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Nervous System

Description: This test is designed in such a way that it will help the learning aspirants to revise the topics thoroughly.
Number of Questions: 15
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Tags: Nervous system Central Nervous System Conduction of Nerve Impulse Generation and Transmission of Nerve Impulse
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Which of the following neurons generate action potentials regardless of stimulus amplitude or duration?

  1. Tonic neurons

  2. Phasic neurons

  3. GABAergic neurons

  4. Fast spiking

  5. Thin-spike neurons


Correct Option: B
Explanation:

These neurons fire in bursts. They generate action potentials for a brief time period at the onset of a stimulus and regardless of stimulus amplitude or duration, and hence behave as signal detectors. Typical example are retinal ganglion cells (neurons).

A person met with an accident and lost his ability to read, understand, and speak. Which of the following lobes of the cerebral hemispheres must have been damaged?

  1. Limbic lobe

  2. Insula lobe

  3. Temporal lobe

  4. Parietal lobe

  5. Frontal lobe


Correct Option: C
Explanation:

This lobe borders the parahippocampal gyrus of the limbic lobe. It is responsible for the ability to read, understand, and speak.

A circadian rhythm is a 24 hour cycle in the physiological processes of all the living organisms. Which of the following hypothalamic nuclei is most important for encoding the set point for this daily circadian rhythms?

  1. Supraoptic nucleus

  2. Arcuate nucleus

  3. Pretectal nucleus

  4. Paraventricular nucleus

  5. Suprachiasmatic nucleus


Correct Option: E
Explanation:

The suprachiasmatic nucleus is a group of brain cells located in the hypothalamus. It regulates the circadian cycles and also influences many physiological and behavioural rhythms occurring over a 24-hour period, such as the sleep/wake cycle.

The Papez circuit is a pathway in the brain's limbic system, which governs the emotions of an organism. Which structure is NOT part of the Papez circuit?

  1. Anterior nucleus of the thalamus

  2. Ventral nucleus of the thalamus

  3. Cingulate gyrus

  4. Hippocampus

  5. Mammillary bodies


Correct Option: B
Explanation:

The ventral nucleus of the thalamus is not a part of the Papez circuit. It acts with the anterior part of the ventral lateral nucleus to modify signals from the basal ganglia.

Which of the following can be EXCLUDED from the visible boundary of the hypothalamus in a hemisected brain?

  1. The internal capsule

  2. The median eminence

  3. The mammillary bodies

  4. The optic chiasm

  5. The anterior commissure


Correct Option: A
Explanation:

The internal capsule is a thick layer of white matter separating the caudate nucleus and thalamus. It is the major route by which the cerebral cortex is connected with the brainstem and spinal cord.

The foremost pathway of the hypothalamus in the central autonomic network is

  1. medial forebrain bundle

  2. dorsal longitudinal fasciculus

  3. stria terminalis

  4. mammillotegmental tract

  5. spinohypothalamic tract


Correct Option: B
Explanation:

The principal pathway of the hypothalamus in the central autonomic network is the dorsal longitudinal fasciculus. It is a bundle of thin, poorly myelinated nerve fibers reciprocally connecting the periventricular zone of the hypothalamus with ventral parts of the central gray substance of the midbrain.

The postcommissural fornix has direct terminal to which of the following structures?

  1. Substantia innominata

  2. Ventromedial nuclei of the hypothalamus

  3. Nucleus basalis of Meynert

  4. Anterior cingulate cortex

  5. Mamillary bodies


Correct Option: E
Explanation:

The postcommissural branch of the fornix conjoins the anterior nucleus of the thalamus and the mammillary bodies of the hypothalamus.

A 60-year old woman with recent damage to the hippocampus from a stroke would likely to have all of the following deficits EXCEPT?

  1. difficulty in learning new facts

  2. difficulty in describing a recent event

  3. difficulty in recalling a childhood memory

  4. difficulty in remembering a face

  5. difficulty in learning a new vocabulary


Correct Option: C
Explanation:

The hippocampus is involved in the formation of new memories, but not in the storage of old memories after they have been consolidated.

A 46-year old man after a road accident was diagnosed as having visual neglect. What cerebral region was most likely to be involved?

  1. Non-dominant parietal-occipital cortex

  2. Dominant parietal-occipital cortex

  3. Dorsal prefrontal cortex

  4. Dominant temporal-occipital cortex

  5. The dominant parietal lobe


Correct Option: A
Explanation:

The non-dominant parietal lobe integrates the contralateral side of the body with its environment enabling people to be aware of this environmental space, and is important for abilities such as drawing. Lesions of the right posterior parietal visuocortex (i.e. parietal-occipital cortex) most likely produces visual neglect. 

The damage to which of the follwing structures can make an individual emotionally labile?

  1. The dorsolateral frontal cortex

  2. The orbital frontal cortex

  3. The left posteroinferior frontal cortex

  4. The medial frontal cortex

  5. The primary motor cortex


Correct Option: B
Explanation:

 The orbital frontal cortex regulates social behaviour of an organism. People with orbital frontal lesions can become emotionally labile.

Which of the following selects the action on the basis of motivation in the body?

  1. Ventral horn

  2. Prefrontal cortex

  3. Supplementary motor area

  4. Premotor cortex

  5. Basal ganglia


Correct Option: E
Explanation:

Basal ganglia is located in forebrain. Its main function is the action selection on the basis of motivation.

While playing a boy fell and got injured. Which of the following cell types will NOT proliferate in the CNS in response to injury in the body?

  1. Neurons

  2. Fibrous astrocytes

  3. Protoplasmic astrocytes

  4. Microglia

  5. Macrophages


Correct Option: A
Explanation:

The neurons do not undergo cell division once they have matured during the development of the organism, thus they will not proliferate in the CNS in response to injury.

Which of the following cells maintains the pH of the extracellular space of the CNS in mammals?

  1. Ependymal cell

  2. Oligodendrocytes

  3. Fibrous astrocytes

  4. Pituicyte

  5. Neural stem cells


Correct Option: C
Explanation:

Fibrous astrocytes are found throughout all white matter. They perform many functions including biochemical support of endothelial cells that form the blood–brain barrier, distribution of nutrients to the nervous tissue and the maintenance of extracellular pH balance.

The process through which a neuron summates synaptic excitation and inhibition is termed as _________.

  1. plasticity

  2. itegration

  3. convergence

  4. disinhibition

  5. inhibition


Correct Option: B
Explanation:

 The nervous system combines information from the different senses (vision, hearing touch, etc), and each part of the brain combines information from many other parts of the brain. All this take place because neurons have dendrites, which are designed to combine or integrate information.

Which of the following processes controls the amount of neurotransmitter released from a nerve ending on a short-term, i.e. minute-to-minute basis?

  1. Actin availability

  2. Calcium inavailability

  3. Axoplasmic transport

  4. Vesicle synthesis in the cell soma

  5. Neurotransmitter synthesis


Correct Option: E
Explanation:

Because there is only sufficient neurotransmitter available in a nerve ending for a minute or so of continued released, the biosynthesis of new neurotransmitter to fill the recycled neurotransmitter vesicle is necessary for continued availability of neurotransmitter for release.

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