Caffeine and human cerebral blood flow: A positron emission tomography study

Abstract

A dissociation between human neural systems that participate in the encoding and later recognition of new memories for faces was demonstrated by measuring memory task-related changes in regional cerebral blood flow with positron emission tomography. There was almost no overlap between the brain structures associated with these memory functions. A region in the right hippocampus and adjacent cortex was activated during memory encoding but not during recognition. The most striking finding in neocortex was the lateralization of prefrontal participation. Encoding activated left prefrontal cortex, whereas recognition activated right prefrontal cortex. These results indicate that the hip-pocampus and adjacent cortex participate in memory function primarily at the time of new memory encoding. Moreover, face recognition is not mediated simply by recapitulation of operations performed at the time of encoding but, rather, involves anatomically dissociable operations. In humans and nonhuman primates, damage to the hippocam-pus and adjacent cortex produces a profound anterograde amnesic syndrome that impairs the ability to form and store new explicit memories (1-5). Although recall for previously stored information can remain largely intact (1, 4, 6), the retrieval of recently formed memories may be impaired (3). Thus, for a limited time after initial storage, access to memories does depend on the integrity of the medial temporal structures, suggesting that these structures may actively participate not only in memory storage but also in the retrieval of recently stored memories. Despite this clear evidence of memory impairment after medial temporal lesions, functional brain imaging studies of human memory have been mostly unsuccessful in demonstrating the participation of the hippocampus and adjacent cortex in either the encoding or the retrieval of new long-term memories (7-12). These same studies, however, consistently demonstrate that the frontal lobes participate in episodic memory encoding and retrieval, although studies of the effects of frontal lobe lesions suggest these areas do not play a critical role in episodic memory processing (13-18). Most previous functional brain imaging studies of memory have used verbal materials and have demonstrated a functional dissociation between left and right prefrontal areas. Whereas left prefron-tal areas are activated during episodic verbal memory encoding , right prefrontal areas are activated during retrieval. Although some studies suggest that right prefrontal areas might also be involved in the retrieval of nonverbal long-term memories, no studies of nonverbal memory encoding have been reported. To clarify the roles played by these brain structures in episodic memory, we investigated memory for a different type The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. of information-namely faces-using an experimental design t...

Caffeine-induced uncoupling of cerebral blood flow and oxygen metabolism: A calibrated BOLD fMRI study

“…A robust CBF decrease of 35% in response to caffeine consumption was observed, in good agreement with previous work Cameron et al, 1990;Field et al, 2003;Liu et al, 2004). However, we measured an accompanying decrease in the BOLD signal which, when analyzed in the context of a mathematical model of the BOLD effect (Davis et al, 1998), suggests that the CBF decrease is not accompanied by a change in CMRO 2 .…”

“…Its main action is to bind to adenosine receptors and block the actions of agonists at these receptors (Fredholm et al, 1999), causing vasoconstriction. The resulting decrease in baseline CBF has been demonstrated using various measurement techniques in humans Bendlin et al, 2006;Cameron et al, 1990;Field et al, 2003;Liu et al, 2004;Mathew and Wilson, 1985). In addition, fMRI has previously been used to study the effects of caffeine on the amplitude (Bendlin et al, 2006;Laurienti et al, 2002Laurienti et al, , 2003Mulderink et al, 2002) and temporal dynamics Liu et al, 2004) of the BOLD response, typically detecting a speeding up of the BOLD response that is compatible with a model for the vasculature in which vasoconstrictive agents cause the arterioles to become more responsive to stimulation (Behzadi and Liu, 2005).…”

Acute caffeine administration impact on working memory-related brain activation and functional connectivity in the elderly: A BOLD and perfusion MRI study

“…As in younger cohorts, caffeine induced a global reduction of baseline perfusion in the range of 20% (Cameron et al, 1990;Mulderink et al, 2002;Vidyasagar et al, 2013). This effect is specific to caffeine, as for example the same effect was found for caffeine-containing tea, while decaffeinated tea did not reduce cerebral perfusion (Vidyasagar et al, 2013).…”

The Effect of Black Tea and Caffeine on Regional Cerebral Blood Flow Measured with Arterial Spin Labeling

“…Caffeine shows a widespread reduction in CBF, that is exaggerated in key regions ( Figure 2; Table 2). A reduction in CBF due to caffeine is well documented in past magnetic resonance and positron emission tomography studies, 27,28 however, to our knowledge the regional specificity of these changes has not previously been reported. The CBF was reduced in widespread regions spanning primarily subcortical gray matter (thalamus, basal ganglia, hippocampus, and posterior cingulum) and isolated frontal, parietal, and occipital regions.…”