neuroscience exam 2 most recent

What is the diencephalon?

A collection of deep brain structures connecting the body and brain; involved in cognition, language, sensation, motor control, and homeostasis.

Where is the thalamus located?

Deep in each hemisphere, above the hypothalamus; the two thalami are separated by the third ventricle.

What is the main function of the thalamus?

A relay station/gatekeeper for sensory information; also integrates motor information and regulates cognition, emotion, and language.

Where is the epithalamus located?

Posterior and superior to the thalamus, near the roof of the third ventricle.

What is the function of the epithalamus?

Regulates sleep/wake cycles and reward processing.

Where is the subthalamus located?

Below the thalamus, above the midbrain.

What is the function of the subthalamus?

Motor function and visuomotor coordination.

Where is the hypothalamus located?

Below the thalamus, near the base of the brain and third ventricle.

What is the function of the hypothalamus?

Controls the autonomic nervous system and homeostasis: temperature, hunger, thirst, emotions, and endocrine functions.

Where is the pituitary gland located?

At the base of the brain, connected to the hypothalamus by a stalk.

What is the function of the pituitary gland?

Synthesizes and releases hormones controlling growth, reproduction, and other endocrine functions.

Where is the pineal gland located?

Posterior part of the epithalamus, near the roof of the third ventricle.

What is the function of the pineal gland?

Produces melatonin, regulating sleep/wake cycles; influences reproductive systems.

Where is the anterior thalamic nucleus?

Anterior tier of the thalamus.

What is the function of the anterior thalamic nucleus?

Integrates visceral/emotional information and helps form new memories.

Where is the ventral anterior (VA) nucleus?

Anterior part of the ventral lateral thalamic tier.

What is the function of the Ventral Anterior nucleus of the thalamus?

Planning and execution of voluntary, skilled movement.

Where is the ventral lateral (VL) nucleus?

Ventral lateral tier of the thalamus.

What is the function of the VL nucleus?

Regulates voluntary movement using information from the basal ganglia and cerebellum.

Where is the ventral posterolateral (VPL) nucleus?

Posterior part of the ventral lateral thalamic tier.

What is the function of the VPL nucleus?

Relays all somatosensory information from the neck down to primary somatosensory cortex.

Where is the ventral posteromedial (VPM) nucleus?

Posterior ventral tier, medial to VPL.

What is the function of the Ventral Posteromedial Nucleus of the thalamus?

Relays sensation from the face/head and taste to the primary sensory cortex.

Where is the pulvinar located?

Posterior end of the thalamus.

What is the function of the pulvinar?

Integrates visual information and language; reading, writing, and language processing.

Where is the medial thalamic nucleus?

Medial tier of the thalamus.

What is the function of the medial thalamic nucleus?

Integrates visceral information with emotion, cognition, personality, and memory.

Where is the lateral geniculate nucleus (LGN)?

Posterolateral thalamus, in the metathalamus.

What is the function of the LGN?

Relays visual information to the primary visual cortex.

Where is the medial geniculate nucleus (MGN)?

Posterior thalamus, medial to the LGN.

What is the function of the Medial Geniculate Nucleus?

Relays auditory information to primary auditory cortex.

What are the three main thalamic tiers?

Anterior, medial, and lateral; the lateral tier includes ventral nuclei.

What can damage to the thalamus cause?

Problems with movement, sensation, language, memory, vision, hearing, cognition, or consciousness.

What is thalamic syndrome?

Abnormal movements such as hemi-ataxia, hemi-dystonia, and jerking movements.

What is thalamic pain syndrome?

Severe burning, tingling, or needle-like pain after thalamic damage.

What can damage to the subthalamus cause?

Hemiballismus: involuntary flinging movements, usually on the opposite side.

What can damage to the hypothalamus cause?

Disrupted body temperature, fluid retention, appetite, and eating patterns.

What can damage to the pineal gland affect?

Melatonin regulation and sleep/wake cycles.

What can pituitary gland damage cause?

Hormone deficiencies or excesses affecting growth, metabolism, and reproduction.

What is epicritic information?

Fine/discriminative touch, vibration, conscious proprioception, and kinesthesia; carried by DCML.

What is protopathic information?

Pain, temperature, and crude/diffuse touch; carried by the anterolateral system.

What are mechanoreceptors?

Receptors responding to mechanical stimuli such as pressure, touch, vibration, and stretch.

What are thermoreceptors?

Receptors detecting temperature changes.

What are nociceptors?

Receptors detecting potentially damaging stimuli (pain).

What are proprioceptors?

Receptors sensing joint position, muscle stretch/tension, and body position.

What is receptor adaptation rate?

The pattern of action potentials produced during a long-lasting stimulus.

What do rapidly adapting receptors detect?

Changes in stimulation, such as movement or vibration; they respond strongly at onset/offset.

What do slowly adapting receptors detect?

Sustained pressure, skin stretch, and continuing stimulation.

What is the general three-neuron somatosensory pathway?

First-order: receptor to cord/medulla; second-order: cord/medulla to thalamus; third-order: thalamus to cortex.

Where are first-order somatosensory neuron cell bodies?

Dorsal root ganglia (DRG).

What is the DCML first-order neuron pathway?

