One of the following molecules should play an active role in transcriptional upregulation of memory genes in the CNS. Identify that molecule. a. CRED b. bad c. bax d. HDAC c. Lingo

Before we can identify which molecule is involved in the transcriptional upregulation of memory genes in the CNS, let's first understand the function of each molecule: a. CREB (cAMP response element-binding protein) - This is a cellular transcription factor that binds to specific DNA sequences called cAMP response elements (CREs), thereby increasing or decreasing the transcription of certain genes. It is known to be involved in the regulation of memory formation and synaptic plasticity in the brain. b. bad (Bcl-2-associated death promoter) - This is a pro-apoptotic protein involved in promoting cell death. c. bax (Bcl-2-associated X protein) - Another pro-apoptotic protein that promotes cell death. d. HDAC (Histone Deacetylase) - This is an enzyme involved in epigenetic gene regulation by removing acetyl groups from histones, thereby altering chromatin structure and affecting gene expression. It has been implicated in several neurological disorders. e. Lingo (Leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein) - This is a protein involved in the inhibition of axonal growth and regeneration in the CNS.

From the functions of the molecules listed above, it is evident that only CREB (cAMP response element-binding protein) plays a role in memory formation and synaptic plasticity in the brain by binding to specific DNA sequences and regulating the transcription of certain genes. Therefore, the correct answer is: a. CREB