Aging affects contrast response functions and adaptation of middle temporal visual area neurons in rhesus monkeys

Investigation of the segregated visual system

“…Similarly, recently it was showed that decreased discrimination capability is related to decreased grey matter volume by aging (Carp et al, 2010). Assumptions state that perceptual impairments in ageing are due to functional rather than morphological changes, which affect the communication between neurons (Hua et al, 2006;Leventhal et al, 2003;Mendelson and Wells, 2002;Schmolesky et al, 2000;Wang et al, 2006;Yang et al, 2008). Unfortunately our findings do not allow an identification of the mechanisms mentioned above; we have merely demonstrated a phenomenon that has previously not been described.…”

“…A number of papers have addressed the connection between aging and the decline of visual functions (Liang et al, 2010;Schmolesky et al, 2000;Spear, 1993;Wang et al, 2006;Wang, 2001;Yang et al, 2008;Yang et al, 2009a;Yu et al, 2006), but we are not aware of any electrophysiological report concerning the effects of aging on the neuronal activity underlying object and shape vision in a high-level visual area such as the monkey inferotemporal cortex (IT).…”

Development of large-scale functional networks over the lifespan

“…Animal studies on gamma aminobutyric acid (GABA), which is the most important inhibitory neurotransmitter of the brain, have consistently shown an age-related decrease of GABA effectiveness in the auditory pathways (Caspary et al, 1995(Caspary et al, , 1999Ling et al, 2005;Walton et al, 1998Walton et al, , 2002. Similar findings exist for the visual system which also show a decrease of GABA functioning (Liang et al, 2010;Yang et al, 2008). Intracortical inhibition in humans has been studied with short-interval pairedpulse protocols over the motor cortex where the first stimulus is given on subthreshold level and suppresses the motor evoked potential following the second stimulus which is given on a suprathreshold level.…”

Visual neuroscience research in China

“…Through international collaborations, Zhou and his colleagues at the University of Science and Technology of China (USTC) have carried out extracellular single unit studies on the RF properties of V1, V2 and MT cells in young and old animals, including monkeys, cats and rats. Their results have shown significant age-related degradation of neural function in cortical areas, which may underlie the declines in visual function that accompany normal aging [65][66][67][68]. Zhou and colleagues also found that V2 cells in older animals exhibited decreased orientation and direction selectivity, increased visually driven and spontaneous activities and decreased signal to noise ratio [66].…”