Which of the following statements about the retina’s operationacross different levels of ambient light is mostaccurate?

1. On-center retinal ganglion cells (RGCs) respond to a small spotof light in the center of its receptive field over an extremelysmall range of ambient intensities.
2. Off-center RGCs respond to a small spot of light in the centerof its receptive field over a broad range of ambientintensities.
3. RGCs generally do not report absolute ambient lightintensities, but rather encode relative intensity differencesbetween its receptive field center and surround.
4. Interactions within the outer plexiform layer do not play animportant role in modulating the photic sensitivity of ganglioncells.
5. Back-propagating action potentials from RGC targets in theventral posterolateral thalamic nuclei alter lightsensitivity.

A student with intractable epilepsy had their corpus callosumsurgically severed in an effort to limit the spread of theseizures.  This procedure resulted in a disruptionof…

1. Axons arising from glutamatergic neurons in Layer 2/3 of thecortex that project to the thalamus and are born first duringembryonic cortical neurogenesis.
2. Axons arising from dopaminergic neurons in Layer 5 of thecortex that project to the striatum and are born during the middleof the period of embryonic cortical neurogenesis.
3. Axons arising from glutamatergic neurons in Layer 2/3 of thecortex that project to other regions of the cortex and are bornlast during embryonic cortical neurogenesis.
4. Axons arising from glutamatergic neurons in Layer 5 of thecortex that are born first during embryonic corticalneurogenesis.
5. None of the above

A colleague has made a new mouse model that exhibits selectivelyloss of Vglut2 (a protein involved in loading glutamate intovesicles) in neurons of the subthalamic nucleus. This results in areduction in indirect pathway glutamatergic output from the basalganglia. The mouse most likely exhibits... a. Inability to initiatemovements b. Hyperlocomotion c. Enhanced visual responsiveness d.Loss of auditory function

During your shift as an emergency room physician, you admit apatient who fell 30 feet while rock climbing onto rocky terrain.Upon examination, the patient has reduced voluntary motor controlof his right leg, a loss of pain and temperature sensation in hisleft side from the hip down, and a loss of fine touch andproprioception in his right side from the hip down. What is thelikely location of his spinal cord lesion?

1. A complete spinal cord lesion at L1
2. A partial lesion localized to the left side of the spinal cordsix segments rostral to T7
3. A partial lesion localized to the right side of the spinal cordsix segments caudal to T7
4. A complete spinal cord lesion three segments caudal to C8
5. A partial lesion localized to the right side of the spinal cordthree segments rostral to S5