Cerebrum, Limbic System, and Higher Order Functions

Flashcards to help review Cerebrum, Limbic System, and Higher Order Functions

Association areas

Regions of cortex that are not involved in primary motor or sensory functions; responsible for higher-level processing

Primary areas

Regions of cortex for direct sensory input or motor output

Brodmann's map

Brain divided into 52 numbered areas based on cell structure (histology)

Areas 39 and 40

Part of Wernicke's area; involved in language comprehension

Areas 41 & 42

Primary and secondary auditory cortex; process sound info from ears

Area 17

Primary visual cortex; processes visual input from retina

6 layers of the cerebrum

Molecular, external granular, external pyramidal, internal granular, internal pyramidal, multiform

Methods of dying the cerebrum

Golgi stain, Nissle stain, Weigert stain

Golgi stain

Stains whole neurons

Nissle stain

Stains cell bodies only; shows neuron density

Weigert stain

Stains axons only; shows connectivity and neural pathways

Primary motor cortex

In precentral gyrus; initiates contralateral fine movements; source of corticospinal & corticobrainstem tracts

Motor homunculus

Body map of the motor cortex; medially (legs) to laterally (face); larger areas correspond to fine motor control (hands + face)

Cortical motor planning areas

Supplementary motor area, premotor cortex, broca's area, inferior frontal gyrus

Inferior frontal gyrus

Area corresponding to Broca's area in the opposite hemisphere

Supplementary motor cortex location

Medial and superior frontal lobe, anterior to precentral gyrus

Supplementary motor cortex function

Initiates movement; plans bimanual & sequential tasks; important for postural control

Premotor cortex location

Lateral frontal lobe, anterior to precentral gyrus

Premotor cortex functions

Control of trunk and girdle muscles; anticipatory postural adjustments based on external cues

Broca's area location

Anteroinferior to premotor cortex (usually left hemisphere)

Broca's area function

Motor programming of speech

Lesion to primary motor cortex

Contralateral paralysis or paresis

Lesion to premotor or supplementary motor areas

Apraxia

Apraxia

Loss of knowledge of how to perform skilled movements, despite intact strength, sensation, and coordination; can be limb or facial (depending on lesion location)

Frontal association areas

Involved in higher-order functions like planning, decision-making, and philosophical thinking

Lesion to frontal association area

Personality changes, impulsivity, difficulty planning, and challenges with social integration/interaction

Emotional lability

Emotional instability often seen in neurological conditions, due to limbic system connections with various brain areas

Somatosensory cortex

In postcentral gyrus; processes tactile and proprioceptive input to identify location, shape, size, and texture of stimuli

Sensory association area

Interprets input from the somatosensory cortex, giving meaning and recognition to objects

Sensory homunculus

Body map of somatosensory cortex; medially (legs + genitals) to laterally (face); larger areas correspond to greater sensory sensitivity (fingertips + lips)

Smudging

With chronic pain, the brain loses precise sensory mapping, leading to poor localization of pain

Lesion to primary somatosensory cortex

Contralateral loss of sensory awareness and localization of touch

Lesion to somatosensory association areas

Tactile agnosia (astereognosis and/or graphesthesia)

Tactile agnosia

Inability to identify objects by touch, despite intact sensation

Asterognosis

Inability to recognize objects by touch

Graphesthesia

Inability to recognize writing on the skin by touch alone

Primary auditory cortex

In brodmann's area 41 (temporal lobe); conscious discrimination of sound loudness and pitch

Primary visual cortex

In brodmann's area 17 (occipital lobe); distinguishes intensity of light, shape, size, and location of objects

Primary vestibular cortex

In parietal insula; discriminates head position and movement, aids in perception of vertical

Sensory pathways tend to be

Diverging

Motor pathways tend to be

Converging

Parietal association areas

Located between somatosensory and visual areas; integrate sensory info, support spatial awareness, and coordinate movement

Parietal lesions

Neglect, losing perception or comprehension of one side of the body (usually contralateral)

Typically presentations with neglect

Leaning away from neglected side; drawing half of a picture; eating from half of the plate

Neglect tends to occur with which lesion to which side?

Right side; leading to left-sided neglect

Flow of visual information

Retina > lateral geniculate nucleus > optic radiations > primary visual cortex

Retinotopic organization

Predictable mapping of visual cortex; adjacent areas of retina correspond to adjacent areas in cortex

Strokes to which artery can cause visual deficits?

