PSYC 311 Final

Arcuate Fasciculus (AF)

"Arching" in Latin, arching fibers coming from somewhere in the temporal lobe and going towards the frontal lobe. It runs underneath the Supramarginal Gyrus (SMG, PF(G)). Geshwind argued that damage here results in conduction aphasia, a deficit in repeating. It connects the expressive parts of language (Broca's area) with the receptive aspects of language (Wernicke's area). It is very important for the phonetic aspects of language.

Insula

"Island" in Latin, it is an island of cortex lost in the Sylvian fissure. The three short anterior gyri are involved with motor production and the two long posterior gyri are involved with somatosensory processing (under the parietal operculum). The entire insula is covered by the frontal, temporal, and parietal operculums (lids).

Ventral Stream

(What) The occipitotemporal visual stream formed by the Inferior Temporal Gyrus (ITG) and the fusiform gyrus. It starts at V1 and moves ventrally through the inferotemporal region.

Selective Controlled Voluntary Memory Retrieval

45 and 47/12 are critical for this, to go back into the traces in the brain and inhibit some irrelevant information to pull out the specific information that is required. This can be tested with a fluency task.

Dyscalculia

A difficulty in calculating.

Alexia/Dyslexia

A difficulty in reading.

Agraphia/Dysgraphia

A difficulty in writing.

Disprosodic Speech

A disorder in the information and the melody that characterizes vocal speech output

Conduction Aphasia

A disorder where the patient cannot repeat or answer direct questions, but can talk spontaneously without mistakes and comprehend information because Wernicke's area and Broca's area are in tact. It may be a disconnection between Wernicke's area and Broca's area at the arcuate fasciculus (Geschwind), but may also be due to damage at the supramarginal gyrus (SMG, PF(G)) above the arcuate fasciculus, possibly because the SMG could be important for the phonological store (Warrington and Schellas).

Ideomotor Apraxia

A failure to use the body to communicate (body gestures), even spontaneously. Patients also tend to have agraphia and conduction aphasia. This is marked by damage to the supramarginal gyrus (SMG, PF(G))

Thalamus

A large, subcortical, grey matter area that guides visual, auditory, and somatosensory sensations and then sends it to other parts of the cortex.

Layer I

A layer with few cells

Inferior Parietal Lobule

A part of the parietal lobe divided into the Supramarginal Gyrus (SMG, area 40, PF(G)) and the Angular Gyrus (AG, area 39, PG) (Geschwind's Territory)

Cerebellum

A small part of the brain that controls our movement

Wernicke's Aphasia

A speech comprehension disorder where the patient could provide spontaneous, nonsensical sentences in a strange combination of syllables. They cut function words. Speech is fluent, fast, effortless, and prosodic. Machinery is in tact. This is marked by damage in the posterior superior temporal lobe in the left hemisphere, as well as damage to the Supramarginal Gyrus (SMG, PF(G)) and the arcuate fasciculus (PG, under SMG).

Amygdala

A subcortical structure beneath the parahippocampal gyrus that deals with emotion. Interaction with the entorhinal cortex leads to the emotional affective component of memory.

Intraparietal Sulcus

A sulcus within the parietal lobe that divides the parietal lobe into superior and inferior parietal lobule.

Calcarine Sulcus

A white stripe halfway through the cortex (striate cortex) surrounded by V1 (area 17). Different parts of the visual field arrive on different parts of this sulcus. Everything in the right visual field will end up on this structure in the left hemisphere, and vice versa.

Right Homonymous Hemianopia

A word meaning "half-blindness", this is a disorder with right visual field deficits characteristic of damage to the striate cortex or the connections that go from the thalamus to the striate cortex. This disorder is not sufficient to cause reading problems. This is due to damage to the optic tract, the thalamus, or to VI to the contralateral side.

Broca's Aphasia

Agramatic, dysprosodic, nonfluent, effortful speech marked by syntax problems, a lack of intonation, and single syllable speech. Due to damage in: Area 44 = pure speech arrest Area 45 = sometimes speech arrest Area 47/12

Jules Dejerine

Alexia with Agraphia: He had an intelligent, well-spoken, highly educated patient who lost the ability to read (a/dyslexia) and write (a/dysgraphia) after a stroke. He had no visual field occipital area damage, he could copy words. This patient had a small lesion in the left inferior parietal lobule localized more posteriorly around the angular gyrus (PG), which is important for visual linguistic symbol processing and is connected to Broca's area (via superior longitudinal fasciculus) and Wernicke's area (via middle longitudinal fasciculus) Alexia without Agraphia: He had a patient with right homonymous hemianopia who could not read, but he could write. However, he could not read what he wrote. He had massive damage to the splenium of the corpus callosum, that enables communication between the posterior parts of the brain (mostly visual information) and to the angular gyrus (AG, PF(G)).

