Chapter 11: Language and Lateralization
Byron Peterson – Wernicke's
Sarah Scott – Broca's
Roger Sperry – Split Brain
∙ Many functions are performed half on one side, half on the other ∙ These two halves usually work together
∙ Corpus collosum connects the two hemispheres
∙ Split brain patient Joe can draw with his left hand what is presented to the right side of his brain, but can’t name it
o Teach us the mind is made up of semiindependent elements
Most important points...
∙ When talking about language and lateralization, it’s easy to see everything from the human point of view (language, writing, reading), but humans are not the only lateralized species.
Don't forget about the age old question of What are the terms used to analyze social class?
o We have more language capabilities than dolphins, or is the most extensive/advanced, but we aren’t the only species that uses some sort of vocalization/sound for communication.
o It’s tempting to think of the left hemisphere doing language, because that wouldn’t apply to other animals.
Maybe left hemisphere is more specialized in communication ∙ Wernicke’s area determines WHAT to say, Broca’s area determines HOW to say it. Don't forget about the age old question of Which is the brightest star?
∙ The cortex determines the intention to do something, but is up to lower brain areas to turn that into action
Cortex – screenwriter, lower regions – actors
Wernicke’s area is one that puts things together, synthesizes them
∙ Is a multimodal area, not just auditory
∙ Communicates with Broca’s area through arcuate fasciculus ∙ Broca’s (nonfluent) is necessary to create response to create production of response to input
Wernicke’s area does semantics; Broca’s area does syntax
∙ Semantics deal with meaning of a communication Don't forget about the age old question of What is sudden uncontrollable sleep attacks?
∙ Syntax is about the rules of language If you want to learn more check out Who is skowronek?
rTMS (transcranial magnetic stimulation) noninvasive treatment
∙ Used as treatment for aphasia
o Have shown increased cortical activation in right hemisphere (overactivation maybe), interferes with recovery
o Small/slow frequency reduces the excitement of target area
o Significant improvement in naming pictures observed following 10 rTMS treatments
o Suppressing an area can be therapeutic
o Functions of cortex are silent
Byron Peterson – look what he does right
∙ He has good syntax, but semantically his brain doesn’t understand what is being said
Sarah Scott – struggles initially with syntax, but understands meaning (semantic)
∙ Syntax improves multiple years after stroke
∙ A bit slow and must think about what she’s going to say, but otherwise, normal and great recovery
Nonhuman primates have a Broca’s area too
Damage to Broca’s region leads to diminished ability to express language, is a close proximity to premotor cortex
Broca’s area does not control/innervate the vocal cords
∙ Broca’s innervates motor cortex, but motor cortex doesn’t innervate vocal cords Don't forget about the age old question of What is behaviorism theory?
∙ Cranial nerves 9 and 10 innervate the speaking aspect of vocal cords ∙ Moving the vocal cords happens not just when we speak but when we breath, swallow, or anything involving movement of the larynx or pharynx
∙ 5 cranial nerves involved in eating, breathing, swallowing, speaking, whistle, etc.
A quick pulse stimulation to our cortex will cause nothing to happen
BUT when you stimulate a rhesus monkey’s cortex long enough, you produce purposeful movements of the arms and hands
∙ All starting positions end up in around the same place.
Broca’s area is widely recognized to be important for speech production, but its specific role in the dynamics of cortical language networks is largely unknown
∙ Contrary to classic notions of this area’s role in speech, our results indicate that the Broca’s area does not participate in production of individual words, but coordinates the transformation of information processing across largescale cortical networks involved in spoken word production, prior to articulation (because there’s something else doing the articulation) If you want to learn more check out What is price ceilings?
Broca’s area is not species specific
∙ Nonhuman primates possess cortical areas in similar locations and have areas homologous to Wernicke’s and Broca’s areas in humans ∙ In both species, the region represents nonlinguistic hand and mouth movements
∙ Both species may have mirror neurons in this region that are involved in understanding the actions and intentions of others
o In both species, the region is likely involved in producing orofacial expressions and in understanding the intentions behind expressions of others
Sarah Scott’s broca’s area thinks how do I form this
o In humans, it has evolved an additional communicative function (speech production)
The King’s Speech (movie)
∙ Speech therapist helps overcome king’s stutter
∙ Uses music/dancing, rhythmic stimulation and activity
o Connection between rhythm of music/dance with rhythm of speech, internalize the rhythmicity
∙ Don’t stammer when he swears
o Swearing is more emotional, therefore, is connected to the right hemisphere
Broca’s area blood flow and stuttering
∙ Connection between forced hand switching and stuttering has largely been forgotten
∙ Stuttering tied to disturbed signal transmission between hemispheres ∙ Connections between stuttering and weak laterality
∙ Dr. M thinks there is a connection between Broca’s area and stuttering ∙ Blood flow is reduced in the Broca’s area of those who stutter
Parkinson’s Music therapy
∙ Some who can’t walk but can dance
∙ The power of music
∙ Uses music to improve speech and other movements