Midterm

• Meissner corpuscles are rapidly adapting
• Slow adapting somatosensory receptors:

  1. Ruffini's corpuscles
  2. Merkel's Disks
• Fast adapting somatosensory receptors:

  1. Meissner corpuscles
  2. Pacinian corpuscles
• Pain fibers enter the spinal cord via the dorsal horn
• touch fibers enter the spinal cord via the dorsal column nucleus after synapsing with the dorsal root ganglion cells
• Only smaller receptive fields can resolve texture patterns
• A complete lesion to the doral column nuclei on the left side of the body will result in a deficit to detect touch stimuli on the left side of the body
• The membrane potential of a bipolar cell with metabotropic glutamate receptor will depolarize in response to glutamate
• The membrane potential of a bipolar cell with ionotropic glutamate receptors will hyperpolarize in response to glutamate
• A visual stimulus in the right visual field will be detected by photoreceptors located in the medial retina of the right eye; retinal ganglion cells located in this side of the retina send their axons to the LGN located in the left side of the brain
• The outer plexiform layer of the retina contains processes of bipolar, photoreceptor and horizontal cells.
• Cortical layer 4 has the highest percentage of neurons with ocular dominance values of 1 and 7
• While neurons in cortical layers 2/3 are the major source of intracortical input to layer 5, they also provide horizontal input to layers 2/3
• Divergence in neuronal circuits refers to communication of one neuron to multiple targets
• Convergence in neuronal circuits refers to communication of multiple neurons to one target
• Serial processing in neuronal circuits refers to neuron C inheriting the response profile from neuron A.
• In reverberation activity in a neuron persists long after stimulus is gone
• In sensory systems, decreasing divergence increases acuity
• Hypothalamus is the site of neural integration of signals from the internal environment, external environment, and cognitive state.
• Systemic input: refer to state of body
• Processive input: refer to higher order cognitve processing
• Circadian Rhythm is the systematic flucuation of a given physiological variable that occurs with a fixed period
• The lead oscillator is an endogenous generator
• The lead oscillator is the suprachiasmatic nucleus.
• Touch Pathway:

  1. DRG neuron
  2. dorsal column nucleus
  3. cross over
  4. medial lemnuiscus
  5. VPN
  6. internal capsule
  7. somatosensory cortex
• Pain Pathway:

  1. DRG neuron
  2. dorsal horn of spinal cord
  3. cross over
  4. spinalthalamic tract
  5. VPN
  6. internal capsule
  7. somatosensory cortex
• The lateral VPN is input from below the neck
• The medial VPN is input from above the neck
• Under scotopic conditions, only rods contribute to vision
• Under mesopic conditions, both rods and cones contribute to vision
• Under photopic conditions, only cones contribute to vision.
• Photoreceptors transmit information by graded potentials
• The five major cell types of the retina:

  1. photoreceptors
  2. bipolar cells
  3. amacrine cells
  4. horizontal cells
  5. retinal ganglion cells
• The five layers of the retina:

  1. Outer nuclear layer
  2. Outer plexiform layer
  3. Inner nuclear layer
  4. Inner plexiform layer
  5. Ganglion cell layer
• The outer nuclear layer contains photoreceptor cell bodies
• The inner nuclear layer contains horizontal, bipolar, and amacrine cell bodies
• The inner plexiform layer contains amacrine, bipolar and ganglion cell processes
• The ganglion layer contains ganglion cell bodies
• Generally, feedforward pathways are driving pathways while feedback pathways are considered modulating pathways
• All projections leaving the cortex are glutamatergic