Receptor → DRG → ascends ipsilaterally in dorsal columns → nucleus gracilis/cuneatus in medulla.

What is the DCML second-order neuron pathway?

Medulla → crosses in medulla → medial lemniscus → VPL of thalamus.

What is the DCML third-order neuron pathway?

VPL of thalamus → primary somatosensory cortex.

Where does the DCML decussate?

In the medulla.

What information does the DCML carry?

Fine touch, vibration, and conscious proprioception/kinesthesia.

What does fasciculus gracilis carry?

Epicritic information from the lower body.

What does fasciculus cuneatus carry?

Epicritic information from the upper body.

What is the anterolateral first-order neuron pathway?

Receptor → DRG → spinal cord dorsal horn, where it synapses.

What is the anterolateral second-order neuron pathway?

Spinal cord dorsal horn → crosses in cord → ascends spinothalamic tracts → VPL.

What is the anterolateral third-order neuron pathway?

VPL of thalamus → primary somatosensory cortex.

Where does the anterolateral system decussate?

In the spinal cord, near the level of entry.

What are the functional differences between the DCML and anterolateral systems?

The DCML carries epicritic information (fine touch, vibration, proprioception/kinesthesia). The anterolateral system carries protopathic information (pain, temperature, crude touch and pressure).

What information does the anterior spinothalamic tract carry?

Crude/diffuse touch and pressure.

What is the main anatomical difference between DCML and anterolateral systems?

DCML ascends ipsilaterally and crosses in medulla; anterolateral crosses in cord then ascends contralaterally.

What does a right-sided spinal cord lesion do to DCML sensation?

Loss of fine touch, vibration, and conscious proprioception on the RIGHT below the lesion.

What does a right-sided spinal cord lesion do to anterolateral sensation?

Loss of pain, temperature, and crude touch on the LEFT below the lesion.

What does a left-sided spinal cord lesion do to DCML sensation?

Loss of fine touch, vibration, and proprioception on the LEFT below the lesion.

What does a left-sided spinal cord lesion do to anterolateral sensation?

Loss of pain, temperature, and crude touch on the RIGHT below the lesion.

What does damage to the right somatosensory strip cause?

Loss/impaired sensation on the LEFT side of the body.

What does damage to the left somatosensory strip cause?

Loss/impaired sensation on the RIGHT side of the body.

What does bilateral somatosensory strip damage cause?

Impaired sensation on BOTH sides of the body.

What does damage to the right Ventral Posterolateral Nucleus thalamus cause?

Impaired body sensation on the LEFT.

What does damage to the left VPL thalamus cause?

Impaired body sensation on the RIGHT.

What does bilateral VPL thalamic damage cause?

Impaired body sensation on BOTH sides.

What can right brainstem damage do to body sensation?

Often affects LEFT body sensation above the sensory crossing; exact pattern depends on tract and level.

What can left brainstem damage do to body sensation?

Often affects RIGHT body sensation above the sensory crossing; exact pattern depends on tract and level.

What can bilateral brainstem sensory pathway damage cause?

Sensory impairment on BOTH sides; patterns depend on location and tracts.

What does complete spinal cord transection cause?

Loss of sensation below the level of injury on both sides.

Where is sensation from below the neck represented in cortex?

Contralateral primary somatosensory cortex (postcentral gyrus), organized as a sensory homunculus.

What does primary somatosensory cortex process?

Conscious perception and basic localization of body sensation.

What does somatosensory association cortex process?

Interprets sensation and integrates it with other senses and previous experiences.

What is unconscious proprioception?

Body position/movement information sent to cerebellum without conscious awareness.

How many neurons are in spinocerebellar pathways?

Two-neuron organization.

Where do spinocerebellar pathways send information?

To the ipsilateral cerebellum for movement coordination.

Does spinocerebellar information reach consciousness?

No; it goes to the cerebellum rather than primary somatosensory cortex.

What does the posterior spinocerebellar pathway do?

Carries unconscious proprioceptive feedback, mainly from lower trunk/leg, ipsilaterally to cerebellum.

What does the anterior spinocerebellar pathway do?

Carries integrated spinal movement/proprioceptive activity; many fibers cross twice before cerebellum.

What is the main difference between anterior and posterior spinocerebellar tracts?

Anterior often crosses twice; posterior ascends ipsilaterally without crossing.

What does the cuneocerebellar pathway carry?

Unconscious proprioceptive information from the upper limb/neck to ipsilateral cerebellum.

What is finger agnosia?

Difficulty identifying, naming, or locating fingers.

What is autotopagnosia?

Inability to identify body parts on oneself, others, or pictures.

What is right-left confusion?

Difficulty distinguishing right from left.

What is Gerstmann syndrome?

Finger agnosia, right-left confusion, acalculia, and agraphia; often left parietal damage.

What is graphesthesia?

Recognizing letters or shapes traced on skin using touch alone.

What is the cornea?

Transparent front surface that helps focus incoming light.

What is the pupil?

Opening through which light enters the eye.

What does the iris do?

Changes pupil size to control the amount of entering light.

What does the lens do?

Focuses light on the retina; produces an inverted, left-right-reversed retinal image.

What is the retina?

Light-sensitive neural layer containing photoreceptors and other retinal cells.

What do rods do?

Detect dim light; important for night and peripheral vision, not color.