage (stroke) but some attempts to get at live brain function with imaging techniques

Fig. 26.1
Localization of function - note that Chapter 26 refers to "association cortex"
some very interesting case studies of people with specific defects like:

Fig. 26.8
prosopagnosia (-agnosia - not knowing) - face recognition deficit in right temporal lobe damage in patient L.H.
fMRI activity increase in right temporal lobe

Fig. 26.5A,B,C
contralateral (hemispatial) neglect syndrome caused by:

Fig. 26.6 A
damage to parietal, temporal and frontal areas.

recall the importance of gyrus to gyrus connections (arcuate fibers of the corona radiata, slide from sheep brain dissection: slide 23)

Recent paper. MT de Schotten et al, Direct evidence for a parietal-frontal pathway subserving spatial awareness in humans, Science 309, 2226-2228, 2005 (see also DGaffan, Widespread cortical networks underlie memory and attention, perspectives, Science 309, 2172-2173).
In the old days, stroke victims were studied on autopsy.
Neurosurgeons (removing cancer for instance) still test awake subject.
Electrical stimulation will temporarily inactivate small areas.
(If there is a loss of function, that area will be spared.)
Here, tumors were in parietal area.
So do line bisection task.
Although gray matter had been implicated, superior occipitofrontal fasciculus (white matter) was found to be most important.
DGraffan (perspectives) argues for a relationship with memory in work on monkeys.

Fig. 26.2
Brodmann areas- based on cytoarchitecture

Fig. 26.3
6 layers in human neocortex, I-not really cells,
II & III - pyramidal cells send and receive input from other areas of cortex
IV - stellate cells receive input
V & VI - Pyrimidal output from cortex

Fig. Box 26A
fewer layers in "archicortex" (hippocampus)
and
in "paleocortex" (pyriform cortex)
[These were terms used in the sheep brain dissection guide.]

There is a lot of emphasis on neural correlates (a nerve in such-and-such are of the brain that does so-and-so) like:

Fig. 26.12 B
a face recognition neuron in the temporal lobe which does not respond as well to degraded or wrong images

Fig. 26.14ABC
a neuron in the frontal cortex which responds specifically in a delayed task (planning)

Language

Recent literature
FOXP2 transcription factor defect leads to dyspraxia (cannot learn speech)
Use RNAi to show defect in zebra finch in area X of brain
("editors' choice," Science 318, 1835-7, 2007, summarizes work published PLoS Biol 5 e321, 2007)
FOXP2 knockout homozygous infants do not make ultrasonic cries when separated from their mothers
(in "Random Samples," CHolden, Science 309, 47, 2005, Gene knockout leaves mice squeakless)

Fig. 26.2
Brodmann areas

Fig. 27.2
Fig. 27.1
Broca - language on left side of brain
Language is one of the most interesting examples of localization of function.
Broca's area and Wernicke's area
Lesions in Broca's area-difficulty speaking but understand (motor aphasia)
Lesions in Wernicke's area - fluent but senseless speech
Some recovery of function => other areas can take over

Wada procedure: inject sodium amytal to one carotid-
show that speech is on left even in most left handed people.

Fig. 27.3 AB
Surgery to cut corpus callosum (to prevent the spread of epilepsy)
Here is the midsaggital close-up from the sheep brain dissection which view is predominated by a collosal body, the corpus callosum slide 10
There are 2 consciousnesses and the two sides of the brain have different capabilities
This work won Roger Sperry (who also did the eye to tectum regeneration in the frog and inferred neurobiotaxis) the 1981 Nobel Prize. Then the work was taken up by Gazzaniga.
Because of the orderly visual projections to the brain, it is possible to present visual stimuli to 1/2 of brain, and, if presented to the left half of the brain. the person can say what it is, but if presented to the right half of the brain, (s)he cannot say what it is but can pick it out (multiple choice) by touch.
Thus experiments distinguish comprehension vs. speech.

Box 27B
argues whether language is actually unique to humans

Border collies (one named Rico) seem able to learn lots of words

Landmark paper RAGardner and BTGardner, Teaching sign language to a chimpanzee, Science 165, 664-672, 1969
American Sign Language (ASL) [used by deaf in North America]
22 months of training in a young female
paper lists 30 signs Washoe could use

Landmark paper DPrimack, Language in a chimpanzee, Science 172, 808-822, 1971
success with Sarah to use plastic chips of various shapes

Fig Box 27B
DRumbaugh and S Savage-Rumbaugh used computer type-writer

Landmark paper HSTerrace et al. Can an ape create a sentence?, Science 206, 891-902, 1979
Nim Chimsky (Noam Chomsky, famous MIT linguist who thought language is unique to humans)
criticized above approaches and created a controversy.

Fig. 27.8
Signers are also impaired by brain damage to language areas

Native English speakers' vs. Non-native speakers' scores on tests as a function of age suggests that there is a critical period for learning language broadly centered early in life (which, of course, everybody knew already in terms of how easy it is relatively for young people to learn a foreign language).

Exam questions from 2005 - 2007 relating to this outline

With answers

In testing a split-brain subject (with a severed corpus callosum), how can you show a visual stimulus to only one hemisphere?

present to temporal retina that innervates ipsilaterall;y (with eye fixation)

Washoe, Sarah and Nim Chimsky were all used in a study of what capability?

language in chimps

What is the more common name applied to the "archicortex" folded in between the neocortex and the paleocortex?

hippocampus

Hemispatial (contralateral neglect was found to result in damage to what brain area (or the white matter under that surface feature)?

parietal lobe

In a subject with a severed corpus callosum, can the right hemisphere "know" what stimulus was presented to it?

yes but it cannot say

How could administering sodium amytal to the carotid address the question of the unilateral location of speech?

into one carotid anesthetizes one side of the brain

How is performance on the line bisection task diagnostic of neglect syndrome?

easy to see if patient cannot decide where the middle of a line is, even during brain surgery

In studies of speech localization to Broca's area, how did Sperry present a visual stimulus to only the left hemisphere?

Right visual field goes to left temporal retina and right nasal retina (to left brain)

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