Forebrain: Definition, Function, Structures, Diagram, Facts, FAQs, Parts

What Is the Forebrain?

The forebrain is the largest and most complicated portion of the human brain. The structures of the forebrain participate in running our day-to-day life. It facilitates high mental functions, sensory perception, and voluntary motor activity.

Structure of the Forebrain

It consists of the structures of cerebrum, thalamus and the hypothalamus.

Cerebrum

• The division into two hemispheres and four lobes: frontal, parietal, temporal and occipital.

Thalamus

• The thalamus acts as a relay station. It is associated with the conduction of sensory and motor signs to the cerebral cortex.

• It takes part in the regulation of consciousness, sleep, and alertness

Hypothalamus

• The hypothalamus is also concerned with significant homeostasis.

• It controls the body temperature, hunger, thirst, sleep, and wakefulness

• It controls a pituitary gland that, in turn, controls the secretion of hormones.

Division of the Forebrain

The forebrain divides into the diencephalon and telencephalon

Diencephalon

• Interposed between the telencephalon and midbrain, the diencephalon comprises the thalamus, hypothalamus epithalamus, and subthalamus. It forms in the third week of embryonic development from the neural tube.

Structures of Diencephalon

• Thalamus: A large grey matter structure that relays sensory information to the cerebral cortex and regulates alertness, sleep, and consciousness.

• Hypothalamus: The hypothalamus is the portion of the brain lying just underneath the thalamus. The pituitary acts at the interface between the nervous and endocrine systems. These processes control metabolic processes to hunger, thirst, sleep, fatigue, and circadian rhythm.

• Epithalamus: A small structure rather located at the dorsal part of the diencephalic region of the brain, consisting of the habenular commissure, habenular nuclei, stria medullaris, and pineal gland producing melatonin and hormones that modulate emotion and conserve energy.

• Subthalamus: It is that part of the diencephalon which lies ventrally to the thalamus and laterally to the hypothalamus. It is composed of grey matter nuclei accompanied by the associated white matter structures.

Telencephalon

• The forebrain forms the cerebrum, which is the largest part of the brain.

• It comprises the cerebral cortex, hippocampus, olfactory bulb, and basal ganglia.

• It allows for voluntary movements that are possible with the help of the cerebellum.

Basal Ganglia

The basal ganglia comprise a group of nuclei linked to the regulation of voluntary motor movements, procedural learning, and habitual behaviours. Through their influence on the activity in the thalamus, they modulate the coordination of movement and posture.

Functions Of The Forebrain

The functions of forebrain are:

• It deals with higher-order functions of the central nervous system involving thought processes, planning, decision-making, and problem-solving.

• It thus processes the information from sense organs about different parts of the body and coordinates voluntary movements.

Points to Remember

• It is in the forebrain that the most elevated and complicated functions of the brain are carried out: cognition and emotion.

• In its turn, through the hypothalamus, it makes a huge impact on the internal environment of the body.

• Thus, damage to the forebrain can be disastrous for cognition and sensation.

Forebrain NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Structure of Forebrain

• Division of Forebrain

Practice Questions for NEET

Q1. Which part of the brain is responsible for thermoregulation?

1. Cerebrum

2. Hypothalamus

3. Corpus callosum

4. Medulla oblongata

Correct answer: 2) Hypothalamus

Explanation:

The hypothalamus contains several centres which control body temperature, and urge for eating and drinking. It also contains several groups of neurosecretory cells, which secrete hormones called hypothalamic hormones. The hypothalamus is the part of the brain involved in thermoregulation. The cerebrum is involved in interpreting touch, vision, hearing, speech, reasoning movement, etc. The Corpus callosum joins two hemispheres of the cerebrum. Medulla oblongata helps regulate breathing, heart function, digestion, etc.

Hence the correct answer is option 4)Hypothalamus.

Q2. Injury localized to the hypothalamus would most likely disrupt:

1. Short-term memory.

2. Coordination during locomotion.

3. Executive function, such as decision-making.

4. Regulation of body temperature.

Correct answer: 4) Regulation of body temperature.

Explanation:

A very important part of the brain called the hypothalamus lies at the base of the thalamus. The hypothalamus contains several centres which control body temperature, and urge for eating and drinking. It also contains several groups of neurosecretory cells, which secrete hormones called hypothalamic hormones.

Hence, the correct answer is option 4)Regulation of body temperature.

Q3. The grey matter of cerebellum exhibits tree-like structure called

1. Arbor vitae

2. Purkinje cells

3. Basket cells

4. Granule cells

Correct answer: 1) Arbor vitae

Explanation:

Three layers of cells and fibres make up the grey matter that surrounds the cerebellum. Arbor vitae are tree-like structures found in the cerebellar grey matter. Characteristically big flask-shaped Purkinje cells are found in the intermediate layer. Granule cells, basket cells, and Golgi cells are also found in the cerebellum. Therefore, the grey matter of the cerebellum exhibits a tree-like structure called arbour vitae.

Hence, the correct answer is option 1) Arbor vitae.

Also Read:

• MCQs on Forebrain

• Synapse

• Autonomic Nervous System

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