What does Systems Neuroscience study?
Circuits/networks of neurons with specific functions
Pyramidal neurons are the major output of cortical circuits.
What is the role of VIP+ interneurons in neural circuits?
Inhibit SST+ interneurons (disinhibitory circuit)
This interaction is crucial for regulating neural activity.
Define Rate Code in neural coding.
Action potential frequency codes stimulus strength
Example: cold receptors increase firing as temperature drops.
What is the body baseline temperature?
≈ 34°C
This is the reference point for temperature sensitivity.
What does Synchrony Code refer to?
Information encoded by precision/timing of spikes among neurons
This method of coding emphasizes the timing of neuronal firing.
What are Graded Potentials?
Amplitude of depolarization = strength of sensory signal
More depolarization leads to more neurotransmitter release.
Describe the pathway of sensory information.
Periphery → subcortical → cortex
This pathway outlines how sensory data is processed in the brain.
What is a Receptive Field (RF)?
Region in environment/body that influences a neuron’s activity
Different neurons detect different features within a sensory system.
What are Topographic Maps in sensory systems?
Neighboring neurons encode neighboring spaces
This organization helps in spatial representation of sensory information.
What is the visible spectrum range?
400–700 nm
This range corresponds to the light visible to the human eye.
What occurs during phototransduction?
Light → neural signals in the retina
This process is essential for converting light into a form the brain can understand.
List the five major retinal cell types from light to deep.
- RGC
- Amacrine
- Bipolar
- Horizontal
- Photoreceptors
RGCs are the only output of the retina, while photoreceptors are the only light detectors.
Compare Rods and Cones in terms of sensitivity and acuity.
Rods: High sensitivity, Low acuity
Cones: Low sensitivity, High acuity
This comparison highlights their different roles in vision.
What is the function of the fovea?
Highest acuity, color vision
Light hits photoreceptors directly here, minimizing distortion.
What happens to photoreceptors in the dark?
Depolarized
In contrast, they are hyperpolarized by light.
Describe the ON vs. OFF center mechanisms in retinal ganglion cells.
ON-center: Light in center → depolarization → ↑ spikes
OFF-center: Light in center → hyperpolarization → ↓ spikes
Horizontal cells provide surround inhibition via GABA.
True or false: Visual perception depends on absolute brightness.
FALSE
Visual perception depends on contrast, not absolute brightness.
What occurs at the optic chiasm?
Nasal retina axons cross; temporal do not
This crossing is crucial for visual field processing.
What does the Superior Colliculus do?
Integrates RGC input from both eyes for same visual object
It controls fast orienting reflexes but is not involved in conscious vision.
What is the function of the Suprachiasmatic Nucleus (SCN)?
Maintains circadian rhythm (~24 hr biological cycle)
It receives input from intrinsically photosensitive RGCs.
What are the layers of the Lateral Geniculate Nucleus (LGN)?
- 1–2: Magnocellular (M-type input)
- 3–6: Parvocellular (P-type input)
- Koniocellular layers in between
Each layer receives input from one eye only.
What is represented by V1 neurons?
~50% represent the fovea
V1 subdivides the visual field into many small regions.
What are the components of V1 Functional Modules (Hypercolumns)?
- Orientation Columns
- Ocular Dominance Columns
- Blobs
Each hypercolumn contains specific structures for processing visual information.
What does the Dorsal Stream process?
Motion & direction
It is associated with the ‘Where/How’ aspect of visual processing.
