Higher visual responses in the temporal cortex of mice.

Area of Science:

• Neuroscience
• Visual System Research
• Mammalian Visual Processing

Background:

• The mammalian visual system, particularly the visual cortex, serves as a key model for research.
• Higher visual areas in primates are divided into dorsal ('where') and ventral ('what') streams.
• The precise organization and function of the mouse ventral stream remain incompletely understood, despite its potential parallels with primate systems.

Purpose of the Study:

• To investigate visual responses within the mouse temporal cortex.
• To elucidate the extent and characteristics of the mouse ventral visual stream.
• To compare visual processing in temporal cortical areas with the primary visual area (V1).

Main Methods:

• Wide-field calcium (Ca2+) imaging was employed in awake mice.
• Visual stimuli, including moving objects of varying sizes, were presented.
• Visual responses in the postrhinal cortex (POR) and ectorhinal and temporal association cortices (ECT) were analyzed.

Main Results:

• The postrhinal cortex (POR) and ectorhinal and temporal association cortices (ECT) exhibited clear visual responses to moving objects.
• Retinotopic maps were not clearly discernible in the POR and ECT.
• Visual responses in the POR and ECT showed reduced sensitivity to object size compared to V1, with differential subarea activation in the ECT based on object size.

Conclusions:

• The mouse ventral visual stream likely extends to the ectorhinal and temporal association cortices (ECT), located ventral to the auditory cortex (AC).
• These identified areas possess distinct response properties that differ significantly from those observed in the primary visual area (V1).
• This study advances our understanding of the organization and functional specialization of the mouse visual cortex.