PhD Scientific Days 2022

Neurosciences I. (Poster discussion will take place in the Aula during the Coffee Break)

Age-dependent Role of Midline Thalamus in Learning

Text of the abstract

Arousal–dependent cognitive functions like memory processes, sleep-wake cycles and stress management are showing age dependency which is well-documented. The thalamo-frontal network also goes through age-related changes, which could be responsible for these behavioral alterations. However, the underlying neuronal mechanism is poorly understood. Previously, the calretinin (CR)-expressing thalamocortical cells in the midline thalamus (MT) were identified as an important neuronal element for cortical arousal. Furthermore, from MT cells were also proved to modulate associative learning. Here we aimed to clarify the age-dependent role of the CR+MT neurons in fear learning processes. First, we found that the bi-directionally control of CR+MT activity differently altered associative fear learning in young (<6 months old) and aged (>18 months old) mice. MT (most probably the CR+ cell population) provides most of the thalamic brain derived neurotrophic factor (BDNF) for the cortex, which is a key factor in many cognitive functions. Furthermore, the BDNF level in the brain shows age-dependent alteration; thus, we measured the control and the fear conditioning evoked thalamic BDNF levels in young (~5-6 months) and aged mice (~18-24 months). We found that the evoked BDNF levels were shown age -dependency. Notably, both isoform of BDNF (the mature- and the pro-BDNF) levels also increased in the thalamo-frontal circuit of the young but not the old mice.
Taken together, our preliminary research proposes that the dorsal midline thalamic BDNF can be a key regulator for age-dependent changes in learning and in other arousal-related behavior. Currently, we are investigating the age-dependent effect of MT-selective BDNF deletion in various cognitive functions on young (~6 months) and aged (~12 months) mice.

This work was supported by the NAP Program (KTIA-NAP-13-2-2015-0010; 2017-1.2.1-NKP-2017-00002); by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund (FM, FK124434, KKP126998; BS, FK135285); by the Cooperative Doctoral Program (AM, KDP-2020-1015461), by the New National Excellence Program of the Ministry for Innovation and Technology (ÚNKP-19-4-ÁTE-8; ÚNKP-20-5-ÁTE-3). FM is a János Bolyai Research Fellow.