Language Laterality, Models, and Surgical Approaches

Comprehensive vocabulary flashcards covering cerebral anatomy, Brodmann areas, the Wernicke-Geschwind and Dual Stream models, hemispheric lateralization, split-brain studies, the Wada test, and cortical mapping.

Brodmann Areas

A standard reference system for the cerebral cortex that divides the brain into 47 regions based on functional differences.

Broca's Area (Brodmann Areas)

Composed of Brodmann Area 44 and Area 45, this cortical region is responsible for encoding and stores motor programs for speaking words.

Wernicke's Area (Brodmann Area)

Designated as Brodmann Area 22, this region is responsible for language decoding and contains sound images of words.

Primary Auditory Cortex

Designated as Brodmann Area 41 (located in Heschel's gyrus), it receives incoming auditory signals such as spoken words.

Angular Gyrus

Designated as Brodmann Area 39, this region plays a key role in transferring visual information from visual areas to Wernicke's area during reading.

Motor Strip (Brodmann Area)

Brodmann Area 4, located along the precentral gyrus, responsible for motor execution.

Somatosensory Strip (Brodmann Areas)

Composed of Brodmann Areas 3, 1, and 2 along the postcentral gyrus, responsible for processing somatosensory inputs.

Wernicke-Geschwind (WG) Model

An early, now obsolete serial model of language processing based on the premise that language consists of two functions: comprehension (sensory/perceptual) and speaking (motor).

Double Dissociation in Language

The clinical finding that two related language processes can function independently of each other, demonstrated by Broca's area handling encoding while Wernicke's area handles decoding.

Dual Stream Model

A speech processing framework by Hickok and Poeppel proposing that language comprehension and production rely on parallel dorsal and ventral networks rather than a single serial loop.

Dorsal Stream

A left-dominant pathway in Hickok and Poeppel's model connecting the parietal-temporal Spt (sensorimotor interface) with the pIFG, premotor cortex, and anterior insula (articulatory network).

Ventral Stream

A speech processing stream in Hickok and Poeppel's model connecting bilateral phonological networks to a lexical interface (pMTG, pITS) and a combinatorial network (aMTG, aITS).

Language Lateralization

The asymmetric specialization of brain hemispheres showing left-hemisphere dominance for core language, supported by aphasia research, studies of life-long signers of ASL, split-brain patients, and the Wada test.

Right Hemisphere Language Roles

Linguistic and communicative capabilities managed by the right hemisphere, specifically processing prosody (rhythm, stress, intonation of speech) and metaphorical language.

Epilepsy

A neurological condition characterized by disrupted electrical signaling and abnormal discharge of brain cells that may cause seizures and changes in behavior or activity.

Cerebral Commissurotomy

A surgical procedure introduced in 1961 as a last-resort treatment for severe epilepsy in which the corpus callosum is severed, disconnecting the two cerebral hemispheres.

Contralateral Wiring in Vision

The anatomical organization where each half of the visual field projects to the opposite cerebral hemisphere: the Left Visual Field (LVF) projects to the right hemisphere, and the Right Visual Field (RVF) projects to the left hemisphere.

Split-Brain Naming Asymmetry

A phenomenon in split-brain patients who can easily verbalize names of objects presented in the Right Visual Field (LH), but report seeing 'nothing' when stimuli are presented in the Left Visual Field (RH) because the RH cannot speak.

Right Hemisphere Language Comprehension in Split-Brain

The capacity of the non-verbal right hemisphere to comprehend simple words when testing permits a non-verbal response, such as pointing or drawing with the left hand.

Hemispherectomy

Surgical disconnection or removal of a cerebral hemisphere; functional language recovery outcomes depend on age, the hemisphere resected (RH vs. LH), disorder etiology (acquired vs. developmental), and seizures.

Wada Test

Also called the Intracarotid Sodium Amobarbital Procedure (ISAP); a pre-surgical test where sodium amobarbital is injected into one carotid or femoral artery to put one hemisphere to sleep, isolating lateralized speech and memory functions.

Sodium Amytal (Sodium Amobarbital)

A barbiturate medication injected into the internal carotid artery during a Wada test that temporarily freezes the targeted hemisphere for approximately $4$ minutes.

Cortical Stimulation Mapping

An intraoperative procedure applying a mild electric current to small cortical sites while the patient is awake to locate and protect critical language areas by observing triggered disruptions like speech arrest.

Individual Variability in Language Maps

The finding from brain stimulation mapping demonstrating that naming sites and specific functions vary across individuals, and that frontal and temporal language areas can be active simultaneously rather than strictly sequentially.