The Neuropharmacological Basis of Attention in Rhesus Macaques

by Stella Mayer
Doctoral thesis
Date of Examination:2024-11-13
Date of issue:2025-03-07
Advisor:Prof. Dr. Stefan Treue
Referee:Prof. Dr. Stefan Treue
Referee:Prof. Dr. Ralf Heinrich
Persistent Address: http://dx.doi.org/10.53846/goediss-11118

 

 

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Abstract

English

This thesis aimed at unraveling the neuropharmacological basis of attention in rhesus macaques, focusing on the involvement of different neurotransmitter systems. Attention, as a selective filtering process, is crucial for processing relevant sensory information while ignoring irrelevant inputs. Despite the critical role neurotransmitters are known to play in modulating neuronal activity, the exact mechanisms by which they influence attentional processes—particularly in primate brains—remain poorly understood. To address this gap, I employed two complementary approaches: in-vivo brain microdialysis to compare several neurotransmitter concentrations across attentional states in area MT of an awake, behaving rhesus macaque, and immunohistochemistry to map the distribution and density of adrenergic receptors across different visual cortical areas (V1, MT, dlPFC), known to be involved in attentional processes. The novel microdialysis technique allowed for the simultaneous measurement of multiple neurotransmitters, revealing that choline, GABA, and norepinephrine contribute significantly to attentional modulation in area MT. Additionally, adrenergic receptor mapping demonstrated region-specific distributions, with α2A receptors in area V1 enhancing sensory filtering, β1/β2 receptors in MT facilitating motion processing, and β1/β2 receptors in dlPFC supporting top-down control. These findings offer a multi-level model of attentional modulation, integrating neurotransmitter fluctuations with receptor distributions to refine our understanding of neurochemical influences on visual attention​.
Keywords: Neuropharmacology; Attention; Microdialysis; Immunohistochemistry; Primate Brain; Primary visual cortex; Middle temporal area; Dorsolateral prefrontal cortex; Neurotransmitter
 
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