Lecture 4 - Hemispheric Specialisation and Split-Brain Practise Flashcards

A set of vocabulary flashcards covering hemispheric asymmetries, corpus callosum functions, split-brain patient studies (W.J. and J.W.), and functional lateralisation as described in the lecture notes.

Hemispheric Specialisation

The concept that brain structures and task specializations differ across the left and right hemispheres of the brain.

Structural Asymmetries

Differences in the physical sizes of brain structures across hemispheres, such as the enlargement of the planum temporale in the left hemisphere.

Functional Asymmetries

Differences in task specialization across hemispheres, also known as lateralisation, where specific functions like language are typically held in the left hemisphere.

Geshwind & Levitsky (1968)

A study of $100$ post-mortem right-handed individuals identifying that the planum temporale was larger in the left hemisphere for $65\%$ of people, symmetrical in $24\%$, and larger in the right in $11\%$.

Planum temporale

The center of Wernicke’s area, which first showed evidence of lateralisation of language processing due to its anatomical size differences.

Vanderauwera et al. (2018)

A study using an asymmetry index and MRI scans that found left lateralisation of language processing is absent in individuals with a familial risk for dyslexia.

Corpus Callosum

The largest white matter structure in the brain, composed of approximately $250$ million axonal fibers that facilitate communication and synchronous processing between hemispheres.

Inhibitory processing

A function of the corpus callosum responsible for halting incompatible behaviors, such as multiple inefficient motor behaviors.

Split-Brain Procedures

A procedure where the corpus callosum is split, often used in the $1940\text{s}$ to treat epilepsy, allowing researchers to understand how hemispheres operate in isolation.

Cross-cuing

A process where one hemisphere subconsciously imitates a behavior (e.g., a hand nudging another) to help the other hemisphere detect stimuli, demonstrating the brain's adaptation to inhibited communication.

Patient W.J.

The first human to undergo a split-brain procedure; his testing demonstrated left lateralisation for verbal reports and right lateralisation for visuospatial tasks.

Left lateralised functions

Functions include language processing, discriminating non-familiar faces with distinguishing features, and processing the emotional configuration of faces.

Right lateralised functions

Functions include visuospatial processing, facial recognition of familiar faces, spatial orientation, and processing the emotional context of speech.

Patient J.W.

A patient used in trials to show a left-hemisphere bias for self-perception and a right-hemisphere bias for perceiving familiar others.

Contralateral Processing

The neurological principle where the left side of the brain controls the right side of the body, and the right side of the brain controls the left side of the body.

Ipsilateral Processing

Exceptions to contralateral control, such as when the left hemisphere overrides the right hemisphere's control of the left hand.

Robinson et al. (1988)

A study using the Navon Letter’s task that found left hemisphere lesions slowed identification of local targets, while right hemisphere lesions slowed identification of global targets.

Theory of Mind (ToM)

The ability to attribute mental states, such as beliefs and intentions, to oneself and others; it activates a bilateral network but relies heavily on the right hemisphere's TPJ.

TPJ (Temporo-parietal junction)

An area in the brain where the right hemisphere portion is considered the most important for the Theory of Mind network.

Dichotic listening tasks

Tasks used to study auditory lateralisation; results typically show the right ear (left brain) is better at word identification, while melodies are right-brain lateralised.