A man when touches a hot object, the sensation of heat is not perceived. Signal reaches the thalamus but is not transmitted to postcentral gyrus. Which of the following is responsible for this?
**Core Concept**
The sensation of heat is mediated by the spinothalamic tract, which transmits pain and temperature information from the body to the thalamus. The thalamus then relays this information to the primary somatosensory cortex (postcentral gyrus) for perception.
**Why the Correct Answer is Right**
The spinothalamic tract is responsible for transmitting pain and temperature information from the body to the thalamus. In this case, the signal reaches the thalamus but is not transmitted to the postcentral gyrus, suggesting a disruption in the spinothalamic tract. This is likely due to a lesion in the lateral spinothalamic tract, which is responsible for transmitting temperature information. The lateral spinothalamic tract synapses in the ventral posterior lateral (VPL) nucleus of the thalamus, which then relays the information to the postcentral gyrus.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question. The medial lemniscus is responsible for transmitting proprioception and vibration information from the body to the thalamus.
**Option B:** This option is incorrect because the dorsal column-medial lemniscus pathway is responsible for transmitting proprioception and vibration information, not temperature information.
**Option C:** This option is incorrect because the anterior spinothalamic tract is responsible for transmitting crude touch and pressure information, not temperature information.
**Clinical Pearl / High-Yield Fact**
The spinothalamic tract is a critical pathway for pain and temperature sensation, and lesions in this tract can result in sensory deficits. The lateral spinothalamic tract is particularly important for temperature sensation, and damage to this tract can result in a loss of temperature perception.
**Correct Answer:** C.