Central Sulcus

Also known as the sulcus of Rolando, this divides the parietal and frontal lobe.

Pre-Central Gyrus

An agranular area where the motor system lies.

External Capsule

An area where axons go between the claustrum and the putamen from the cortex down to subcortical structures (projection fibers)

Extreme Capsule

An area where axons go between the insula and the claustrum from the superior lateral temporal cortex to the frontal lobe, one of the most important language pathways enabling communication between auditory areas and certain ventral, lateral areas. This is important for meaning extraction.

Internal Capsule

An area where axons go between the thalamus and the globus pallidus.

Pars Opercularis

Area 44, stimulation results in pure speech arrest. This area is dysgranular, layer IV is not well defined.

Pars Triangularis

Area 45, granular, typical prefrontal cortex. This is involved in active memory retrieval.

Pars Orbitalis

Area 47/12, granular, typical prefrontal cortex. This is involved in active memory retrieval

Angular Gyrus

Area PG or 39, this is the cortex around the three branches at the end of the superior temporal sulcus.

Visual System

Areas 17 (primary), 18, and 19 in the occipital lobe and the inferior parietal lobule. Retina -> Lateral Geniculate Nucleus -> Thalamus -> V1

Somatosensory System

Areas 3 (primary), 1 and 2 on the post-central gyrus, this area has a prominent layer 4. The somatosensory homunculus was discovered by Dr. Penfield. Dorsal stimulation leads to reactions in the feet and legs and ventral stimulation leads to reactions in the face. It is not drawn proportional to body part size, but to the amount of cortex dedicated to it's function. Somatotopic representation is inverted. Lips are represented toward the bottom and legs at the top (longer Betz cells).

Motor System

Areas 4 (primary) and 6 (pre-motor, which has four maps of the body) on the pre-central gyrus, this area is agranular. The primary cortex has very large cells in layer V called Betz cells, but the pre-motor does not. The motor homunculus was discovered by Dr. Penfield. Dorsal stimulation leads to reactions in the feet and legs and ventral stimulation leads to reactions in the face. The Betz cells in layer V in area 4 are largest at the top.

Granular Areas

Areas that have a well developed layer IV.

Agranular Areas

Areas without cells in layer IV, motor cortical areas are mostly this.

Superior Longitudinal Fasciculus

Axons going from the angular gyrus (AG, PG, in the parietal lobe) towards the frontal lobe and terminate in pars triangularis (area 45). This is the most important language pathway.

Commissural Fibers

Axons that enable the left and right hemisphere of the brain to talk to each other. The corpus callosum is an example.

Projection Fibers

Axons that go down from the cortex to subcortical nuclei areas that enable communication between subcortical areas and other parts of cortex.

Granular Neurons

Between the pyramidal neurons, very small neurons with short axons that don't go outside the white matter.

Limbic Cortex or Gyrus

Created by the circle of the cingluate gyrus with the parahippocampal gyrus, that makes its way back up to the frontal lobe in a circle. It is phylogenetically old. It regulates emotions, drives, and other things.

Apraxia

Difficulties in action that are not explained by simple motor problems. "Praxis" in Greek means "action". It was defined by Liepmann as an inability to perform an action not caused by motor or somatosensory specific problems.

Parieto-Occipital Sulcus

Divides the superior parietal lobule (PE) from the occipital lobe.

Association Fibers

Fibers that are found within the hemisphere and enable communication between cortical areas within the same hemisphere.

Cingulate Gyrus

Found on the frontal and parietal lobe, this has older cortical areas and does not have a layer IV; it is agranular. With the parahippocampal gyrus, it encircles the limbic system.

Parahippocampal Gyrus

Found on the medial surface of the temporal lobe, this lies above the hippocampus and amygdala. With the cingulate gyrus, it encircles the limbic system. It starts from the boarders of the occipital lobe and goes down to the temporal lobe. It terminates at the uncus.

Semantics

From the Greek word for "sign", the interpretation or the study of the meaning of words in the sentences. It is controlled in the body by area 45 via the extreme capsule.

Cerebral Cortex

Grey matter of the brain with neurons arranged in six layers that vary in thickness, this area is cytoarchitectonic.

Sperry and Gazzinga's Split Brain Experiments

If the information went into the right visual field, then patients had no problem saying what they saw. If information went into the left visual field, then the patients now said that they didn't see anything because language is generally lateralized to the left hemisphere. They flashed a word to the right hemisphere and had the patient retrieve the object with their left hand from a bag. Although they claimed they did not see anything, they were still able to do this. Spatial processing is generally lateralized to the right hemisphere.

Broca's Area

In area 44 (and possibly 45), this left hemispheric area is involved with language processing. Stimulation results in pure speech arrest.

Superior Temporal Gyrus (STG)

Involved in auditory signals.

