Diencephalon, Limbic System, Cerebrum and Basal Nuclei

These flashcards cover key structures and functions of the diencephalon (thalamus and hypothalamus), limbic system, cerebral cortex, white-matter fiber types, and basal nuclei, highlighting their roles in sensory processing, emotion, memory, autonomic regulation, and motor control.

Which gland is housed in the epithalamus and what hormone does it secrete?

The pineal gland, which secretes melatonin to regulate the sleep/wake cycle.

Which structure forms the walls of the diencephalon and composes most of its volume?

The thalamus.

What part of the diencephalon forms its floor and links the nervous and endocrine systems?

The hypothalamus.

What is the thalamus’ primary role in sensory processing?

It is the final relay point to the primary sensory cortex and acts as a filter, passing on only a small portion of incoming sensory information.

How does the thalamus coordinate activities between the basal nuclei and the cerebrum?

By relaying information between them.

Name the five major groups of thalamic nuclei.

Anterior, medial, ventral, posterior, and lateral groups.

Which thalamic nuclei group is part of the limbic system and involved in emotion and motivation?

The anterior nuclei (anterior group).

Which thalamic group connects the hypothalamus’ emotional centers with the frontal lobes, providing awareness of emotional states?

The medial group.

What information does the ventral group of thalamic nuclei relay to the cerebral cortex?

Motor information from the basal nuclei and cerebellum, and sensory information about touch, pressure, pain, temperature, and proprioception.

Which posterior group nucleus integrates sensory information from the cerebral cortex?

The pulvinar nuclei.

What information does the lateral geniculate nucleus transmit and to where?

Visual information from the optic tract to the occipital lobes and midbrain.

What does the medial geniculate nucleus relay?

Auditory information to appropriate areas of the cerebral cortex from inner-ear receptors.

How does the lateral group of thalamic nuclei influence emotion and sensory integration?

It forms feedback loops with the limbic system and parietal lobes, affecting emotional states and integrating sensory information.

List three ways hypothalamic centers may be stimulated.

(1) Sensory information from the cerebrum, brainstem, and spinal cord; (2) changes in CSF and interstitial fluid composition; (3) chemical stimuli in circulating blood via permeable capillaries.

Which hypothalamic function involves subconscious control of skeletal muscle patterns linked to emotions?

Directing somatic motor patterns associated with rage, pleasure, pain, and sexual arousal.

How does the hypothalamus control autonomic functions?

By adjusting and coordinating activities of autonomic centers in the pons and medulla, regulating heart rate, blood pressure, respiration, and digestion.

How does the hypothalamus coordinate the nervous and endocrine systems?

By inhibiting or stimulating the pituitary gland through regulatory hormones.

Name the two hormones secreted by the hypothalamus and state their functions.

Antidiuretic hormone (ADH) restricts water loss by the kidneys; oxytocin stimulates smooth-muscle contraction in the uterus, mammary glands, and prostate.

Which hypothalamic centers generate hunger, thirst, and satiety?

The feeding center, thirst center, and satiety center.

How does the hypothalamus regulate body temperature?

The preoptic area communicates with the vasomotor center in the medulla to adjust peripheral blood-vessel diameter and hence heat loss or retention.

Which hypothalamic nucleus controls circadian rhythms?

The suprachiasmatic nucleus.

What are the functions of the mammillary bodies?

They process olfactory sensory information, control reflex movements related to eating (chewing, licking, swallowing), and are involved in memory.

State three main functions of the limbic system.

(1) Establishing emotional states; (2) linking conscious cerebral functions with unconscious autonomic functions; (3) facilitating memory storage and retrieval.

Which limbic structure helps regulate heart rate during fear, controls fight-or-flight, and links emotions to memories?

The amygdaloidal body (amygdala).

Name the three gyri that compose the limbic lobe.

Cingulate gyrus, dentate gyrus, and parahippocampal gyrus.

What is the main role of the hippocampus?

Learning and the storage and retrieval of new long-term memories.

What is the fornix?

A white-matter tract connecting the hippocampus with the hypothalamus (especially the mammillary bodies).

Which deep groove divides the two cerebral hemispheres?

The longitudinal fissure.

What sulcus separates the frontal and parietal lobes?

The central sulcus.

What sulcus separates the parietal lobe from the occipital lobe?

The parieto-occipital sulcus.

State three general principles about cerebral hemispheres’ functional organization.

(1) Each hemisphere controls the opposite side of the body; (2) the hemispheres have distinct specialized functions; (3) precise localization of functions to specific cortical regions is imprecise.

What are association fibers and their two subtypes?

They interconnect cortical areas within the same hemisphere; short association fibers are arcuate fibers, long ones are longitudinal fasciculi.

What are commissural fibers and give two examples.

Fibers that interconnect the two cerebral hemispheres; examples are the corpus callosum and anterior commissure.

What are projection fibers, and what is the entire collection of projection fibers called?

Fibers linking the cerebral cortex with the diencephalon, brainstem, cerebellum, and spinal cord; collectively called the internal capsule.

List the major components of the basal nuclei.

The caudate nucleus and the lentiform nucleus (which includes the putamen and globus pallidus).

What is the primary role of the basal nuclei in movement?

Subconscious control of skeletal muscle tone and coordination of learned movement patterns (they do not initiate movement but set overall rhythm and pattern).

Where does input to the basal nuclei come from, and where does its output go?

Input from sensory, motor, and integrative cortical areas to the caudate nucleus and putamen; output from the globus pallidus to the thalamus, which then projects to the appropriate cortical areas.

How does dopamine from the substantia nigra affect basal nuclei activity, and what disorder results when this dopamine is deficient?

Dopamine inhibits basal nuclei activity; loss of dopamine (e.g., due to substantia nigra damage) leads to increased muscle tone and the symptoms of Parkinson’s disease.