The Visual System
These particles of electromagnetic energy are the physical stimulus detected by photoreceptors in the retina.
What are photons?
This structure serves as the primary input nucleus of the basal ganglia.
What is the striatum (caudate nucleus and putamen)?
This type of neuron, the sole output of the cerebellar cortex, sends inhibitory projections to the deep cerebellar nuclei.
What are Purkinje cells?
These subfields form the hippocampus proper.
What are CA1, CA2, CA3?
Degeneration of dopaminergic neurons in the substantia nigra pars compacta leads to this disorder.
What is Parkinson's disease?
These cells are the first in the retina to fire action potentials.
What are retinal ganglion cells (RGCs)?
The globus pallidus pars interna and this midbrain structure form the main output nuclei of the basal ganglia.
What is the substantia nigra pars reticulata (SNr)?
These excitatory inputs arise from pontine nuclei, spinal cord, and vestibular nuclei, and synapse onto granule cells in rosette formations.
What are mossy fibers?
This region of the hippocampal formation performs pattern separation and exhibits adult neurogenesis.
What is the dentate gyrus (DG)?
Hyperactivity in cortico-striato-thalamo-cortical loops contributes to the intrusive thoughts and repetitive behaviors characteristic of this condition.
What is obsessive-compulsive disorder?
This small depression in the retina contains the highest density of cones and provides the sharpest visual acuity.
What is the fovea?
Remember! Rodents are non-foveate.
This neurotransmitter from the substantia nigra pars compacta modulates striatal activity.
What is dopamine?
This reflex helps keep images stable on the retina during sustained visual motion.
What is the opto-kinetic reflex (OKR)?
This major input pathway arises from layer II of the entorhinal cortex.
What is the perforant path?
A unilateral lesion of this nucleus disrupts relay of visual information to the primary visual cortex.
What is the lateral geniculate nucleus (LGN)?
Fibers from this half of each retina cross at the optic chiasm.
What are the nasal retinal fibers?
The indirect pathway follows this sequence (starting in the striatum).
What is D2-MSN --> GPe --> STN --> SNr/GPi?
Plasticity at this synapse is a cellular mechanism for motor learning and VOR adaptation.
What are parallel fiber - Purkinje cell synapses?
This transitional cortex bridges the hippocampus (receiving input from CA1 pyramidal neurons) to the neocortex.
What is the subiculum?
Bilateral lesions of this white matter tract cause profound anterograde amnesia.
What is the fornix?
The ventral visual stream, also called the "what" pathway, follows this sequence.
What is V1 --> V2 --> V4?
During stop-signal or Go/No-Go tasks, this basal ganglia pathway is rapidly recruited to cancel a planned movement.
What is the hyperdirect pathway?
Inputs from these fibers give rise to complex spikes.
What are climbing fibers?
These spatially tuned neurons contribute to the formation of a cognitive map of the environment. (Name at least two).
What are place cells, grid cells, and head-direction cells?
Disinhibition of the thalamaus due to infarct of the subthalamic nucleus produces this violent flinging movement of the limbs.
What is hemiballismus?