Forebrain (Exam 2)

Where is association cortex located?

Prefrontal cortex; Parieto-occipital-temporal cortex

Explain cerebral commissures.

Discrete bundles of axons that cross the midline

What are the two commissures of the cerebral cortex?

Corpus Callosum; Anterior Commissure

What happens if there is a lesion of the corpus callosum?

Can result in epilepsy and the feeling of having two minds

What are the limbic and olfactory cortical areas?

Allocortex; Hippocampus

Where is the hippocampus located?

In temporal lobe in the parahippocampal gyrus

Where is the amygdala and what does it do?

Anterior temporal lobe; involved in conditioned fear response

What is the tract of the limbic system called?

Fornix; Leads from hippocampus to mammillary bodies of hypothalamus

What is the basal ganglia?

A group of nuclei in the midbrain, diencephalon, and telencephalon; Important roles in motor system and motivation

What are the 4 major nuclei of the basal ganglia?

Striatum; Globus Pallidus; Subthalamic Nucleus; Substantial Nigra

What are the three sub-nuclei of the Striatum?

Caudate Nucleus; Putamen; Nucleus Accumbens

Where is the globus pallidus located?

Medial to putamen

What is the subthalamic nucleus and where is it located?

Part of diencephalon; Ventral to thalamus and dorso-lateral to mammillary bodies

What are the three primary brain vesicles?

Prosencephalon; Mesencephalon; Rhombencephalon

Where is the diencephalon located?

Rostral to midbrain, caudal and surrounded by telencephalon

What are the four parts of the diencephalon?

Epithalamus; Thalamus; Subthalamus; Hypothalamus

What are the essential functions of the hypothalamus?

Temperature regulation; Feeding & drinking; Circadian rhythms; Aggression and flight; Sexual activity

What is the neuroendocrine function of the hypothalamus?

The release of hormones into blood that act on the pituitary gland

Where is the pituitary gland located?

Attached to hypothalamus via pituitary stalk

Describe the thalamus.

Two halves (left and right) separated by third ventricle and connected via interthalamic adhesion

What is the Thalamic Reticular Nucleus?

Thin shell of neurons surrounding the thalamus; Controls whether information can be relayed to the cortex

What is the internal medullary lamina?

A sheet of axons that run through the middle of the thalamus; Divides the thalamic relay

What are the three major regions of thalamic relay?

Anterior (anterior nucleus); Medial (dorsomedial nucleus); Lateral (lateral group of nuclei)

What are the intralaminar nuclei?

Clusters of neurons amidst the axons of the internal medullary lamina

What are the three types of nuclei in the thalamus?

Specific, Association, Non-specific

What are the 6 specific thalamic nuclei and their functions?

Ventral Anterior and Lateral: Motor; Ventral Posterior Lateral and Medial: touch & pain; Medial Geniculate Nucleus: Hearing; Lateral Geniculate Nucleus: Vision

How do relay nuclei work?

Send axons to cerebral cortex; Project axons to cortical regions serving same functions as the thalamic regions

What is the projection of relay nuclei?

IPSILATERAL (same side)

What are the associated thalamus nuclei?

Regions that respond to more than one sense; Dorsomedial nucleus; Pulvinar Nucleus

What are the non-specific nuclei of the thalamus?

Shell of intralaminar regions; Reticular nucleus; Important for attention and arousal

Describe the input/output of thalamic relay nuclei.

Hypothalamus→Anterior→cingulate cortex; Cerebellum→ventral lateral→ motor cortex; Retina→ lateral geniculate→visual cortex

Why do we have a thalamus?

Flow of information from thalamus to cortex is gated by inputs from the cortex and brain stem reticular

How does the thalamic reticular nucleus connect to the thalamus?

It inhibits the output of other thalamic nuclei

What is the internal capsule?

Similar to a highway - axons enter and exit the cortex

What is the telencephalon?

Two hemispheres separated by the interhemispheric fissure

What are the three interrelated parts of the telencephalon?

Neocortex; Limbic and olfactory cortex; Basal Ganglia

What are the lobes of the cerebral cortex?

Frontal, parietal, occipital, temporal

How many layers does the allocortex have?

3-5 cell layers; Contains the hippocampus

How many layers does the neocortex have?

Six cell layers

Explain the wiring of the neocortex.

Thalamus projects to layer IV; Layer IV projects to II & III; Layer V projects to brainstem and/or spinal cord

What are the primary cortical regions?

Primary Sensory Cortex; Primary Motor Cortex

What does the primary sensory cortex do?

Innervated by specific thalamic relay nuclei for the same sense

What does the primary motor cortex do?

Innervates spinal cord or brainstem and controls motoneurons

What is association cortex?

E.g. visual cortex → association cortex → speech, writing, correlation

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