Table 1.
microbiome treatment | cognition/behaviour assay method | cognitive/behaviour assay result | neurological/physiology assays results | reference |
---|---|---|---|---|
germ free (GF), recolonized (ex-GF) and conventionally colonized (CC) | choice of empty versus social chamber interactions with novel versus familiar mice food-preference test following demonstrator observation |
chamber sociability: GF < CC = ex-GF social recognition: GF and ex-GF < CC social observation of demonstrator: GF < CC = ex-GF social information transfer: GF = ex-GF = CC |
— | [18] |
GF, ex-GF and CC | cued fear conditioning (tone + shock in experimental context (i.e. box)) | acquisition: GF = ex-GF = CC cue recall: GF < ex-GF = CC context recall: GF = CC = ex-GF extinction: GF < CC; ex-GF < CC |
genome-wide RNA sequencing of amygdala shows altered gene expressions | [19] |
GF, CC, CC-pathogen infected (CC-in), CC-in with probiotics (CC-in-pro) | light–dark box novel object recognition T-maze tests performed following exposure to acute stress (AS) or no stress (NS) |
anxiety: CC-in = CC; GF = CC recognition and working memory (NS): CC-in = CC; GF < CC recognition and working memory (AS): CC-in < CC; GF < CC object and working memory (NS): CC-in-pro = CC-in object and working memory (AS): CC-in-pro > CC-in |
differences in corticosterone and hippocampal BDNF and c-Fos | [10] |
anxious mouse strains fed different Bifidobacteria probiotics: B. longum and B. breve | object recognition task Barnes maze cued fear conditioning |
recognition memory: B. longum and B. breve > control mice spatial learning: B. longum = control = B. breve spatial memory: B. longum > control; B. breve = control fear conditioning learning and memory to context: B. longum and B. breve = control fear conditioning memory to cue and extinction: B. longum = control = B. breve |
no difference in basal corticosterone across treatment groups | [20] |
microbiome manipulation through restricted diets: high fat (hf), high sugar (hs), normal chow (nc) | step-down latency and open field test novel object recognition/location Morris water maze |
anxiety and recognition memory: hf = hs = nc long-term spatial memory: hs < hf = nc reverse learning: hs = hf < nc |
— | [21] |
beef (b) versus normal chow (nc) diet | novel apparatus neophobia hole-board box |
anxiety: b < nc working memory: b > nc spatial memory: b > nc |
— | [9] |
high fat transplanted microbiome (hft), normal chow transplanted microbiome (nct) | elevated plus and open field assays cued fear conditioning |
anxiety: hft > nct cue acquisition, memory and extinction: hft < nct context memory: hft = nct |
differences in protein expression in brain (e.g. BDNF) | [7] |
CC, antibiotic-treated (Abx), + exercise (exc), + probiotics (pro), + CC faecal transplant (ft) | novel object recognition | short-term memory: no difference across groups long-term memory: Abx and Abx-ft < CC Abx-exc and Abx-pro = CC CC-exc and CC-pro = CC |
differences in neurogenesis across treatment groups | [22] |
CC, antibiotic-treated (Abx) | object recognition task Barnes maze |
recognition memory: Abx < CC spatial learning and memory: Abx = CC |
differences in protein and receptor expression in hippocampus, amygdala and hypothalamus | [23] |
OTUs from gut microbiome | open field assay and light/dark box cued fear conditioning |
bacterial OTUs identified as either positively or negatively associated with anxiety and context memory | — | [24] |
natural variation in microbiome age 1 (quantified as clusters of microbial taxa and diversity indexes) | Mullen Scales of Early Learning at age 1 and age 2 | higher scores associated with high levels of Bacteroides rather than high levels of faecalibacterium. High microbiome diversity associated with poor scores on visual reception, expressive and receptive language skills at age 2 | higher microbiome diversity associated with larger left precentral gyrus, left amygdala and right angular gyrus at age 2 | [16] |
biopsied colon microbiome from patients with cirrhosis of the liver | psychometric test batteries for psychomotor speed, vasomotor coordination, attention, set shifting and inhibitory control | bacterial OTUs identified as either positively or negatively associated with cognitive performance across cognitive tests | bacterial OTUs identified as either positively or negatively associated with liver inflammation | [17] |