Here are some background items on the topic of cerebral specialization or lateralization of brain function. Most are based on Gazzaniga's analysis of split brain patients.


Sketches of the visual fields and pathways

 


Loss of one hemisphere - effects of hemispherectomy

an image of young girl's brain after hemispherectomy due to intractable seizures-- Rasmussen's syndrome.

A recent graphic description of the problem, surgery, and history of surgical treatment of seizures from the New Yorker.

A case of right hemisphere removal and recovery (plasticity).

Link to WGBH series on brain; hemispherectomy cases. This site has an excellent history of brain research and brain function overview -- in addition to the case studies in the series.

http://www.pbs.org/wnet/brain/episode2/index.html

There are several good discussions of the surgery and its rationale on the web; Google it.

These cases are extremely puzzling and interesting; how could even close to normal behavior develop after removal of half of your brain? To some extent the answer is that it doesn't. See recent papers by Susan Curtiss and her colleagues. (e.g.Curtiss and Shaefer, 200x) Syntactic development in children with hemispherectomy: The Infl- system). On the other hand, some recoveries approach miraclehood.

www.linguistics.ucla.edu/people/curtiss/isys1.pdf

Also keep in mind that these children had serious problems before surgery so that normal brain development was precluded; hence inferences from their cases to normal brain specialization issues ought to be done very gingerly.

 

But what does develop is far more than I would have expected -- especially in children with hemispherectomies after age two. Even if the left hemisphere goes, most of these children seem to redevelop functional language. Here is an abstract of one survey:

Title: Language after hemispherectomy.
Author(s): de Bode, Stella, U California, Los Angeles, CA, US
Curtiss, Susan
Source: Brain & Cognition, Vol 43(1-3), Jun-Aug 2000. pp. 135-138. Journal
ISSN: 0278-2626 (Print)
Language: English
Key Concepts: left vs right hemispherectomy, spoken language & model of brain maturation & progressive lateralization, pediatric epilepsy surgery patients


Abstract: Studied the spoken language of 49 children who had undergone hemispherectomy as part of a pediatric epilepsy surgery research program and analyzed, among a number of clinical factors, the relation between acquired vs developmental pathology and spoken language outcomes. This paper briefly reviews the results of the study and attempts to explain (1) why "the early" is not always better, (2) why so many right hemispherectomies fail to develop language, and (3) why some left hemispherectomized children develop remarkably good language despite removal of the "language" hemisphere. This account will rest on the proposed model of brain maturation and progressive lateralization. An attempt is made to show how factors like etiology, time of the insult, and presence of epilepsy, can factored into the proposed model. (PsycINFO Database Record (c) 2002 APA, all rights reserved)

***

Author(s):         Boatman D; Freeman J; Vining E; Pulsifer M; Miglioretti D; Minahan R; Carson B; Brandt J; McKhann G
Author's Address:     Department of Neurology, and Krieger Mind/Brain Institute, Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA.
Title:         Language recovery after left hemispherectomy in children with late-onset seizures.
Language:         English
Source:     Ann Neurol, 1999 Oct; Vol. 46 (4), pp. 579-86.
Country: UNITED STATES
ISSN:        0364-5134
Pub. Type:        Journal Article
Journal ID(s):   Journal Code: 6AE NLM ID: 7707449
Subset:      IM
MeSH Heading:         Brain:*SU. Encephalitis:*PX/*SU. Language:*. Seizures:*SU. Adolescence. Age of Onset. Child. Neuropsychological Tests. Female. Human. Male. Support, Non-U.S. Gov't. Support, U.S. Gov't, P.H.S.
Abstract: We investigated the language capabilities of the isolated right hemisphere in 6 children (age, 7-14 years) after left hemidecorticectomy for treatment of Rasmussen's syndrome. Patients were right-handed before surgery and had at least 5 years of normal language development before the onset of seizures. Language testing included speech sound (phoneme) discrimination, single word and phrasal comprehension, repetition, and naming. Within 4 to 16 days after surgery, patients showed improved phoneme discrimination compared with their performance shortly before surgery. Other language functions remained severely impaired until at least 6 months after surgery. By 1 year after surgery, receptive functions were comparable with, or surpassed, patient presurgery performance. Although word repetition was intact by 1 year after surgery, naming remained impaired, and patient speech was limited largely to production of single words. These results suggest that the right hemisphere is innately capable of supporting multiple aspects of phoneme processing. Recovery of higher level receptive and, to a lesser extent, expressive language functions is attributed to plasticity of the right hemisphere, which appears to persist beyond the proposed critical period for language acquisition and lateralization.
Grant Information:   R29-DC03081 DC NIDCD
Revision Date: 20001218
Entry Date(s):   Date Created: 19991203 Date Completed: 19991203
Citation ID(s):   Medline UI: 99442252 PMID: 10514094
Note:         Not held by UNH
Database:          MEDLINE

There's also a book -- a case study:

Battro, A. N. (2000). Half a brain is enough: The story of Nico. Cambridge: Cambridge University Press.

The Journal of Neurology (1996) published a review of some of the earliest cases.

Hemispherectomy: a hemidecortication approach and review of 52 cases

Benjamin S. Carson, M.D., Sam P. Javedan, John M. Freeman, M.D., Eileen P. G. Vining, M.D., Aaron L. Zuckerberg, M.D., Jeremy A. Lauer, M.S., and Michael Guarnieri, Ph.D.

Miscellaneous links

Handedness and the brain

laterality, facial asymmetry and pesonal interests

The whole brain atlas -- (See it all.)