Medial Temporal Gyrus (MTG)

Involved in multi-sensory signals (poly-sensory), it is formed by the ITG and the fusiform gyrus, and the parahippocampal gyrus and is important for object recognition. Damage must be bilateral for global amnesia. Unilateral damage leads to material specific deficits. The left is important for remembering verbal material and the right is important for remembering nonverbal material. Squire and Zola Morgan had memory impairments for H+ lesion, but Mishkin did not. SFN poster claimed H+ monkey could do subtle recognition tasks.

Pre-Frontal Cortex

Involved in the highest levels of cognitive processing and known for planning, organizing, thinking ahead, and tracking what's in your mind.

Inferior Temporal Gyrus

Involved in visual signals.

Pyramidal Neurons

Large, typical neurons with axons that travel to the white matter. In layer V, these go all the way to the top of the cortex, having apical dendrites, which go to the white matter or another area of the brain, and basal dendrites. These are mostly found in layers III and V

Wada Chart

Left Handed/Ambidextrous: Left Hemisphere - 70% Bilateral - 15% Right Hemisphere - 15% Right Handed: Left Hemisphere - 96% Bilateral - -- Right Hemisphere - 4% The two 15% are more vulnerable to strokes and speech problems after surgery.

Aphasia

Linguistic disorders that have to do with brain damage in the left part of the brain

Area 3

Located in the central sulcus, this has a smaller receptive field with continuous firing without continuous stimulation. This is SI and an example is the fingers. It has the largest and widest layer IV. It has 3 maps of the body.

Area 1

Located on the postcentral gyrus, it responds to on/off stimulation and to vibration and tactile information. It has a larger receptive field.

Genu

Meaning "knee" in Latin, this is the knee looking part of the corpus callosum. It is in the front of the brain and most of the axons are from the pre-frontal areas. This area is the cortical axons of the frontal areas crossing over.

Layer V

Neurons here give feedback to subcortical areas. It is important for movement and action.

Neologism

New words, characteristic of Wernicke's aphasia

Sympathetic Apraxia

No motor damage to the right hemisphere, but to the left hemisphere. However, the patient is unable to communicate with the left side of their body, but they can produce spontaneous movement, as long as it is not a communicative gesture. Auditory information is processed in the left hemisphere first. There is massive damage to the left motor and premotor areas, therefore they cannot relate information to the right hemisphere through the genu. Patients often also have Broca's aphasia.

Transcortical Aphasia

No spontaneous speech or evidence of comprehension, the patient is parrot like. They repeat what they hear. They can also finish common phrases and songs. This is due to widespread cortical damage, but the perisylvian region is spared. This is important because it is evidence that language areas are not localized only to this area, although it's key areas are here.

Supramarginal Gyrus (SMG)

PF, Area 40, surrounding the posterior ascending ramus (Latin for "branch") of the Sylvian fissure. This area is granular. The arcuate fasciculus runs underneath this. The neurons here are related to the body and the objects of the environment.

Semantic Dementia (Frontal Temporal Degeneration)

Patients (usually 30s-50s) who had problems in comprehending the meaning of words or the meaning of sentences, due to a severe gradual and progressive deterioration of the temporal lobe (usually the left, often frontal temporal areas). It starts gradually with a word finding difficulty -> impaired comprehension of word meaning -> trouble classifying objects -> muteness. fMRI shows atrophy, destruction, degeneration, deterioration, mostly of the temporal lobe often bilaterally but mostly unilaterally on the left side Elizabeth Warrington noticed category specific impairments and impairments in listing word synonyms.

The Corpus Callosum is primarily made up of which type of neurons?

Pyramidal neurons of layer III, Cortico-cortical connections.

Roger Sperry (1950s)

Sectioned the optic chaism, corpus callosum, and anterior commissural in cats and covered one eye and trained the cat on a visual discrimination task. They then uncovered that eye and covered the other one and tested them on the same visual discrimination task. They had to re-learn the task on this eye and it took just as long. If the anterior commissural and corpus callosum are severed, communication between the left and right cerebral cortex of the hemispheres is terminated. This was also proven true for tactile stimulation.

Elizabeth Warrington and Conduction Aphasia

She believed that just because a patient may have damage to the arcuate fasciculus and has conduction aphasia does not mean that it was damage to the arcuate fasciculus that caused the damage. There was also damage to the cortex, specifically the supramarginal gyrus, area PF(G). Perhaps conduction aphasia is a reflection of some role of the supramarginal cortex in cognitive processing. The SMG might be critical for verbal, short-term memory (phonological store). Conduction aphasia may be a problem of memory rather than a problem of communication between Broca and Wernicke's areas.

Lateral

Side view

Morphology

Studying the shape of the brain, the shape of the sulci and gyri differ between people. We can stain the cortical areas under the microscope and study the cytoarchitecture.

