Midbrain Lesions & Neurotransmitters

damages the 3rd nerve

Also know as tofranil

Lesion by the posterior commissure can cause paralysis of upward gaze. The posterior commissure is a structure in the brain that is involved in the control of eye movements. When it is damaged or affected by a lesion, it can result in the inability to move the eyes upward. This is known as paralysis of upward gaze. The other options, paralysis of downward gaze, lateral gaze, and medial gaze, are not associated with lesions in the posterior commissure.

Parinaud's syndrome is a condition characterized by paralysis of upward gaze, which is consistent with the given correct answer. This syndrome is caused by a lesion in the midbrain, specifically affecting the vertical gaze centers. Other symptoms may include pupillary abnormalities, convergence-retraction nystagmus, and eyelid retraction.

Weber's syndrome is a midbrain lesion that presents with contralateral upper motor neuron (UMN) signs and ipsilateral third nerve palsy. This means that there will be weakness and spasticity on the side opposite to the lesion, along with paralysis of the eye muscles on the same side as the lesion. Therefore, Weber's syndrome is the correct answer.

The raphe nucleus is known to produce serotonin. Serotonin is a neurotransmitter that plays a role in regulating mood, sleep, appetite, and other important functions in the brain. It is involved in various physiological processes and is often associated with feelings of well-being and happiness. Serotonin is also targeted by many antidepressant medications, as imbalances in serotonin levels have been linked to depression and other mood disorders. Therefore, it is reasonable to conclude that the raphe nucleus produces serotonin.

1st piece of the puzzle

Also known as marsilid

The locus ceruleus is a small nucleus in the brainstem that is responsible for producing and releasing norepinephrine. Norepinephrine is a neurotransmitter that plays a role in various functions such as attention, arousal, and stress response. It is involved in regulating mood, sleep, and heart rate. Therefore, it is the correct answer because the locus ceruleus is known for producing norepinephrine, not epinephrine, serotonin, or GABA.

Depression is often associated with a decrease in serotonin levels. Serotonin is a neurotransmitter that plays a crucial role in regulating mood, emotions, and sleep. When serotonin levels are low, it can lead to feelings of sadness, hopelessness, and a lack of interest in activities. Therefore, a lowering of serotonin is believed to contribute to the development of depression.

Benedikt's syndrome is a midbrain lesion that presents with a contralateral tremor and an ipsilateral third nerve palsy. This combination of symptoms is characteristic of Benedikt's syndrome. Parinaud's syndrome, on the other hand, is characterized by vertical gaze palsy and pupillary abnormalities, while Weber's syndrome is characterized by a contralateral hemiparesis and ipsilateral oculomotor nerve palsy. Therefore, the correct answer is Benedikt's syndrome.