Cortical Structures, Language Networks, and Hemispheric Lateralization

Vocabulary flashcards covering cortical neuroanatomy, white matter tracts, the dual-stream model of language processing, and hemispheric lateralization based on SLH/LIN 350 lecture notes.

Medial

Directional term referring to structures located toward the brain's or body's midline.

Lateral

Directional term referring to structures located toward the sides of the body or brain.

Dorsal

Anatomical term referring to structures atop the brain or on/toward the back of a four-legged animal (equivalent to superior in human brain structures).

Ventral

Anatomical term referring to structures toward the bottom of the brain or on/toward the belly of four-legged animals (equivalent to inferior in human brain structures).

Anterior

Anatomical term meaning located near or toward the front of the head or front of the animal.

Posterior

Anatomical term meaning located near or toward the back or tail of an animal.

Rostral

Directional term meaning toward the beak or front of the animal.

Caudal

Directional term meaning near or toward the tail of the animal.

Superior

Directional term meaning above with respect to location within the nervous system.

Inferior

Directional term meaning below with respect to location within the nervous system.

Coronal Section

Plane of section cut vertically from the crown of the head down, yielding a frontal view of internal brain structures.

Horizontal Section

Plane of section cut along the horizon (axial plane), yielding a dorsal view looking down on the brain from above.

Sagittal Section

Plane of section cut lengthways from front to back, yielding a medial view of the brain from the side.

Grey Matter

Tissue layer composed of the cell bodies of neurons, forming the outer cerebral cortex (about 2-3 mm deep) and deep subcortical nuclei.

White Matter

Nervous tissue made up of myelinated axon bundles that serve as structural communication highways connecting cortical and subcortical regions.

Corpus Callosum

Major interhemispheric white matter tract that connects the left and right cerebral hemispheres, enabling bilateral coordination.

Gyrus

The raised hills, ridges, or bumps located between folds on the surface of the cerebral cortex.

Sulcus

The valleys, indentations, or grooves between gyri on the cerebral cortex, with particularly large sulci referred to as fissures.

Heschl's Gyrus

Cortical region located inside the lateral sulcus on the temporal lobe that houses the primary auditory cortex and serves as the first major cortical station for auditory processing.

Superior Temporal Gyrus (STG)

Major temporal lobe gyrus responsible for sound processing and language understanding, containing Wernicke's area in its posterior portion.

Inferior Frontal Gyrus (IFG)

Frontal lobe gyrus containing Broca's area, involved in speech production, language planning, and semantic word relationships.

Supramarginal Gyrus

Cortical structure located directly above the lateral sulcus and STG; in the left hemisphere, it processes spoken/written words, supports phonological choices, and aids verbal working memory.

Angular Gyrus

Parietal structure arching over the superior temporal sulcus that helps translate written words into meaning by routing visual input to language processing centers.

Middle Temporal Gyrus (MTG)

Temporal lobe gyrus situated below the STG that assists with sound recognition, comprehension, reading, and retrieving word meanings from memory.

Wernicke-Geschwind Model

Historical model of language processing developed by Carl Wernicke (1874) and revamped by Norman Geschwind (1972) that proposed a serial pathway between Heschl's gyrus, Wernicke's area, the arcuate fasciculus, Broca's area, and the motor cortex.

Diffusion Tensor Imaging (DTI)

Noninvasive brain imaging technique that measures the directionality of water diffusion along axons to map white matter pathways and structural connectivity.

Arcuate Fasciculus

Major dorsal white matter tract connecting posterior temporal language regions (Wernicke's) to frontal regions (Broca's), playing a central role in speech repetition.

Superior Longitudinal Fasciculus

Broad dorsal white matter tract connecting frontal, parietal, and temporal regions, overlapping functionally with the arcuate fasciculus.

Uncinate Fasciculus

White matter tract linking the anterior temporal lobe to the frontal lobe as part of the ventral semantic pathway.

Inferior Fronto-Occipital Fasciculus (IFOF)

Long ventral white matter pathway linking occipital and temporal lobes to the frontal lobe, implicated in semantic processing and reading.

Inferior Longitudinal Fasciculus (ILF)

Ventral white matter pathway connecting occipital and temporal regions involved in processing visual signals, object recognition, and face recognition.

Frontal Aslant Tract (FAT)

White matter pathway connecting the supplementary motor area (SMA)/pre-SMA to Broca's area, implicated in speech initiation and fluency.

Dual-Stream Model of Speech Processing

Prevailing model proposed by Hickok and Poeppel (2007) describing two parallel pathways: a ventral stream for sound-to-meaning mapping and a dorsal stream for sound-to-articulation mapping.

Phonological Network

System of brain regions along the superior temporal sulcus (STS) that processes speech sounds into meaningful units before routing information to the dorsal and ventral streams.

Ventral Stream

Pathway in the dual-stream model that maps acoustic speech signals into conceptual and semantic representations ("sound to meaning").

Lexical Interface

Component of the ventral stream (pMTG, pITS) that links phonological representations to semantic information.

Combinatorial Network

Component of the ventral stream (aMTG, aITS) responsible for integrating individual words into complex semantic phrases and syntactic structures.

Dorsal Stream

Pathway in the dual-stream model that links auditory speech signals directly to motor articulatory representations ("sound to articulation").

Articulatory Network

Component of the dorsal stream comprising the pIFG, premotor cortex, and anterior insula that mediates speech production planning and execution.

Insula

Cortical region located deep within the lateral (Sylvian) fissure, whose anterior portion participates in the dorsal stream articulatory pathway.

Dichotic Listening

Noninvasive behavioral test presenting different acoustic stimuli simultaneously to each ear to measure auditory processing and hemispheric language dominance.

Right Ear Advantage

Phenomenon in dichotic listening where speech sounds presented to the right ear are reported more accurately due to direct contralateral projection to the dominant left auditory cortex.

Wada Procedure

Invasive diagnostic test that temporarily anesthetizes one brain hemisphere via sodium amytal injection into the carotid artery to evaluate language lateralization.

Split-Brain Patient

An individual who has undergone surgical transection or removal of the corpus callosum, preventing direct neural communication between the left and right hemispheres.

Corpus Callosotomy

Surgical procedure involving the cutting or removal of the corpus callosum to stop the spread of severe, intractable epileptic seizures.