Phonetic Paraphasia

Substituting one sound for something else.

Perisylvian Region

The area around the Sylvian Fissure, including Broca's area, the supramarginal gyrus (SMG, PF), the insula, the oral and facial areas, etc

Syntax

The arrangement of words in a correctly constructed sentence in a particular language, the grammar of everyday language. It is controlled in the body by area 44.

Phonetics

The articulation of sounds of the language and how we comprehend them. The supramarginal gyrus (SMG, PF(G)), the most posterior parts of the superior temporal gyrus, the arcuate fasciculus, the superior longitudinal fasciculus, the left inferior parietal region, ventral premotor orofacial area 6, and Broca's region (area 44) are important for this.

Layer IV

The axons here do not go very far outside the area. They go to layers within the same cortical area and distribute information. This is the target of thalamic inputs.

Body

The center of the corpus callosum, it conjoins the motor and somatosensory areas. This is the central part.

What can be found medial to the extreme capsule but lateral to the external capsule?

The claustrum

Rostrum

The front end of the corpus callosum, most of the axons come from the base (orbital part) of the frontal lobe.

Medial

The inside of the brain, you need to remove a hemisphere to see this.

Retina

The light sensitive region at the back of the eyes. The light that hits the inner parts (nasal retina) cross over to the other side and the light that hits the outer parts (temporal retina) goes directly to the Lateral Geniculate Nucleus. It has a small receptive field that is contralateral and is retinotopically organized. It has its own receptive field and the axons form the optic nerve.

Pyriform Cortex (Primary Olfactory Cortex)

The most posterior part of the frontal lobe continuing up on to the most medial part of the temporal lobe, it is very old and only has three layers.

Splenium

The part most posterior of the corpus callosum, this is where the visual axons of the occipital lobe and parietal axons are crossing over. Damage to this area keeps the left and right visual areas of the brain from communicating.

Semantic Aphasia

The patient cannot categorize properly. This is marked by damage in the extreme capsule fasciculus, which is important for controlled voluntary memory retrieval.

Anterior Commissure

The point where the fibers from the anterior part of the temporal lobe in the left and the right hemisphere cross.

Commissurotomy

The sectioning of the hemispheres

Agramatism

The syntax is severely disturbed, characteristic of Broca's aphasia.

Brain Stem

This area continues until the spinal cord

Posterior Parietal Cortex

This can be divided into the Superior Parietal Lobule (PE) and the Inferior Parietal Lobule.

Superior Temporal Sulcus

This divides the lateral temporal lobe into the Superior Temporal Gyrus (STG) and the Medial Temporal Gyrus (MTG)

Uncinate Fasciculus Structure

This joins the lower part of the frontal lobe with the lower part of the temporal lobe

Layer III

This layer has neurons that come down and go to another cortical area. The neurons here give rise to the corpus callosum.

The Hippocampus.

This lies below the parahippocampal gyrus in the temporal lobe. This was one of the first cortical areas to evolve in the mammalian lineage. It has it's own connections through the fornix to the mammillary body and septal (nasal) region. It is a spatial machinery that let's us navigate our environment in space. The cells here create a framework within which the animal now has to attach different experiences (cognitive map). Right hemisphere damage results in the inability to place objects on a table where they belong after being displaced (Mary Lou Smith). The left hemisphere is a cognitive map for semantic and linguistic context. It is a scaffold upon which we continuously attach new knowledge about a stimulus.

Area 2

This responds to joint activity and is the largest receptive field. It responds to on/off stimulation.

Medial-Occipital-Temporal Sulcus

This separates the parahippocampal gyrus from the fusiform gyrus

Cingulate Sulcus

This starts and goes all around the corpus callosum and ends in an upward direction.

Semantic Information

Understanding Concepts

Sodium Amytal

Used by Wada to detected handedness v brain lateralization of language, this is an anesthetic substance which momentarily paralyzes the left or right hemisphere for about ten minutes, also paralyzing the contralateral side of the body. When the language-dominant hemisphere is paralyzed, the patient will stop speaking. This is used to localize language in a particular patient to protect the area during surgery. Before the drug is administered, they use the Edenburg questionnaire to assess handedness.

Fasciculus

Various kinds of white matter fibers, a bundle/group of axons. The three major types are commissural fibers, projection fibers, and association fibers. These are bi-directional.

Heschl's Gyri

Where the primary auditory cortex lies beneath the Sylvian fissure.

Corpus Callosum

White matter fibers and cables (axons) from millions of cells that are crossing over from the right hemisphere to the cortex and on the other side and vice versa. This area is an example of commissural fibers (Great Cerebral Commissural) and is the largest set of fibers. This area can be divided into the splenium, body, genu, and rostrum. It connects the right and left hemispheres of cerebral cortex, not the entire brain.