Posterior cerebral artery (PCA)

Lesion to primary visual cortex

Visual field deficits, scotoma, cortical blindness

Scotoma

Blind spot

Cortical blindness

Loss of vision due to damage to primary visual cortex despite intact eyes and optic pathways

Lesion to visual association areas

Visual agnosia, prosopagnosia

Visual agnosia

Inability to recognize objects despite intact vision

Prosopagnosia

Inability to recognize faces

Lesion to primary auditory cortex

Cortical deafness

Cortical deafness

Loss of hearing despite intact auditory pathways

Lesion to auditory association areas

Impaired speech comprehension (dominant side), inability to differentiate environmental sounds (non-dominant side)

Temporal association areas

Involved in recognizing language patterns, linking visual stimuli to meaning and recognition, and processing memories

Lesion to broca's area

Expressive aphasia

Expressive aphasia

Difficulty in speech production and word formation, despite intact comprehension

Lesion to wernicke's area

Receptive/fluent aphasia

Receptive/fluent aphasia

Difficulty with language comprehension; individuals can produce sounds but output is meaningless

Wernicke's area location

Left temporoparietal junction

Arcuate fasciculus

Bundle of axons that connects Wernicke's area and Broca's area

Lesion to arcuate fasciculus

Conduction aphasia

Conduction aphasia

Speech and writing tend to be meaningless despite normal understanding of written and spoken language

Lesion to which side of the brain will have greater effects on language?

Left

Language disorders

Aphasia (speech), agraphia (writing), alexia (reading)

3 categories of subcortical white matter

Projection, commissural, association

Projection fibers

Connect cortex with subcortical structures (spinal cord, basal ganglia, brainstem, thalamus)

Almost all projection fibers travel through the

Internal capsule

Commissural fibers

Run horizontally, connect corresponding areas between hemispheres

The largest group of commissural fibers is the

Corpus callosum

Anterior commisure

Connects the temporal lobes across hemispheres; transmits olfactory information

Posterior commissure

Just superior to cerebral aqueduct; connections for pupillary light reflex

Association fibers

Connect cortical regions within one hemisphere

Short association fibers

Connect adjacent gyri

Long association fibers

Connect different lobes within a hemisphere

Cingulum

Association fibers connecting frontal, parietal, and temporal cortices to limbic structures (e.g., hippocampus)

Uncinate fasciculus

Connects the amygdala (temporal lobe) to the frontal lobe

Inferior longitudinal fasciculus

Connects occipital and temporal lobes

Superior longitudinal fasciculus

Connects cortices of all lobes (frontal to occipital lobe)

What type of imaging allows us to trace bundles?

Diffusion tensor imaging; type of MRI that maps white matter tracts by tracking diffusion of water

Internal capsule

Projection fibers descending from corona radiata; divided into anterior limb, genu, and posterior limb

Arcuate fibers

Short association fibers; connecting adjacent gyri

Thalamus function

Acts as a relay center and selective filter for the cerebral cortex; regulates and integrates sensory, motor, and cognitive info

Three main types of thalamic nuclei

Relay, association, nonspecific

Relay nuclei of thalamus

Receives specific information and sends it directly to localized areas of cerebral cortex

Relay nuclei of thalamus include

Ventral anterior, ventral lateral, ventral posterolateral; ventral posteromedial; medial geniculate; lateral geniculate

Association nuclei of thalamus

Connects reciprocally to large areas of the cortex

Association nuclei of thalamus include

Medial group, anterior, lateral dorsal, midline, lateral posterior, pulvinar

Nonspecific nuclei of thalamus

Receive multiple types of inputs and project to widespread areas of cortex

Nonspecific nuclei of thalamus include

Intralaminar, reticular

Intralaminar thalamic nuclei

Afferents from reticular formation; involved in arousal and attention

Medial geniculate thalamic nuclei

Relays auditory info

Lateral geniculate thalamic nuclei

Relays visual info

Ventral posteromedial thalamic nuclei

Relays sensory info from the face

Ventral posterolateral thalamic nucleu

Relays sensory info from the body

Lesion to thalamus

Symptoms and severity depend on location and size of lesion

Lesion to relay nuclei of thalamus

Affects ascending or thalamocortical tracts; may lose contralateral sensation/proprioception